// Copyright 2016 Joe Wilm, The Alacritty Project Contributors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

//! Line and Column newtypes for strongly typed tty/grid/terminal APIs

/// Indexing types and implementations for Grid and Line
use std::cmp::{Ord, Ordering};
use std::fmt;
use std::ops::{self, Deref, Add, Range};

/// The side of a cell
#[derive(Debug, Copy, Clone, Eq, PartialEq)]
pub enum Side {
    Left,
    Right
}

/// Index in the grid using row, column notation
#[derive(Debug, Clone, Copy, Default, Eq, PartialEq, Serialize, Deserialize, PartialOrd)]
pub struct Point {
    pub line: Line,
    pub col: Column,
}

impl Point {
    pub fn new(line: Line, col: Column) -> Point {
        Point { line: line, col: col }
    }
}

impl Ord for Point {
    fn cmp(&self, other: &Point) -> Ordering {
        use std::cmp::Ordering::*;
        match (self.line.cmp(&other.line), self.col.cmp(&other.col)) {
            (Equal,   Equal) => Equal,
            (Equal,   ord) |
            (ord,     Equal) => ord,
            (Less,    _)     => Less,
            (Greater, _)     => Greater,
        }
    }
}

/// A line
///
/// Newtype to avoid passing values incorrectly
#[derive(Debug, Copy, Clone, Eq, PartialEq, Default, Ord, PartialOrd, Serialize, Deserialize)]
pub struct Line(pub usize);

impl fmt::Display for Line {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "{}", self.0)
    }
}

/// A column
///
/// Newtype to avoid passing values incorrectly
#[derive(Debug, Copy, Clone, Eq, PartialEq, Default, Ord, PartialOrd, Serialize, Deserialize)]
pub struct Column(pub usize);

impl fmt::Display for Column {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "{}", self.0)
    }
}

/// A linear index
///
/// Newtype to avoid passing values incorrectly
#[derive(Debug, Copy, Clone, Eq, PartialEq, Default, Ord, PartialOrd, Serialize, Deserialize)]
pub struct Linear(pub usize);

impl fmt::Display for Linear {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "Linear({})", self.0)
    }
}

// Copyright 2015 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.
//
// implements binary operators "&T op U", "T op &U", "&T op &U"
// based on "T op U" where T and U are expected to be `Copy`able
macro_rules! forward_ref_binop {
    (impl $imp:ident, $method:ident for $t:ty, $u:ty) => {
        impl<'a> $imp<$u> for &'a $t {
            type Output = <$t as $imp<$u>>::Output;

            #[inline]
            fn $method(self, other: $u) -> <$t as $imp<$u>>::Output {
                $imp::$method(*self, other)
            }
        }

        impl<'a> $imp<&'a $u> for $t {
            type Output = <$t as $imp<$u>>::Output;

            #[inline]
            fn $method(self, other: &'a $u) -> <$t as $imp<$u>>::Output {
                $imp::$method(self, *other)
            }
        }

        impl<'a, 'b> $imp<&'a $u> for &'b $t {
            type Output = <$t as $imp<$u>>::Output;

            #[inline]
            fn $method(self, other: &'a $u) -> <$t as $imp<$u>>::Output {
                $imp::$method(*self, *other)
            }
        }
    }
}

/// Macro for deriving deref
macro_rules! deref {
    ($ty:ty, $target:ty) => {
        impl Deref for $ty {
            type Target = $target;

            #[inline]
            fn deref(&self) -> &$target {
                &self.0
            }
        }
    }
}

macro_rules! add {
    ($ty:ty, $construct:expr) => {
        impl ops::Add<$ty> for $ty {
            type Output = $ty;

            #[inline]
            fn add(self, rhs: $ty) -> $ty {
                $construct(self.0 + rhs.0)
            }
        }
    }
}

macro_rules! sub {
    ($ty:ty, $construct:expr) => {
        impl ops::Sub<$ty> for $ty {
            type Output = $ty;

            #[inline]
            fn sub(self, rhs: $ty) -> $ty {
                $construct(self.0 - rhs.0)
            }
        }

        impl<'a> ops::Sub<$ty> for &'a $ty {
            type Output = $ty;

            #[inline]
            fn sub(self, rhs: $ty) -> $ty {
                $construct(self.0 - rhs.0)
            }
        }

        impl<'a> ops::Sub<&'a $ty> for $ty {
            type Output = $ty;

            #[inline]
            fn sub(self, rhs: &'a $ty) -> $ty {
                $construct(self.0 - rhs.0)
            }
        }

        impl<'a, 'b> ops::Sub<&'a $ty> for &'b $ty {
            type Output = $ty;

            #[inline]
            fn sub(self, rhs: &'a $ty) -> $ty {
                $construct(self.0 - rhs.0)
            }
        }
    }
}

/// This exists because we can't implement Iterator on Range
/// and the existing impl needs the unstable Step trait
/// This should be removed and replaced with a Step impl
/// in the ops macro when `step_by` is stabilized
pub struct IndexRange<T>(pub Range<T>);

impl<T> From<Range<T>> for IndexRange<T> {
    fn from(from: Range<T>) -> Self {
        IndexRange(from)
    }
}

pub enum RangeInclusive<Idx> {
    Empty {
        at: Idx,
    },
    NonEmpty {
        start: Idx,
        end: Idx,
    },
}

impl<Idx> RangeInclusive<Idx> {
    pub fn new(from: Idx, to: Idx) -> Self {
        RangeInclusive::NonEmpty {
            start: from,
            end: to
        }
    }
}

macro_rules! inclusive {
    ($ty:ty, $steps_add_one:expr) => {
        // impl copied from stdlib, can be removed when inclusive_range is stabilized
        impl Iterator for RangeInclusive<$ty> {
            type Item = $ty;

            #[inline]
            fn next(&mut self) -> Option<$ty> {
                use index::RangeInclusive::*;

                // this function has a sort of odd structure due to borrowck issues
                // we may need to replace self.range, so borrows of start and end need to end early

                let at_end;
                match *self {
                    Empty { .. } => return None, // empty iterators yield no values

                    NonEmpty { ref mut start, ref mut end } => {

                        // march start towards (maybe past!) end and yield the old value
                        if start <= end {
                            let old = *start;
                            *start = old + 1;
                            return Some(old);
                        }
                        at_end = *end;
                    }
                };

                // got this far; the range is empty, replace it
                *self = Empty { at: at_end };
                None
            }

            #[inline]
            fn size_hint(&self) -> (usize, Option<usize>) {
                use index::RangeInclusive::*;

                match *self {
                    Empty { .. } => (0, Some(0)),

                    NonEmpty { ref start, ref end } => {
                        let added = $steps_add_one(start, end);
                        match added {
                            Some(hint) => (hint.saturating_add(1), hint.checked_add(1)),
                            None       => (0, None)
                        }
                    }
                }
            }
        }
    }
}

fn steps_add_one_u8(start: &u8, end: &u8) -> Option<usize> {
    if *start < *end {
        Some((*end - *start) as usize)
    } else {
        None
    }
}
inclusive!(u8, steps_add_one_u8);

#[test]
fn test_range() {
    assert_eq!(RangeInclusive::new(1,10).collect::<Vec<_>>(),
               vec![1,2,3,4,5,6,7,8,9,10]);
}

// can be removed if range_contains is stabilized
pub trait Contains {
    type Content;
    fn contains_(&self, item: Self::Content) -> bool;
}

impl<T: PartialOrd<T>> Contains for Range<T> {
    type Content = T;
    fn contains_(&self, item: Self::Content) -> bool {
        (self.start <= item) && (item < self.end)
    }
}

impl<T: PartialOrd<T>> Contains for RangeInclusive<T> {
    type Content = T;
    fn contains_(&self, item: Self::Content) -> bool {
        if let RangeInclusive::NonEmpty{ref start, ref end} = *self {
            (*start <= item) && (item <= *end)
        } else { false }
    }
}

macro_rules! ops {
    ($ty:ty, $construct:expr) => {
        add!($ty, $construct);
        sub!($ty, $construct);
        deref!($ty, usize);
        forward_ref_binop!(impl Add, add for $ty, $ty);

        impl $ty {
            #[inline]
            #[allow(trivial_numeric_casts)]
            fn steps_between(start: &$ty, end: &$ty, by: &$ty) -> Option<usize> {
                if *by == $construct(0) { return None; }
                if *start < *end {
                    // Note: We assume $t <= usize here
                    let diff = (*end - *start).0;
                    let by = by.0;
                    if diff % by > 0 {
                        Some(diff / by + 1)
                    } else {
                        Some(diff / by)
                    }
                } else {
                    Some(0)
                }
            }

            #[inline]
            fn steps_between_by_one(start: &$ty, end: &$ty) -> Option<usize> {
                Self::steps_between(start, end, &$construct(1))
            }
        }

        impl Iterator for IndexRange<$ty> {
            type Item = $ty;
            #[inline]
            fn next(&mut self) -> Option<$ty> {
                if self.0.start < self.0.end {
                    let old = self.0.start;
                    self.0.start = old + 1;
                    Some(old)
                } else {
                    None
                }
            }
            #[inline]
            fn size_hint(&self) -> (usize, Option<usize>) {
                match Self::Item::steps_between_by_one(&self.0.start, &self.0.end) {
                    Some(hint) => (hint, Some(hint)),
                    None => (0, None)
                }
            }
        }

        inclusive!($ty, <$ty>::steps_between_by_one);

        impl DoubleEndedIterator for IndexRange<$ty> {
            #[inline]
            fn next_back(&mut self) -> Option<$ty> {
                if self.0.start < self.0.end {
                    let new = self.0.end - 1;
                    self.0.end = new;
                    Some(new)
                } else {
                    None
                }
            }
        }
        impl ops::AddAssign<$ty> for $ty {
            #[inline]
            fn add_assign(&mut self, rhs: $ty) {
                self.0 += rhs.0
            }
        }

        impl ops::SubAssign<$ty> for $ty {
            #[inline]
            fn sub_assign(&mut self, rhs: $ty) {
                self.0 -= rhs.0
            }
        }

        impl ops::AddAssign<usize> for $ty {
            #[inline]
            fn add_assign(&mut self, rhs: usize) {
                self.0 += rhs
            }
        }

        impl ops::SubAssign<usize> for $ty {
            #[inline]
            fn sub_assign(&mut self, rhs: usize) {
                self.0 -= rhs
            }
        }

        impl From<usize> for $ty {
            #[inline]
            fn from(val: usize) -> $ty {
                $construct(val)
            }
        }

        impl ops::Add<usize> for $ty {
            type Output = $ty;

            #[inline]
            fn add(self, rhs: usize) -> $ty {
                $construct(self.0 + rhs)
            }
        }

        impl ops::Sub<usize> for $ty {
            type Output = $ty;

            #[inline]
            fn sub(self, rhs: usize) -> $ty {
                $construct(self.0 - rhs)
            }
        }
    }
}

ops!(Line, Line);
ops!(Column, Column);
ops!(Linear, Linear);

#[cfg(test)]
mod tests {
    use super::{Line, Column, Point};

    #[test]
    fn location_ordering() {
        assert!(Point::new(Line(0), Column(0)) == Point::new(Line(0), Column(0)));
        assert!(Point::new(Line(1), Column(0)) > Point::new(Line(0), Column(0)));
        assert!(Point::new(Line(0), Column(1)) > Point::new(Line(0), Column(0)));
        assert!(Point::new(Line(1), Column(1)) > Point::new(Line(0), Column(0)));
        assert!(Point::new(Line(1), Column(1)) > Point::new(Line(0), Column(1)));
        assert!(Point::new(Line(1), Column(1)) > Point::new(Line(1), Column(0)));
    }
}