use std::sync::Arc;

use api_types::{
    ADMIN_SETTINGS, ADMIN_SHARES, ADMIN_USERS, AUTH_APP_PASSWORDS, AUTH_LOGIN, AUTH_LOGOUT,
    AUTH_ME, AUTH_MODE, AUTH_PASSKEY_LOGIN, AUTH_PASSKEYS, AUTH_PASSKEYS_REGISTER, AUTH_PASSWORD,
    AUTH_SETUP, DAV, DAV_SHARE, FILES, FINISH_SUFFIX, PIM, SEARCH, SHARE, SHARE_UNLOCK_SUFFIX,
    SHARES, WELL_KNOWN_CALDAV, WELL_KNOWN_CARDDAV,
};
use axum::Router;
use axum::http::HeaderValue;
use axum::routing::{any, delete, get, post, put};
use tower_http::set_header::SetResponseHeaderLayer;

use crate::error::AppState;

/// Content-Security-Policy tuned to the built Trunk frontend.
///
/// * `script-src 'unsafe-inline'` — Trunk emits one inline bootstrap module
///   in index.html; every real JS file also carries an SRI integrity hash.
/// * `'wasm-unsafe-eval'` — compiling the same-origin WASM module.
/// * `style-src 'unsafe-inline'` — the context menu sets an inline `style=`.
/// * Everything else locked to the same origin; frames/plugins banned.
const CSP: &str = "default-src 'self'; script-src 'self' 'unsafe-inline' 'wasm-unsafe-eval'; style-src 'self' 'unsafe-inline'; img-src 'self' data: blob:; media-src 'self' blob:; connect-src 'self'; font-src 'self' data:; object-src 'none'; base-uri 'self'; form-action 'self'; frame-ancestors 'none';";

/// Content-Security-Policy for served *user files* that the browser would
/// treat as a scripting document (HTML, SVG, XML). Lets such a file render as
/// a real page — the "share an HTML page" flow — without letting it act as the
/// app.
///
/// The security hinges on one omission: `allow-scripts` **without**
/// `allow-same-origin`. That forces the document into a unique opaque origin,
/// so its JavaScript cannot read the session cookie's origin, cannot touch
/// `localStorage`, and cannot call `/api` as the viewer (the server sends no
/// CORS headers, so every cross-origin read fails). Never add
/// `allow-same-origin` here.
///
/// Also deliberately absent:
/// * `allow-top-navigation` — a shared page cannot silently redirect the
///   viewer elsewhere. `-by-user-activation` still lets links work on click.
/// * `allow-popups-to-escape-sandbox` — a popup would drop the sandbox.
///
/// `connect-src *` is deliberate: a shared page may call third-party APIs.
/// The trade-off is that it can also beacon (report that the link was opened,
/// and anything the page itself contains). It cannot exfiltrate anything of
/// the viewer's — the opaque origin means it has no session and no CORS read
/// access to this server.
pub(crate) const FILE_CSP: &str = "default-src 'self'; script-src 'self' 'unsafe-inline'; style-src 'self' 'unsafe-inline'; img-src 'self' data: blob:; media-src 'self' blob:; font-src 'self' data:; connect-src *; object-src 'none'; frame-ancestors 'none'; sandbox allow-scripts allow-forms allow-modals allow-downloads allow-popups allow-top-navigation-by-user-activation;";

/// Apply [`FILE_CSP`] to a response that declares a scriptable type.
///
/// The router's CSP layer is `if_not_present`, so without this such a response
/// keeps the *app* policy: same origin, scripts allowed. A `GET` of a shared
/// HTML file is a top-level navigation, which carries the session cookie under
/// `SameSite=Lax`, so the page would then run as the viewer against `/api`.
pub(crate) fn sandbox_scriptable<B>(resp: &mut axum::http::Response<B>) {
    let scriptable = resp
        .headers()
        .get(axum::http::header::CONTENT_TYPE)
        .and_then(|v| v.to_str().ok())
        .is_some_and(is_scriptable_mime);
    if scriptable {
        resp.headers_mut().insert(
            "content-security-policy",
            HeaderValue::from_static(FILE_CSP),
        );
    }
}

/// Content-Security-Policy for inline (preview) files that are *not*
/// scripting documents (PDF, media, …): the preview modal embeds them in a
/// same-origin `<iframe>`. Scriptable files never get this — see [`FILE_CSP`].
pub(crate) const INLINE_CSP: &str = "frame-ancestors 'self';";

/// True for MIME types the browser parses as a scripting document. These are
/// the responses that need [`FILE_CSP`]; everything else keeps the app policy.
///
/// This reads the *declared* type — the same value that becomes the
/// `Content-Type` header — on purpose. If the sandbox decision and the render
/// decision ever read different inputs, a file can be rendered as a scripting
/// document without being sandboxed.
pub(crate) fn is_scriptable_mime(mime: &str) -> bool {
    let base = mime.split(';').next().unwrap_or("").trim();
    matches!(
        base,
        "text/html" | "application/xhtml+xml" | "image/svg+xml" | "text/xml" | "application/xml"
    ) || base.ends_with("+xml")
}

mod admin;
mod app_passwords;
mod auth;
pub(crate) mod common;
mod dav;
mod files;
mod passkeys;
mod pim;
mod search;
mod shares;
mod spa;

pub fn router(state: Arc<AppState>) -> Router {
    // Route patterns: the server side of the shared endpoint strings in
    // `api_types` (axum copies them into the route table on insert).
    let files_root = format!("{FILES}/{{root_id}}");
    let files_item = format!("{FILES}/{{root_id}}/{{*path}}");
    let shares_id = format!("{SHARES}/{{id}}");
    let share_token = format!("{SHARE}/{{token}}");
    let share_unlock = format!("{SHARE}/{{token}}{SHARE_UNLOCK_SUFFIX}");
    let admin_user_id = format!("{ADMIN_USERS}/{{id}}");
    let passkey_id = format!("{AUTH_PASSKEYS}/{{id}}");
    let app_password_id = format!("{AUTH_APP_PASSWORDS}/{{id}}");
    let passkey_register_finish = format!("{AUTH_PASSKEYS_REGISTER}{FINISH_SUFFIX}");
    let passkey_login_finish = format!("{AUTH_PASSKEY_LOGIN}{FINISH_SUFFIX}");
    let admin_share_id = format!("{ADMIN_SHARES}/{{id}}");
    // A wildcard needs something to capture, so `/dav/` gets its own pattern:
    // mount clients ask for it with the trailing slash, which matches neither
    // the bare path nor `{*path}`.
    let dav_root = format!("{DAV}/");
    let dav_item = format!("{DAV}/{{*path}}");
    let dav_share = format!("{DAV_SHARE}/{{*path}}");
    let pim_root = format!("{PIM}/");
    let pim_item = format!("{PIM}/{{*path}}");

    Router::new()
        .route(AUTH_LOGIN, post(auth::login))
        .route(AUTH_LOGOUT, post(auth::logout))
        .route(AUTH_ME, get(auth::me).put(auth::update_profile))
        .route(AUTH_SETUP, post(auth::setup))
        .route(
            AUTH_PASSWORD,
            post(passkeys::change_password).delete(passkeys::delete_password),
        )
        .route(AUTH_MODE, put(passkeys::set_mode))
        // axum matches a literal segment before a parameter, so `/register`
        // and `{id}` can both live under this path.
        .route(AUTH_PASSKEYS, get(passkeys::list))
        .route(AUTH_PASSKEYS_REGISTER, post(passkeys::register_begin))
        .route(&passkey_register_finish, post(passkeys::register_finish))
        .route(&passkey_id, delete(passkeys::delete))
        .route(AUTH_PASSKEY_LOGIN, post(passkeys::login_begin))
        .route(&passkey_login_finish, post(passkeys::login_finish))
        .route(
            AUTH_APP_PASSWORDS,
            get(app_passwords::list).post(app_passwords::create),
        )
        .route(&app_password_id, delete(app_passwords::delete))
        .route(SEARCH, get(search::search))
        .route(
            &files_root,
            get(files::file_get)
                .put(files::file_put)
                .post(files::dispatch),
        )
        .route(
            &files_item,
            get(files::file_get)
                .put(files::file_put)
                .post(files::dispatch)
                .delete(files::delete),
        )
        .route(SHARES, get(shares::list))
        .route(SHARES, post(shares::create))
        .route(&shares_id, delete(shares::delete))
        .route(&share_token, get(shares::resolve))
        .route(&share_unlock, post(shares::unlock))
        .route(ADMIN_USERS, get(admin::list_users))
        .route(ADMIN_USERS, post(admin::create_user))
        .route(&admin_user_id, put(admin::update_user))
        .route(&admin_user_id, delete(admin::delete_user))
        .route(ADMIN_SHARES, get(admin::list_shares))
        .route(&admin_share_id, delete(admin::delete_share))
        .route(ADMIN_SETTINGS, get(admin::get_settings))
        .route(ADMIN_SETTINGS, put(admin::update_settings))
        // `any`, not a method filter: WebDAV's verbs (PROPFIND, MKCOL, MOVE, …)
        // are not in axum's `MethodFilter`, and a method router's fallback
        // takes every one of them.
        .route(DAV, any(dav::user))
        .route(&dav_root, any(dav::user))
        .route(&dav_item, any(dav::user))
        .route(&dav_share, any(dav::share))
        .route(WELL_KNOWN_CALDAV, any(pim::well_known))
        .route(WELL_KNOWN_CARDDAV, any(pim::well_known))
        .route(PIM, any(pim::handle))
        .route(&pim_root, any(pim::handle))
        .route(&pim_item, any(pim::handle))
        .fallback(spa::fallback)
        // The editor save body is checked against `MAX_TEXT_BYTES` in the
        // handler; axum's default limit is the same 2 MiB, which would win
        // with a plain 413 instead of the localized error.
        .layer(axum::extract::DefaultBodyLimit::max(
            files::MAX_TEXT_BYTES as usize + 64 * 1024,
        ))
        .with_state(state)
        // Hard security headers on every response (API and static alike).
        // CSP/XFO are `if_not_present` so file responses can substitute
        // [`FILE_CSP`] or the same-origin-framable [`INLINE_CSP`]; everything
        // else gets the app policy.
        .layer(SetResponseHeaderLayer::if_not_present(
            "content-security-policy".parse().unwrap(),
            HeaderValue::from_static(CSP),
        ))
        .layer(SetResponseHeaderLayer::overriding(
            "x-content-type-options".parse().unwrap(),
            HeaderValue::from_static("nosniff"),
        ))
        .layer(SetResponseHeaderLayer::if_not_present(
            "x-frame-options".parse().unwrap(),
            HeaderValue::from_static("DENY"),
        ))
        // Not `no-referrer`: that makes browsers send `Origin: null` on
        // same-origin POSTs, which breaks the passkey origin check.
        .layer(SetResponseHeaderLayer::overriding(
            "referrer-policy".parse().unwrap(),
            HeaderValue::from_static("same-origin"),
        ))
}