use typst_utils::singleton;

use crate::foundations::{elem, Content, NativeElement};

/// Inserts a line break.
///
/// Advances the paragraph to the next line. A single trailing line break at the
/// end of a paragraph is ignored, but more than one creates additional empty
/// lines.
///
/// # Example
/// ```example
/// *Date:* 26.12.2022 \
/// *Topic:* Infrastructure Test \
/// *Severity:* High \
/// ```
///
/// # Syntax
/// This function also has dedicated syntax: To insert a line break, simply write
/// a backslash followed by whitespace. This always creates an unjustified
/// break.
#[elem(title = "Line Break")]
pub struct LinebreakElem {
    /// Whether to justify the line before the break.
    ///
    /// This is useful if you found a better line break opportunity in your
    /// justified text than Typst did.
    ///
    /// ```example
    /// #set par(justify: true)
    /// #let jb = linebreak(justify: true)
    ///
    /// I have manually tuned the #jb
    /// line breaks in this paragraph #jb
    /// for an _interesting_ result. #jb
    /// ```
    #[default(false)]
    pub justify: bool,
}

impl LinebreakElem {
    /// Get the globally shared linebreak element.
    pub fn shared() -> &'static Content {
        singleton!(Content, LinebreakElem::new().pack())
    }
}