use std::ops::Deref;

use pallas_codec::utils::CborWrap;
use pallas_crypto::hash::Hash;
use pallas_primitives::{
    conway::{
        AuxiliaryData, Certificate, DatumOption, ExUnits as PallasExUnits, NativeScript, NetworkId,
        NonZeroInt, PlutusData, PlutusScript, PostAlonzoTransactionOutput,
        PseudoScript as PallasScript, PseudoTransactionOutput, Redeemer, RedeemerTag,
        TransactionBody, TransactionInput, Tx, Value, WitnessSet,
    },
    Fragment, NonEmptyKeyValuePairs, NonEmptySet, PositiveCoin,
};
use pallas_traverse::ComputeHash;

use crate::{
    scriptdata,
    transaction::{
        model::{
            BuilderEra, BuiltTransaction, DatumKind, ExUnits, Output, RedeemerPurpose, ScriptKind,
            StagingTransaction,
        },
        Bytes, Bytes32, TransactionStatus,
    },
    TxBuilderError,
};

pub trait BuildConway {
    fn build_conway_raw(self) -> Result<BuiltTransaction, TxBuilderError>;

    // fn build_babbage(staging_tx: StagingTransaction, resolver: (), params: ()) ->
    // Result<BuiltTransaction, TxBuilderError>;
}

impl BuildConway for StagingTransaction {
    fn build_conway_raw(self) -> Result<BuiltTransaction, TxBuilderError> {
        let mut inputs = self
            .inputs
            .unwrap_or_default()
            .iter()
            .map(|x| TransactionInput {
                transaction_id: x.tx_hash.0.into(),
                index: x.txo_index,
            })
            .collect::<Vec<_>>();

        inputs.sort_unstable_by_key(|x| (x.transaction_id, x.index));

        let outputs = self
            .outputs
            .unwrap_or_default()
            .iter()
            .map(Output::build_babbage_raw)
            .collect::<Result<Vec<_>, _>>()?;

        let mint = NonEmptyKeyValuePairs::from_vec(
            self.mint
                .iter()
                .flat_map(|x| x.deref().iter())
                .map(|(pid, assets)| {
                    (
                        Hash::<28>::from(pid.0),
                        NonEmptyKeyValuePairs::from_vec(
                            assets
                                .iter()
                                .map(|(n, x)| (n.clone().into(), NonZeroInt::try_from(*x).unwrap()))
                                .collect::<Vec<_>>(),
                        )
                        .unwrap(),
                    )
                })
                .collect::<Vec<_>>(),
        );

        let collateral = NonEmptySet::from_vec(
            self.collateral_inputs
                .unwrap_or_default()
                .iter()
                .map(|x| TransactionInput {
                    transaction_id: x.tx_hash.0.into(),
                    index: x.txo_index,
                })
                .collect(),
        );

        let required_signers = NonEmptySet::from_vec(
            self.disclosed_signers
                .unwrap_or_default()
                .iter()
                .map(|x| x.0.into())
                .collect(),
        );

        let network_id = if let Some(nid) = self.network_id {
            match NetworkId::try_from(nid) {
                Err(()) => return Err(TxBuilderError::InvalidNetworkId),
                Ok(network_id) => Some(network_id),
            }
        } else {
            None
        };

        let collateral_return = self
            .collateral_output
            .as_ref()
            .map(Output::build_babbage_raw)
            .transpose()?;

        let reference_inputs = NonEmptySet::from_vec(
            self.reference_inputs
                .unwrap_or_default()
                .iter()
                .map(|x| TransactionInput {
                    transaction_id: x.tx_hash.0.into(),
                    index: x.txo_index,
                })
                .collect(),
        );

        let (mut native_script, mut plutus_v1_script, mut plutus_v2_script, mut plutus_v3_script) =
            (vec![], vec![], vec![], vec![]);

        for (_, script) in self.scripts.unwrap_or_default() {
            match script.kind {
                ScriptKind::Native => {
                    let script = NativeScript::decode_fragment(&script.bytes.0)
                        .map_err(|_| TxBuilderError::MalformedScript)?;

                    native_script.push(script)
                }
                ScriptKind::PlutusV1 => {
                    let script = PlutusScript::<1>(script.bytes.into());

                    plutus_v1_script.push(script)
                }
                ScriptKind::PlutusV2 => {
                    let script = PlutusScript::<2>(script.bytes.into());

                    plutus_v2_script.push(script)
                }
                ScriptKind::PlutusV3 => {
                    let script = PlutusScript::<3>(script.bytes.into());

                    plutus_v3_script.push(script)
                }
            }
        }

        let plutus_data = self
            .datums
            .unwrap_or_default()
            .iter()
            .map(|x| {
                PlutusData::decode_fragment(x.1.as_ref())
                    .map_err(|_| TxBuilderError::MalformedDatum)
            })
            .collect::<Result<Vec<_>, _>>()?;

        let mut mint_policies = mint
            .iter()
            .flat_map(|x| x.deref().iter())
            .map(|(p, _)| *p)
            .collect::<Vec<_>>();

        mint_policies.sort_unstable_by_key(|x| *x);

        let mut redeemers = vec![];

        if let Some(rdmrs) = self.redeemers {
            for (purpose, (pd, ex_units)) in rdmrs.deref().iter() {
                let ex_units = if let Some(ExUnits { mem, steps }) = ex_units {
                    PallasExUnits {
                        mem: *mem,
                        steps: *steps,
                    }
                } else {
                    todo!("ExUnits budget calculation not yet implement") // TODO
                };

                let data = PlutusData::decode_fragment(pd.as_ref())
                    .map_err(|_| TxBuilderError::MalformedDatum)?;

                match purpose {
                    RedeemerPurpose::Spend(ref txin) => {
                        let index = inputs
                            .iter()
                            .position(|x| {
                                (*x.transaction_id, x.index) == (txin.tx_hash.0, txin.txo_index)
                            })
                            .ok_or(TxBuilderError::RedeemerTargetMissing)?
                            as u32;

                        redeemers.push(Redeemer {
                            tag: RedeemerTag::Spend,
                            index,
                            data,
                            ex_units,
                        })
                    }
                    RedeemerPurpose::Mint(pid) => {
                        let index = mint_policies
                            .iter()
                            .position(|x| x.as_slice() == pid.0)
                            .ok_or(TxBuilderError::RedeemerTargetMissing)?
                            as u32;

                        redeemers.push(Redeemer {
                            tag: RedeemerTag::Mint,
                            index,
                            data,
                            ex_units,
                        })
                    } // todo!("reward and cert redeemers not yet supported"), // TODO
                }
            }
        };

        let witness_set_redeemers = pallas_primitives::conway::Redeemers::List(
            pallas_codec::utils::MaybeIndefArray::Def(redeemers.clone()),
        );

        let script_data_hash = self.language_view.map(|language_view| {
            let dta = scriptdata::ScriptData {
                redeemers: witness_set_redeemers.clone(),
                datums: if !plutus_data.is_empty() {
                    Some(plutus_data.clone())
                } else {
                    None
                },
                language_view,
            };

            dta.hash()
        });

        let mut pallas_tx = Tx {
            transaction_body: TransactionBody {
                inputs: pallas_primitives::Set::from(inputs),
                outputs,
                ttl: self.invalid_from_slot,
                validity_interval_start: self.valid_from_slot,
                fee: self.fee.unwrap_or_default(),
                certificates: NonEmptySet::from_vec(
                    self.certificates
                        .as_deref()
                        .unwrap_or(&[])
                        .iter()
                        .map(|bytes| {
                            Certificate::decode_fragment(bytes)
                                .map_err(|_| TxBuilderError::CorruptedTxBytes)
                        })
                        .collect::<Result<Vec<_>, _>>()?,
                ),
                withdrawals: None, // TODO
                auxiliary_data_hash: None, // TODO (accept user input)
                mint,
                script_data_hash,
                collateral,
                required_signers,
                network_id,
                collateral_return,
                reference_inputs,
                total_collateral: None,    // TODO
                voting_procedures: None,   // TODO
                proposal_procedures: None, // TODO
                treasury_value: None,      // TODO
                donation: None,            // TODO
            },
            transaction_witness_set: WitnessSet {
                vkeywitness: None,
                native_script: NonEmptySet::from_vec(native_script),
                bootstrap_witness: None,
                plutus_v1_script: NonEmptySet::from_vec(plutus_v1_script),
                plutus_v2_script: NonEmptySet::from_vec(plutus_v2_script),
                plutus_v3_script: NonEmptySet::from_vec(plutus_v3_script),
                plutus_data: NonEmptySet::from_vec(plutus_data),
                redeemer: if redeemers.is_empty() {
                    None
                } else {
                    Some(witness_set_redeemers)
                },
            },
            success: true, // TODO
            auxiliary_data: self
                .auxiliary_data
                .as_deref()
                .map(AuxiliaryData::decode_fragment)
                .transpose()
                .map_err(|_| TxBuilderError::CorruptedTxBytes)?
                .into(),
        };

        // TODO: pallas auxiliary_data_hash should be Hash<32> not Bytes
        pallas_tx.transaction_body.auxiliary_data_hash = pallas_tx
            .auxiliary_data
            .clone()
            .map(|ad| ad.compute_hash().to_vec().into())
            .into();

        Ok(BuiltTransaction {
            version: self.version,
            era: BuilderEra::Conway,
            status: TransactionStatus::Built,
            tx_hash: Bytes32(*pallas_tx.transaction_body.compute_hash()),
            tx_bytes: Bytes(pallas_tx.encode_fragment().unwrap()),
            signatures: None,
        })
    }

    // fn build_babbage(staging_tx: StagingTransaction) -> Result<BuiltTransaction,
    // TxBuilderError> {     todo!()
    // }
}

impl Output {
    pub fn build_babbage_raw(
        &self,
    ) -> Result<PseudoTransactionOutput<PostAlonzoTransactionOutput>, TxBuilderError> {
        let assets = NonEmptyKeyValuePairs::from_vec(
            self.assets
                .iter()
                .flat_map(|x| x.deref().iter())
                .map(|(pid, assets)| {
                    (
                        pid.0.into(),
                        assets
                            .iter()
                            .map(|(n, x)| (n.clone().into(), PositiveCoin::try_from(*x).unwrap()))
                            .collect::<Vec<_>>()
                            .try_into()
                            .unwrap(),
                    )
                })
                .collect::<Vec<_>>(),
        );

        let value = match assets {
            Some(assets) => Value::Multiasset(self.lovelace, assets),
            None => Value::Coin(self.lovelace),
        };

        let datum_option = if let Some(ref d) = self.datum {
            match d.kind {
                DatumKind::Hash => {
                    let dh: [u8; 32] = d
                        .bytes
                        .as_ref()
                        .try_into()
                        .map_err(|_| TxBuilderError::MalformedDatumHash)?;
                    Some(DatumOption::Hash(dh.into()))
                }
                DatumKind::Inline => {
                    let pd = PlutusData::decode_fragment(d.bytes.as_ref())
                        .map_err(|_| TxBuilderError::MalformedDatum)?;
                    Some(DatumOption::Data(CborWrap(pd)))
                }
            }
        } else {
            None
        };

        let script_ref = if let Some(ref s) = self.script {
            let script = match s.kind {
                ScriptKind::Native => PallasScript::NativeScript(
                    NativeScript::decode_fragment(s.bytes.as_ref())
                        .map_err(|_| TxBuilderError::MalformedScript)?,
                ),
                ScriptKind::PlutusV1 => PallasScript::PlutusV1Script(PlutusScript::<1>(
                    s.bytes.as_ref().to_vec().into(),
                )),
                ScriptKind::PlutusV2 => PallasScript::PlutusV2Script(PlutusScript::<2>(
                    s.bytes.as_ref().to_vec().into(),
                )),
                ScriptKind::PlutusV3 => PallasScript::PlutusV3Script(PlutusScript::<3>(
                    s.bytes.as_ref().to_vec().into(),
                )),
            };

            Some(CborWrap(script))
        } else {
            None
        };

        Ok(PseudoTransactionOutput::PostAlonzo(
            PostAlonzoTransactionOutput {
                address: self.address.to_vec().into(),
                value,
                datum_option,
                script_ref,
            },
        ))
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::transaction::model::StagingTransaction;
    use pallas_codec::minicbor;
    use pallas_primitives::alonzo::{AuxiliaryData, Metadatum, PostAlonzoAuxiliaryData};
    use pallas_traverse::ComputeHash;

    /// Encode a CIP-25-shaped auxiliary data, attach it to a tx, and
    /// confirm the built tx body carries the matching auxiliary_data_hash.
    /// Round-trip protection for the fork's metadata plumbing.
    #[test]
    fn auxiliary_data_round_trips_through_build() {
        // Minimal CIP-25-style metadata: label 721 → text "test".
        let metadata: pallas_primitives::alonzo::Metadata = vec![
            (721u64, Metadatum::Text("test".into())),
        ]
        .into();
        let aux = AuxiliaryData::PostAlonzo(PostAlonzoAuxiliaryData {
            metadata: Some(metadata),
            native_scripts: None,
            plutus_scripts: None,
        });
        let aux_bytes = minicbor::to_vec(&aux).expect("encode aux");
        let expected_hash = aux.compute_hash();

        let tx = StagingTransaction::new()
            .auxiliary_data(aux_bytes)
            .network_id(0)
            .fee(180_000)
            .build_conway_raw()
            .expect("build_conway_raw");

        // The body's auxiliary_data_hash should match the aux's
        // compute_hash output.
        let body =
            pallas_primitives::conway::Tx::decode_fragment(tx.tx_bytes.as_ref())
                .expect("decode tx_bytes");
        let body_aux_hash_bytes: Vec<u8> = body
            .transaction_body
            .auxiliary_data_hash
            .clone()
            .expect("auxiliary_data_hash should be set when aux is attached")
            .to_vec();
        assert_eq!(body_aux_hash_bytes, expected_hash.to_vec());

        // And the auxiliary_data should round-trip back.
        let pallas_aux = match body.auxiliary_data {
            pallas_codec::utils::Nullable::Some(a) => a,
            other => panic!("expected Some(aux), got {other:?}"),
        };
        // Re-encode the aux that came back and compare.
        let round_tripped_bytes = minicbor::to_vec(&pallas_aux).expect("re-encode aux");
        let original_again = minicbor::to_vec(&aux).expect("re-encode original");
        assert_eq!(round_tripped_bytes, original_again);
    }

    #[test]
    fn certificates_plumb_through_to_tx_body() {
        use pallas_primitives::conway::{Certificate, StakeCredential};
        use pallas_crypto::hash::Hash;

        // A trivial stake-registration cert.
        let stake_pkh = Hash::<28>::from([7u8; 28]);
        let cert = Certificate::StakeRegistration(StakeCredential::AddrKeyhash(stake_pkh));
        let cert_bytes = minicbor::to_vec(&cert).expect("encode cert");

        let tx = StagingTransaction::new()
            .add_certificate(cert_bytes)
            .network_id(0)
            .fee(180_000)
            .build_conway_raw()
            .expect("build_conway_raw");

        let body = pallas_primitives::conway::Tx::decode_fragment(tx.tx_bytes.as_ref())
            .expect("decode tx_bytes");
        let certs = body
            .transaction_body
            .certificates
            .expect("certificates field populated");
        let certs_vec: Vec<_> = certs.to_vec();
        assert_eq!(certs_vec.len(), 1);
        match &certs_vec[0] {
            Certificate::StakeRegistration(StakeCredential::AddrKeyhash(h)) => {
                assert_eq!(h.as_ref(), &[7u8; 28]);
            }
            other => panic!("expected StakeRegistration, got {other:?}"),
        }
    }

    #[test]
    fn no_certificates_means_none() {
        let tx = StagingTransaction::new()
            .network_id(0)
            .fee(180_000)
            .build_conway_raw()
            .expect("build_conway_raw");
        let body = pallas_primitives::conway::Tx::decode_fragment(tx.tx_bytes.as_ref())
            .expect("decode tx_bytes");
        assert!(body.transaction_body.certificates.is_none());
    }

    #[test]
    fn no_auxiliary_data_means_no_hash() {
        let tx = StagingTransaction::new()
            .network_id(0)
            .fee(180_000)
            .build_conway_raw()
            .expect("build_conway_raw");
        let body =
            pallas_primitives::conway::Tx::decode_fragment(tx.tx_bytes.as_ref())
                .expect("decode tx_bytes");
        assert!(body.transaction_body.auxiliary_data_hash.is_none());
    }
}