topcoat-core 0.10.0

//! The form URLs render in: relative to the site root or absolute.

use crate::context::{Cx, try_request_context};

/// The form a URL renders in when the code writing it does not choose one.
///
/// URLs are relative to the site root by default. Register the absolute form
/// with [`Cx::with`] when the rendered content needs complete URLs. Read the
/// current choice with [`url_form`].
///
/// ```
/// use topcoat::context::{Cx, UrlForm, url_form};
///
/// let cx = Cx::default();
/// assert_eq!(url_form(&cx), UrlForm::Relative);
///
/// let cx = cx.with(UrlForm::Absolute);
/// assert_eq!(url_form(&cx), UrlForm::Absolute);
/// ```
#[derive(Debug, Default, Clone, Copy, PartialEq, Eq)]
pub enum UrlForm {
    /// The URL renders relative to the site root, like `/posts/42`.
    #[default]
    Relative,
    /// The URL renders with its scheme and host, like
    /// `https://example.com/posts/42`.
    Absolute,
}

/// Returns the [`UrlForm`] in effect for this context.
///
/// URLs render [`Relative`](UrlForm::Relative) unless an enclosing scope
/// registered another form on the request context.
#[inline]
#[must_use]
pub fn url_form(cx: &Cx) -> UrlForm {
    try_request_context::<UrlForm>(cx)
        .copied()
        .unwrap_or_default()
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn defaults_to_relative() {
        assert_eq!(url_form(&Cx::default()), UrlForm::Relative);
    }

    #[test]
    fn a_scope_registers_another_form() {
        let cx = Cx::default().with(UrlForm::Absolute);
        assert_eq!(url_form(&cx), UrlForm::Absolute);
    }

    #[test]
    fn an_inner_scope_shadows_the_outer_form() {
        let cx = Cx::default().with(UrlForm::Absolute);
        let inner = cx.with(UrlForm::Relative);
        assert_eq!(url_form(&inner), UrlForm::Relative);
        assert_eq!(url_form(&cx), UrlForm::Absolute);
    }
}