use crate::{Header, SealedHeader, TransactionSigned, H256};
use reth_rlp::{Decodable, DecodeError, Encodable, RlpDecodable, RlpEncodable};
use std::ops::Deref;

/// Ethereum full block.
#[derive(Debug, Clone, PartialEq, Eq, Default, RlpEncodable, RlpDecodable)]
pub struct Block {
    /// Block header.
    pub header: Header,
    /// Transactions in this block.
    pub body: Vec<TransactionSigned>,
    /// Ommers/uncles header
    pub ommers: Vec<SealedHeader>,
}

impl Deref for Block {
    type Target = Header;
    fn deref(&self) -> &Self::Target {
        &self.header
    }
}

/// Sealed Ethereum full block.
#[derive(Debug, Clone, PartialEq, Eq, Default, RlpEncodable, RlpDecodable)]
pub struct BlockLocked {
    /// Locked block header.
    pub header: SealedHeader,
    /// Transactions with signatures.
    pub body: Vec<TransactionSigned>,
    /// Ommer/uncle headers
    pub ommers: Vec<SealedHeader>,
}

impl BlockLocked {
    /// Header hash.
    pub fn hash(&self) -> H256 {
        self.header.hash()
    }
}

impl Deref for BlockLocked {
    type Target = Header;
    fn deref(&self) -> &Self::Target {
        self.header.as_ref()
    }
}

/// Either a block hash _or_ a block number
#[derive(Copy, Clone, Debug, PartialEq, Eq)]
pub enum BlockHashOrNumber {
    /// A block hash
    Hash(H256),
    /// A block number
    Number(u64),
}

impl From<H256> for BlockHashOrNumber {
    fn from(value: H256) -> Self {
        BlockHashOrNumber::Hash(value)
    }
}

impl From<u64> for BlockHashOrNumber {
    fn from(value: u64) -> Self {
        BlockHashOrNumber::Number(value)
    }
}

/// Allows for RLP encoding of either a block hash or block number
impl Encodable for BlockHashOrNumber {
    fn length(&self) -> usize {
        match self {
            Self::Hash(block_hash) => block_hash.length(),
            Self::Number(block_number) => block_number.length(),
        }
    }
    fn encode(&self, out: &mut dyn bytes::BufMut) {
        match self {
            Self::Hash(block_hash) => block_hash.encode(out),
            Self::Number(block_number) => block_number.encode(out),
        }
    }
}

/// Allows for RLP decoding of a block hash or block number
impl Decodable for BlockHashOrNumber {
    fn decode(buf: &mut &[u8]) -> Result<Self, DecodeError> {
        let header: u8 = *buf.first().ok_or(DecodeError::InputTooShort)?;
        // if the byte string is exactly 32 bytes, decode it into a Hash
        // 0xa0 = 0x80 (start of string) + 0x20 (32, length of string)
        if header == 0xa0 {
            // strip the first byte, parsing the rest of the string.
            // If the rest of the string fails to decode into 32 bytes, we'll bubble up the
            // decoding error.
            let hash = H256::decode(buf)?;
            Ok(Self::Hash(hash))
        } else {
            // a block number when encoded as bytes ranges from 0 to any number of bytes - we're
            // going to accept numbers which fit in less than 64 bytes.
            // Any data larger than this which is not caught by the Hash decoding should error and
            // is considered an invalid block number.
            Ok(Self::Number(u64::decode(buf)?))
        }
    }
}