//! Rendering helpers: Askama fragment rendering and HTML escaping for raw
//! `format!`-built markup.

/// Render an Askama fragment to an HTML string, surfacing a render failure as an
/// `AppError` (mapped to 500 + an `HX-Error` header by the error responder) instead
/// of the silent `.render().unwrap_or_default()` blank swap, which installs an
/// empty HTMX fragment with no error signal (ultra-fuzz Run 12 doubledown S-A). Use
/// this for HTMX fragment handlers that return `Result`.
pub fn render_fragment(template: &impl askama::Template) -> crate::error::Result<String> {
    template.render().map_err(|e| {
        tracing::error!(error = ?e, "fragment render failed");
        crate::error::AppError::Internal(anyhow::anyhow!("template render failed"))
    })
}

/// Escape HTML special characters, including `'` so the output is safe in
/// single-quoted attribute contexts as well as element text. Use whenever a
/// value is interpolated into a raw `format!`-built HTML string instead of an
/// auto-escaped template.
pub fn escape_html(s: &str) -> String {
    s.replace('&', "&amp;")
        .replace('<', "&lt;")
        .replace('>', "&gt;")
        .replace('"', "&quot;")
        .replace('\'', "&#39;")
}