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use std::fmt::Debug;

/// Create a new, immutable position (column, line);
///
/// # Examples
/// ```
/// use tty_interface::{Position, pos};
///
/// let position = pos!(1, 2);
/// assert_eq!(1, position.x());
/// assert_eq!(2, position.y());
/// ```
#[macro_export]
macro_rules! pos {
    ($x: expr, $y: expr) => {
        Position::new($x, $y)
    };
}

/// A coordinate position in the terminal. May be absolute or relative to some buffer's origin.
#[derive(Eq, PartialEq, Copy, Clone)]
pub struct Position {
    x: u16,
    y: u16,
}

impl Position {
    /// Create a new, immutable position.
    ///
    /// # Examples
    /// ```
    /// use tty_interface::Position;
    ///
    /// let origin = Position::new(2, 4);
    /// assert_eq!(2, origin.x());
    /// assert_eq!(4, origin.y());
    /// ```
    pub fn new(x: u16, y: u16) -> Position {
        Position { x, y }
    }

    /// This position's column value.
    pub fn x(&self) -> u16 {
        self.x
    }

    /// This position's line value.
    pub fn y(&self) -> u16 {
        self.y
    }
}

impl PartialOrd for Position {
    fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
        Some(self.cmp(other))
    }
}

impl Ord for Position {
    fn cmp(&self, other: &Self) -> std::cmp::Ordering {
        match self.y().cmp(&other.y()) {
            std::cmp::Ordering::Equal => self.x().cmp(&other.x()),
            ordering => ordering,
        }
    }
}

impl Debug for Position {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        write!(f, "Position({}, {})", self.x(), self.y())
    }
}

#[cfg(test)]
mod tests {
    use std::cmp::Ordering;

    use crate::{pos, Position};

    #[test]
    fn position_initialization() {
        let cases = [(0, 0), (0, 3), (8, 2), (4, 6)];

        for (x, y) in cases {
            let position = pos!(x, y);

            assert_eq!(x, position.x());
            assert_eq!(y, position.y());
        }
    }

    #[test]
    fn position_comparison() {
        let assert_case = |first: (u16, u16), second: (u16, u16), expected: Ordering| {
            let first_position = pos!(first.0, first.1);
            let second_position = pos!(second.0, second.1);

            assert_eq!(
                expected,
                first_position.cmp(&second_position),
                "comparing {:?} and {:?}",
                first_position,
                second_position
            );

            assert_eq!(
                Some(expected),
                first_position.partial_cmp(&second_position),
                "comparing {:?} and {:?}",
                first_position,
                second_position,
            );
        };

        let positions = [(0, 0), (0, 1), (1, 0), (1, 1)];

        let cases = [
            (positions[0], positions[0], Ordering::Equal),
            (positions[0], positions[1], Ordering::Less),
            (positions[0], positions[2], Ordering::Less),
            (positions[0], positions[3], Ordering::Less),
            (positions[1], positions[0], Ordering::Greater),
            (positions[1], positions[1], Ordering::Equal),
            (positions[1], positions[2], Ordering::Greater),
            (positions[1], positions[3], Ordering::Less),
            (positions[2], positions[0], Ordering::Greater),
            (positions[2], positions[1], Ordering::Less),
            (positions[2], positions[2], Ordering::Equal),
            (positions[2], positions[3], Ordering::Less),
            (positions[3], positions[0], Ordering::Greater),
            (positions[3], positions[1], Ordering::Greater),
            (positions[3], positions[2], Ordering::Greater),
            (positions[3], positions[3], Ordering::Equal),
        ];

        for case in cases {
            assert_case(case.0, case.1, case.2);
        }
    }
}