use std::str::FromStr;
use std::fmt;
use std::hash::{Hash, Hasher};
use std::ops::{Index, IndexMut, BitOr};
use rustc_serialize::hex::*;
use error::EthcoreError;
use rand::Rng;
use rand::os::OsRng;
use bytes::BytesConvertable;

/// types implementing FixedHash must be also BytesConvertable
pub trait FixedHash: Sized + BytesConvertable {
	fn new() -> Self;
	fn random() -> Self;
	fn randomize(&mut self);
	fn mut_bytes(&mut self) -> &mut [u8];
	fn shift_bloom<'a, T>(&'a mut self, b: &T) -> &'a mut Self where T: FixedHash;
	fn bloom_part<T>(&self) -> T where T: FixedHash;
}

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

		impl BytesConvertable for $from {
			fn bytes(&self) -> &[u8] {
				&self.0
			}
		}

		impl FixedHash for $from {
			fn new() -> $from {
				$from([0; $size])
			}

			fn random() -> $from {
				let mut hash = $from::new();
				hash.randomize();
				hash
			}

			fn randomize(&mut self) {
				let mut rng = OsRng::new().unwrap();
				rng.fill_bytes(&mut self.0);
			}

			fn mut_bytes(&mut self) -> &mut [u8] {
				&mut self.0
			}

			fn shift_bloom<'a, T>(&'a mut self, b: &T) -> &'a mut Self where T: FixedHash {
				let bp: Self = b.bloom_part();
				let new_self = &bp | self;

				// impl |= instead

				unsafe {
					use std::{mem, ptr};
					ptr::copy(new_self.0.as_ptr(), self.0.as_mut_ptr(), mem::size_of::<Self>());
				}

				self
			}

			fn bloom_part<T>(&self) -> T where T: FixedHash {
				panic!()
			}
		}

		impl FromStr for $from {
			type Err = EthcoreError;

			fn from_str(s: &str) -> Result<$from, EthcoreError> {
				let a = try!(s.from_hex());
				if a.len() != $size { return Err(EthcoreError::BadSize); }
				let mut ret = $from([0;$size]);
				for i in 0..$size {
					ret.0[i] = a[i];
				}
				Ok(ret)
			}
		}

		impl fmt::Debug for $from {
			fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
				for i in self.0.iter() {
					try!(write!(f, "{:02x}", i));
				}
				Ok(())
			}
		}
		impl fmt::Display for $from {
			fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
				(self as &fmt::Debug).fmt(f)
			}
		}

		impl Clone for $from {
			fn clone(&self) -> $from {
				unsafe {
					use std::{mem, ptr};
					let mut ret: $from = mem::uninitialized();
					ptr::copy(self.0.as_ptr(), ret.0.as_mut_ptr(), mem::size_of::<$from>());
					ret
				}
			}
		}

		impl PartialEq for $from {
			fn eq(&self, other: &Self) -> bool {
				for i in 0..$size {
					if self.0[i] != other.0[i] {
						return false;
					}
				}
				true
			}
		}

		impl Hash for $from {
			fn hash<H>(&self, state: &mut H) where H: Hasher {
				state.write(&self.0);
				state.finish();
			}
		}

		impl Index<usize> for $from {
			type Output = u8;

			fn index<'a>(&'a self, index: usize) -> &'a u8 {
				&self.0[index]
			}
		}
		impl IndexMut<usize> for $from {
			fn index_mut<'a>(&'a mut self, index: usize) -> &'a mut u8 {
				&mut self.0[index]
			}
		}

		impl<'a> BitOr for &'a $from {
			type Output = $from;

			fn bitor(self, rhs: Self) -> Self::Output {
				unsafe {
					use std::mem;
					let mut ret: $from = mem::uninitialized();
					for i in 0..$size {
						ret.0[i] = self.0[i] | rhs.0[i];
					}
					ret
				}
			}
		}

		impl BitOr for $from {
			type Output = $from;

			fn bitor(self, rhs: Self) -> Self::Output {
				&self | &rhs
			}
		}

	}
}

impl_hash!(H64, 8);
impl_hash!(H128, 16);
impl_hash!(Address, 20);
impl_hash!(H256, 32);
impl_hash!(H512, 64);
impl_hash!(H520, 65);
impl_hash!(H1024, 128);
impl_hash!(H2048, 256);

#[test]
fn hash() {
	let h = H64([0x01, 0x23, 0x45, 0x67, 0x89, 0xab, 0xcd, 0xef]);
	assert_eq!(H64::from_str("0123456789abcdef").unwrap(), h);
	assert_eq!(format!("{}", h), "0123456789abcdef");
	assert_eq!(format!("{:?}", h), "0123456789abcdef");
	assert!(h == h);
	assert!(h != H64([0x01, 0x23, 0x45, 0x67, 0x89, 0xab, 0xcd, 0xee]));
	assert!(h != H64([0; 8]));
}

#[test]
fn hash_bitor() {
	let a = H64([1; 8]);
	let b = H64([2; 8]);
	let c = H64([3; 8]);

	// borrow
	assert_eq!(&a | &b, c);

	// move
	assert_eq!(a | b, c);
}