//! 把前端构建产物（dist/）嵌入本库。
//!
//! `build.rs` 会调用 bun（无则 npm）执行前端构建，随后将 dist/ 下所有文件以
//! `include_bytes!` 生成到 `$OUT_DIR/dist_embed.rs`，由本文件引入后对外提供：
//!
//! - [`index()`]：`index.html`（SPA 入口）
//! - [`file(path)`]：按请求路径取任意静态资源，如 `/assets/index-xxx.js`
//! - [`exists(path)`] / [`paths()`]：资源存在性查询与清单

mod dist_embed {
    include!(concat!(env!("OUT_DIR"), "/dist_embed.rs"));
}

/// 一个嵌入在库中的 dist 静态资源。
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct Asset {
    /// 相对 dist/ 的路径（不含前导斜杠），如 `assets/index-xxx.js`。
    pub path: &'static str,
    /// 按扩展名推断的 MIME type。
    pub mime: &'static str,
    /// 文件内容。
    pub content: &'static [u8],
}

/// SPA 入口 `index.html`。
pub fn index() -> Asset {
    Asset {
        path: "index.html",
        mime: "text/html; charset=utf-8",
        content: dist_embed::INDEX,
    }
}

/// 按请求路径查找嵌入的资源。
///
/// 接受 `/assets/x.js`、`assets/x.js`、带 `?query`/`#hash` 的路径；
/// 根路径与 `index.html` 归一到 [`index()`]；含 `..` 的越界路径返回 `None`。
pub fn file(path: &str) -> Option<Asset> {
    let key = normalize(path)?;
    if key.is_empty() || key == "index.html" {
        return Some(index());
    }
    dist_embed::FILES
        .iter()
        .find(|(p, _)| *p == key.as_str())
        .map(|(p, content)| Asset {
            path: p,
            mime: mime_of(p),
            content,
        })
}

pub fn exists(path: &str) -> bool {
    match normalize(path) {
        None => false,
        Some(key) => {
            key.is_empty()
                || key == "index.html"
                || dist_embed::FILES.iter().any(|(p, _)| *p == key.as_str())
        }
    }
}

pub fn paths() -> &'static [&'static str] {
    dist_embed::PATHS
}

fn normalize(path: &str) -> Option<String> {
    let path = path.split(['?', '#']).next().unwrap_or(path);
    let mut segs: Vec<&str> = Vec::new();
    for seg in path.split('/') {
        match seg {
            "" | "." => {}
            ".." => return None,
            s => segs.push(s),
        }
    }
    Some(segs.join("/"))
}

fn mime_of(path: &str) -> &'static str {
    let ext = path
        .rsplit_once('.')
        .map_or("", |(_, e)| e)
        .to_ascii_lowercase();
    match ext.as_str() {
        "html" | "htm" => "text/html; charset=utf-8",
        "js" | "mjs" => "text/javascript; charset=utf-8",
        "css" => "text/css; charset=utf-8",
        "json" | "map" => "application/json",
        "webmanifest" => "application/manifest+json",
        "svg" => "image/svg+xml",
        "png" => "image/png",
        "jpg" | "jpeg" => "image/jpeg",
        "gif" => "image/gif",
        "webp" => "image/webp",
        "avif" => "image/avif",
        "ico" => "image/x-icon",
        "wasm" => "application/wasm",
        "ttf" => "font/ttf",
        "otf" => "font/otf",
        "woff" => "font/woff",
        "woff2" => "font/woff2",
        "eot" => "application/vnd.ms-fontobject",
        "txt" => "text/plain; charset=utf-8",
        "xml" => "application/xml",
        "mp4" => "video/mp4",
        "webm" => "video/webm",
        "pdf" => "application/pdf",
        _ => "application/octet-stream",
    }
}

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

    #[test]
    fn index_is_html() {
        let a = index();
        assert_eq!(a.mime, "text/html; charset=utf-8");
        assert!(
            a.content
                .to_ascii_lowercase()
                .windows(5)
                .any(|w| w == b"<html")
        );
    }

    #[test]
    fn lookup_with_and_without_leading_slash() {
        let js = paths()
            .iter()
            .find(|p| p.ends_with(".js"))
            .expect("js in dist");
        let a = file(&format!("/{js}")).unwrap();
        assert_eq!(a.path, *js);
        assert_eq!(a.mime, "text/javascript; charset=utf-8");
        assert_eq!(file(js).unwrap().content, a.content);
        let css = paths()
            .iter()
            .find(|p| p.ends_with(".css"))
            .expect("css in dist");
        assert_eq!(file(css).unwrap().mime, "text/css; charset=utf-8");
    }

    #[test]
    fn wasm_mime() {
        if let Some(w) = paths().iter().find(|p| p.ends_with(".wasm")) {
            assert_eq!(file(w).unwrap().mime, "application/wasm");
        }
    }

    #[test]
    fn root_and_index_normalize() {
        assert_eq!(file("/").unwrap().path, "index.html");
        assert_eq!(file("").unwrap().path, "index.html");
        assert_eq!(file("/?q=1").unwrap().path, "index.html");
        assert_eq!(file("index.html").unwrap().path, "index.html");
    }

    #[test]
    fn traversal_rejected_and_missing_none() {
        assert!(file("/../../etc/passwd").is_none());
        assert!(file("assets/../../x").is_none());
        assert!(file("no-such-file.xyz").is_none());
        assert!(!exists("../x"));
        assert!(exists("/"));
    }
}