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// Copyright 2015-2019 Parity Technologies (UK) Ltd.
// This file is part of Parity Ethereum.

// Parity Ethereum is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// Parity Ethereum is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with Parity Ethereum.  If not, see <http://www.gnu.org/licenses/>.

use super::Error;
use rustc_hex::{FromHex, ToHex};
use serde::{
    de::{Error as SerdeError, Visitor},
    Deserialize, Deserializer, Serialize, Serializer,
};
use std::{cmp::Ordering, fmt, ops, str};

macro_rules! impl_hash {
    ($name:ident, $size:expr) => {
        pub struct $name([u8; $size]);

        impl $name {
            pub fn at(&self, idx: usize) -> u8 {
                assert!(idx < $size);
                self.0[idx]
            }
        }

        impl fmt::Debug for $name {
            fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
                let self_ref: &[u8] = &self.0;
                write!(f, "{:?}", self_ref)
            }
        }

        impl PartialEq for $name {
            fn eq(&self, other: &Self) -> bool {
                let self_ref: &[u8] = &self.0;
                let other_ref: &[u8] = &other.0;
                self_ref == other_ref
            }
        }

        impl ops::Deref for $name {
            type Target = [u8];

            fn deref(&self) -> &Self::Target { &self.0 }
        }

        impl Serialize for $name {
            fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
            where S: Serializer {
                serializer.serialize_str(&self.0.to_hex::<String>())
            }
        }

        impl<'a> Deserialize<'a> for $name {
            fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
            where D: Deserializer<'a> {
                struct HashVisitor;

                impl<'b> Visitor<'b> for HashVisitor {
                    type Value = $name;

                    fn expecting(
                        &self, formatter: &mut fmt::Formatter,
                    ) -> fmt::Result {
                        write!(formatter, "a hex-encoded {}", stringify!($name))
                    }

                    fn visit_str<E>(
                        self, value: &str,
                    ) -> Result<Self::Value, E>
                    where E: SerdeError {
                        value.parse().map_err(SerdeError::custom)
                    }

                    fn visit_string<E>(
                        self, value: String,
                    ) -> Result<Self::Value, E>
                    where E: SerdeError {
                        self.visit_str(value.as_ref())
                    }
                }

                deserializer.deserialize_any(HashVisitor)
            }
        }

        impl str::FromStr for $name {
            type Err = Error;

            fn from_str(value: &str) -> Result<Self, Self::Err> {
                match value.from_hex::<Vec<u8>>() {
                    Ok(ref hex) if hex.len() == $size => {
                        let mut hash = [0u8; $size];
                        hash.clone_from_slice(hex);
                        Ok($name(hash))
                    }
                    _ => Err(Error::InvalidH256),
                }
            }
        }

        impl From<&'static str> for $name {
            fn from(s: &'static str) -> Self {
                s.parse().expect(&format!(
                    "invalid string literal for {}: '{}'",
                    stringify!($name),
                    s
                ))
            }
        }

        impl From<[u8; $size]> for $name {
            fn from(bytes: [u8; $size]) -> Self { $name(bytes) }
        }

        impl Into<[u8; $size]> for $name {
            fn into(self) -> [u8; $size] { self.0 }
        }
    };
}

impl_hash!(H128, 16);
impl_hash!(H160, 20);
impl_hash!(H256, 32);

// FIXME: find a better hash type.
impl PartialOrd for H160 {
    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
        Some(self.cmp(other))
    }
}

impl Eq for H160 {}

impl Ord for H160 {
    fn cmp(&self, other: &Self) -> Ordering { self.0.cmp(&other.0) }
}