use crate::diag::SourceResult;
use crate::engine::Engine;
use crate::foundations::{elem, Content, Packed, Show, StyleChain};
use crate::text::TextElem;

/// Displays text in small capitals.
///
/// # Example
/// ```example
/// Hello \
/// #smallcaps[Hello]
/// ```
///
/// # Smallcaps fonts
/// By default, this enables the OpenType `smcp` feature for the font. Not all
/// fonts support this feature. Sometimes smallcaps are part of a dedicated
/// font. This is, for example, the case for the _Latin Modern_ family of fonts.
/// In those cases, you can use a show-set rule to customize the appearance of
/// the text in smallcaps:
///
/// ```typ
/// #show smallcaps: set text(font: "Latin Modern Roman Caps")
/// ```
///
/// In the future, this function will support synthesizing smallcaps from normal
/// letters, but this is not yet implemented.
///
/// # Smallcaps headings
/// You can use a [show rule]($styling/#show-rules) to apply smallcaps
/// formatting to all your headings. In the example below, we also center-align
/// our headings and disable the standard bold font.
///
/// ```example
/// #set par(justify: true)
/// #set heading(numbering: "I.")
///
/// #show heading: smallcaps
/// #show heading: set align(center)
/// #show heading: set text(
///   weight: "regular"
/// )
///
/// = Introduction
/// #lorem(40)
/// ```
#[elem(title = "Small Capitals", Show)]
pub struct SmallcapsElem {
    /// The content to display in small capitals.
    #[required]
    pub body: Content,
}

impl Show for Packed<SmallcapsElem> {
    #[typst_macros::time(name = "smallcaps", span = self.span())]
    fn show(&self, _: &mut Engine, _: StyleChain) -> SourceResult<Content> {
        Ok(self.body().clone().styled(TextElem::set_smallcaps(true)))
    }
}