/*
 * Copyright (C) 2026 Mateusz Gruszczyński @linuxiarz.pl
 * Source-Available Code / Dual-Licensed.
 *
 * Free for non-commercial and evaluation use under terms of BSL/GPLv3.
 * Commercial or production use requires a valid paid license.
 * See LICENSE file in repository root for details.
 */

use axum::{
    http::{HeaderValue, header},
    response::{Html, IntoResponse, Response},
};

const MODULES: &[&str] = &[
    "api",
    "authorship",
    "auth-ui",
    "clipboard",
    "collaboration",
    "collaboration-session",
    "editor-format",
    "emoji-data",
    "emoji-picker",
    "image-alias",
    "image-upload",
    "logger",
    "line-links",
    "markdown",
    "modal",
    "note-api",
    "note-editor",
    "note-files",
    "preview-edit",
    "render-queue",
    "session",
    "socket",
    "toast",
    "theme",
    "url-state",
    "vendor-libs",
    "security",
];

pub fn render_html(
    template: &str,
    asset_version: &str,
    registration_enabled: bool,
    external_auth: bool,
    frontend_log_level: &str,
    upload_max_size_bytes: usize,
    entrypoint: &str,
) -> Response {
    let urls = AssetUrls::new(asset_version);
    let frontend_config = frontend_config(
        frontend_log_level,
        upload_max_size_bytes,
        external_auth,
        asset_version,
    );
    let app_stylesheets = format!(
        "{}{}",
        urls.stylesheet("styles"),
        urls.stylesheet_path("libs/rustpad-player/player.css"),
    );
    let html = template
        .replace("__APP_THEME_BOOTSTRAP__", theme_bootstrap())
        .replace("__APP_STYLESHEET__", &app_stylesheets)
        .replace("__APP_IMPORT_MAP__", &urls.import_map())
        .replace("__APP_ENTRYPOINT__", &urls.entrypoint(entrypoint))
        .replace(
            "__REGISTRATION_ENABLED__",
            if registration_enabled {
                "true"
            } else {
                "false"
            },
        )
        .replace(
            "</head>",
            &format!(
                r#"<link rel="icon" href="/favicon.svg" type="image/svg+xml"><link rel="icon" href="/favicon.ico" sizes="any"><link rel="icon" href="/favicon-32.png" type="image/png" sizes="32x32"><link rel="apple-touch-icon" href="/apple-touch-icon.png">{frontend_config}</head>"#
            ),
        );

    let mut response = Html(html).into_response();
    response.headers_mut().insert(
        header::CACHE_CONTROL,
        HeaderValue::from_static("private, no-cache, no-store"),
    );
    response
}

pub fn theme_bootstrap() -> &'static str {
    r#"<script>(()=>{const key="rustpad:theme";let theme=matchMedia("(prefers-color-scheme: light)").matches?"light":"dark";try{const saved=localStorage.getItem(key);if(saved==="light"||saved==="dark")theme=saved}catch{}const root=document.documentElement;root.dataset.theme=theme;root.style.colorScheme=theme;const meta=document.querySelector('meta[name="color-scheme"]');if(meta)meta.content=theme})();</script>"#
}

pub fn stylesheet_tag(asset_version: &str, name: &str) -> String {
    AssetUrls::new(asset_version).stylesheet(name)
}

fn frontend_config(
    frontend_log_level: &str,
    upload_max_size_bytes: usize,
    external_auth: bool,
    asset_version: &str,
) -> String {
    format!(
        r#"<script>window.__RUSTPAD_CONFIG__=Object.freeze({{frontendLogLevel:"{}",uploadMaxSizeBytes:{},externalAuth:{},assetVersion:"{}"}});</script>"#,
        escape_js_string(frontend_log_level),
        upload_max_size_bytes,
        external_auth,
        escape_js_string(asset_version),
    )
}

struct AssetUrls<'a> {
    version: &'a str,
}

impl<'a> AssetUrls<'a> {
    fn new(version: &'a str) -> Self {
        Self { version }
    }

    fn url(&self, path: &str) -> String {
        format!("/assets/{path}?v={}", self.version)
    }

    fn stylesheet(&self, name: &str) -> String {
        self.stylesheet_path(&format!("css/{name}.css"))
    }

    fn stylesheet_path(&self, path: &str) -> String {
        format!(r#"<link rel="stylesheet" href="{}">"#, self.url(path))
    }

    fn entrypoint(&self, name: &str) -> String {
        format!(
            r#"<script type="module" src="{}"></script>"#,
            self.url(&format!("js/{name}.js"))
        )
    }

    fn import_map(&self) -> String {
        let imports = MODULES
            .iter()
            .map(|module| {
                format!(
                    r#""@rustpad/{module}":"{}""#,
                    self.url(&format!("js/{module}.js"))
                )
            })
            .collect::<Vec<_>>()
            .join(",");

        format!(r#"<script type="importmap">{{"imports":{{{imports}}}}}</script>"#)
    }
}

fn escape_js_string(value: &str) -> String {
    value
        .replace('\\', "\\\\")
        .replace('"', "\\\"")
        .replace('<', "\\u003c")
}