// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at https://mozilla.org/MPL/2.0/.

//! Functionality related to certificates.

use {
    crate::{apple_certificates::KnownCertificate, error::AppleCodesignError},
    bcder::{
        encode::{PrimitiveContent, Values},
        ConstOid, Oid,
    },
    bytes::Bytes,
    pkcs8::EncodePrivateKey,
    std::{
        fmt::{Display, Formatter},
        str::FromStr,
    },
    x509_certificate::{
        certificate::KeyUsage, rfc4519::OID_COUNTRY_NAME, CapturedX509Certificate,
        InMemorySigningKeyPair, KeyAlgorithm, X509CertificateBuilder,
    },
};

/// Extended Key Usage extension.
///
/// 2.5.29.37
const OID_EXTENDED_KEY_USAGE: ConstOid = Oid(&[85, 29, 37]);

/// Extended Key Usage purpose for code signing.
///
/// 1.3.6.1.5.5.7.3.3
const OID_EKU_PURPOSE_CODE_SIGNING: ConstOid = Oid(&[43, 6, 1, 5, 5, 7, 3, 3]);

/// Extended Key Usage for purpose of `Safari Developer`.
///
/// 1.2.840.113635.100.4.8
const OID_EKU_PURPOSE_SAFARI_DEVELOPER: ConstOid = Oid(&[42, 134, 72, 134, 247, 99, 100, 4, 8]);

/// Extended Key Usage for purpose of `3rd Party Mac Developer Installer`.
///
/// 1.2.840.113635.100.4.9
const OID_EKU_PURPOSE_3RD_PARTY_MAC_DEVELOPER_INSTALLER: ConstOid =
    Oid(&[42, 134, 72, 134, 247, 99, 100, 4, 9]);

/// Extended Key Usage for purpose of `Developer ID Installer`.
///
/// 1.2.840.113635.100.4.13
const OID_EKU_PURPOSE_DEVELOPER_ID_INSTALLER: ConstOid =
    Oid(&[42, 134, 72, 134, 247, 99, 100, 4, 13]);

/// All OIDs known for extended key usage.
const ALL_OID_EKUS: &[&ConstOid; 4] = &[
    &OID_EKU_PURPOSE_CODE_SIGNING,
    &OID_EKU_PURPOSE_SAFARI_DEVELOPER,
    &OID_EKU_PURPOSE_3RD_PARTY_MAC_DEVELOPER_INSTALLER,
    &OID_EKU_PURPOSE_DEVELOPER_ID_INSTALLER,
];

/// Extension for `Apple Signing`.
///
/// 1.2.840.113635.100.6.1.1
const OID_EXTENSION_APPLE_SIGNING: ConstOid = Oid(&[42, 134, 72, 134, 247, 99, 100, 6, 1, 1]);

/// Extension for `iPhone Developer`.
///
/// 1.2.840.113635.100.6.1.2
const OID_EXTENSION_IPHONE_DEVELOPER: ConstOid = Oid(&[42, 134, 72, 134, 247, 99, 100, 6, 1, 2]);

/// Extension for `Apple iPhone OS Application Signing`
///
/// 1.2.840.113635.100.6.1.3
const OID_EXTENSION_IPHONE_OS_APPLICATION_SIGNING: ConstOid =
    Oid(&[42, 134, 72, 134, 247, 99, 100, 6, 1, 3]);

/// Extension for `Apple Developer Certificate (Submission)`.
///
/// May also be referred to as `iPhone Distribution`.
///
/// 1.2.840.113635.100.6.1.4
const OID_EXTENSION_APPLE_DEVELOPER_CERTIFICATE_SUBMISSION: ConstOid =
    Oid(&[42, 134, 72, 134, 247, 99, 100, 6, 1, 4]);

/// Extension for `Safari Developer`.
///
/// 1.2.840.113635.100.6.1.5
const OID_EXTENSION_SAFARI_DEVELOPER: ConstOid = Oid(&[42, 134, 72, 134, 247, 99, 100, 6, 1, 5]);

/// Extension for `Apple iPhone OS VPN Signing`
///
/// 1.2.840.113635.100.6.1.6
const OID_EXTENSION_IPHONE_OS_VPN_SIGNING: ConstOid =
    Oid(&[42, 134, 72, 134, 247, 99, 100, 6, 1, 6]);

/// Extension for `Apple Mac App Signing (Development)`.
///
/// May also appear as `3rd Party Mac Developer Application`.
///
/// 1.2.840.113635.100.6.1.7
const OID_EXTENSION_APPLE_MAC_APP_SIGNING_DEVELOPMENT: ConstOid =
    Oid(&[42, 134, 72, 134, 247, 99, 100, 6, 1, 7]);

/// Extension for `Apple Mac App Signing Submission`.
///
/// 1.2.840.113635.100.6.1.8
const OID_EXTENSION_APPLE_MAC_APP_SIGNING_SUBMISSION: ConstOid =
    Oid(&[42, 134, 72, 134, 247, 99, 100, 6, 1, 8]);

/// Extension for `Mac App Store Code Signing`.
///
/// 1.2.840.113635.100.6.1.9
const OID_EXTENSION_APPLE_MAC_APP_STORE_CODE_SIGNING: ConstOid =
    Oid(&[42, 134, 72, 134, 247, 99, 100, 6, 1, 9]);

/// Extension for `Mac App Store Installer Signing`.
///
/// 1.2.840.113635.100.6.1.10
const OID_EXTENSION_APPLE_MAC_APP_STORE_INSTALLER_SIGNING: ConstOid =
    Oid(&[42, 134, 72, 134, 247, 99, 100, 6, 1, 10]);

// 1.2.840.113635.100.6.1.11 is unknown.

/// Extension for `Mac Developer`.
///
/// 1.2.840.113635.100.6.1.12
const OID_EXTENSION_MAC_DEVELOPER: ConstOid = Oid(&[42, 134, 72, 134, 247, 99, 100, 6, 1, 12]);

/// Extension for `Developer ID Application`.
///
/// 1.2.840.113635.100.6.1.13
const OID_EXTENSION_DEVELOPER_ID_APPLICATION: ConstOid =
    Oid(&[42, 134, 72, 134, 247, 99, 100, 6, 1, 13]);

/// Extension for `Developer ID Installer`.
///
/// 1.2.840.113635.100.6.1.14
const OID_EXTENSION_DEVELOPER_ID_INSTALLER: ConstOid =
    Oid(&[42, 134, 72, 134, 247, 99, 100, 6, 1, 14]);

// 1.2.840.113635.100.6.1.15 looks to have something to do with core OS functionality,
// as it appears in search results for hacking Apple OS booting.

/// Extension for `Apple Pay Passbook Signing`
///
/// 1.2.840.113635.100.6.1.16
const OID_EXTENSION_PASSBOOK_SIGNING: ConstOid = Oid(&[42, 134, 72, 134, 247, 99, 100, 6, 1, 16]);

/// Extension for `Web Site Push Notifications Signing`
///
/// 1.2.840.113635.100.6.1.17
const OID_EXTENSION_WEBSITE_PUSH_NOTIFICATION_SIGNING: ConstOid =
    Oid(&[42, 134, 72, 134, 247, 99, 100, 6, 1, 17]);

/// Extension for `Developer ID Kernel`.
///
/// 1.2.840.113635.100.6.1.18
const OID_EXTENSION_DEVELOPER_ID_KERNEL: ConstOid =
    Oid(&[42, 134, 72, 134, 247, 99, 100, 6, 1, 18]);

/// Extension for `Developer ID Date`.
///
/// This OID doesn't have a description in Apple tooling. But it
/// holds a UtcDate (with hours, minutes, and seconds all set to 0) and seems to
/// denote a date constraint to apply to validation. This is likely used
/// to validating timestamping constrains for certificate validity.
///
/// 1.2.840.113635.100.6.1.33
const OID_EXTENSION_DEVELOPER_ID_DATE: ConstOid = Oid(&[42, 134, 72, 134, 247, 99, 100, 6, 1, 33]);

/// Extension for `TestFlight`.
///
/// 1.2.840.113635.100.6.1.25.1
const OID_EXTENSION_TEST_FLIGHT: ConstOid = Oid(&[42, 134, 72, 134, 247, 99, 100, 6, 1, 25, 1]);

/// All OIDs associated with non Certificate Authority extensions.
const ALL_OID_NON_CA_EXTENSIONS: &[&ConstOid; 18] = &[
    &OID_EXTENSION_APPLE_SIGNING,
    &OID_EXTENSION_IPHONE_DEVELOPER,
    &OID_EXTENSION_IPHONE_OS_APPLICATION_SIGNING,
    &OID_EXTENSION_APPLE_DEVELOPER_CERTIFICATE_SUBMISSION,
    &OID_EXTENSION_SAFARI_DEVELOPER,
    &OID_EXTENSION_IPHONE_OS_VPN_SIGNING,
    &OID_EXTENSION_APPLE_MAC_APP_SIGNING_DEVELOPMENT,
    &OID_EXTENSION_APPLE_MAC_APP_SIGNING_SUBMISSION,
    &OID_EXTENSION_APPLE_MAC_APP_STORE_CODE_SIGNING,
    &OID_EXTENSION_APPLE_MAC_APP_STORE_INSTALLER_SIGNING,
    &OID_EXTENSION_MAC_DEVELOPER,
    &OID_EXTENSION_DEVELOPER_ID_APPLICATION,
    &OID_EXTENSION_DEVELOPER_ID_INSTALLER,
    &OID_EXTENSION_PASSBOOK_SIGNING,
    &OID_EXTENSION_WEBSITE_PUSH_NOTIFICATION_SIGNING,
    &OID_EXTENSION_DEVELOPER_ID_KERNEL,
    &OID_EXTENSION_DEVELOPER_ID_DATE,
    &OID_EXTENSION_TEST_FLIGHT,
];

/// UserID.
///
/// 0.9.2342.19200300.100.1.1
pub const OID_USER_ID: ConstOid = Oid(&[9, 146, 38, 137, 147, 242, 44, 100, 1, 1]);

/// OID used for email address in RDN in Apple generated code signing certificates.
const OID_EMAIL_ADDRESS: ConstOid = Oid(&[42, 134, 72, 134, 247, 13, 1, 9, 1]);

/// Apple Worldwide Developer Relations.
///
/// 1.2.840.113635.100.6.2.1
const OID_CA_EXTENSION_APPLE_WORLDWIDE_DEVELOPER_RELATIONS: ConstOid =
    Oid(&[42, 134, 72, 134, 247, 99, 100, 6, 2, 1]);

/// Apple Application Integration.
///
/// 1.2.840.113635.100.6.2.3
const OID_CA_EXTENSION_APPLE_APPLICATION_INTEGRATION: ConstOid =
    Oid(&[42, 134, 72, 134, 247, 99, 100, 6, 2, 3]);

/// Developer ID Certification Authority
///
/// 1.2.840.113635.100.6.2.6
const OID_CA_EXTENSION_DEVELOPER_ID: ConstOid = Oid(&[42, 134, 72, 134, 247, 99, 100, 6, 2, 6]);

/// Apple Timestamp.
///
/// 1.2.840.113635.100.6.2.9
const OID_CA_EXTENSION_APPLE_TIMESTAMP: ConstOid = Oid(&[42, 134, 72, 134, 247, 99, 100, 6, 2, 9]);

/// Developer Authentication Certification Authority.
///
/// 1.2.840.113635.100.6.2.11
const OID_CA_EXTENSION_DEVELOPER_AUTHENTICATION: ConstOid =
    Oid(&[42, 134, 72, 134, 247, 99, 100, 6, 2, 11]);

/// Apple Application Integration CA - G3
///
/// 1.2.840.113635.100.6.2.14
const OID_CA_EXTENSION_APPLE_APPLICATION_INTEGRATION_G3: ConstOid =
    Oid(&[42, 134, 72, 134, 247, 99, 100, 6, 2, 14]);

/// Apple Worldwide Developer Relations CA - G2
///
/// 1.2.840.113635.100.6.2.15
const OID_CA_EXTENSION_APPLE_WORLDWIDE_DEVELOPER_RELATIONS_G2: ConstOid =
    Oid(&[42, 134, 72, 134, 247, 99, 100, 6, 2, 15]);

/// Apple Software Update Certification.
///
/// 1.2.840.113635.100.6.2.19
const OID_CA_EXTENSION_APPLE_SOFTWARE_UPDATE_CERTIFICATION: ConstOid =
    Oid(&[42, 134, 72, 134, 247, 99, 100, 6, 2, 19]);

/// Apple Application Integration CA - G1.
///
/// This was introduced in `Apple Application Integration CA 7 - G1`
/// The previous `Apple Application Integration CA 5 - G1` certificate
/// had the legacy 1.2.840.113635.100.6.2.3 extension.
///
/// 1.2.840.113635.100.6.2.31
const OID_CA_EXTENSION_APPLE_APPLICATION_INTEGRATION_G1: ConstOid =
    Oid(&[42, 134, 72, 134, 247, 99, 100, 6, 2, 31]);

const ALL_OID_CA_EXTENSIONS: &[&ConstOid; 9] = &[
    &OID_CA_EXTENSION_APPLE_WORLDWIDE_DEVELOPER_RELATIONS,
    &OID_CA_EXTENSION_APPLE_APPLICATION_INTEGRATION,
    &OID_CA_EXTENSION_DEVELOPER_ID,
    &OID_CA_EXTENSION_APPLE_TIMESTAMP,
    &OID_CA_EXTENSION_DEVELOPER_AUTHENTICATION,
    &OID_CA_EXTENSION_APPLE_APPLICATION_INTEGRATION_G3,
    &OID_CA_EXTENSION_APPLE_WORLDWIDE_DEVELOPER_RELATIONS_G2,
    &OID_CA_EXTENSION_APPLE_SOFTWARE_UPDATE_CERTIFICATION,
    &OID_CA_EXTENSION_APPLE_APPLICATION_INTEGRATION_G1,
];

/// Describes the type of code signing that a certificate is authorized to perform.
///
/// Code signing certificates are issued with extended key usage (EKU) attributes
/// denoting what that certificate will be used for. They basically say *I'm authorized
/// to sign X*.
///
/// This type describes the different code signing key usages defined on Apple
/// platforms.
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub enum ExtendedKeyUsagePurpose {
    /// Code signing.
    CodeSigning,

    /// Safari Developer.
    SafariDeveloper,

    /// 3rd Party Mac Developer Installer Packaging Signing.
    ///
    /// The certificate can be used to sign Mac installer packages.
    ThirdPartyMacDeveloperInstaller,

    /// Developer ID Installer.
    DeveloperIdInstaller,
}

impl ExtendedKeyUsagePurpose {
    /// Obtain all variants of this enumeration.
    pub fn all() -> Vec<Self> {
        vec![
            Self::CodeSigning,
            Self::SafariDeveloper,
            Self::ThirdPartyMacDeveloperInstaller,
            Self::DeveloperIdInstaller,
        ]
    }

    pub fn all_oids() -> &'static [&'static ConstOid] {
        ALL_OID_EKUS
    }

    pub fn as_oid(&self) -> ConstOid {
        match self {
            Self::CodeSigning => OID_EKU_PURPOSE_CODE_SIGNING,
            Self::SafariDeveloper => OID_EKU_PURPOSE_SAFARI_DEVELOPER,
            Self::ThirdPartyMacDeveloperInstaller => {
                OID_EKU_PURPOSE_3RD_PARTY_MAC_DEVELOPER_INSTALLER
            }
            Self::DeveloperIdInstaller => OID_EKU_PURPOSE_DEVELOPER_ID_INSTALLER,
        }
    }
}

impl Display for ExtendedKeyUsagePurpose {
    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
        match self {
            ExtendedKeyUsagePurpose::CodeSigning => f.write_str("Code Signing"),
            ExtendedKeyUsagePurpose::SafariDeveloper => f.write_str("Safari Developer"),
            ExtendedKeyUsagePurpose::ThirdPartyMacDeveloperInstaller => {
                f.write_str("3rd Party Mac Developer Installer Packaging Signing")
            }
            ExtendedKeyUsagePurpose::DeveloperIdInstaller => f.write_str("Developer ID Installer"),
        }
    }
}

impl TryFrom<&Oid> for ExtendedKeyUsagePurpose {
    type Error = AppleCodesignError;

    fn try_from(oid: &Oid) -> Result<Self, Self::Error> {
        // Surely there is a way to use `match`. But the `Oid` type is a bit wonky.
        if oid.as_ref() == OID_EKU_PURPOSE_CODE_SIGNING.as_ref() {
            Ok(Self::CodeSigning)
        } else if oid.as_ref() == OID_EKU_PURPOSE_SAFARI_DEVELOPER.as_ref() {
            Ok(Self::SafariDeveloper)
        } else if oid.as_ref() == OID_EKU_PURPOSE_3RD_PARTY_MAC_DEVELOPER_INSTALLER.as_ref() {
            Ok(Self::ThirdPartyMacDeveloperInstaller)
        } else if oid.as_ref() == OID_EKU_PURPOSE_DEVELOPER_ID_INSTALLER.as_ref() {
            Ok(Self::DeveloperIdInstaller)
        } else {
            Err(AppleCodesignError::OidIsntCertificateAuthority)
        }
    }
}

/// Describes one of the many X.509 certificate extensions found on Apple code signing certificates.
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub enum CodeSigningCertificateExtension {
    /// Apple Signing.
    ///
    /// (Appears to be deprecated).
    AppleSigning,

    /// iPhone Developer.
    IPhoneDeveloper,

    /// Apple iPhone OS Application Signing.
    IPhoneOsApplicationSigning,

    /// Apple Developer Certificate (Submission).
    ///
    /// May also be referred to as `iPhone Distribution`.
    AppleDeveloperCertificateSubmission,

    /// Safari Developer.
    SafariDeveloper,

    /// Apple iPhone OS VPN Signing.
    IPhoneOsVpnSigning,

    /// Apple Mac App Signing (Development).
    ///
    /// Also known as `3rd Party Mac Developer Application`.
    AppleMacAppSigningDevelopment,

    /// Apple Mac App Signing Submission.
    AppleMacAppSigningSubmission,

    /// Mac App Store Code Signing.
    AppleMacAppStoreCodeSigning,

    /// Mac App Store Installer Signing.
    AppleMacAppStoreInstallerSigning,

    /// Mac Developer.
    MacDeveloper,

    /// Developer ID Application.
    DeveloperIdApplication,

    /// Developer ID Date.
    DeveloperIdDate,

    /// Developer ID Installer.
    DeveloperIdInstaller,

    /// Apple Pay Passbook Signing.
    ApplePayPassbookSigning,

    /// Web Site Push Notifications Signing.
    WebsitePushNotificationSigning,

    /// Developer ID Kernel.
    DeveloperIdKernel,

    /// TestFlight.
    TestFlight,
}

impl CodeSigningCertificateExtension {
    /// Obtain all variants of this enumeration.
    pub fn all() -> Vec<Self> {
        vec![
            Self::AppleSigning,
            Self::IPhoneDeveloper,
            Self::IPhoneOsApplicationSigning,
            Self::AppleDeveloperCertificateSubmission,
            Self::SafariDeveloper,
            Self::IPhoneOsVpnSigning,
            Self::AppleMacAppSigningDevelopment,
            Self::AppleMacAppSigningSubmission,
            Self::AppleMacAppStoreCodeSigning,
            Self::AppleMacAppStoreInstallerSigning,
            Self::MacDeveloper,
            Self::DeveloperIdApplication,
            Self::DeveloperIdDate,
            Self::DeveloperIdInstaller,
            Self::ApplePayPassbookSigning,
            Self::WebsitePushNotificationSigning,
            Self::DeveloperIdKernel,
            Self::TestFlight,
        ]
    }

    /// All OIDs known to be extensions in code signing certificates.
    pub fn all_oids() -> &'static [&'static ConstOid] {
        ALL_OID_NON_CA_EXTENSIONS
    }

    pub fn as_oid(&self) -> ConstOid {
        match self {
            Self::AppleSigning => OID_EXTENSION_APPLE_SIGNING,
            Self::IPhoneDeveloper => OID_EXTENSION_IPHONE_DEVELOPER,
            Self::IPhoneOsApplicationSigning => OID_EXTENSION_IPHONE_OS_APPLICATION_SIGNING,
            Self::AppleDeveloperCertificateSubmission => {
                OID_EXTENSION_APPLE_DEVELOPER_CERTIFICATE_SUBMISSION
            }
            Self::SafariDeveloper => OID_EXTENSION_SAFARI_DEVELOPER,
            Self::IPhoneOsVpnSigning => OID_EXTENSION_IPHONE_OS_VPN_SIGNING,
            Self::AppleMacAppSigningDevelopment => OID_EXTENSION_APPLE_MAC_APP_SIGNING_DEVELOPMENT,
            Self::AppleMacAppSigningSubmission => OID_EXTENSION_APPLE_MAC_APP_SIGNING_SUBMISSION,
            Self::AppleMacAppStoreCodeSigning => OID_EXTENSION_APPLE_MAC_APP_STORE_CODE_SIGNING,
            Self::AppleMacAppStoreInstallerSigning => {
                OID_EXTENSION_APPLE_MAC_APP_STORE_INSTALLER_SIGNING
            }
            Self::MacDeveloper => OID_EXTENSION_MAC_DEVELOPER,
            Self::DeveloperIdApplication => OID_EXTENSION_DEVELOPER_ID_APPLICATION,
            Self::DeveloperIdDate => OID_EXTENSION_DEVELOPER_ID_DATE,
            Self::DeveloperIdInstaller => OID_EXTENSION_DEVELOPER_ID_INSTALLER,
            Self::ApplePayPassbookSigning => OID_EXTENSION_PASSBOOK_SIGNING,
            Self::WebsitePushNotificationSigning => OID_EXTENSION_WEBSITE_PUSH_NOTIFICATION_SIGNING,
            Self::DeveloperIdKernel => OID_EXTENSION_DEVELOPER_ID_KERNEL,
            Self::TestFlight => OID_EXTENSION_TEST_FLIGHT,
        }
    }
}

impl Display for CodeSigningCertificateExtension {
    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
        match self {
            CodeSigningCertificateExtension::AppleSigning => f.write_str("Apple Signing"),
            CodeSigningCertificateExtension::IPhoneDeveloper => f.write_str("iPhone Developer"),
            CodeSigningCertificateExtension::IPhoneOsApplicationSigning => {
                f.write_str("Apple iPhone OS Application Signing")
            }
            CodeSigningCertificateExtension::AppleDeveloperCertificateSubmission => {
                f.write_str("Apple Developer Certificate (Submission)")
            }
            CodeSigningCertificateExtension::SafariDeveloper => f.write_str("Safari Developer"),
            CodeSigningCertificateExtension::IPhoneOsVpnSigning => {
                f.write_str("Apple iPhone OS VPN Signing")
            }
            CodeSigningCertificateExtension::AppleMacAppSigningDevelopment => {
                f.write_str("Apple Mac App Signing (Development)")
            }
            CodeSigningCertificateExtension::AppleMacAppSigningSubmission => {
                f.write_str("Apple Mac App Signing Submission")
            }
            CodeSigningCertificateExtension::AppleMacAppStoreCodeSigning => {
                f.write_str("Mac App Store Code Signing")
            }
            CodeSigningCertificateExtension::AppleMacAppStoreInstallerSigning => {
                f.write_str("Mac App Store Installer Signing")
            }
            CodeSigningCertificateExtension::MacDeveloper => f.write_str("Mac Developer"),
            CodeSigningCertificateExtension::DeveloperIdApplication => {
                f.write_str("Developer ID Application")
            }
            CodeSigningCertificateExtension::DeveloperIdDate => f.write_str("Developer ID Date"),
            CodeSigningCertificateExtension::DeveloperIdInstaller => {
                f.write_str("Developer ID Installer")
            }
            CodeSigningCertificateExtension::ApplePayPassbookSigning => {
                f.write_str("Apple Pay Passbook Signing")
            }
            CodeSigningCertificateExtension::WebsitePushNotificationSigning => {
                f.write_str("Web Site Push Notifications Signing")
            }
            CodeSigningCertificateExtension::DeveloperIdKernel => {
                f.write_str("Developer ID Kernel")
            }
            CodeSigningCertificateExtension::TestFlight => f.write_str("TestFlight"),
        }
    }
}

impl TryFrom<&Oid> for CodeSigningCertificateExtension {
    type Error = AppleCodesignError;

    fn try_from(oid: &Oid) -> Result<Self, Self::Error> {
        // Surely there is a way to use `match`. But the `Oid` type is a bit wonky.
        let o = oid.as_ref();

        if o == OID_EXTENSION_APPLE_SIGNING.as_ref() {
            Ok(Self::AppleSigning)
        } else if o == OID_EXTENSION_IPHONE_DEVELOPER.as_ref() {
            Ok(Self::IPhoneDeveloper)
        } else if o == OID_EXTENSION_IPHONE_OS_APPLICATION_SIGNING.as_ref() {
            Ok(Self::IPhoneOsApplicationSigning)
        } else if o == OID_EXTENSION_APPLE_DEVELOPER_CERTIFICATE_SUBMISSION.as_ref() {
            Ok(Self::AppleDeveloperCertificateSubmission)
        } else if o == OID_EXTENSION_SAFARI_DEVELOPER.as_ref() {
            Ok(Self::SafariDeveloper)
        } else if o == OID_EXTENSION_IPHONE_OS_VPN_SIGNING.as_ref() {
            Ok(Self::IPhoneOsVpnSigning)
        } else if o == OID_EXTENSION_APPLE_MAC_APP_SIGNING_DEVELOPMENT.as_ref() {
            Ok(Self::AppleMacAppSigningDevelopment)
        } else if o == OID_EXTENSION_APPLE_MAC_APP_SIGNING_SUBMISSION.as_ref() {
            Ok(Self::AppleMacAppSigningSubmission)
        } else if o == OID_EXTENSION_APPLE_MAC_APP_STORE_CODE_SIGNING.as_ref() {
            Ok(Self::AppleMacAppStoreCodeSigning)
        } else if o == OID_EXTENSION_APPLE_MAC_APP_STORE_INSTALLER_SIGNING.as_ref() {
            Ok(Self::AppleMacAppStoreInstallerSigning)
        } else if o == OID_EXTENSION_MAC_DEVELOPER.as_ref() {
            Ok(Self::MacDeveloper)
        } else if o == OID_EXTENSION_DEVELOPER_ID_APPLICATION.as_ref() {
            Ok(Self::DeveloperIdApplication)
        } else if o == OID_EXTENSION_DEVELOPER_ID_INSTALLER.as_ref() {
            Ok(Self::DeveloperIdInstaller)
        } else if o == OID_EXTENSION_PASSBOOK_SIGNING.as_ref() {
            Ok(Self::ApplePayPassbookSigning)
        } else if o == OID_EXTENSION_WEBSITE_PUSH_NOTIFICATION_SIGNING.as_ref() {
            Ok(Self::WebsitePushNotificationSigning)
        } else if o == OID_EXTENSION_DEVELOPER_ID_KERNEL.as_ref() {
            Ok(Self::DeveloperIdKernel)
        } else if o == OID_EXTENSION_DEVELOPER_ID_DATE.as_ref() {
            Ok(Self::DeveloperIdDate)
        } else if o == OID_EXTENSION_TEST_FLIGHT.as_ref() {
            Ok(Self::TestFlight)
        } else {
            Err(AppleCodesignError::OidIsntCodeSigningExtension)
        }
    }
}

/// Denotes specific certificate extensions on Apple certificate authority certificates.
///
/// Apple's CA certificates have extensions that appear to identify the role of
/// that CA. This enumeration defines those.
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub enum CertificateAuthorityExtension {
    /// Apple Worldwide Developer Relations.
    ///
    /// An intermediate CA.
    AppleWorldwideDeveloperRelations,

    /// Apple Application Integration.
    AppleApplicationIntegration,

    /// Developer ID Certification Authority.
    DeveloperId,

    /// Apple Timestamp.
    AppleTimestamp,

    /// Developer Authentication Certification Authority.
    DeveloperAuthentication,

    /// Application Application Integration CA - G3.
    AppleApplicationIntegrationG3,

    /// Apple Worldwide Developer Relations CA - G2.
    AppleWorldwideDeveloperRelationsG2,

    /// Apple Software Update Certification.
    AppleSoftwareUpdateCertification,

    /// Apple Application Integration CA - G1.
    AppleApplicationIntegrationG1,
}

impl CertificateAuthorityExtension {
    /// Obtain all variants of this enumeration.
    pub fn all() -> Vec<Self> {
        vec![
            Self::AppleWorldwideDeveloperRelations,
            Self::AppleApplicationIntegration,
            Self::DeveloperId,
            Self::AppleTimestamp,
            Self::DeveloperAuthentication,
            Self::AppleApplicationIntegrationG3,
            Self::AppleWorldwideDeveloperRelationsG2,
            Self::AppleSoftwareUpdateCertification,
            Self::AppleApplicationIntegrationG1,
        ]
    }

    /// All the known OIDs constituting Apple CA extensions.
    pub fn all_oids() -> &'static [&'static ConstOid] {
        ALL_OID_CA_EXTENSIONS
    }

    pub fn as_oid(&self) -> ConstOid {
        match self {
            Self::AppleWorldwideDeveloperRelations => {
                OID_CA_EXTENSION_APPLE_WORLDWIDE_DEVELOPER_RELATIONS
            }
            Self::AppleApplicationIntegration => OID_CA_EXTENSION_APPLE_APPLICATION_INTEGRATION,
            Self::DeveloperId => OID_CA_EXTENSION_DEVELOPER_ID,
            Self::AppleTimestamp => OID_CA_EXTENSION_APPLE_TIMESTAMP,
            Self::DeveloperAuthentication => OID_CA_EXTENSION_DEVELOPER_AUTHENTICATION,
            Self::AppleApplicationIntegrationG3 => {
                OID_CA_EXTENSION_APPLE_APPLICATION_INTEGRATION_G3
            }
            Self::AppleWorldwideDeveloperRelationsG2 => {
                OID_CA_EXTENSION_APPLE_WORLDWIDE_DEVELOPER_RELATIONS_G2
            }
            Self::AppleSoftwareUpdateCertification => {
                OID_CA_EXTENSION_APPLE_SOFTWARE_UPDATE_CERTIFICATION
            }
            Self::AppleApplicationIntegrationG1 => {
                OID_CA_EXTENSION_APPLE_APPLICATION_INTEGRATION_G1
            }
        }
    }
}

impl Display for CertificateAuthorityExtension {
    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
        match self {
            CertificateAuthorityExtension::AppleWorldwideDeveloperRelations => {
                f.write_str("Apple Worldwide Developer Relations")
            }
            CertificateAuthorityExtension::AppleApplicationIntegration => {
                f.write_str("Apple Application Integration")
            }
            CertificateAuthorityExtension::DeveloperId => {
                f.write_str("Developer ID Certification Authority")
            }
            CertificateAuthorityExtension::AppleTimestamp => f.write_str("Apple Timestamp"),
            CertificateAuthorityExtension::DeveloperAuthentication => {
                f.write_str("Developer Authentication Certification Authority")
            }
            CertificateAuthorityExtension::AppleApplicationIntegrationG3 => {
                f.write_str("Apple Application Integration CA - G3")
            }
            CertificateAuthorityExtension::AppleWorldwideDeveloperRelationsG2 => {
                f.write_str("Apple Worldwide Developer Relations CA - G2")
            }
            CertificateAuthorityExtension::AppleSoftwareUpdateCertification => {
                f.write_str("Apple Software Update Certification")
            }
            CertificateAuthorityExtension::AppleApplicationIntegrationG1 => {
                f.write_str("Apple Application Integration CA - G1")
            }
        }
    }
}

impl TryFrom<&Oid> for CertificateAuthorityExtension {
    type Error = AppleCodesignError;

    fn try_from(oid: &Oid) -> Result<Self, Self::Error> {
        // Surely there is a way to use `match`. But the `Oid` type is a bit wonky.
        if oid.as_ref() == OID_CA_EXTENSION_APPLE_WORLDWIDE_DEVELOPER_RELATIONS.as_ref() {
            Ok(Self::AppleWorldwideDeveloperRelations)
        } else if oid.as_ref() == OID_CA_EXTENSION_APPLE_APPLICATION_INTEGRATION.as_ref() {
            Ok(Self::AppleApplicationIntegration)
        } else if oid.as_ref() == OID_CA_EXTENSION_DEVELOPER_ID.as_ref() {
            Ok(Self::DeveloperId)
        } else if oid.as_ref() == OID_CA_EXTENSION_APPLE_TIMESTAMP.as_ref() {
            Ok(Self::AppleTimestamp)
        } else if oid.as_ref() == OID_CA_EXTENSION_DEVELOPER_AUTHENTICATION.as_ref() {
            Ok(Self::DeveloperAuthentication)
        } else if oid.as_ref() == OID_CA_EXTENSION_APPLE_APPLICATION_INTEGRATION_G3.as_ref() {
            Ok(Self::AppleApplicationIntegrationG3)
        } else if oid.as_ref() == OID_CA_EXTENSION_APPLE_WORLDWIDE_DEVELOPER_RELATIONS_G2.as_ref() {
            Ok(Self::AppleWorldwideDeveloperRelationsG2)
        } else if oid.as_ref() == OID_CA_EXTENSION_APPLE_SOFTWARE_UPDATE_CERTIFICATION.as_ref() {
            Ok(Self::AppleSoftwareUpdateCertification)
        } else if oid.as_ref() == OID_CA_EXTENSION_APPLE_APPLICATION_INTEGRATION_G1.as_ref() {
            Ok(Self::AppleApplicationIntegrationG1)
        } else {
            Err(AppleCodesignError::OidIsntCertificateAuthority)
        }
    }
}

/// Describes combinations of certificate extensions for Apple code signing certificates.
///
/// Code signing certificates contain various X.509 extensions denoting them for
/// code signing.
///
/// This type represents various common extensions as used on Apple platforms.
///
/// Typically, you'll want to apply at most one of these extensions to a
/// new certificate in order to mark it as compatible for code signing.
///
/// This type essentially encapsulates the logic for handling of different
/// "profiles" attached to the different code signing certificates that Apple
/// issues.
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub enum CertificateProfile {
    /// Mac Installer Distribution.
    ///
    /// In `Keychain Access.app`, this might render as `3rd Party Mac Developer Installer`.
    ///
    /// Certificates are marked for EKU with `3rd Party Developer Installer Package
    /// Signing`.
    ///
    /// They also have the `Apple Mac App Signing (Submission)` extension.
    ///
    /// Typically issued by `Apple Worldwide Developer Relations Certificate
    /// Authority`.
    MacInstallerDistribution,

    /// Apple Distribution.
    ///
    /// Certificates are marked for EKU with `Code Signing`. They also have
    /// extensions `Apple Mac App Signing (Development)` and
    /// `Apple Developer Certificate (Submission)`.
    ///
    /// Typically issued by `Apple Worldwide Developer Relations Certificate Authority`.
    AppleDistribution,

    /// Apple Development.
    ///
    /// Certificates are marked for EKU with `Code Signing`. They also have
    /// extensions `Apple Developer Certificate (Development)` and
    /// `Mac Developer`.
    ///
    /// Typically issued by `Apple Worldwide Developer Relations Certificate
    /// Authority`.
    AppleDevelopment,

    /// Developer ID Application.
    ///
    /// Certificates are marked for EKU with `Code Signing`. They also have
    /// extensions for `Developer ID Application` and `Developer ID Date`.
    DeveloperIdApplication,

    /// Developer ID Installer.
    ///
    /// Certificates are marked for EKU with `Developer ID Application`. They also
    /// have extensions `Developer ID Installer` and `Developer ID Date`.
    DeveloperIdInstaller,
}

impl CertificateProfile {
    pub fn all() -> &'static [Self] {
        &[
            Self::MacInstallerDistribution,
            Self::AppleDistribution,
            Self::AppleDevelopment,
            Self::DeveloperIdApplication,
            Self::DeveloperIdInstaller,
        ]
    }

    /// Obtain the string values that variants are recognized as.
    pub fn str_names() -> [&'static str; 5] {
        [
            "mac-installer-distribution",
            "apple-distribution",
            "apple-development",
            "developer-id-application",
            "developer-id-installer",
        ]
    }
}

impl Display for CertificateProfile {
    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
        match self {
            CertificateProfile::MacInstallerDistribution => {
                f.write_str("mac-installer-distribution")
            }
            CertificateProfile::AppleDistribution => f.write_str("apple-distribution"),
            CertificateProfile::AppleDevelopment => f.write_str("apple-development"),
            CertificateProfile::DeveloperIdApplication => f.write_str("developer-id-application"),
            CertificateProfile::DeveloperIdInstaller => f.write_str("developer-id-installer"),
        }
    }
}

impl FromStr for CertificateProfile {
    type Err = AppleCodesignError;

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        match s {
            "apple-distribution" => Ok(Self::AppleDistribution),
            "apple-development" => Ok(Self::AppleDevelopment),
            "developer-id-application" => Ok(Self::DeveloperIdApplication),
            "developer-id-installer" => Ok(Self::DeveloperIdInstaller),
            "mac-installer-distribution" => Ok(Self::MacInstallerDistribution),
            _ => Err(AppleCodesignError::UnknownCertificateProfile(s.to_string())),
        }
    }
}

/// Extends functionality of [CapturedX509Certificate] with Apple specific certificate knowledge.
pub trait AppleCertificate: Sized {
    /// Whether this is a known Apple root certificate authority.
    ///
    /// We define this criteria as a certificate in our built-in list of known
    /// Apple certificates that has the same subject and issuer Names.
    fn is_apple_root_ca(&self) -> bool;

    /// Whether this is a known Apple intermediate certificate authority.
    ///
    /// This is similar to [Self::is_apple_root_ca] except it doesn't match against
    /// known self-signed Apple certificates.
    fn is_apple_intermediate_ca(&self) -> bool;

    /// Find [CertificateAuthorityExtension] present on this certificate.
    ///
    /// If this is non-empty, the certificate says it is an Apple certificate
    /// whose role is issuing other certificates using for signing things.
    ///
    /// This function does not perform trust validation that the underlying
    /// certificate is a legitimate Apple issued certificate: just that it has
    /// the desired property.
    fn apple_ca_extensions(&self) -> Vec<CertificateAuthorityExtension>;

    /// Obtain all of Apple's [ExtendedKeyUsagePurpose] in this certificate.
    fn apple_extended_key_usage_purposes(&self) -> Vec<ExtendedKeyUsagePurpose>;

    /// Obtain all of Apple's [CodeSigningCertificateExtension] in this certificate.
    fn apple_code_signing_extensions(&self) -> Vec<CodeSigningCertificateExtension>;

    /// Attempt to guess the [CertificateProfile] associated with this certificate.
    ///
    /// This keys off present certificate extensions to guess which profile it
    /// belongs to. Incorrect guesses are possible, which is why *guess* is in the
    /// function name.
    ///
    /// Returns `None` if we don't think a [CertificateProfile] is associated with
    /// this extension.
    fn apple_guess_profile(&self) -> Option<CertificateProfile>;

    /// Attempt to resolve the certificate issuer chain back to [AppleCertificate].
    ///
    /// This is a glorified wrapper around [CapturedX509Certificate::resolve_signing_chain]
    /// that filters matches against certificates in our known set of Apple
    /// certificates and maps them back to our [KnownCertificate] Rust enumeration.
    ///
    /// False negatives (read: missing certificates) can be encountered if
    /// we don't know about an Apple CA certificate.
    fn apple_issuing_chain(&self) -> Vec<KnownCertificate>;

    /// Whether this certificate chains back to a known Apple root certificate authority.
    ///
    /// This is true if the resolved certificate issuance chain (which is
    /// confirmed via verifying the cryptographic signatures on certificates)
    /// ands in a certificate that is known to be an Apple root CA.
    fn chains_to_apple_root_ca(&self) -> bool;

    /// Obtain the chain of issuing certificates, back to a known Apple root.
    ///
    /// The returned chain starts with this certificate and ends with a known
    /// Apple root certificate authority. None is returned if this certificate
    /// doesn't appear to chain to a known Apple root CA.
    fn apple_root_certificate_chain(&self) -> Option<Vec<CapturedX509Certificate>>;

    /// Attempt to resolve the *team id* of an Apple issued certificate.
    ///
    /// The *team id* is a value like `AB42XYZ789` that is attached to your
    /// Apple Developer account. It seems to always be embedded in signing
    /// certificates as the Organizational Unit field of the subject. So this
    /// function is just a shortcut for retrieving that.
    fn apple_team_id(&self) -> Option<String>;

    /// Whether this is a certificate pretending to be signed by an Apple CA but isn't really.
    fn is_test_apple_signed_certificate(&self) -> bool;
}

impl AppleCertificate for CapturedX509Certificate {
    fn is_apple_root_ca(&self) -> bool {
        KnownCertificate::all_roots().contains(&self)
    }

    fn is_apple_intermediate_ca(&self) -> bool {
        KnownCertificate::all().contains(&self) && !KnownCertificate::all_roots().contains(&self)
    }

    fn apple_ca_extensions(&self) -> Vec<CertificateAuthorityExtension> {
        let cert: &x509_certificate::rfc5280::Certificate = self.as_ref();

        cert.iter_extensions()
            .filter_map(|extension| CertificateAuthorityExtension::try_from(&extension.id).ok())
            .collect::<Vec<_>>()
    }

    fn apple_extended_key_usage_purposes(&self) -> Vec<ExtendedKeyUsagePurpose> {
        let cert: &x509_certificate::rfc5280::Certificate = self.as_ref();

        cert.iter_extensions()
            .filter_map(|extension| {
                if extension.id.as_ref() == OID_EXTENDED_KEY_USAGE.as_ref() {
                    if let Some(oid) = extension.try_decode_sequence_single_oid() {
                        ExtendedKeyUsagePurpose::try_from(&oid).ok()
                    } else {
                        None
                    }
                } else {
                    None
                }
            })
            .collect::<Vec<_>>()
    }

    fn apple_code_signing_extensions(&self) -> Vec<CodeSigningCertificateExtension> {
        let cert: &x509_certificate::rfc5280::Certificate = self.as_ref();

        cert.iter_extensions()
            .filter_map(|extension| {
                CodeSigningCertificateExtension::try_from(&extension.id).ok()
            })
            .collect::<Vec<_>>()
    }

    fn apple_guess_profile(&self) -> Option<CertificateProfile> {
        let ekus = self.apple_extended_key_usage_purposes();
        let signing = self.apple_code_signing_extensions();

        // Some EKUs uniquely identify the certificate profile. We don't yet handle
        // all EKUs because we don't have profiles defined for them.
        //
        // Ideally this logic stays in sync with apple_certificate_profile().
        if ekus.contains(&ExtendedKeyUsagePurpose::DeveloperIdInstaller) {
            Some(CertificateProfile::DeveloperIdInstaller)
        } else if ekus.contains(&ExtendedKeyUsagePurpose::ThirdPartyMacDeveloperInstaller) {
            Some(CertificateProfile::MacInstallerDistribution)
            // That's all the EKUs that have a 1:1 to CertificateProfile. Now look at
            // code signing extensions.
        } else if signing.contains(&CodeSigningCertificateExtension::DeveloperIdApplication) {
            Some(CertificateProfile::DeveloperIdApplication)
        } else if signing.contains(&CodeSigningCertificateExtension::IPhoneDeveloper)
            && signing.contains(&CodeSigningCertificateExtension::MacDeveloper)
        {
            Some(CertificateProfile::AppleDevelopment)
        } else if signing.contains(&CodeSigningCertificateExtension::AppleMacAppSigningDevelopment)
            && signing
                .contains(&CodeSigningCertificateExtension::AppleDeveloperCertificateSubmission)
        {
            Some(CertificateProfile::AppleDistribution)
        } else {
            None
        }
    }

    fn apple_issuing_chain(&self) -> Vec<KnownCertificate> {
        self.resolve_signing_chain(KnownCertificate::all().iter().copied())
            .into_iter()
            .filter_map(|cert| KnownCertificate::try_from(cert).ok())
            .collect::<Vec<_>>()
    }

    fn chains_to_apple_root_ca(&self) -> bool {
        if self.is_apple_root_ca() {
            true
        } else {
            self.resolve_signing_chain(KnownCertificate::all().iter().copied())
                .into_iter()
                .any(|cert| cert.is_apple_root_ca())
        }
    }

    fn apple_root_certificate_chain(&self) -> Option<Vec<CapturedX509Certificate>> {
        let mut chain = vec![self.clone()];

        for cert in self.resolve_signing_chain(KnownCertificate::all().iter().copied()) {
            chain.push(cert.clone());

            if cert.is_apple_root_ca() {
                break;
            }
        }

        if chain.last().unwrap().is_apple_root_ca() {
            Some(chain)
        } else {
            None
        }
    }

    fn apple_team_id(&self) -> Option<String> {
        self.subject_name()
            .find_first_attribute_string(Oid(
                x509_certificate::rfc4519::OID_ORGANIZATIONAL_UNIT_NAME
                    .as_ref()
                    .into(),
            ))
            .unwrap_or(None)
    }

    fn is_test_apple_signed_certificate(&self) -> bool {
        if let Ok(digest) = self.sha256_fingerprint() {
            hex::encode(digest)
                == "5939ad5770d8b977b38d07533754371314744e87a8d606433f689e9bc6b980a0"
        } else {
            false
        }
    }
}

/// Extensions to [X509CertificateBuilder] specializing in Apple certificate behavior.
///
/// Most callers should call [Self::apple_certificate_profile] to configure
/// a preset profile for the certificate being generated. After that - and it is
/// important it is after - call [Self::apple_subject] to define the subject
/// field. If you call this after registering code signing extensions, it
/// detects the appropriate format for the Common Name field.
pub trait AppleCertificateBuilder: Sized {
    /// This functions defines common attributes on the certificate subject.
    ///
    /// `team_id` is your Apple team id. It is a short alphanumeric string. You
    /// can find this at <https://developer.apple.com/account/#/membership/>.
    fn apple_subject(
        &mut self,
        team_id: &str,
        person_name: &str,
        country: &str,
    ) -> Result<(), AppleCodesignError>;

    /// Add an email address to the certificate's subject name.
    fn apple_email_address(&mut self, address: &str) -> Result<(), AppleCodesignError>;

    /// Add an [ExtendedKeyUsagePurpose] to this certificate.
    fn apple_extended_key_usage(
        &mut self,
        usage: ExtendedKeyUsagePurpose,
    ) -> Result<(), AppleCodesignError>;

    /// Add a certificate extension as defined by a [CodeSigningCertificateExtension] instance.
    fn apple_code_signing_certificate_extension(
        &mut self,
        extension: CodeSigningCertificateExtension,
    ) -> Result<(), AppleCodesignError>;

    /// Add a [CertificateProfile] to this builder.
    ///
    /// All certificate extensions relevant to this profile are added.
    ///
    /// This should be the first function you call after creating an instance
    /// because other functions rely on the state that it sets.
    fn apple_certificate_profile(
        &mut self,
        profile: CertificateProfile,
    ) -> Result<(), AppleCodesignError>;

    /// Find code signing extensions that are currently registered.
    fn apple_code_signing_extensions(&self) -> Vec<CodeSigningCertificateExtension>;
}

impl AppleCertificateBuilder for X509CertificateBuilder {
    fn apple_subject(
        &mut self,
        team_id: &str,
        person_name: &str,
        country: &str,
    ) -> Result<(), AppleCodesignError> {
        // TODO the subject schema here isn't totally accurate. While OU does always
        // appear to be the team id, the user id attribute can be something else.
        // For example, for Apple Development, there are a similarly formatted yet
        // different value. But the team id does still appear.
        self.subject()
            .append_utf8_string(Oid(OID_USER_ID.as_ref().into()), team_id)
            .map_err(|e| AppleCodesignError::CertificateBuildError(format!("{e:?}")))?;

        // Common Name is derived from the profile in use.

        let extensions = self.apple_code_signing_extensions();

        let common_name =
            if extensions.contains(&CodeSigningCertificateExtension::DeveloperIdApplication) {
                format!("Developer ID Application: {person_name} ({team_id})")
            } else if extensions.contains(&CodeSigningCertificateExtension::DeveloperIdInstaller) {
                format!("Developer ID Installer: {person_name} ({team_id})")
            } else if extensions
                .contains(&CodeSigningCertificateExtension::AppleDeveloperCertificateSubmission)
            {
                format!("Apple Distribution: {person_name} ({team_id})")
            } else if extensions
                .contains(&CodeSigningCertificateExtension::AppleMacAppSigningSubmission)
            {
                format!("3rd Party Mac Developer Installer: {person_name} ({team_id})")
            } else if extensions.contains(&CodeSigningCertificateExtension::MacDeveloper) {
                format!("Apple Development: {person_name} ({team_id})")
            } else {
                format!("{person_name} ({team_id})")
            };

        self.subject()
            .append_common_name_utf8_string(&common_name)
            .map_err(|e| AppleCodesignError::CertificateBuildError(format!("{e:?}")))?;

        self.subject()
            .append_organizational_unit_utf8_string(team_id)
            .map_err(|e| AppleCodesignError::CertificateBuildError(format!("{e:?}")))?;

        self.subject()
            .append_organization_utf8_string(person_name)
            .map_err(|e| AppleCodesignError::CertificateBuildError(format!("{e:?}")))?;

        self.subject()
            .append_printable_string(Oid(OID_COUNTRY_NAME.as_ref().into()), country)
            .map_err(|e| AppleCodesignError::CertificateBuildError(format!("{e:?}")))?;

        Ok(())
    }

    fn apple_email_address(&mut self, address: &str) -> Result<(), AppleCodesignError> {
        self.subject()
            .append_utf8_string(Oid(OID_EMAIL_ADDRESS.as_ref().into()), address)
            .map_err(|e| AppleCodesignError::CertificateBuildError(format!("{e:?}")))?;

        Ok(())
    }

    fn apple_extended_key_usage(
        &mut self,
        usage: ExtendedKeyUsagePurpose,
    ) -> Result<(), AppleCodesignError> {
        let payload =
            bcder::encode::sequence(Oid(Bytes::copy_from_slice(usage.as_oid().as_ref())).encode())
                .to_captured(bcder::Mode::Der);

        self.add_extension_der_data(
            Oid(OID_EXTENDED_KEY_USAGE.as_ref().into()),
            true,
            payload.as_slice(),
        );

        Ok(())
    }

    fn apple_code_signing_certificate_extension(
        &mut self,
        extension: CodeSigningCertificateExtension,
    ) -> Result<(), AppleCodesignError> {
        let (critical, payload) = match extension {
            CodeSigningCertificateExtension::IPhoneDeveloper => {
                // SEQUENCE (3 elem)
                //   OBJECT IDENTIFIER 1.2.840.113635.100.6.1.2
                //   BOOLEAN true
                //   OCTET STRING (2 byte) 0500
                //     NULL
                (true, Bytes::copy_from_slice(&[0x05, 0x00]))
            }
            CodeSigningCertificateExtension::AppleDeveloperCertificateSubmission => {
                // SEQUENCE (3 elem)
                //   OBJECT IDENTIFIER 1.2.840.113635.100.6.1.4
                //   BOOLEAN true
                //   OCTET STRING (2 byte) 0500
                //     NULL
                (true, Bytes::copy_from_slice(&[0x05, 0x00]))
            }
            CodeSigningCertificateExtension::AppleMacAppSigningDevelopment => {
                // SEQUENCE (3 elem)
                //   OBJECT IDENTIFIER 1.2.840.113635.100.6.1.7
                //   BOOLEAN true
                //   OCTET STRING (2 byte) 0500
                //     NULL
                (true, Bytes::copy_from_slice(&[0x05, 0x00]))
            }
            CodeSigningCertificateExtension::AppleMacAppSigningSubmission => {
                // SEQUENCE (3 elem)
                //   OBJECT IDENTIFIER 1.2.840.113635.100.6.1.8
                //   BOOLEAN true
                //   OCTET STRING (2 byte) 0500
                //   NULL
                (true, Bytes::copy_from_slice(&[0x05, 0x00]))
            }
            CodeSigningCertificateExtension::MacDeveloper => {
                // SEQUENCE (3 elem)
                //   OBJECT IDENTIFIER 1.2.840.113635.100.6.1.12
                //   BOOLEAN true
                //   OCTET STRING (2 byte) 0500
                //     NULL
                (true, Bytes::copy_from_slice(&[0x05, 0x00]))
            }
            CodeSigningCertificateExtension::DeveloperIdApplication => {
                // SEQUENCE (3 elem)
                //   OBJECT IDENTIFIER 1.2.840.113635.100.6.1.13
                //   BOOLEAN true
                //   OCTET STRING (2 byte) 0500
                //     NULL
                (true, Bytes::copy_from_slice(&[0x05, 0x00]))
            }
            CodeSigningCertificateExtension::DeveloperIdInstaller => {
                // SEQUENCE (3 elem)
                //   OBJECT IDENTIFIER 1.2.840.113635.100.6.1.14
                //   BOOLEAN true
                //   OCTET STRING (2 byte) 0500
                //   NULL
                (true, Bytes::copy_from_slice(&[0x05, 0x00]))
            }

            // The rest of these probably have the same payload. But until we see
            // them, don't take chances.
            _ => {
                return Err(AppleCodesignError::CertificateBuildError(format!(
                    "don't know how to handle code signing extension {extension:?}"
                )));
            }
        };

        self.add_extension_der_data(
            Oid(Bytes::copy_from_slice(extension.as_oid().as_ref())),
            critical,
            payload,
        );

        Ok(())
    }

    fn apple_certificate_profile(
        &mut self,
        profile: CertificateProfile,
    ) -> Result<(), AppleCodesignError> {
        // Try to keep this logic in sync with apple_guess_profile().
        match profile {
            CertificateProfile::DeveloperIdApplication => {
                self.constraint_not_ca();
                self.apple_extended_key_usage(ExtendedKeyUsagePurpose::CodeSigning)?;
                self.key_usage(KeyUsage::DigitalSignature);

                // OID_EXTENSION_DEVELOPER_ID_DATE comes next. But we don't know what
                // that should be. It is a UTF8String instead of an ASN.1 time type
                // because who knows.

                self.apple_code_signing_certificate_extension(
                    CodeSigningCertificateExtension::DeveloperIdApplication,
                )?;
            }
            CertificateProfile::DeveloperIdInstaller => {
                self.constraint_not_ca();
                self.apple_extended_key_usage(ExtendedKeyUsagePurpose::DeveloperIdInstaller)?;
                self.key_usage(KeyUsage::DigitalSignature);

                // OID_EXTENSION_DEVELOPER_ID_DATE comes next.

                self.apple_code_signing_certificate_extension(
                    CodeSigningCertificateExtension::DeveloperIdInstaller,
                )?;
            }
            CertificateProfile::AppleDevelopment => {
                self.constraint_not_ca();
                self.apple_extended_key_usage(ExtendedKeyUsagePurpose::CodeSigning)?;
                self.key_usage(KeyUsage::DigitalSignature);
                self.apple_code_signing_certificate_extension(
                    CodeSigningCertificateExtension::IPhoneDeveloper,
                )?;
                self.apple_code_signing_certificate_extension(
                    CodeSigningCertificateExtension::MacDeveloper,
                )?;
            }
            CertificateProfile::AppleDistribution => {
                self.constraint_not_ca();
                self.apple_extended_key_usage(ExtendedKeyUsagePurpose::CodeSigning)?;
                self.key_usage(KeyUsage::DigitalSignature);

                // OID_EXTENSION_DEVELOPER_ID_DATE comes next.

                self.apple_code_signing_certificate_extension(
                    CodeSigningCertificateExtension::AppleMacAppSigningDevelopment,
                )?;
                self.apple_code_signing_certificate_extension(
                    CodeSigningCertificateExtension::AppleDeveloperCertificateSubmission,
                )?;
            }
            CertificateProfile::MacInstallerDistribution => {
                self.constraint_not_ca();
                self.apple_extended_key_usage(
                    ExtendedKeyUsagePurpose::ThirdPartyMacDeveloperInstaller,
                )?;
                self.key_usage(KeyUsage::DigitalSignature);

                self.apple_code_signing_certificate_extension(
                    CodeSigningCertificateExtension::AppleMacAppSigningSubmission,
                )?;
            }
        }

        Ok(())
    }

    fn apple_code_signing_extensions(&self) -> Vec<CodeSigningCertificateExtension> {
        self.extensions()
            .iter()
            .filter_map(|ext| {
                CodeSigningCertificateExtension::try_from(&ext.id).ok()
            })
            .collect::<Vec<_>>()
    }
}

/// Create a new self-signed X.509 certificate suitable for signing code.
///
/// The created certificate contains all the extensions needed to convey
/// that it is used for code signing and should resemble certificates.
///
/// However, because the certificate isn't signed by Apple or another
/// trusted certificate authority, binaries signed with the certificate
/// may not pass Apple's verification requirements and the OS may refuse
/// to proceed. Needless to say, only use certificates generated with this
/// function for testing purposes only.
pub fn create_self_signed_code_signing_certificate(
    algorithm: KeyAlgorithm,
    profile: CertificateProfile,
    team_id: &str,
    person_name: &str,
    country: &str,
    validity_duration: chrono::Duration,
) -> Result<(CapturedX509Certificate, InMemorySigningKeyPair), AppleCodesignError> {
    let mut builder = X509CertificateBuilder::default();

    builder.apple_certificate_profile(profile)?;
    builder.apple_subject(team_id, person_name, country)?;
    builder.validity_duration(validity_duration);

    // x509-certificate crate doesn't support RSA key generation. So do
    // that ourselves.
    if matches!(algorithm, KeyAlgorithm::Rsa) {
        let private_key = rsa::RsaPrivateKey::new(&mut rand::thread_rng(), 2048).map_err(|e| {
            AppleCodesignError::CertificateBuildError(format!("error generating RSA key: {}", e))
        })?;
        let key_pair = InMemorySigningKeyPair::from_pkcs8_der(
            private_key
                .to_pkcs8_der()
                .map_err(|e| {
                    AppleCodesignError::CertificateGeneric(format!(
                        "error converting RSA key to DER: {}",
                        e
                    ))
                })?
                .as_bytes(),
        )?;

        let cert = builder.create_with_key_pair(&key_pair)?;

        Ok((cert, key_pair))
    } else {
        Ok(builder.create_with_random_keypair(algorithm)?)
    }
}

#[cfg(test)]
mod tests {
    use {
        super::*,
        cryptographic_message_syntax::{SignedData, SignedDataBuilder, SignerBuilder},
        x509_certificate::EcdsaCurve,
    };

    #[test]
    fn generate_self_signed_certificate_ecdsa() {
        for curve in EcdsaCurve::all() {
            create_self_signed_code_signing_certificate(
                KeyAlgorithm::Ecdsa(*curve),
                CertificateProfile::DeveloperIdInstaller,
                "team1",
                "Joe Developer",
                "US",
                chrono::Duration::hours(1),
            )
            .unwrap();
        }
    }

    #[test]
    fn generate_self_signed_certificate_ed25519() {
        create_self_signed_code_signing_certificate(
            KeyAlgorithm::Ed25519,
            CertificateProfile::DeveloperIdInstaller,
            "team2",
            "Joe Developer",
            "US",
            chrono::Duration::hours(1),
        )
        .unwrap();
    }

    #[test]
    fn generate_all_profiles() {
        for profile in CertificateProfile::all() {
            create_self_signed_code_signing_certificate(
                KeyAlgorithm::Ed25519,
                *profile,
                "team",
                "Joe Developer",
                "Wakanda",
                chrono::Duration::hours(1),
            )
            .unwrap();
        }
    }

    #[test]
    fn cms_self_signed_certificate_signing_ecdsa() {
        for curve in EcdsaCurve::all() {
            let (cert, signing_key) = create_self_signed_code_signing_certificate(
                KeyAlgorithm::Ecdsa(*curve),
                CertificateProfile::DeveloperIdInstaller,
                "team",
                "Joe Developer",
                "US",
                chrono::Duration::hours(1),
            )
            .unwrap();

            let plaintext = "hello, world";

            let cms = SignedDataBuilder::default()
                .certificate(cert.clone())
                .content_inline(plaintext.as_bytes().to_vec())
                .signer(SignerBuilder::new(&signing_key, cert.clone()))
                .build_der()
                .unwrap();

            let signed_data = SignedData::parse_ber(&cms).unwrap();

            for signer in signed_data.signers() {
                signer
                    .verify_signature_with_signed_data(&signed_data)
                    .unwrap();
            }
        }
    }

    #[test]
    fn cms_self_signed_certificate_signing_ed25519() {
        let (cert, signing_key) = create_self_signed_code_signing_certificate(
            KeyAlgorithm::Ed25519,
            CertificateProfile::DeveloperIdInstaller,
            "team",
            "Joe Developer",
            "US",
            chrono::Duration::hours(1),
        )
        .unwrap();

        let plaintext = "hello, world";

        let cms = SignedDataBuilder::default()
            .certificate(cert.clone())
            .content_inline(plaintext.as_bytes().to_vec())
            .signer(SignerBuilder::new(&signing_key, cert))
            .build_der()
            .unwrap();

        let signed_data = SignedData::parse_ber(&cms).unwrap();

        for signer in signed_data.signers() {
            signer
                .verify_signature_with_signed_data(&signed_data)
                .unwrap();
        }
    }

    #[test]
    fn third_mac_mac() {
        let der = include_bytes!("testdata/apple-signed-3rd-party-mac.cer");
        let cert = CapturedX509Certificate::from_der(der.to_vec()).unwrap();

        assert_eq!(
            cert.apple_extended_key_usage_purposes(),
            vec![ExtendedKeyUsagePurpose::ThirdPartyMacDeveloperInstaller]
        );
        assert_eq!(
            cert.apple_code_signing_extensions(),
            vec![CodeSigningCertificateExtension::AppleMacAppSigningSubmission]
        );
        assert_eq!(
            cert.apple_guess_profile(),
            Some(CertificateProfile::MacInstallerDistribution)
        );
        assert_eq!(
            cert.apple_issuing_chain(),
            vec![
                KnownCertificate::WwdrG3,
                KnownCertificate::AppleRootCa,
                KnownCertificate::AppleComputerIncRoot
            ]
        );
        assert!(cert.chains_to_apple_root_ca());
        assert_eq!(
            cert.apple_root_certificate_chain(),
            Some(vec![
                cert.clone(),
                (*KnownCertificate::WwdrG3).clone(),
                (*KnownCertificate::AppleRootCa).clone()
            ])
        );
        assert_eq!(cert.apple_team_id(), Some("MK22MZP987".into()));

        let mut builder = X509CertificateBuilder::default();
        builder
            .apple_certificate_profile(CertificateProfile::MacInstallerDistribution)
            .unwrap();

        let built = builder
            .create_with_random_keypair(KeyAlgorithm::Ecdsa(EcdsaCurve::Secp256r1))
            .unwrap()
            .0;

        assert_eq!(
            built.apple_extended_key_usage_purposes(),
            cert.apple_extended_key_usage_purposes()
        );
        assert_eq!(
            built.apple_code_signing_extensions(),
            cert.apple_code_signing_extensions()
        );
        assert_eq!(built.apple_guess_profile(), cert.apple_guess_profile());
        assert_eq!(built.apple_issuing_chain(), vec![]);
        assert!(!built.chains_to_apple_root_ca());
        assert!(built.apple_root_certificate_chain().is_none());
    }

    #[test]
    fn apple_development() {
        let der = include_bytes!("testdata/apple-signed-apple-development.cer");
        let cert = CapturedX509Certificate::from_der(der.to_vec()).unwrap();

        assert_eq!(
            cert.apple_extended_key_usage_purposes(),
            vec![ExtendedKeyUsagePurpose::CodeSigning]
        );
        assert_eq!(
            cert.apple_code_signing_extensions(),
            vec![
                CodeSigningCertificateExtension::IPhoneDeveloper,
                CodeSigningCertificateExtension::MacDeveloper
            ]
        );
        assert_eq!(
            cert.apple_guess_profile(),
            Some(CertificateProfile::AppleDevelopment)
        );
        assert_eq!(
            cert.apple_issuing_chain(),
            vec![
                KnownCertificate::WwdrG3,
                KnownCertificate::AppleRootCa,
                KnownCertificate::AppleComputerIncRoot
            ],
        );
        assert!(cert.chains_to_apple_root_ca());
        assert_eq!(
            cert.apple_root_certificate_chain(),
            Some(vec![
                cert.clone(),
                (*KnownCertificate::WwdrG3).clone(),
                (*KnownCertificate::AppleRootCa).clone()
            ])
        );
        assert_eq!(cert.apple_team_id(), Some("MK22MZP987".into()));

        let mut builder = X509CertificateBuilder::default();
        builder
            .apple_certificate_profile(CertificateProfile::AppleDevelopment)
            .unwrap();

        let built = builder
            .create_with_random_keypair(KeyAlgorithm::Ecdsa(EcdsaCurve::Secp256r1))
            .unwrap()
            .0;

        assert_eq!(
            built.apple_extended_key_usage_purposes(),
            cert.apple_extended_key_usage_purposes()
        );
        assert_eq!(
            built.apple_code_signing_extensions(),
            cert.apple_code_signing_extensions()
        );
        assert_eq!(built.apple_guess_profile(), cert.apple_guess_profile());
        assert_eq!(built.apple_issuing_chain(), vec![]);
        assert!(!built.chains_to_apple_root_ca());
        assert!(built.apple_root_certificate_chain().is_none());
    }

    #[test]
    fn apple_distribution() {
        let der = include_bytes!("testdata/apple-signed-apple-distribution.cer");
        let cert = CapturedX509Certificate::from_der(der.to_vec()).unwrap();

        assert_eq!(
            cert.apple_extended_key_usage_purposes(),
            vec![ExtendedKeyUsagePurpose::CodeSigning]
        );
        assert_eq!(
            cert.apple_code_signing_extensions(),
            vec![
                CodeSigningCertificateExtension::AppleMacAppSigningDevelopment,
                CodeSigningCertificateExtension::AppleDeveloperCertificateSubmission
            ]
        );
        assert_eq!(
            cert.apple_guess_profile(),
            Some(CertificateProfile::AppleDistribution)
        );
        assert_eq!(
            cert.apple_issuing_chain(),
            vec![
                KnownCertificate::WwdrG3,
                KnownCertificate::AppleRootCa,
                KnownCertificate::AppleComputerIncRoot
            ],
        );
        assert!(cert.chains_to_apple_root_ca());
        assert_eq!(
            cert.apple_root_certificate_chain(),
            Some(vec![
                cert.clone(),
                (*KnownCertificate::WwdrG3).clone(),
                (*KnownCertificate::AppleRootCa).clone()
            ])
        );
        assert_eq!(cert.apple_team_id(), Some("MK22MZP987".into()));

        let mut builder = X509CertificateBuilder::default();
        builder
            .apple_certificate_profile(CertificateProfile::AppleDistribution)
            .unwrap();

        let built = builder
            .create_with_random_keypair(KeyAlgorithm::Ecdsa(EcdsaCurve::Secp256r1))
            .unwrap()
            .0;

        assert_eq!(
            built.apple_extended_key_usage_purposes(),
            cert.apple_extended_key_usage_purposes()
        );
        assert_eq!(
            built.apple_code_signing_extensions(),
            cert.apple_code_signing_extensions()
        );
        assert_eq!(built.apple_guess_profile(), cert.apple_guess_profile());
        assert_eq!(built.apple_issuing_chain(), vec![]);
        assert!(!built.chains_to_apple_root_ca());
        assert!(built.apple_root_certificate_chain().is_none());
    }

    #[test]
    fn apple_developer_id_application() {
        let der = include_bytes!("testdata/apple-signed-developer-id-application.cer");
        let cert = CapturedX509Certificate::from_der(der.to_vec()).unwrap();

        assert_eq!(
            cert.apple_extended_key_usage_purposes(),
            vec![ExtendedKeyUsagePurpose::CodeSigning]
        );
        assert_eq!(
            cert.apple_code_signing_extensions(),
            vec![
                CodeSigningCertificateExtension::DeveloperIdDate,
                CodeSigningCertificateExtension::DeveloperIdApplication
            ]
        );
        assert_eq!(
            cert.apple_guess_profile(),
            Some(CertificateProfile::DeveloperIdApplication)
        );
        assert_eq!(
            cert.apple_issuing_chain(),
            vec![
                KnownCertificate::DeveloperIdG1,
                KnownCertificate::AppleRootCa,
                KnownCertificate::AppleComputerIncRoot
            ]
        );
        assert!(cert.chains_to_apple_root_ca());
        assert_eq!(
            cert.apple_root_certificate_chain(),
            Some(vec![
                cert.clone(),
                (*KnownCertificate::DeveloperIdG1).clone(),
                (*KnownCertificate::AppleRootCa).clone()
            ])
        );
        assert_eq!(cert.apple_team_id(), Some("MK22MZP987".into()));

        let mut builder = X509CertificateBuilder::default();
        builder
            .apple_certificate_profile(CertificateProfile::DeveloperIdApplication)
            .unwrap();

        let built = builder
            .create_with_random_keypair(KeyAlgorithm::Ecdsa(EcdsaCurve::Secp256r1))
            .unwrap()
            .0;

        assert_eq!(
            built.apple_extended_key_usage_purposes(),
            cert.apple_extended_key_usage_purposes()
        );
        assert_eq!(
            built.apple_code_signing_extensions(),
            // We don't write out the date extension.
            cert.apple_code_signing_extensions()
                .into_iter()
                .filter(|e| !matches!(e, CodeSigningCertificateExtension::DeveloperIdDate))
                .collect::<Vec<_>>()
        );
        assert_eq!(built.apple_guess_profile(), cert.apple_guess_profile());
        assert_eq!(built.apple_issuing_chain(), vec![]);
        assert!(!built.chains_to_apple_root_ca());
        assert!(built.apple_root_certificate_chain().is_none());
    }

    #[test]
    fn apple_developer_id_installer() {
        let der = include_bytes!("testdata/apple-signed-developer-id-installer.cer");
        let cert = CapturedX509Certificate::from_der(der.to_vec()).unwrap();

        assert_eq!(
            cert.apple_extended_key_usage_purposes(),
            vec![ExtendedKeyUsagePurpose::DeveloperIdInstaller]
        );
        assert_eq!(
            cert.apple_code_signing_extensions(),
            vec![
                CodeSigningCertificateExtension::DeveloperIdDate,
                CodeSigningCertificateExtension::DeveloperIdInstaller
            ]
        );
        assert_eq!(
            cert.apple_guess_profile(),
            Some(CertificateProfile::DeveloperIdInstaller)
        );
        assert_eq!(
            cert.apple_issuing_chain(),
            vec![
                KnownCertificate::DeveloperIdG1,
                KnownCertificate::AppleRootCa,
                KnownCertificate::AppleComputerIncRoot
            ]
        );
        assert!(cert.chains_to_apple_root_ca());
        assert_eq!(
            cert.apple_root_certificate_chain(),
            Some(vec![
                cert.clone(),
                (*KnownCertificate::DeveloperIdG1).clone(),
                (*KnownCertificate::AppleRootCa).clone()
            ])
        );
        assert_eq!(cert.apple_team_id(), Some("MK22MZP987".into()));

        let mut builder = X509CertificateBuilder::default();
        builder
            .apple_certificate_profile(CertificateProfile::DeveloperIdInstaller)
            .unwrap();

        let built = builder
            .create_with_random_keypair(KeyAlgorithm::Ecdsa(EcdsaCurve::Secp256r1))
            .unwrap()
            .0;

        assert_eq!(
            built.apple_extended_key_usage_purposes(),
            cert.apple_extended_key_usage_purposes()
        );
        assert_eq!(
            built.apple_code_signing_extensions(),
            // We don't write out the date extension.
            cert.apple_code_signing_extensions()
                .into_iter()
                .filter(|e| !matches!(e, CodeSigningCertificateExtension::DeveloperIdDate))
                .collect::<Vec<_>>()
        );
        assert_eq!(built.apple_guess_profile(), cert.apple_guess_profile());
        assert_eq!(built.apple_issuing_chain(), vec![]);
        assert!(!built.chains_to_apple_root_ca());
        assert!(built.apple_root_certificate_chain().is_none());
    }
}
