//! Askama templates for the public embed widgets (`/embed/*`). Ported from
//! hand-rolled `format!` HTML so user-derived fields (titles, creator names,
//! descriptions, URLs) are autoescaped by Askama rather than per-field by hand.

use askama::Template;

/// The spacing layer the embeds inline, written by `build.rs` from
/// makeover-geometry at Pointer density.
///
/// An embed cannot link a stylesheet: it renders inside an iframe on somebody
/// else's page, so its whole design system has to arrive in the document. That
/// is why these five templates carry a `<style>` block when nothing else in the
/// tree does. What it must not mean is that the values were copied by hand,
/// which is what it meant until this existed.
pub const EMBED_GEOMETRY_CSS: &str = include_str!("../../static/embed-geometry.css");

/// The colour layer for an embed: the platform default theme, resolved through
/// makeover the same way every page's is.
///
/// Always the default. Serving a creator's chosen theme into a third-party page
/// is a separate product question, and this is not the place to answer it by
/// accident.
pub fn embed_theme_css() -> &'static str {
    crate::theming::theme_css(None)
}

#[derive(Template)]
#[template(path = "embed/item_button.html")]
pub struct EmbedItemButtonTemplate {
    pub title: String,
    pub price_display: String,
    pub purchase_url: String,
    pub button_text: String,
    pub cover_image_url: Option<String>,
    /// Design-system layers, inlined because an embed cannot link a sheet.
    pub theme_css: &'static str,
    pub geometry_css: &'static str,
}

#[derive(Template)]
#[template(path = "embed/item_card.html")]
pub struct EmbedItemCardTemplate {
    pub title: String,
    pub price_display: String,
    pub purchase_url: String,
    pub button_text: String,
    pub cover_image_url: Option<String>,
    pub creator_display_name: String,
    pub profile_url: String,
    /// Empty string = no description block.
    pub description_excerpt: String,
    pub is_horizontal: bool,
    /// Design-system layers, inlined because an embed cannot link a sheet.
    pub theme_css: &'static str,
    pub geometry_css: &'static str,
}

#[derive(Template)]
#[template(path = "embed/item_player.html")]
pub struct EmbedItemPlayerTemplate {
    pub title: String,
    pub price_display: String,
    pub purchase_url: String,
    pub button_text: String,
    pub creator_display_name: String,
    pub cover_image_url: Option<String>,
    pub preview_url: String,
    /// Design-system layers, inlined because an embed cannot link a sheet.
    pub theme_css: &'static str,
    pub geometry_css: &'static str,
}

#[derive(Template)]
#[template(path = "embed/tip_button.html")]
pub struct EmbedTipButtonTemplate {
    pub display_name: String,
    pub username: String,
    pub tip_url: String,
    pub avatar_url: Option<String>,
    /// Design-system layers, inlined because an embed cannot link a sheet.
    pub theme_css: &'static str,
    pub geometry_css: &'static str,
}

#[derive(Template)]
#[template(path = "embed/project_card.html")]
pub struct EmbedProjectCardTemplate {
    pub title: String,
    pub creator_display_name: String,
    pub profile_url: String,
    pub project_url: String,
    pub cover_image_url: Option<String>,
    /// Empty string = no description block.
    pub description_excerpt: String,
    pub item_count: usize,
    pub category_label: String,
    /// Design-system layers, inlined because an embed cannot link a sheet.
    pub theme_css: &'static str,
    pub geometry_css: &'static str,
}

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

    /// Everything a template needs that is not the design system. The values are
    /// deliberately hex-free so a literal in the output came from the CSS.
    fn sample() -> (
        EmbedItemButtonTemplate,
        EmbedItemCardTemplate,
        EmbedItemPlayerTemplate,
        EmbedTipButtonTemplate,
        EmbedProjectCardTemplate,
    ) {
        let url = || "https://makenot.work/i/one".to_string();
        (
            EmbedItemButtonTemplate {
                title: "Item".into(),
                price_display: "$9".into(),
                purchase_url: url(),
                button_text: "Buy".into(),
                cover_image_url: Some(url()),
                theme_css: embed_theme_css(),
                geometry_css: EMBED_GEOMETRY_CSS,
            },
            EmbedItemCardTemplate {
                title: "Item".into(),
                price_display: "$9".into(),
                purchase_url: url(),
                button_text: "Buy".into(),
                cover_image_url: Some(url()),
                creator_display_name: "Creator".into(),
                profile_url: url(),
                description_excerpt: "About it.".into(),
                is_horizontal: true,
                theme_css: embed_theme_css(),
                geometry_css: EMBED_GEOMETRY_CSS,
            },
            EmbedItemPlayerTemplate {
                title: "Item".into(),
                price_display: "$9".into(),
                purchase_url: url(),
                button_text: "Buy".into(),
                creator_display_name: "Creator".into(),
                cover_image_url: Some(url()),
                preview_url: url(),
                theme_css: embed_theme_css(),
                geometry_css: EMBED_GEOMETRY_CSS,
            },
            EmbedTipButtonTemplate {
                display_name: "Creator".into(),
                username: "creator".into(),
                tip_url: url(),
                avatar_url: Some(url()),
                theme_css: embed_theme_css(),
                geometry_css: EMBED_GEOMETRY_CSS,
            },
            EmbedProjectCardTemplate {
                title: "Project".into(),
                creator_display_name: "Creator".into(),
                profile_url: url(),
                project_url: url(),
                cover_image_url: Some(url()),
                description_excerpt: "About it.".into(),
                item_count: 3,
                category_label: "Music".into(),
                theme_css: embed_theme_css(),
                geometry_css: EMBED_GEOMETRY_CSS,
            },
        )
    }

    /// Strip the injected `:root { ... }` blocks. What is left is the template's
    /// own CSS, which is where a hand-copied value would be.
    fn without_injected_roots(rendered: &str) -> String {
        let mut out = String::with_capacity(rendered.len());
        let mut rest = rendered;
        while let Some(start) = rest.find(":root") {
            out.push_str(&rest[..start]);
            let Some(open) = rest[start..].find('{') else {
                break;
            };
            let Some(close) = rest[start + open..].find('}') else {
                break;
            };
            rest = &rest[start + open + close + 1..];
        }
        out.push_str(rest);
        out
    }

    fn hex_literals(css: &str) -> Vec<String> {
        css.split('#')
            .skip(1)
            .map(|tail| {
                tail.chars()
                    .take_while(char::is_ascii_hexdigit)
                    .collect::<String>()
            })
            .filter(|run| run.len() == 3 || run.len() == 6)
            .map(|run| format!("#{run}"))
            .collect()
    }

    /// The regression guard the drift got past. `#5a4bd6` sat in all five
    /// templates as the button hover violet and matched no token anywhere in the
    /// tree: the real `--action-hover` is a different colour. Nothing could have
    /// caught it, because nothing was looking.
    #[test]
    fn no_embed_template_writes_its_own_colour() {
        let (button, card, player, tip, project) = sample();
        for (name, rendered) in [
            ("item_button", button.render().expect("render")),
            ("item_card", card.render().expect("render")),
            ("item_player", player.render().expect("render")),
            ("tip_button", tip.render().expect("render")),
            ("project_card", project.render().expect("render")),
        ] {
            let own = without_injected_roots(&rendered);
            let found = hex_literals(&own);
            assert!(
                found.is_empty(),
                "{name} writes its own colour: {found:?}. Use the token instead; \
                 a literal here drifts from the theme and nothing will report it.",
            );
        }
    }

    /// The stripper only earns its assertion if the blocks it strips were there.
    /// Without this, a handler that stopped passing `theme_css` would leave the
    /// test above passing on an empty document.
    #[test]
    fn every_embed_injects_both_design_system_layers() {
        let (button, card, player, tip, project) = sample();
        for (name, rendered) in [
            ("item_button", button.render().expect("render")),
            ("item_card", card.render().expect("render")),
            ("item_player", player.render().expect("render")),
            ("tip_button", tip.render().expect("render")),
            ("project_card", project.render().expect("render")),
        ] {
            assert!(
                rendered.contains("--action-hover"),
                "{name} did not inject the theme layer",
            );
            assert!(
                rendered.contains("--geometry-base"),
                "{name} did not inject the spacing layer",
            );
        }
    }
}