use std::io::{self, Error, ErrorKind};

use ring::digest::{digest, SHA256};
use serde::{Deserialize, Serialize};

use crate::{avax, avm::fx, codec, ids, key, platformvm, secp256k1fx};

/// ref. https://pkg.go.dev/github.com/ava-labs/avalanchego/vms/avm#Tx
/// ref. https://pkg.go.dev/github.com/ava-labs/avalanchego/vms/avm#ExportTx
/// ref. https://pkg.go.dev/github.com/ava-labs/avalanchego/vms/avm#UnsignedTx
#[derive(Debug, Serialize, Deserialize, Eq, PartialEq, Clone)]
pub struct Tx {
    /// The transaction ID is empty for unsigned tx
    /// as long as "avax.BaseTx.Metadata" is "None".
    /// Once Metadata is updated with signing and "Tx.Initialize",
    /// Tx.ID() is non-empty.
    pub unsigned_tx: avax::BaseTx,
    pub destination_chain_id: ids::Id,
    pub destination_chain_transferable_outputs: Option<Vec<avax::TransferableOutput>>,
    pub fx_creds: Vec<fx::Credential>,
}

impl Default for Tx {
    fn default() -> Self {
        Self::default()
    }
}

impl Tx {
    pub fn default() -> Self {
        Self {
            unsigned_tx: avax::BaseTx::default(),
            destination_chain_id: ids::Id::default(),
            destination_chain_transferable_outputs: None,
            fx_creds: Vec::new(),
        }
    }

    pub fn new(unsigned_tx: avax::BaseTx) -> Self {
        Self {
            unsigned_tx,
            ..Self::default()
        }
    }

    pub fn type_name() -> String {
        "avm.ExportTx".to_string()
    }

    pub fn type_id() -> u32 {
        *(codec::X_TYPES.get(&Self::type_name()).unwrap()) as u32
    }

    /// Returns the transaction ID.
    /// Only non-empty if the embedded metadata is updated
    /// with the signing process.
    pub fn tx_id(&self) -> ids::Id {
        if self.unsigned_tx.metadata.is_some() {
            let m = self.unsigned_tx.metadata.clone().unwrap();
            m.id
        } else {
            ids::Id::default()
        }
    }

    /// ref. https://pkg.go.dev/github.com/ava-labs/avalanchego/vms/avm#Tx.SignSECP256K1Fx
    /// ref. https://pkg.go.dev/github.com/ava-labs/avalanchego/utils/crypto#PrivateKeyED25519.SignHash
    /// TODO: support ledger signing
    pub fn sign<T: key::secp256k1::SignOnly>(&mut self, signers: Vec<Vec<T>>) -> io::Result<()> {
        // marshal "unsigned tx" with the codec version
        let type_id = Self::type_id();
        let packer = self.unsigned_tx.pack(codec::VERSION, type_id)?;

        // "avalanchego" marshals the whole struct again for signed bytes
        // even when the underlying "unsigned_tx" is already once marshaled
        // ref. https://pkg.go.dev/github.com/ava-labs/avalanchego/vms/avm#Tx.SignSECP256K1Fx
        //
        // reuse the underlying packer to avoid marshaling the unsigned tx twice
        // just marshal the next fields in the struct and pack them all together
        // in the existing packer
        let unsigned_tx_bytes = packer.take_bytes();
        packer.set_bytes(&unsigned_tx_bytes);

        // pack the second field in the struct
        packer.pack_bytes(self.destination_chain_id.as_ref())?;

        // pack the third field in the struct
        if self.destination_chain_transferable_outputs.is_some() {
            let destination_chain_transferable_outputs = self
                .destination_chain_transferable_outputs
                .as_ref()
                .unwrap();
            packer.pack_u32(destination_chain_transferable_outputs.len() as u32)?;

            for transferable_output in destination_chain_transferable_outputs.iter() {
                // "TransferableOutput.Asset" is struct and serialize:"true"
                // but embedded inline in the struct "TransferableOutput"
                // so no need to encode type ID
                // ref. https://pkg.go.dev/github.com/ava-labs/avalanchego/vms/components/avax#TransferableOutput
                // ref. https://pkg.go.dev/github.com/ava-labs/avalanchego/vms/components/avax#Asset
                packer.pack_bytes(transferable_output.asset_id.as_ref())?;

                // fx_id is serialize:"false" thus skipping serialization

                // decide the type
                // ref. https://pkg.go.dev/github.com/ava-labs/avalanchego/vms/components/avax#TransferableOutput
                if transferable_output.transfer_output.is_none()
                    && transferable_output.stakeable_lock_out.is_none()
                {
                    return Err(Error::new(
                        ErrorKind::InvalidInput,
                        "unexpected Nones in TransferableOutput transfer_output and stakeable_lock_out",
                    ));
                }
                let type_id_transferable_out = {
                    if transferable_output.transfer_output.is_some() {
                        secp256k1fx::TransferOutput::type_id()
                    } else {
                        platformvm::StakeableLockOut::type_id()
                    }
                };
                // marshal type ID for "secp256k1fx::TransferOutput" or "platformvm::StakeableLockOut"
                packer.pack_u32(type_id_transferable_out)?;

                match type_id_transferable_out {
                    7 => {
                        // "secp256k1fx::TransferOutput"
                        // ref. https://pkg.go.dev/github.com/ava-labs/avalanchego/vms/secp256k1fx#TransferOutput
                        let transfer_output = transferable_output.transfer_output.clone().unwrap();

                        // marshal "secp256k1fx.TransferOutput.Amt" field
                        packer.pack_u64(transfer_output.amount)?;

                        // "secp256k1fx.TransferOutput.OutputOwners" is struct and serialize:"true"
                        // but embedded inline in the struct "TransferOutput"
                        // so no need to encode type ID
                        // ref. https://pkg.go.dev/github.com/ava-labs/avalanchego/vms/secp256k1fx#TransferOutput
                        // ref. https://pkg.go.dev/github.com/ava-labs/avalanchego/vms/secp256k1fx#OutputOwners
                        packer.pack_u64(transfer_output.output_owners.locktime)?;
                        packer.pack_u32(transfer_output.output_owners.threshold)?;
                        packer.pack_u32(transfer_output.output_owners.addrs.len() as u32)?;
                        for addr in transfer_output.output_owners.addrs.iter() {
                            packer.pack_bytes(addr.as_ref())?;
                        }
                    }
                    22 => {
                        // "platformvm::StakeableLockOut"
                        // ref. https://pkg.go.dev/github.com/ava-labs/avalanchego/vms/platformvm#StakeableLockOut
                        let stakeable_lock_out =
                            transferable_output.stakeable_lock_out.clone().unwrap();

                        // marshal "platformvm::StakeableLockOut.locktime" field
                        packer.pack_u64(stakeable_lock_out.locktime)?;

                        // "platformvm.StakeableLockOut.TransferOutput" is struct and serialize:"true"
                        // but embedded inline in the struct "StakeableLockOut"
                        // so no need to encode type ID
                        // ref. https://pkg.go.dev/github.com/ava-labs/avalanchego/vms/platformvm#StakeableLockOut
                        // ref. https://pkg.go.dev/github.com/ava-labs/avalanchego/vms/secp256k1fx#TransferOutput
                        // ref. https://pkg.go.dev/github.com/ava-labs/avalanchego/vms/secp256k1fx#OutputOwners
                        //
                        // marshal "secp256k1fx.TransferOutput.Amt" field
                        packer.pack_u64(stakeable_lock_out.transfer_output.amount)?;
                        packer
                            .pack_u64(stakeable_lock_out.transfer_output.output_owners.locktime)?;
                        packer
                            .pack_u32(stakeable_lock_out.transfer_output.output_owners.threshold)?;
                        packer.pack_u32(
                            stakeable_lock_out.transfer_output.output_owners.addrs.len() as u32,
                        )?;
                        for addr in stakeable_lock_out
                            .transfer_output
                            .output_owners
                            .addrs
                            .iter()
                        {
                            packer.pack_bytes(addr.as_ref())?;
                        }
                    }
                    _ => {
                        return Err(Error::new(
                            ErrorKind::InvalidInput,
                            format!(
                                "unexpected type ID {} for TransferableOutput",
                                type_id_transferable_out
                            ),
                        ));
                    }
                }
            }
        } else {
            packer.pack_u32(0_u32)?;
        }

        // take bytes just for hashing computation
        let unsigned_tx_bytes = packer.take_bytes();
        packer.set_bytes(&unsigned_tx_bytes);

        // compute sha256 for marshaled "unsigned tx" bytes
        // IMPORTANT: take the hash only for the type "avm.ExportTx" unsigned tx
        // not other fields -- only hash "avm.ExportTx.*" but not "avm.Tx.Creds"
        // ref. https://pkg.go.dev/github.com/ava-labs/avalanchego/vms/avm#ExportTx
        let hash: Vec<u8> = digest(&SHA256, &unsigned_tx_bytes).as_ref().into();

        // number of of credentials
        let fx_creds_len = signers.len() as u32;
        // pack the fourth field in the struct
        packer.pack_u32(fx_creds_len)?;

        // sign the hash with the signers (in case of multi-sig)
        // and combine all signatures into a secp256k1fx credential
        self.fx_creds = Vec::new();
        for keys in signers.iter() {
            let mut sigs: Vec<Vec<u8>> = Vec::new();
            for k in keys.iter() {
                let sig = k.sign_recoverable_digest_sha256(&hash);
                sigs.push(Vec::from(sig));
            }

            let mut cred = secp256k1fx::Credential::default();
            cred.signatures = sigs;

            let mut fx_cred = fx::Credential::default();
            fx_cred.cred = cred;

            // add a new credential to "Tx"
            self.fx_creds.push(fx_cred);
        }
        if fx_creds_len > 0 {
            // pack each "fx_cred" which is "secp256k1fx.Credential"
            // marshal type ID for "secp256k1fx.Credential"
            let cred_type_id = secp256k1fx::Credential::type_id();
            for fx_cred in self.fx_creds.iter() {
                packer.pack_u32(cred_type_id)?;
                packer.pack_u32(fx_cred.cred.signatures.len() as u32)?;
                for sig in fx_cred.cred.signatures.iter() {
                    packer.pack_bytes(sig)?;
                }
            }
        }
        let signed_tx_bytes = packer.take_bytes();
        let tx_id: Vec<u8> = digest(&SHA256, &signed_tx_bytes).as_ref().into();

        // update "BaseTx.Metadata" with id/unsigned bytes/bytes
        // ref. "avalanchego/vms/avm.Tx.SignSECP256K1Fx"
        // ref. "avalanchego/vms/components/avax.BaseTx.Metadata.Initialize"
        self.unsigned_tx.metadata = Some(avax::Metadata {
            id: ids::Id::from_slice(&tx_id),
            unsigned_bytes: unsigned_tx_bytes.to_vec(),
            bytes: signed_tx_bytes.to_vec(),
        });

        Ok(())
    }
}

/// RUST_LOG=debug cargo test --package avalanche-types --lib -- avm::export::test_export_tx_serialization_with_two_signers --exact --show-output
/// ref. "avalanchego/vms/avm.TestExportTxSerialization"
#[test]
fn test_export_tx_serialization_with_two_signers() {
    let mut tx = Tx {
        unsigned_tx: avax::BaseTx {
            network_id: 2,
            blockchain_id: ids::Id::from_slice(&<Vec<u8>>::from([
                0xff, 0xff, 0xff, 0xff, 0xee, 0xee, 0xee, 0xee, //
                0xdd, 0xdd, 0xdd, 0xdd, 0xcc, 0xcc, 0xcc, 0xcc, //
                0xbb, 0xbb, 0xbb, 0xbb, 0xaa, 0xaa, 0xaa, 0xaa, //
                0x99, 0x99, 0x99, 0x99, 0x88, 0x88, 0x88, 0x88, //
            ])),
            transferable_inputs: Some(vec![avax::TransferableInput {
                utxo_id: avax::UtxoId {
                    tx_id: ids::Id::from_slice(&<Vec<u8>>::from([
                        0x0f, 0x2f, 0x4f, 0x6f, 0x8e, 0xae, 0xce, 0xee, //
                        0x0d, 0x2d, 0x4d, 0x6d, 0x8c, 0xac, 0xcc, 0xec, //
                        0x0b, 0x2b, 0x4b, 0x6b, 0x8a, 0xaa, 0xca, 0xea, //
                        0x09, 0x29, 0x49, 0x69, 0x88, 0xa8, 0xc8, 0xe8, //
                    ])),
                    ..avax::UtxoId::default()
                },
                asset_id: ids::Id::from_slice(&<Vec<u8>>::from([
                    0x1f, 0x3f, 0x5f, 0x7f, 0x9e, 0xbe, 0xde, 0xfe, //
                    0x1d, 0x3d, 0x5d, 0x7d, 0x9c, 0xbc, 0xdc, 0xfc, //
                    0x1b, 0x3b, 0x5b, 0x7b, 0x9a, 0xba, 0xda, 0xfa, //
                    0x19, 0x39, 0x59, 0x79, 0x98, 0xb8, 0xd8, 0xf8, //
                ])),
                transfer_input: Some(secp256k1fx::TransferInput {
                    amount: 1000,
                    sig_indices: vec![0],
                }),
                ..avax::TransferableInput::default()
            }]),
            memo: Some(vec![0x00, 0x01, 0x02, 0x03]),
            ..avax::BaseTx::default()
        },
        destination_chain_id: ids::Id::from_slice(&<Vec<u8>>::from([
            0x1f, 0x8f, 0x9f, 0x0f, 0x1e, 0x8e, 0x9e, 0x0e, //
            0x2d, 0x7d, 0xad, 0xfd, 0x2c, 0x7c, 0xac, 0xfc, //
            0x3b, 0x6b, 0xbb, 0xeb, 0x3a, 0x6a, 0xba, 0xea, //
            0x49, 0x59, 0xc9, 0xd9, 0x48, 0x58, 0xc8, 0xd8, //
        ])),
        ..Tx::default()
    };

    // ref. "avalanchego/vms/avm/vm_test.go"
    let test_key = key::secp256k1::private_key::Key::from_cb58(
        "PrivateKey-24jUJ9vZexUM6expyMcT48LBx27k1m7xpraoV62oSQAHdziao5",
    )
    .expect("failed to load private key");
    let keys1: Vec<key::secp256k1::private_key::Key> = vec![test_key.clone(), test_key.clone()];
    let keys2: Vec<key::secp256k1::private_key::Key> = vec![test_key.clone(), test_key.clone()];
    let signers: Vec<Vec<key::secp256k1::private_key::Key>> = vec![keys1, keys2];
    tx.sign(signers).expect("failed to sign");
    let tx_metadata = tx.unsigned_tx.metadata.clone().unwrap();
    let signed_bytes = tx_metadata.bytes;
    assert_eq!(
        tx.tx_id().to_string(),
        "pYd4ShaZqEcGnEsK8PshrtwyjSoCA9YfkYqnLTUDdqdu8xoUX"
    );

    let expected_signed_bytes: &[u8] = &[
        // codec version
        0x00, 0x00, //
        //
        // avm.ExportTx type ID
        0x00, 0x00, 0x00, 0x04, //
        //
        // network id
        0x00, 0x00, 0x00, 0x02, //
        //
        // blockchain id
        0xff, 0xff, 0xff, 0xff, 0xee, 0xee, 0xee, 0xee, //
        0xdd, 0xdd, 0xdd, 0xdd, 0xcc, 0xcc, 0xcc, 0xcc, //
        0xbb, 0xbb, 0xbb, 0xbb, 0xaa, 0xaa, 0xaa, 0xaa, //
        0x99, 0x99, 0x99, 0x99, 0x88, 0x88, 0x88, 0x88, //
        //
        // outs.len()
        0x00, 0x00, 0x00, 0x00, //
        //
        // NOTE: fx_id is serialize:"false"
        //
        // ins.len()
        0x00, 0x00, 0x00, 0x01, //
        //
        // "Tx.destination_chain_outs[0]" TransferableInput.utxo_id.tx_id
        0x0f, 0x2f, 0x4f, 0x6f, 0x8e, 0xae, 0xce, 0xee, //
        0x0d, 0x2d, 0x4d, 0x6d, 0x8c, 0xac, 0xcc, 0xec, //
        0x0b, 0x2b, 0x4b, 0x6b, 0x8a, 0xaa, 0xca, 0xea, //
        0x09, 0x29, 0x49, 0x69, 0x88, 0xa8, 0xc8, 0xe8, //
        //
        // "Tx.destination_chain_outs[0]" TransferableInput.utxo_id.output_index
        0x00, 0x00, 0x00, 0x00, //
        //
        // "Tx.destination_chain_outs[0]" TransferableInput.asset_id
        0x1f, 0x3f, 0x5f, 0x7f, 0x9e, 0xbe, 0xde, 0xfe, //
        0x1d, 0x3d, 0x5d, 0x7d, 0x9c, 0xbc, 0xdc, 0xfc, //
        0x1b, 0x3b, 0x5b, 0x7b, 0x9a, 0xba, 0xda, 0xfa, //
        0x19, 0x39, 0x59, 0x79, 0x98, 0xb8, 0xd8, 0xf8, //
        //
        // "Tx.destination_chain_outs[0]" secp256k1fx.TransferInput type ID
        0x00, 0x00, 0x00, 0x05, //
        //
        // "Tx.destination_chain_outs[0]" TransferableInput.input.secp256k1fx::TransferInput.amount
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x03, 0xe8, //
        //
        // "Tx.destination_chain_outs[0]" TransferableInput.input.secp256k1fx::TransferInput.sig_indices.len()
        0x00, 0x00, 0x00, 0x01, //
        //
        // "Tx.destination_chain_outs[0]" TransferableInput.input.secp256k1fx::TransferInput.sig_indices[0]
        0x00, 0x00, 0x00, 0x00, //
        //
        // memo.len()
        0x00, 0x00, 0x00, 0x04, //
        //
        // memo
        0x00, 0x01, 0x02, 0x03, //
        //
        // Tx.destination_chain
        0x1f, 0x8f, 0x9f, 0x0f, 0x1e, 0x8e, 0x9e, 0x0e, //
        0x2d, 0x7d, 0xad, 0xfd, 0x2c, 0x7c, 0xac, 0xfc, //
        0x3b, 0x6b, 0xbb, 0xeb, 0x3a, 0x6a, 0xba, 0xea, //
        0x49, 0x59, 0xc9, 0xd9, 0x48, 0x58, 0xc8, 0xd8, //
        //
        // Tx.destination_chain_outs.len()
        0x00, 0x00, 0x00, 0x00, //
        //
        // number of of credentials (avax.Tx.fx_creds.len())
        0x00, 0x00, 0x00, 0x02, //
        //
        //
        // NOTE: fx_id is serialize:"false"
        //
        // struct field type ID "fx::Credential.cred"
        // "secp256k1fx.Credential" type ID
        0x00, 0x00, 0x00, 0x09, //
        //
        // number of signers ("fx::Credential.cred.sigs.len()")
        0x00, 0x00, 0x00, 0x02, //
        //
        // first 65-byte signature
        0x2, 0xa, 0x87, 0x33, 0x4e, 0x89, 0x6a, 0x82, 0x38, 0xd1, 0xd9, 0x44, 0x82, 0x8e, 0x49,
        0x1d, 0x40, 0xc2, 0x37, 0x7f, 0xae, 0xb4, 0xbb, 0xc9, 0x1d, 0x12, 0x8c, 0xf, 0xb6, 0xb6,
        0xd9, 0xba, 0x2d, 0xb0, 0xd3, 0xc4, 0x7c, 0x93, 0x32, 0xfc, 0x7e, 0xac, 0xa5, 0xc8, 0x74,
        0x63, 0x89, 0x8c, 0x60, 0x1f, 0xb0, 0x24, 0x19, 0x2d, 0x49, 0xe0, 0xd0, 0x20, 0x43, 0xe7,
        0x9f, 0xe6, 0x35, 0xd, 0x1, //
        //
        // second 65-byte signature
        0x2, 0xa, 0x87, 0x33, 0x4e, 0x89, 0x6a, 0x82, 0x38, 0xd1, 0xd9, 0x44, 0x82, 0x8e, 0x49,
        0x1d, 0x40, 0xc2, 0x37, 0x7f, 0xae, 0xb4, 0xbb, 0xc9, 0x1d, 0x12, 0x8c, 0xf, 0xb6, 0xb6,
        0xd9, 0xba, 0x2d, 0xb0, 0xd3, 0xc4, 0x7c, 0x93, 0x32, 0xfc, 0x7e, 0xac, 0xa5, 0xc8, 0x74,
        0x63, 0x89, 0x8c, 0x60, 0x1f, 0xb0, 0x24, 0x19, 0x2d, 0x49, 0xe0, 0xd0, 0x20, 0x43, 0xe7,
        0x9f, 0xe6, 0x35, 0xd, 0x1, //
        //
        //
        // NOTE: fx_id is serialize:"false"
        //
        // struct field type ID "fx::Credential.cred"
        // "secp256k1fx.Credential" type ID
        0x00, 0x00, 0x00, 0x09, //
        //
        // number of signers ("fx::Credential.cred.sigs.len()")
        0x00, 0x00, 0x00, 0x02, //
        //
        // first 65-byte signature
        0x2, 0xa, 0x87, 0x33, 0x4e, 0x89, 0x6a, 0x82, 0x38, 0xd1, 0xd9, 0x44, 0x82, 0x8e, 0x49,
        0x1d, 0x40, 0xc2, 0x37, 0x7f, 0xae, 0xb4, 0xbb, 0xc9, 0x1d, 0x12, 0x8c, 0xf, 0xb6, 0xb6,
        0xd9, 0xba, 0x2d, 0xb0, 0xd3, 0xc4, 0x7c, 0x93, 0x32, 0xfc, 0x7e, 0xac, 0xa5, 0xc8, 0x74,
        0x63, 0x89, 0x8c, 0x60, 0x1f, 0xb0, 0x24, 0x19, 0x2d, 0x49, 0xe0, 0xd0, 0x20, 0x43, 0xe7,
        0x9f, 0xe6, 0x35, 0xd, 0x1, //
        //
        // second 65-byte signature
        0x2, 0xa, 0x87, 0x33, 0x4e, 0x89, 0x6a, 0x82, 0x38, 0xd1, 0xd9, 0x44, 0x82, 0x8e, 0x49,
        0x1d, 0x40, 0xc2, 0x37, 0x7f, 0xae, 0xb4, 0xbb, 0xc9, 0x1d, 0x12, 0x8c, 0xf, 0xb6, 0xb6,
        0xd9, 0xba, 0x2d, 0xb0, 0xd3, 0xc4, 0x7c, 0x93, 0x32, 0xfc, 0x7e, 0xac, 0xa5, 0xc8, 0x74,
        0x63, 0x89, 0x8c, 0x60, 0x1f, 0xb0, 0x24, 0x19, 0x2d, 0x49, 0xe0, 0xd0, 0x20, 0x43, 0xe7,
        0x9f, 0xe6, 0x35, 0xd, 0x1, //
    ];
    // for c in &signed_bytes {
    //     print!("{:#02x},", *c);
    // }
    assert!(cmp_manager::eq_vectors(
        expected_signed_bytes,
        &signed_bytes
    ));
}
