// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
// Copyright by contributors to this project.
// SPDX-License-Identifier: (Apache-2.0 OR MIT)

use connection_strategy::ConnectionStrategy;
use group_state::SqLiteGroupStateStorage;
use psk::SqLitePreSharedKeyStorage;
use rusqlite::Connection;
use storage::{SqLiteApplicationStorage, SqLiteKeyPackageStorage};
use thiserror::Error;

mod application;
mod group_state;
mod key_package;
mod psk;

#[cfg(any(feature = "sqlcipher", feature = "sqlcipher-bundled"))]
mod cipher;

#[cfg(test)]
pub(crate) mod test_utils;

/// Connection strategies.
pub mod connection_strategy;

/// SQLite storage components.
pub mod storage {
    pub use {
        crate::application::{Item, SqLiteApplicationStorage},
        crate::group_state::SqLiteGroupStateStorage,
        crate::key_package::SqLiteKeyPackageStorage,
        crate::psk::SqLitePreSharedKeyStorage,
    };
}

#[derive(Debug, Error)]
/// SQLite data storage error.
pub enum SqLiteDataStorageError {
    #[error(transparent)]
    /// SQLite error.
    SqlEngineError(Box<dyn std::error::Error + Send + Sync + 'static>),
    #[error(transparent)]
    /// Stored data is not compatible with the expected data type.
    DataConversionError(Box<dyn std::error::Error + Send + Sync + 'static>),
    #[error("epoch ID {0} exceeds maximum supported value (i64::MAX)")]
    /// Epoch ID is too large to store in SQLite.
    ///
    /// SQLite uses signed 64-bit integers, limiting epoch IDs to values up to 9,223,372,036,854,775,807.
    EpochIdOverflow(u64),
    #[error("timestamp {0} exceeds maximum supported value (i64::MAX)")]
    /// Timestamp is too large to store in SQLite.
    ///
    /// SQLite uses signed 64-bit integers, limiting timestamps to values up to 9,223,372,036,854,775,807.
    TimestampOverflow(u64),
    #[cfg(any(feature = "sqlcipher", feature = "sqlcipher-bundled"))]
    #[error("invalid key, must use SqlCipherKey::RawKeyWithSalt with plaintext_header_size > 0")]
    /// Invalid SQLCipher key header.
    SqlCipherKeyInvalidWithHeader,
}

impl mls_rs_core::error::IntoAnyError for SqLiteDataStorageError {
    fn into_dyn_error(self) -> Result<Box<dyn std::error::Error + Send + Sync>, Self> {
        Ok(self.into())
    }
}

#[derive(Clone, Debug)]
pub enum JournalMode {
    Delete,
    Truncate,
    Persist,
    Memory,
    Wal,
    Off,
}

/// Note: for in-memory dbs (such as what the tests use), the only available options are MEMORY or OFF
/// Invalid modes do not error, only no-op
impl JournalMode {
    fn as_str(&self) -> &'static str {
        match self {
            JournalMode::Delete => "DELETE",
            JournalMode::Truncate => "TRUNCATE",
            JournalMode::Persist => "PERSIST",
            JournalMode::Memory => "MEMORY",
            JournalMode::Wal => "WAL",
            JournalMode::Off => "OFF",
        }
    }
}

#[derive(Clone, Debug)]
/// SQLite data storage engine.
pub struct SqLiteDataStorageEngine<CS>
where
    CS: ConnectionStrategy,
{
    connection_strategy: CS,
    journal_mode: Option<JournalMode>,
}

impl<CS> SqLiteDataStorageEngine<CS>
where
    CS: ConnectionStrategy,
{
    pub fn new(
        connection_strategy: CS,
    ) -> Result<SqLiteDataStorageEngine<CS>, SqLiteDataStorageError> {
        Ok(SqLiteDataStorageEngine {
            connection_strategy,
            journal_mode: None,
        })
    }

    /// A `journal_mode` of `None` means the SQLite default is used.
    pub fn with_journal_mode(self, journal_mode: Option<JournalMode>) -> Self {
        Self {
            journal_mode,
            ..self
        }
    }

    fn create_connection(&self) -> Result<Connection, SqLiteDataStorageError> {
        let connection = self.connection_strategy.make_connection()?;

        // Run SQL to establish the schema
        let current_schema = connection
            .pragma_query_value(None, "user_version", |rows| rows.get::<_, u32>(0))
            .map_err(|e| SqLiteDataStorageError::SqlEngineError(e.into()))?;

        if let Some(journal_mode) = &self.journal_mode {
            connection
                .pragma_update(None, "journal_mode", journal_mode.as_str())
                .map_err(|e| SqLiteDataStorageError::SqlEngineError(e.into()))?;
        }

        if current_schema < 1 {
            create_tables_v1(&connection)?;
        }

        Ok(connection)
    }

    /// Returns a struct that implements the `GroupStateStorage` trait for use in MLS.
    pub fn group_state_storage(&self) -> Result<SqLiteGroupStateStorage, SqLiteDataStorageError> {
        Ok(SqLiteGroupStateStorage::new(self.create_connection()?))
    }

    /// Returns a struct that implements the `KeyPackageStorage` trait for use in MLS.
    pub fn key_package_storage(&self) -> Result<SqLiteKeyPackageStorage, SqLiteDataStorageError> {
        Ok(SqLiteKeyPackageStorage::new(self.create_connection()?))
    }

    /// Returns a struct that implements the `PreSharedKeyStorage` trait for use in MLS.
    pub fn pre_shared_key_storage(
        &self,
    ) -> Result<SqLitePreSharedKeyStorage, SqLiteDataStorageError> {
        Ok(SqLitePreSharedKeyStorage::new(self.create_connection()?))
    }

    /// Returns a key value store that can be used to store application specific data.
    pub fn application_data_storage(
        &self,
    ) -> Result<SqLiteApplicationStorage, SqLiteDataStorageError> {
        Ok(SqLiteApplicationStorage::new(self.create_connection()?))
    }
}

fn create_tables_v1(connection: &Connection) -> Result<(), SqLiteDataStorageError> {
    connection
        .execute_batch(
            "BEGIN;
            CREATE TABLE mls_group (
                group_id BLOB PRIMARY KEY,
                snapshot BLOB NOT NULL
            ) WITHOUT ROWID;
            CREATE TABLE epoch (
                group_id BLOB,
                epoch_id INTEGER,
                epoch_data BLOB NOT NULL,
                FOREIGN KEY (group_id) REFERENCES mls_group (group_id) ON DELETE CASCADE
                PRIMARY KEY (group_id, epoch_id)
            ) WITHOUT ROWID;
            CREATE TABLE key_package (
                id BLOB PRIMARY KEY,
                expiration INTEGER,
                data BLOB NOT NULL
            ) WITHOUT ROWID;
            CREATE INDEX key_package_exp ON key_package (expiration);
            CREATE TABLE psk (
                psk_id BLOB PRIMARY KEY,
                data BLOB NOT NULL
            ) WITHOUT ROWID;
            CREATE TABLE kvs (
                key TEXT PRIMARY KEY,
                value BLOB NOT NULL
            ) WITHOUT ROWID;
            PRAGMA user_version = 1;
            COMMIT;",
        )
        .map_err(|e| SqLiteDataStorageError::SqlEngineError(e.into()))
}

#[cfg(test)]
mod tests {
    use tempfile::tempdir;

    use crate::{
        connection_strategy::{FileConnectionStrategy, MemoryStrategy},
        SqLiteDataStorageEngine,
    };

    #[test]
    pub fn user_version_test() {
        let database = SqLiteDataStorageEngine::new(MemoryStrategy).unwrap();

        let _connection = database.create_connection().unwrap();

        // Create another connection to make sure the migration doesn't try to happen again.
        let connection = database.create_connection().unwrap();

        // Run SQL to establish the schema
        let current_schema = connection
            .pragma_query_value(None, "user_version", |rows| rows.get::<_, u32>(0))
            .unwrap();

        assert_eq!(current_schema, 1);
    }

    #[test]
    pub fn journal_mode_test() {
        let temp = tempdir().unwrap();

        // Connect with journal_mode other than the default of MEMORY
        let database = SqLiteDataStorageEngine::new(FileConnectionStrategy::new(
            &temp.path().join("test_db.sqlite"),
        ))
        .unwrap();

        let connection = database
            .with_journal_mode(Some(crate::JournalMode::Truncate))
            .create_connection()
            .unwrap();

        let journal_mode = connection
            .pragma_query_value(None, "journal_mode", |rows| rows.get::<_, String>(0))
            .unwrap();

        assert_eq!(journal_mode, "truncate");
    }

    #[test]
    pub fn extended_schema_version_test() {
        // Test that downstream applications can extend the schema beyond version 1
        // without breaking mls-rs connection creation
        let temp = tempdir().unwrap();
        let database = SqLiteDataStorageEngine::new(FileConnectionStrategy::new(
            &temp.path().join("extended_schema_test.sqlite"),
        ))
        .unwrap();

        // Initialize database (creates v1 schema)
        let connection = database.create_connection().unwrap();

        // Simulate downstream application extending schema
        connection
            .execute_batch(
                "BEGIN;
                CREATE TABLE custom_table (
                    id INTEGER PRIMARY KEY,
                    data TEXT NOT NULL
                );
                PRAGMA user_version = 2;
                COMMIT;",
            )
            .unwrap();

        drop(connection);

        // Create new connection - should not try to recreate tables
        let connection2 = database.create_connection().unwrap();

        // Verify user_version is still 2
        let current_schema = connection2
            .pragma_query_value(None, "user_version", |rows| rows.get::<_, u32>(0))
            .unwrap();

        assert_eq!(current_schema, 2);

        // Verify both mls-rs tables and custom table exist
        let mls_table_exists: bool = connection2
            .query_row(
                "SELECT COUNT(*) FROM sqlite_master WHERE type='table' AND name='mls_group'",
                [],
                |row| row.get(0),
            )
            .map(|count: i32| count > 0)
            .unwrap();

        let custom_table_exists: bool = connection2
            .query_row(
                "SELECT COUNT(*) FROM sqlite_master WHERE type='table' AND name='custom_table'",
                [],
                |row| row.get(0),
            )
            .map(|count: i32| count > 0)
            .unwrap();

        assert!(mls_table_exists);
        assert!(custom_table_exists);
    }
}
