use std::ops::Range;

/// Stores the start and end byte position
#[derive(Clone, Copy, Default, PartialEq, Eq)]
pub struct Span {
    pub head: u32,
    pub tail: u32,
}

impl std::fmt::Debug for Span {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        let Self { head, tail } = self;
        write!(f, "[{head}:{tail}]")
    }
}

#[expect(non_snake_case)]
/// Stores the start and end byte position
pub const fn Span(head: u32, tail: u32) -> Span {
    Span { head, tail }
}

impl Span {
    /// Updates `self` to include all but the last byte in `other`
    pub fn merge(self, other: Span) -> Span {
        Span { head: self.head.min(other.head), tail: self.tail.max(other.head) }
    }
}

impl From<Span> for Range<usize> {
    fn from(value: Span) -> Self {
        let Span { head, tail } = value;
        (head as usize)..(tail as usize)
    }
}

impl std::fmt::Display for Span {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        let Self { head, tail } = self;
        write!(f, "{head}:{tail}")
    }
}