// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

use T = self::inst::T;
use T_SIGNED = self::inst::T_SIGNED;

use from_str::FromStr;
use num::{ToStrRadix, FromStrRadix};
use num::strconv;
use prelude::*;

pub use cmp::{min, max};

pub static bits : uint = inst::bits;
pub static bytes : uint = (inst::bits / 8);

pub static min_value: T = 0 as T;
pub static max_value: T = 0 as T - 1 as T;

#[inline(always)]
pub fn add(x: T, y: T) -> T { x + y }
#[inline(always)]
pub fn sub(x: T, y: T) -> T { x - y }
#[inline(always)]
pub fn mul(x: T, y: T) -> T { x * y }
#[inline(always)]
pub fn quot(x: T, y: T) -> T { x / y }
#[inline(always)]
pub fn rem(x: T, y: T) -> T { x % y }

#[inline(always)]
pub fn lt(x: T, y: T) -> bool { x < y }
#[inline(always)]
pub fn le(x: T, y: T) -> bool { x <= y }
#[inline(always)]
pub fn eq(x: T, y: T) -> bool { x == y }
#[inline(always)]
pub fn ne(x: T, y: T) -> bool { x != y }
#[inline(always)]
pub fn ge(x: T, y: T) -> bool { x >= y }
#[inline(always)]
pub fn gt(x: T, y: T) -> bool { x > y }

#[inline(always)]
/**
 * Iterate over the range [`start`,`start`+`step`..`stop`)
 *
 */
pub fn range_step(start: T,
                       stop: T,
                       step: T_SIGNED,
                       it: &fn(T) -> bool) {
    let mut i = start;
    if step == 0 {
        fail!(~"range_step called with step == 0");
    }
    if step >= 0 {
        while i < stop {
            if !it(i) { break }
            // avoiding overflow. break if i + step > max_value
            if i > max_value - (step as T) { break; }
            i += step as T;
        }
    } else {
        while i > stop {
            if !it(i) { break }
            // avoiding underflow. break if i + step < min_value
            if i < min_value + ((-step) as T) { break; }
            i -= -step as T;
        }
    }
}

#[inline(always)]
/// Iterate over the range [`lo`..`hi`)
pub fn range(lo: T, hi: T, it: &fn(T) -> bool) {
    range_step(lo, hi, 1 as T_SIGNED, it);
}

#[inline(always)]
/// Iterate over the range [`hi`..`lo`)
pub fn range_rev(hi: T, lo: T, it: &fn(T) -> bool) {
    range_step(hi, lo, -1 as T_SIGNED, it);
}

/// Computes the bitwise complement
#[inline(always)]
pub fn compl(i: T) -> T {
    max_value ^ i
}

impl Num for T {}

#[cfg(notest)]
impl Ord for T {
    #[inline(always)]
    fn lt(&self, other: &T) -> bool { (*self) < (*other) }
    #[inline(always)]
    fn le(&self, other: &T) -> bool { (*self) <= (*other) }
    #[inline(always)]
    fn ge(&self, other: &T) -> bool { (*self) >= (*other) }
    #[inline(always)]
    fn gt(&self, other: &T) -> bool { (*self) > (*other) }
}

#[cfg(notest)]
impl Eq for T {
    #[inline(always)]
    fn eq(&self, other: &T) -> bool { return (*self) == (*other); }
    #[inline(always)]
    fn ne(&self, other: &T) -> bool { return (*self) != (*other); }
}

impl num::Zero for T {
    #[inline(always)]
    fn zero() -> T { 0 }
}

impl num::One for T {
    #[inline(always)]
    fn one() -> T { 1 }
}

#[cfg(notest)]
impl Add<T,T> for T {
    #[inline(always)]
    fn add(&self, other: &T) -> T { *self + *other }
}

#[cfg(notest)]
impl Sub<T,T> for T {
    #[inline(always)]
    fn sub(&self, other: &T) -> T { *self - *other }
}

#[cfg(notest)]
impl Mul<T,T> for T {
    #[inline(always)]
    fn mul(&self, other: &T) -> T { *self * *other }
}

#[cfg(stage0,notest)]
impl Div<T,T> for T {
    #[inline(always)]
    fn div(&self, other: &T) -> T { *self / *other }
}
#[cfg(not(stage0),notest)]
impl Quot<T,T> for T {
    #[inline(always)]
    fn quot(&self, other: &T) -> T { *self / *other }
}

#[cfg(stage0,notest)]
impl Modulo<T,T> for T {
    #[inline(always)]
    fn modulo(&self, other: &T) -> T { *self % *other }
}
#[cfg(not(stage0),notest)]
impl Rem<T,T> for T {
    #[inline(always)]
    fn rem(&self, other: &T) -> T { *self % *other }
}

#[cfg(notest)]
impl Neg<T> for T {
    #[inline(always)]
    fn neg(&self) -> T { -*self }
}

impl Unsigned for T {}

impl Integer for T {
    /// Unsigned integer division. Returns the same result as `quot` (`/`).
    #[inline(always)]
    fn div(&self, other: &T) -> T { *self / *other }

    /// Unsigned integer modulo operation. Returns the same result as `rem` (`%`).
    #[inline(always)]
    fn modulo(&self, other: &T) -> T { *self / *other }

    /// Calculates `div` and `modulo` simultaneously
    #[inline(always)]
    fn div_mod(&self, other: &T) -> (T,T) {
        (*self / *other, *self % *other)
    }

    /// Calculates `quot` (`\`) and `rem` (`%`) simultaneously
    #[inline(always)]
    fn quot_rem(&self, other: &T) -> (T,T) {
        (*self / *other, *self % *other)
    }

    /// Calculates the Greatest Common Divisor (GCD) of the number and `other`
    #[inline(always)]
    fn gcd(&self, other: &T) -> T {
        // Use Euclid's algorithm
        let mut m = *self, n = *other;
        while m != 0 {
            let temp = m;
            m = n % temp;
            n = temp;
        }
        n
    }

    /// Calculates the Lowest Common Multiple (LCM) of the number and `other`
    #[inline(always)]
    fn lcm(&self, other: &T) -> T {
        (*self * *other) / self.gcd(other)
    }

    /// Returns `true` if the number can be divided by `other` without leaving a remainder
    #[inline(always)]
    fn divisible_by(&self, other: &T) -> bool { *self % *other == 0 }

    /// Returns `true` if the number is divisible by `2`
    #[inline(always)]
    fn is_even(&self) -> bool { self.divisible_by(&2) }

    /// Returns `true` if the number is not divisible by `2`
    #[inline(always)]
    fn is_odd(&self) -> bool { !self.is_even() }
}

#[cfg(notest)]
impl BitOr<T,T> for T {
    #[inline(always)]
    fn bitor(&self, other: &T) -> T { *self | *other }
}

#[cfg(notest)]
impl BitAnd<T,T> for T {
    #[inline(always)]
    fn bitand(&self, other: &T) -> T { *self & *other }
}

#[cfg(notest)]
impl BitXor<T,T> for T {
    #[inline(always)]
    fn bitxor(&self, other: &T) -> T { *self ^ *other }
}

#[cfg(notest)]
impl Shl<T,T> for T {
    #[inline(always)]
    fn shl(&self, other: &T) -> T { *self << *other }
}

#[cfg(notest)]
impl Shr<T,T> for T {
    #[inline(always)]
    fn shr(&self, other: &T) -> T { *self >> *other }
}

#[cfg(notest)]
impl Not<T> for T {
    #[inline(always)]
    fn not(&self) -> T { !*self }
}

// String conversion functions and impl str -> num

/// Parse a string as a number in base 10.
#[inline(always)]
pub fn from_str(s: &str) -> Option<T> {
    strconv::from_str_common(s, 10u, false, false, false,
                             strconv::ExpNone, false, false)
}

/// Parse a string as a number in the given base.
#[inline(always)]
pub fn from_str_radix(s: &str, radix: uint) -> Option<T> {
    strconv::from_str_common(s, radix, false, false, false,
                             strconv::ExpNone, false, false)
}

/// Parse a byte slice as a number in the given base.
#[inline(always)]
pub fn parse_bytes(buf: &[u8], radix: uint) -> Option<T> {
    strconv::from_str_bytes_common(buf, radix, false, false, false,
                                   strconv::ExpNone, false, false)
}

impl FromStr for T {
    #[inline(always)]
    fn from_str(s: &str) -> Option<T> {
        from_str(s)
    }
}

impl FromStrRadix for T {
    #[inline(always)]
    fn from_str_radix(s: &str, radix: uint) -> Option<T> {
        from_str_radix(s, radix)
    }
}

// String conversion functions and impl num -> str

/// Convert to a string as a byte slice in a given base.
#[inline(always)]
pub fn to_str_bytes<U>(n: T, radix: uint, f: &fn(v: &[u8]) -> U) -> U {
    let (buf, _) = strconv::to_str_bytes_common(&n, radix, false,
                            strconv::SignNeg, strconv::DigAll);
    f(buf)
}

/// Convert to a string in base 10.
#[inline(always)]
pub fn to_str(num: T) -> ~str {
    let (buf, _) = strconv::to_str_common(&num, 10u, false,
                            strconv::SignNeg, strconv::DigAll);
    buf
}

/// Convert to a string in a given base.
#[inline(always)]
pub fn to_str_radix(num: T, radix: uint) -> ~str {
    let (buf, _) = strconv::to_str_common(&num, radix, false,
                            strconv::SignNeg, strconv::DigAll);
    buf
}

impl ToStr for T {
    #[inline(always)]
    fn to_str(&self) -> ~str {
        to_str(*self)
    }
}

impl ToStrRadix for T {
    #[inline(always)]
    fn to_str_radix(&self, radix: uint) -> ~str {
        to_str_radix(*self, radix)
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use super::inst::T;
    use prelude::*;

    #[test]
    fn test_num() {
        num::test_num(10 as T, 2 as T);
    }

    #[test]
    fn test_gcd() {
        assert_eq!((10 as T).gcd(&2), 2 as T);
        assert_eq!((10 as T).gcd(&3), 1 as T);
        assert_eq!((0 as T).gcd(&3), 3 as T);
        assert_eq!((3 as T).gcd(&3), 3 as T);
        assert_eq!((56 as T).gcd(&42), 14 as T);
    }

    #[test]
    fn test_lcm() {
        assert_eq!((1 as T).lcm(&0), 0 as T);
        assert_eq!((0 as T).lcm(&1), 0 as T);
        assert_eq!((1 as T).lcm(&1), 1 as T);
        assert_eq!((8 as T).lcm(&9), 72 as T);
        assert_eq!((11 as T).lcm(&5), 55 as T);
        assert_eq!((99 as T).lcm(&17), 1683 as T);
    }

    #[test]
    fn test_bitwise_ops() {
        assert_eq!(0b1110 as T, (0b1100 as T).bitor(&(0b1010 as T)));
        assert_eq!(0b1000 as T, (0b1100 as T).bitand(&(0b1010 as T)));
        assert_eq!(0b0110 as T, (0b1100 as T).bitxor(&(0b1010 as T)));
        assert_eq!(0b1110 as T, (0b0111 as T).shl(&(1 as T)));
        assert_eq!(0b0111 as T, (0b1110 as T).shr(&(1 as T)));
        assert_eq!(max_value - (0b1011 as T), (0b1011 as T).not());
    }

    #[test]
    pub fn test_to_str() {
        assert_eq!(to_str_radix(0 as T, 10u), ~"0");
        assert_eq!(to_str_radix(1 as T, 10u), ~"1");
        assert_eq!(to_str_radix(2 as T, 10u), ~"2");
        assert_eq!(to_str_radix(11 as T, 10u), ~"11");
        assert_eq!(to_str_radix(11 as T, 16u), ~"b");
        assert_eq!(to_str_radix(255 as T, 16u), ~"ff");
        assert_eq!(to_str_radix(0xff as T, 10u), ~"255");
    }

    #[test]
    pub fn test_from_str() {
        assert_eq!(from_str(~"0"), Some(0u as T));
        assert_eq!(from_str(~"3"), Some(3u as T));
        assert_eq!(from_str(~"10"), Some(10u as T));
        assert_eq!(u32::from_str(~"123456789"), Some(123456789 as u32));
        assert_eq!(from_str(~"00100"), Some(100u as T));

        assert!(from_str(~"").is_none());
        assert!(from_str(~" ").is_none());
        assert!(from_str(~"x").is_none());
    }

    #[test]
    pub fn test_parse_bytes() {
        use str::to_bytes;
        assert_eq!(parse_bytes(to_bytes(~"123"), 10u), Some(123u as T));
        assert_eq!(parse_bytes(to_bytes(~"1001"), 2u), Some(9u as T));
        assert_eq!(parse_bytes(to_bytes(~"123"), 8u), Some(83u as T));
        assert_eq!(u16::parse_bytes(to_bytes(~"123"), 16u), Some(291u as u16));
        assert_eq!(u16::parse_bytes(to_bytes(~"ffff"), 16u), Some(65535u as u16));
        assert_eq!(parse_bytes(to_bytes(~"z"), 36u), Some(35u as T));

        assert!(parse_bytes(to_bytes(~"Z"), 10u).is_none());
        assert!(parse_bytes(to_bytes(~"_"), 2u).is_none());
    }

    #[test]
    fn test_uint_to_str_overflow() {
        let mut u8_val: u8 = 255_u8;
        assert_eq!(u8::to_str(u8_val), ~"255");

        u8_val += 1 as u8;
        assert_eq!(u8::to_str(u8_val), ~"0");

        let mut u16_val: u16 = 65_535_u16;
        assert_eq!(u16::to_str(u16_val), ~"65535");

        u16_val += 1 as u16;
        assert_eq!(u16::to_str(u16_val), ~"0");

        let mut u32_val: u32 = 4_294_967_295_u32;
        assert_eq!(u32::to_str(u32_val), ~"4294967295");

        u32_val += 1 as u32;
        assert_eq!(u32::to_str(u32_val), ~"0");

        let mut u64_val: u64 = 18_446_744_073_709_551_615_u64;
        assert_eq!(u64::to_str(u64_val), ~"18446744073709551615");

        u64_val += 1 as u64;
        assert_eq!(u64::to_str(u64_val), ~"0");
    }

    #[test]
    fn test_uint_from_str_overflow() {
        let mut u8_val: u8 = 255_u8;
        assert_eq!(u8::from_str(~"255"), Some(u8_val));
        assert!(u8::from_str(~"256").is_none());

        u8_val += 1 as u8;
        assert_eq!(u8::from_str(~"0"), Some(u8_val));
        assert!(u8::from_str(~"-1").is_none());

        let mut u16_val: u16 = 65_535_u16;
        assert_eq!(u16::from_str(~"65535"), Some(u16_val));
        assert!(u16::from_str(~"65536").is_none());

        u16_val += 1 as u16;
        assert_eq!(u16::from_str(~"0"), Some(u16_val));
        assert!(u16::from_str(~"-1").is_none());

        let mut u32_val: u32 = 4_294_967_295_u32;
        assert_eq!(u32::from_str(~"4294967295"), Some(u32_val));
        assert!(u32::from_str(~"4294967296").is_none());

        u32_val += 1 as u32;
        assert_eq!(u32::from_str(~"0"), Some(u32_val));
        assert!(u32::from_str(~"-1").is_none());

        let mut u64_val: u64 = 18_446_744_073_709_551_615_u64;
        assert_eq!(u64::from_str(~"18446744073709551615"), Some(u64_val));
        assert!(u64::from_str(~"18446744073709551616").is_none());

        u64_val += 1 as u64;
        assert_eq!(u64::from_str(~"0"), Some(u64_val));
        assert!(u64::from_str(~"-1").is_none());
    }

    #[test]
    #[should_fail]
    #[ignore(cfg(windows))]
    pub fn to_str_radix1() {
        uint::to_str_radix(100u, 1u);
    }

    #[test]
    #[should_fail]
    #[ignore(cfg(windows))]
    pub fn to_str_radix37() {
        uint::to_str_radix(100u, 37u);
    }

    #[test]
    pub fn test_ranges() {
        let mut l = ~[];

        for range(0,3) |i| {
            l.push(i);
        }
        for range_rev(13,10) |i| {
            l.push(i);
        }
        for range_step(20,26,2) |i| {
            l.push(i);
        }
        for range_step(36,30,-2) |i| {
            l.push(i);
        }
        for range_step(max_value - 2, max_value, 2) |i| {
            l.push(i);
        }
        for range_step(max_value - 3, max_value, 2) |i| {
            l.push(i);
        }
        for range_step(min_value + 2, min_value, -2) |i| {
            l.push(i);
        }
        for range_step(min_value + 3, min_value, -2) |i| {
            l.push(i);
        }

        assert_eq!(l, ~[0,1,2,
                        13,12,11,
                        20,22,24,
                        36,34,32,
                        max_value-2,
                        max_value-3,max_value-1,
                        min_value+2,
                        min_value+3,min_value+1]);

        // None of the `fail`s should execute.
        for range(0,0) |_i| {
            fail!(~"unreachable");
        }
        for range_rev(0,0) |_i| {
            fail!(~"unreachable");
        }
        for range_step(10,0,1) |_i| {
            fail!(~"unreachable");
        }
        for range_step(0,1,-10) |_i| {
            fail!(~"unreachable");
        }
    }

    #[test]
    #[should_fail]
    #[ignore(cfg(windows))]
    fn test_range_step_zero_step_up() {
        for range_step(0,10,0) |_i| {}
    }
    #[test]
    #[should_fail]
    #[ignore(cfg(windows))]
    fn test_range_step_zero_step_down() {
        for range_step(0,-10,0) |_i| {}
    }
}