// Rust Bitcoin Library
// Written by
//   The Rust Bitcoin developers
//
// To the extent possible under law, the author(s) have dedicated all
// copyright and related and neighboring rights to this software to
// the public domain worldwide. This software is distributed without
// any warranty.
//
// You should have received a copy of the CC0 Public Domain Dedication
// along with this software.
// If not, see <http://creativecommons.org/publicdomain/zero/1.0/>.
//

//! Raw PSBT key-value pairs.
//!
//! Raw PSBT key-value pairs as defined at
//! <https://github.com/bitcoin/bips/blob/master/bip-0174.mediawiki>.
//!

use crate::prelude::*;
use core::fmt;

use crate::io;
use crate::consensus::encode::{self, ReadExt, WriteExt, Decodable, Encodable, VarInt, serialize, deserialize, MAX_VEC_SIZE};
use crate::hashes::hex;
use crate::util::psbt::Error;
use crate::util::read_to_end;

/// A PSBT key in its raw byte form.
#[derive(Debug, PartialEq, Hash, Eq, Clone, Ord, PartialOrd)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
pub struct Key {
    /// The type of this PSBT key.
    pub type_value: u8,
    /// The key itself in raw byte form.
    #[cfg_attr(feature = "serde", serde(with = "::serde_utils::hex_bytes"))]
    pub key: Vec<u8>,
}

/// A PSBT key-value pair in its raw byte form.
#[derive(Debug, PartialEq)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
pub struct Pair {
    /// The key of this key-value pair.
    pub key: Key,
    /// The value of this key-value pair in raw byte form.
    #[cfg_attr(feature = "serde", serde(with = "::serde_utils::hex_bytes"))]
    pub value: Vec<u8>,
}

/// Default implementation for proprietary key subtyping
pub type ProprietaryType = u8;

/// Proprietary keys (i.e. keys starting with 0xFC byte) with their internal
/// structure according to BIP 174.
#[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
pub struct ProprietaryKey<Subtype=ProprietaryType> where Subtype: Copy + From<u8> + Into<u8> {
    /// Proprietary type prefix used for grouping together keys under some
    /// application and avoid namespace collision
    #[cfg_attr(feature = "serde", serde(with = "::serde_utils::hex_bytes"))]
    pub prefix: Vec<u8>,
    /// Custom proprietary subtype
    pub subtype: Subtype,
    /// Additional key bytes (like serialized public key data etc)
    #[cfg_attr(feature = "serde", serde(with = "::serde_utils::hex_bytes"))]
    pub key: Vec<u8>,
}

impl fmt::Display for Key {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "type: {:#x}, key: ", self.type_value)?;
        hex::format_hex(&self.key[..], f)
    }
}

impl Decodable for Key {
    fn consensus_decode<D: io::Read>(mut d: D) -> Result<Self, encode::Error> {
        let VarInt(byte_size): VarInt = Decodable::consensus_decode(&mut d)?;

        if byte_size == 0 {
            return Err(Error::NoMorePairs.into());
        }

        let key_byte_size: u64 = byte_size - 1;

        if key_byte_size > MAX_VEC_SIZE as u64 {
            return Err(encode::Error::OversizedVectorAllocation {
                requested: key_byte_size as usize,
                max: MAX_VEC_SIZE,
            })
        }

        let type_value: u8 = Decodable::consensus_decode(&mut d)?;

        let mut key = Vec::with_capacity(key_byte_size as usize);
        for _ in 0..key_byte_size {
            key.push(Decodable::consensus_decode(&mut d)?);
        }

        Ok(Key { type_value, key })
    }
}

impl Encodable for Key {
    fn consensus_encode<S: io::Write>(&self, mut s: S) -> Result<usize, io::Error> {
        let mut len = 0;
        len += VarInt((self.key.len() + 1) as u64).consensus_encode(&mut s)?;

        len += self.type_value.consensus_encode(&mut s)?;

        for key in &self.key {
            len += key.consensus_encode(&mut s)?
        }

        Ok(len)
    }
}

impl Encodable for Pair {
    fn consensus_encode<S: io::Write>(&self, mut s: S) -> Result<usize, io::Error> {
        let len = self.key.consensus_encode(&mut s)?;
        Ok(len + self.value.consensus_encode(s)?)
    }
}

impl Decodable for Pair {
    fn consensus_decode<D: io::Read>(mut d: D) -> Result<Self, encode::Error> {
        Ok(Pair {
            key: Decodable::consensus_decode(&mut d)?,
            value: Decodable::consensus_decode(d)?,
        })
    }
}

impl<Subtype> Encodable for ProprietaryKey<Subtype> where Subtype: Copy + From<u8> + Into<u8> {
    fn consensus_encode<W: io::Write>(&self, mut e: W) -> Result<usize, io::Error> {
        let mut len = self.prefix.consensus_encode(&mut e)? + 1;
        e.emit_u8(self.subtype.into())?;
        e.write_all(&self.key)?;
        len += self.key.len();
        Ok(len)
    }
}

impl<Subtype> Decodable for ProprietaryKey<Subtype> where Subtype: Copy + From<u8> + Into<u8> {
    fn consensus_decode<D: io::Read>(mut d: D) -> Result<Self, encode::Error> {
        let prefix = Vec::<u8>::consensus_decode(&mut d)?;
        let subtype = Subtype::from(d.read_u8()?);
        let key = read_to_end(d)?;

        Ok(ProprietaryKey { prefix, subtype, key })
    }
}

impl<Subtype> ProprietaryKey<Subtype> where Subtype: Copy + From<u8> + Into<u8> {
    /// Constructs [ProprietaryKey] from [Key]; returns
    /// [Error::InvalidProprietaryKey] if `key` do not starts with 0xFC byte
    pub fn from_key(key: Key) -> Result<Self, Error> {
        if key.type_value != 0xFC {
            return Err(Error::InvalidProprietaryKey)
        }

        Ok(deserialize(&key.key)?)
    }

    /// Constructs full [Key] corresponding to this proprietary key type
    pub fn to_key(&self) -> Key {
        Key {
            type_value: 0xFC,
            key: serialize(self)
        }
    }
}