use typst::eval::Scope;

use super::*;

/// A text operator in an equation.
///
/// ## Example { #example }
/// ```example
/// $ tan x = (sin x)/(cos x) $
/// $ op("custom",
///      limits: #true)_(n->oo) n $
/// ```
///
/// ## Predefined Operators { #predefined }
/// Typst predefines the operators `arccos`,  `arcsin`,  `arctan`,  `arg`,
/// `cos`,  `cosh`,  `cot`, `ctg`, `coth`,  `csc`,  `deg`,  `det`,  `dim`,
/// `exp`, `gcd`,  `hom`,  `mod`,  `inf`,  `ker`,  `lg`,  `lim`,  `ln`,  `log`,
/// `max`, `min`,  `Pr`,  `sec`,  `sin`,  `sinc`,  `sinh`,  `sup`,  `tan`, `tg`,
/// `tanh`, `liminf`, and `limsup`.
///
/// Display: Text Operator
/// Category: math
#[element(LayoutMath)]
pub struct OpElem {
    /// The operator's text.
    #[required]
    pub text: EcoString,

    /// Whether the operator should show attachments as limits in display mode.
    #[default(false)]
    pub limits: bool,
}

impl LayoutMath for OpElem {
    #[tracing::instrument(skip(ctx))]
    fn layout_math(&self, ctx: &mut MathContext) -> SourceResult<()> {
        let fragment =
            ctx.layout_text(&TextElem::new(self.text()).spanned(self.span()))?;
        ctx.push(
            FrameFragment::new(ctx, fragment.into_frame())
                .with_class(MathClass::Large)
                .with_limits(if self.limits(ctx.styles()) {
                    Limits::Display
                } else {
                    Limits::Never
                }),
        );
        Ok(())
    }
}

macro_rules! ops {
    ($($name:ident $(: $value:literal)? $(($tts:tt))?),* $(,)?) => {
        pub(super) fn define(math: &mut Scope) {
            $(math.define(
                stringify!($name),
                OpElem::new(ops!(@name $name $(: $value)?).into())
                    .with_limits(ops!(@limit $($tts)*))
                    .pack()
            );)*

            let dif = |d| {
                HElem::new(THIN.into()).pack()
                    + MathStyleElem::new(TextElem::packed(d)).with_italic(Some(false)).pack()
            };
            math.define("dif", dif('d'));
            math.define("Dif", dif('D'));
        }
    };
    (@name $name:ident) => { stringify!($name) };
    (@name $name:ident: $value:literal) => { $value };
    (@limit limits) => { true };
    (@limit) => { false };
}

ops! {
    arccos,
    arcsin,
    arctan,
    arg,
    cos,
    cosh,
    cot,
    ctg,
    coth,
    csc,
    deg,
    det (limits),
    dim,
    exp,
    gcd (limits),
    hom,
    mod,
    inf (limits),
    ker,
    lg,
    lim (limits),
    ln,
    log,
    max (limits),
    min (limits),
    Pr (limits),
    sec,
    sin,
    sinc,
    sinh,
    sup (limits),
    tan,
    tg,
    tanh,
    liminf: "lim inf" (limits),
    limsup: "lim sup" (limits),
}