use crate::parser::errors::{OpError, OpResult};
use bitcoin::blockdata::opcodes::{all, All};
use bitcoin::blockdata::script::Instruction;
use bitcoin::util::address::Payload;
use bitcoin::{Address, Network, PubkeyHash, PublicKey, Script};
use bitcoin_hashes::{hash160, Hash};
use serde::{Deserialize, Serialize};
use std::fmt;
use Instruction::{Op, PushBytes};

#[derive(Debug, Clone, PartialEq, Eq, Hash, PartialOrd, Ord, Serialize, Deserialize)]
pub enum Type {
    OpReturn,
    Pay2MultiSig,
    Pay2PublicKey,
    Pay2PublicKeyHash,
    Pay2ScriptHash,
    Pay2WitnessPublicKeyHash,
    Pay2WitnessScriptHash,
    WitnessProgram,
    Unspendable,
    NotRecognised,
}

impl fmt::Display for Type {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match *self {
            Type::OpReturn => write!(f, "OpReturn"),
            Type::Pay2MultiSig => write!(f, "Pay2MultiSig"),
            Type::Pay2PublicKey => write!(f, "Pay2PublicKey"),
            Type::Pay2PublicKeyHash => write!(f, "Pay2PublicKeyHash"),
            Type::Pay2ScriptHash => write!(f, "Pay2ScriptHash"),
            Type::Pay2WitnessPublicKeyHash => write!(f, "Pay2WitnessPublicKeyHash"),
            Type::Pay2WitnessScriptHash => write!(f, "Pay2WitnessScriptHash"),
            Type::WitnessProgram => write!(f, "WitnessProgram"),
            Type::Unspendable => write!(f, "Unspendable"),
            Type::NotRecognised => write!(f, "NotRecognised"),
        }
    }
}

#[derive(Clone, Debug, Serialize, Deserialize)]
pub struct ScriptInfo {
    pub addresses: Vec<Address>,
    pub pattern: Type,
}

impl ScriptInfo {
    pub fn new(address: Option<Address>, pattern: Type) -> Self {
        if let Some(address) = address {
            Self::new_from_vec(vec![address], pattern)
        } else {
            Self::new_from_vec(Vec::new(), pattern)
        }
    }

    pub fn new_from_vec(addresses: Vec<Address>, pattern: Type) -> Self {
        Self { addresses, pattern }
    }
}

fn p2pk_to_address(script: &Script) -> Option<Address> {
    assert!(script.is_p2pk());
    let pk = match script.instructions().next() {
        Some(Ok(Instruction::PushBytes(bytes))) => bytes,
        _ => {
            unreachable!()
        }
    };

    let pkh = hash160::Hash::hash(pk);

    let address = Address {
        payload: Payload::PubkeyHash(PubkeyHash::from_slice(&pkh).ok()?),
        network: Network::Bitcoin,
    };
    Some(address)
}

trait Cmp {
    fn ge(&self, other: &Self) -> bool;
}

impl Cmp for bitcoin::blockdata::opcodes::All {
    fn ge(&self, other: &Self) -> bool {
        self.into_u8() >= other.into_u8()
    }
}

fn decode_from_op_n(op: &All) -> i32 {
    if op.eq(&all::OP_PUSHBYTES_0) {
        0
    } else if op.eq(&all::OP_PUSHNUM_NEG1) {
        -1
    } else {
        op.into_u8() as i32 + 1 - all::OP_PUSHNUM_1.into_u8() as i32
    }
}

/// according to bitcoinj
fn is_multisig(script: &Script) -> bool {
    let mut chunks: Vec<Instruction> = Vec::new();
    for i in script.instructions() {
        if let Ok(i) = i {
            chunks.push(i);
        } else {
            return false;
        }
    }
    if chunks.len() < 4 {
        return false;
    }
    let last_chunk = chunks.get(chunks.len() - 1).unwrap();
    // Must end in OP_CHECKMULTISIG[VERIFY].
    match last_chunk {
        PushBytes(_) => {
            return false;
        }
        Op(op) => {
            if !(op.eq(&all::OP_CHECKMULTISIG) || op.eq(&all::OP_CHECKMULTISIGVERIFY)) {
                return false;
            }
        }
    }
    let second_last_chunk = chunks.get(chunks.len() - 2).unwrap();
    // Second to last chunk must be an OP_N opcode and there should be that many data chunks (keys).
    match second_last_chunk {
        PushBytes(_) => {
            return false;
        }
        Op(op) => {
            if !(op.eq(&all::OP_PUSHNUM_NEG1)
                || op.eq(&all::OP_PUSHBYTES_0)
                || (op.ge(&all::OP_PUSHNUM_1) && all::OP_PUSHNUM_16.ge(op)))
            {
                return false;
            } else {
                let num_keys = decode_from_op_n(op);
                if num_keys < 1 || (num_keys + 3) as usize != chunks.len() {
                    return false;
                }
            }
        }
    }
    // the rest must be data
    for i in 1..(chunks.len() - 2) {
        match chunks.get(i).unwrap() {
            PushBytes(_) => {}
            Op(_) => {
                return false;
            }
        }
    }
    let first_chunk = chunks.get(0).unwrap();
    // First chunk must be an OP_N opcode too.
    match first_chunk {
        PushBytes(_) => {
            return false;
        }
        Op(op) => {
            if !(op.eq(&all::OP_PUSHNUM_NEG1)
                || op.eq(&all::OP_PUSHBYTES_0)
                || (op.ge(&all::OP_PUSHNUM_1) && all::OP_PUSHNUM_16.ge(op)))
            {
                return false;
            } else {
                if decode_from_op_n(op) < 1 {
                    return false;
                }
            }
        }
    }
    return true;
}

fn get_pub_keys(script: &Script) -> OpResult<Vec<PublicKey>> {
    assert!(is_multisig(script));
    let ops: Vec<Instruction> = script.instructions().map(|o| o.unwrap()).collect();
    if let Op(op) = ops.get(ops.len() - 2).unwrap() {
        let num_keys = decode_from_op_n(op);
        let mut public_keys = Vec::with_capacity(num_keys as usize);
        for i in 0..num_keys {
            if let Some(PushBytes(data)) = ops.get(i as usize + 1) {
                match PublicKey::from_slice(data) {
                    Ok(pk) => public_keys.push(pk),
                    Err(_) => return Err(OpError::from("failed to parse public key")),
                }
            } else {
                // assert! is_multisig
                unreachable!()
            }
        }
        Ok(public_keys)
    } else {
        // assert! is_multisig
        unreachable!()
    }
}

/// get list of keys from multisig transaction
/// return empty list if the script cannot be parsed
fn pub_keys_to_addresses(script: &Script) -> Vec<Address> {
    assert!(is_multisig(script));
    if let Ok(pub_keys) = get_pub_keys(&script) {
        pub_keys
            .iter()
            .map(|k| Address {
                payload: Payload::PubkeyHash(k.pubkey_hash()),
                network: Network::Bitcoin,
            })
            .collect()
    } else {
        Vec::new()
    }
}

pub fn evaluate_script(script: &Script, net: Network) -> ScriptInfo {
    let address = Address::from_script(&script, net);
    if script.is_p2pk() {
        ScriptInfo::new(p2pk_to_address(&script), Type::Pay2PublicKey)
    } else if script.is_p2pkh() {
        ScriptInfo::new(address, Type::Pay2PublicKeyHash)
    } else if script.is_p2sh() {
        ScriptInfo::new(address, Type::Pay2ScriptHash)
    } else if script.is_v0_p2wpkh() {
        ScriptInfo::new(address, Type::Pay2WitnessPublicKeyHash)
    } else if script.is_v0_p2wsh() {
        ScriptInfo::new(address, Type::Pay2WitnessScriptHash)
    } else if script.is_witness_program() {
        ScriptInfo::new(address, Type::WitnessProgram)
    } else if script.is_op_return() {
        ScriptInfo::new(address, Type::OpReturn)
    } else if script.is_provably_unspendable() {
        ScriptInfo::new(address, Type::Unspendable)
    } else if is_multisig(&script) {
        ScriptInfo::new_from_vec(pub_keys_to_addresses(&script), Type::Pay2MultiSig)
    } else {
        ScriptInfo::new(address, Type::NotRecognised)
    }
}

#[cfg(test)]
mod tests {
    use super::{evaluate_script, Type};
    use bitcoin::hashes::hex::{FromHex, ToHex};
    use bitcoin::{Network, Script};

    #[test]
    fn test_bitcoin_script_p2pkh() {
        // Raw output script: 76a91412ab8dc588ca9d5787dde7eb29569da63c3a238c88ac
        //                    OP_DUP OP_HASH160 OP_PUSHDATA0(20 bytes) 12ab8dc588ca9d5787dde7eb29569da63c3a238c OP_EQUALVERIFY OP_CHECKSIG
        let bytes = [
            0x76 as u8, 0xa9, 0x14, 0x12, 0xab, 0x8d, 0xc5, 0x88, 0xca, 0x9d, 0x57, 0x87, 0xdd,
            0xe7, 0xeb, 0x29, 0x56, 0x9d, 0xa6, 0x3c, 0x3a, 0x23, 0x8c, 0x88, 0xac,
        ];
        let result = evaluate_script(
            &Script::from_hex(&bytes.to_hex()).unwrap(),
            Network::Bitcoin,
        );
        assert_eq!(
            result.addresses.get(0).unwrap().to_string(),
            String::from("12higDjoCCNXSA95xZMWUdPvXNmkAduhWv")
        );
        assert_eq!(result.pattern, Type::Pay2PublicKeyHash);
    }

    #[test]
    fn test_bitcoin_script_p2pk() {
        // https://blockchain.info/tx/e36f06a8dfe44c3d64be2d3fe56c77f91f6a39da4a5ffc086ecb5db9664e8583
        // Raw output script: 0x41 0x044bca633a91de10df85a63d0a24cb09783148fe0e16c92e937fc4491580c860757148effa0595a955f44078b48ba67fa198782e8bb68115da0daa8fde5301f7f9 OP_CHECKSIG
        //                    OP_PUSHDATA0(65 bytes) 0x04bdca... OP_CHECKSIG
        let bytes = [
            0x41 as u8, // Push next 65 bytes
            0x04, 0x4b, 0xca, 0x63, 0x3a, 0x91, 0xde, 0x10, 0xdf, 0x85, 0xa6, 0x3d, 0x0a, 0x24,
            0xcb, 0x09, 0x78, 0x31, 0x48, 0xfe, 0x0e, 0x16, 0xc9, 0x2e, 0x93, 0x7f, 0xc4, 0x49,
            0x15, 0x80, 0xc8, 0x60, 0x75, 0x71, 0x48, 0xef, 0xfa, 0x05, 0x95, 0xa9, 0x55, 0xf4,
            0x40, 0x78, 0xb4, 0x8b, 0xa6, 0x7f, 0xa1, 0x98, 0x78, 0x2e, 0x8b, 0xb6, 0x81, 0x15,
            0xda, 0x0d, 0xaa, 0x8f, 0xde, 0x53, 0x01, 0xf7, 0xf9, 0xac,
        ]; // OP_CHECKSIG
        let result = evaluate_script(
            &Script::from_hex(&bytes.to_hex()).unwrap(),
            Network::Bitcoin,
        );
        assert_eq!(
            result.addresses.get(0).unwrap().to_string(),
            String::from("1LEWwJkDj8xriE87ALzQYcHjTmD8aqDj1f")
        );
        assert_eq!(result.pattern, Type::Pay2PublicKey);
    }

    #[test]
    fn test_bitcoin_script_p2ms() {
        // 2-of-3 Multi sig output
        // OP_2 33 0x022df8750480ad5b26950b25c7ba79d3e37d75f640f8e5d9bcd5b150a0f85014da
        // 33 0x03e3818b65bcc73a7d64064106a859cc1a5a728c4345ff0b641209fba0d90de6e9
        // 33 0x021f2f6e1e50cb6a953935c3601284925decd3fd21bc445712576873fb8c6ebc18 OP_3 OP_CHECKMULTISIG
        let bytes = [
            0x52 as u8, 0x21, 0x02, 0x2d, 0xf8, 0x75, 0x04, 0x80, 0xad, 0x5b, 0x26, 0x95, 0x0b,
            0x25, 0xc7, 0xba, 0x79, 0xd3, 0xe3, 0x7d, 0x75, 0xf6, 0x40, 0xf8, 0xe5, 0xd9, 0xbc,
            0xd5, 0xb1, 0x50, 0xa0, 0xf8, 0x50, 0x14, 0xda, 0x21, 0x03, 0xe3, 0x81, 0x8b, 0x65,
            0xbc, 0xc7, 0x3a, 0x7d, 0x64, 0x06, 0x41, 0x06, 0xa8, 0x59, 0xcc, 0x1a, 0x5a, 0x72,
            0x8c, 0x43, 0x45, 0xff, 0x0b, 0x64, 0x12, 0x09, 0xfb, 0xa0, 0xd9, 0x0d, 0xe6, 0xe9,
            0x21, 0x02, 0x1f, 0x2f, 0x6e, 0x1e, 0x50, 0xcb, 0x6a, 0x95, 0x39, 0x35, 0xc3, 0x60,
            0x12, 0x84, 0x92, 0x5d, 0xec, 0xd3, 0xfd, 0x21, 0xbc, 0x44, 0x57, 0x12, 0x57, 0x68,
            0x73, 0xfb, 0x8c, 0x6e, 0xbc, 0x18, 0x53, 0xae,
        ];

        let result = evaluate_script(
            &Script::from_hex(&bytes.to_hex()).unwrap(),
            Network::Bitcoin,
        );
        assert_eq!(result.pattern, Type::Pay2MultiSig);
    }

    #[test]
    fn test_bitcoin_script_p2sh() {
        // Raw output script: a914e9c3dd0c07aac76179ebc76a6c78d4d67c6c160a
        //                    OP_HASH160 20 0xe9c3dd0c07aac76179ebc76a6c78d4d67c6c160a OP_EQUAL
        let bytes = [
            0xa9 as u8, 0x14, // OP_HASH160, OP_PUSHDATA0(20 bytes)
            0xe9, 0xc3, 0xdd, 0x0c, 0x07, 0xaa, 0xc7, 0x61, 0x79, 0xeb, 0xc7, 0x6a, 0x6c, 0x78,
            0xd4, 0xd6, 0x7c, 0x6c, 0x16, 0x0a, 0x87,
        ]; // OP_EQUAL
        let result = evaluate_script(
            &Script::from_hex(&bytes.to_hex()).unwrap(),
            Network::Bitcoin,
        );
        assert_eq!(
            result.addresses.get(0).unwrap().to_string(),
            String::from("3P14159f73E4gFr7JterCCQh9QjiTjiZrG")
        );
        assert_eq!(result.pattern, Type::Pay2ScriptHash);
    }

    #[test]
    fn test_bitcoin_script_non_standard() {
        // Raw output script: 736372697074
        //                    OP_IFDUP OP_IF OP_2SWAP OP_VERIFY OP_2OVER OP_DEPTH
        let bytes = [0x73 as u8, 0x63, 0x72, 0x69, 0x70, 0x74];
        let result = evaluate_script(
            &Script::from_hex(&bytes.to_hex()).unwrap(),
            Network::Bitcoin,
        );
        assert_eq!(result.addresses.get(0), None);
        assert_eq!(result.pattern, Type::NotRecognised);
    }

    #[test]
    fn test_bitcoin_bogus_script() {
        let bytes = [0x4c as u8, 0xFF, 0x00];
        let result = evaluate_script(
            &Script::from_hex(&bytes.to_hex()).unwrap(),
            Network::Bitcoin,
        );
        assert_eq!(result.addresses.get(0), None);
        assert_eq!(result.pattern, Type::NotRecognised);
    }
}