use std::collections::BTreeMap;

use axum::{response::IntoResponse, Json};
use ruma::api::client::{
	discovery::{
		discover_homeserver::{self, HomeserverInfo, SlidingSyncProxyInfo},
		discover_support::{self, Contact},
		get_supported_versions,
	},
	error::ErrorKind,
};

use crate::{services, Error, Result, Ruma};

/// # `GET /_matrix/client/versions`
///
/// Get the versions of the specification and unstable features supported by
/// this server.
///
/// - Versions take the form MAJOR.MINOR.PATCH
/// - Only the latest PATCH release will be reported for each MAJOR.MINOR value
/// - Unstable features are namespaced and may include version information in
///   their name
///
/// Note: Unstable features are used while developing new features. Clients
/// should avoid using unstable features in their stable releases
pub(crate) async fn get_supported_versions_route(
	_body: Ruma<get_supported_versions::Request>,
) -> Result<get_supported_versions::Response> {
	let resp = get_supported_versions::Response {
		versions: vec![
			"r0.0.1".to_owned(),
			"r0.1.0".to_owned(),
			"r0.2.0".to_owned(),
			"r0.3.0".to_owned(),
			"r0.4.0".to_owned(),
			"r0.5.0".to_owned(),
			"r0.6.0".to_owned(),
			"r0.6.1".to_owned(),
			"v1.1".to_owned(),
			"v1.2".to_owned(),
			"v1.3".to_owned(),
			"v1.4".to_owned(),
			"v1.5".to_owned(),
		],
		unstable_features: BTreeMap::from_iter([
			("org.matrix.e2e_cross_signing".to_owned(), true),
			("org.matrix.msc2285.stable".to_owned(), true), /* private read receipts (https://github.com/matrix-org/matrix-spec-proposals/pull/2285) */
			("uk.half-shot.msc2666.query_mutual_rooms".to_owned(), true), /* query mutual rooms (https://github.com/matrix-org/matrix-spec-proposals/pull/2666) */
			("org.matrix.msc2836".to_owned(), true), /* threading/threads (https://github.com/matrix-org/matrix-spec-proposals/pull/2836) */
			("org.matrix.msc2946".to_owned(), true), /* spaces/hierarchy summaries (https://github.com/matrix-org/matrix-spec-proposals/pull/2946) */
			("org.matrix.msc3026.busy_presence".to_owned(), true), /* busy presence status (https://github.com/matrix-org/matrix-spec-proposals/pull/3026) */
			("org.matrix.msc3827".to_owned(), true), /* filtering of /publicRooms by room type (https://github.com/matrix-org/matrix-spec-proposals/pull/3827) */
			("org.matrix.msc3575".to_owned(), true), /* sliding sync (https://github.com/matrix-org/matrix-spec-proposals/pull/3575/files#r1588877046) */
		]),
	};

	Ok(resp)
}

/// # `GET /.well-known/matrix/client`
///
/// Returns the .well-known URL if it is configured, otherwise returns 404.
pub(crate) async fn well_known_client(
	_body: Ruma<discover_homeserver::Request>,
) -> Result<discover_homeserver::Response> {
	let client_url = match services().globals.well_known_client() {
		Some(url) => url.to_string(),
		None => return Err(Error::BadRequest(ErrorKind::NotFound, "Not found.")),
	};

	Ok(discover_homeserver::Response {
		homeserver: HomeserverInfo {
			base_url: client_url.clone(),
		},
		identity_server: None,
		sliding_sync_proxy: Some(SlidingSyncProxyInfo {
			url: client_url,
		}),
		tile_server: None,
	})
}

/// # `GET /.well-known/matrix/support`
///
/// Server support contact and support page of a homeserver's domain.
pub(crate) async fn well_known_support(_body: Ruma<discover_support::Request>) -> Result<discover_support::Response> {
	let support_page = services()
		.globals
		.well_known_support_page()
		.as_ref()
		.map(ToString::to_string);

	let role = services().globals.well_known_support_role().clone();

	// support page or role must be either defined for this to be valid
	if support_page.is_none() && role.is_none() {
		return Err(Error::BadRequest(ErrorKind::NotFound, "Not found."));
	}

	let email_address = services().globals.well_known_support_email().clone();
	let matrix_id = services().globals.well_known_support_mxid().clone();

	// if a role is specified, an email address or matrix id is required
	if role.is_some() && (email_address.is_none() && matrix_id.is_none()) {
		return Err(Error::BadRequest(ErrorKind::NotFound, "Not found."));
	}

	// TOOD: support defining multiple contacts in the config
	let mut contacts: Vec<Contact> = vec![];

	if let Some(role) = role {
		let contact = Contact {
			role,
			email_address,
			matrix_id,
		};

		contacts.push(contact);
	}

	// support page or role+contacts must be either defined for this to be valid
	if contacts.is_empty() && support_page.is_none() {
		return Err(Error::BadRequest(ErrorKind::NotFound, "Not found."));
	}

	Ok(discover_support::Response {
		contacts,
		support_page,
	})
}

/// # `GET /client/server.json`
///
/// Endpoint provided by sliding sync proxy used by some clients such as Element
/// Web as a non-standard health check.
pub(crate) async fn syncv3_client_server_json() -> Result<impl IntoResponse> {
	let server_url = match services().globals.well_known_client() {
		Some(url) => url.to_string(),
		None => match services().globals.well_known_server() {
			Some(url) => url.to_string(),
			None => return Err(Error::BadRequest(ErrorKind::NotFound, "Not found.")),
		},
	};

	Ok(Json(serde_json::json!({
		"server": server_url,
		"version": conduit::version(),
	})))
}

/// # `GET /_conduwuit/server_version`
///
/// Conduwuit-specific API to get the server version, results akin to
/// `/_matrix/federation/v1/version`
pub(crate) async fn conduwuit_server_version() -> Result<impl IntoResponse> {
	Ok(Json(serde_json::json!({
		"name": conduit::version::name(),
		"version": conduit::version::version(),
	})))
}

/// # `GET /_conduwuit/local_user_count`
///
/// conduwuit-specific API to return the amount of users registered on this
/// homeserver. Endpoint is disabled if federation is disabled for privacy. This
/// only includes active users (not deactivated, no guests, etc)
pub(crate) async fn conduwuit_local_user_count() -> Result<impl IntoResponse> {
	let user_count = services().users.list_local_users()?.len();

	Ok(Json(serde_json::json!({
		"count": user_count
	})))
}