use std::{fmt::Debug, mem, sync::Arc};

use bytes::BytesMut;
use conduwuit::{
	Err, PduEvent, Result, debug_warn, err, trace,
	utils::{stream::TryIgnore, string_from_bytes},
	warn,
};
use database::{Deserialized, Ignore, Interfix, Json, Map};
use futures::{Stream, StreamExt};
use ipaddress::IPAddress;
use ruma::{
	DeviceId, OwnedDeviceId, RoomId, UInt, UserId,
	api::{
		IncomingResponse, MatrixVersion, OutgoingRequest, SendAccessToken,
		client::push::{Pusher, PusherKind, set_pusher},
		push_gateway::send_event_notification::{
			self,
			v1::{Device, Notification, NotificationCounts, NotificationPriority},
		},
	},
	events::{
		AnySyncTimelineEvent, StateEventType, TimelineEventType,
		room::power_levels::RoomPowerLevelsEventContent,
	},
	push::{
		Action, PushConditionPowerLevelsCtx, PushConditionRoomCtx, PushFormat, Ruleset, Tweak,
	},
	serde::Raw,
	uint,
};

use crate::{Dep, client, globals, rooms, sending, users};

pub struct Service {
	db: Data,
	services: Services,
}

struct Services {
	globals: Dep<globals::Service>,
	client: Dep<client::Service>,
	state_accessor: Dep<rooms::state_accessor::Service>,
	state_cache: Dep<rooms::state_cache::Service>,
	users: Dep<users::Service>,
	sending: Dep<sending::Service>,
}

struct Data {
	senderkey_pusher: Arc<Map>,
	pushkey_deviceid: Arc<Map>,
}

impl crate::Service for Service {
	fn build(args: crate::Args<'_>) -> Result<Arc<Self>> {
		Ok(Arc::new(Self {
			db: Data {
				senderkey_pusher: args.db["senderkey_pusher"].clone(),
				pushkey_deviceid: args.db["pushkey_deviceid"].clone(),
			},
			services: Services {
				globals: args.depend::<globals::Service>("globals"),
				client: args.depend::<client::Service>("client"),
				state_accessor: args
					.depend::<rooms::state_accessor::Service>("rooms::state_accessor"),
				state_cache: args.depend::<rooms::state_cache::Service>("rooms::state_cache"),
				users: args.depend::<users::Service>("users"),
				sending: args.depend::<sending::Service>("sending"),
			},
		}))
	}

	fn name(&self) -> &str { crate::service::make_name(std::module_path!()) }
}

impl Service {
	pub async fn set_pusher(
		&self,
		sender: &UserId,
		sender_device: &DeviceId,
		pusher: &set_pusher::v3::PusherAction,
	) -> Result {
		match pusher {
			| set_pusher::v3::PusherAction::Post(data) => {
				let pushkey = data.pusher.ids.pushkey.as_str();

				if pushkey.len() > 512 {
					return Err!(Request(InvalidParam(
						"Push key length cannot be greater than 512 bytes."
					)));
				}

				if data.pusher.ids.app_id.as_str().len() > 64 {
					return Err!(Request(InvalidParam(
						"App ID length cannot be greater than 64 bytes."
					)));
				}

				// add some validation to the pusher URL
				let pusher_kind = &data.pusher.kind;
				if let PusherKind::Http(http) = pusher_kind {
					let url = &http.url;
					let url = url::Url::parse(&http.url).map_err(|e| {
						err!(Request(InvalidParam(
							warn!(%url, "HTTP pusher URL is not a valid URL: {e}")
						)))
					})?;

					if ["http", "https"]
						.iter()
						.all(|&scheme| scheme != url.scheme().to_lowercase())
					{
						return Err!(Request(InvalidParam(
							warn!(%url, "HTTP pusher URL is not a valid HTTP/HTTPS URL")
						)));
					}

					if let Ok(ip) =
						IPAddress::parse(url.host_str().expect("URL previously validated"))
					{
						if !self.services.client.valid_cidr_range(&ip) {
							return Err!(Request(InvalidParam(
								warn!(%url, "HTTP pusher URL is a forbidden remote address")
							)));
						}
					}
				}

				let pushkey = data.pusher.ids.pushkey.as_str();
				let key = (sender, pushkey);
				self.db.senderkey_pusher.put(key, Json(pusher));
				self.db.pushkey_deviceid.insert(pushkey, sender_device);
			},
			| set_pusher::v3::PusherAction::Delete(ids) => {
				self.delete_pusher(sender, ids.pushkey.as_str()).await;
			},
		}

		Ok(())
	}

	pub async fn delete_pusher(&self, sender: &UserId, pushkey: &str) {
		let key = (sender, pushkey);
		self.db.senderkey_pusher.del(key);
		self.db.pushkey_deviceid.remove(pushkey);

		self.services
			.sending
			.cleanup_events(None, Some(sender), Some(pushkey))
			.await
			.ok();
	}

	pub async fn get_pusher_device(&self, pushkey: &str) -> Result<OwnedDeviceId> {
		self.db.pushkey_deviceid.get(pushkey).await.deserialized()
	}

	pub async fn get_pusher(&self, sender: &UserId, pushkey: &str) -> Result<Pusher> {
		let senderkey = (sender, pushkey);
		self.db
			.senderkey_pusher
			.qry(&senderkey)
			.await
			.deserialized()
	}

	pub async fn get_pushers(&self, sender: &UserId) -> Vec<Pusher> {
		let prefix = (sender, Interfix);
		self.db
			.senderkey_pusher
			.stream_prefix(&prefix)
			.ignore_err()
			.map(|(_, pusher): (Ignore, Pusher)| pusher)
			.collect()
			.await
	}

	pub fn get_pushkeys<'a>(
		&'a self,
		sender: &'a UserId,
	) -> impl Stream<Item = &str> + Send + 'a {
		let prefix = (sender, Interfix);
		self.db
			.senderkey_pusher
			.keys_prefix(&prefix)
			.ignore_err()
			.map(|(_, pushkey): (Ignore, &str)| pushkey)
	}

	#[tracing::instrument(skip(self, dest, request))]
	pub async fn send_request<T>(&self, dest: &str, request: T) -> Result<T::IncomingResponse>
	where
		T: OutgoingRequest + Debug + Send,
	{
		const VERSIONS: [MatrixVersion; 1] = [MatrixVersion::V1_0];

		let dest = dest.replace(self.services.globals.notification_push_path(), "");
		trace!("Push gateway destination: {dest}");

		let http_request = request
			.try_into_http_request::<BytesMut>(&dest, SendAccessToken::IfRequired(""), &VERSIONS)
			.map_err(|e| {
				err!(BadServerResponse(warn!(
					"Failed to find destination {dest} for push gateway: {e}"
				)))
			})?
			.map(BytesMut::freeze);

		let reqwest_request = reqwest::Request::try_from(http_request)?;

		if let Some(url_host) = reqwest_request.url().host_str() {
			trace!("Checking request URL for IP");
			if let Ok(ip) = IPAddress::parse(url_host) {
				if !self.services.client.valid_cidr_range(&ip) {
					return Err!(BadServerResponse("Not allowed to send requests to this IP"));
				}
			}
		}

		let response = self.services.client.pusher.execute(reqwest_request).await;

		match response {
			| Ok(mut response) => {
				// reqwest::Response -> http::Response conversion

				trace!("Checking response destination's IP");
				if let Some(remote_addr) = response.remote_addr() {
					if let Ok(ip) = IPAddress::parse(remote_addr.ip().to_string()) {
						if !self.services.client.valid_cidr_range(&ip) {
							return Err!(BadServerResponse(
								"Not allowed to send requests to this IP"
							));
						}
					}
				}

				let status = response.status();
				let mut http_response_builder = http::Response::builder()
					.status(status)
					.version(response.version());
				mem::swap(
					response.headers_mut(),
					http_response_builder
						.headers_mut()
						.expect("http::response::Builder is usable"),
				);

				let body = response.bytes().await?; // TODO: handle timeout

				if !status.is_success() {
					debug_warn!("Push gateway response body: {:?}", string_from_bytes(&body));
					return Err!(BadServerResponse(warn!(
						"Push gateway {dest} returned unsuccessful HTTP response: {status}"
					)));
				}

				let response = T::IncomingResponse::try_from_http_response(
					http_response_builder
						.body(body)
						.expect("reqwest body is valid http body"),
				);
				response.map_err(|e| {
					err!(BadServerResponse(warn!(
						"Push gateway {dest} returned invalid response: {e}"
					)))
				})
			},
			| Err(e) => {
				warn!("Could not send request to pusher {dest}: {e}");
				Err(e.into())
			},
		}
	}

	#[tracing::instrument(skip(self, user, unread, pusher, ruleset, pdu))]
	pub async fn send_push_notice(
		&self,
		user: &UserId,
		unread: UInt,
		pusher: &Pusher,
		ruleset: Ruleset,
		pdu: &PduEvent,
	) -> Result<()> {
		let mut notify = None;
		let mut tweaks = Vec::new();

		let power_levels: RoomPowerLevelsEventContent = self
			.services
			.state_accessor
			.room_state_get(&pdu.room_id, &StateEventType::RoomPowerLevels, "")
			.await
			.and_then(|ev| {
				serde_json::from_str(ev.content.get()).map_err(|e| {
					err!(Database(error!("invalid m.room.power_levels event: {e:?}")))
				})
			})
			.unwrap_or_default();

		for action in self
			.get_actions(user, &ruleset, &power_levels, &pdu.to_sync_room_event(), &pdu.room_id)
			.await
		{
			let n = match action {
				| Action::Notify => true,
				| Action::SetTweak(tweak) => {
					tweaks.push(tweak.clone());
					continue;
				},
				| _ => false,
			};

			if notify.is_some() {
				return Err!(Database(
					r#"Malformed pushrule contains more than one of these actions: ["dont_notify", "notify", "coalesce"]"#
				));
			}

			notify = Some(n);
		}

		if notify == Some(true) {
			self.send_notice(unread, pusher, tweaks, pdu).await?;
		}
		// Else the event triggered no actions

		Ok(())
	}

	#[tracing::instrument(skip(self, user, ruleset, pdu), level = "debug")]
	pub async fn get_actions<'a>(
		&self,
		user: &UserId,
		ruleset: &'a Ruleset,
		power_levels: &RoomPowerLevelsEventContent,
		pdu: &Raw<AnySyncTimelineEvent>,
		room_id: &RoomId,
	) -> &'a [Action] {
		let power_levels = PushConditionPowerLevelsCtx {
			users: power_levels.users.clone(),
			users_default: power_levels.users_default,
			notifications: power_levels.notifications.clone(),
		};

		let room_joined_count = self
			.services
			.state_cache
			.room_joined_count(room_id)
			.await
			.unwrap_or(1)
			.try_into()
			.unwrap_or_else(|_| uint!(0));

		let user_display_name = self
			.services
			.users
			.displayname(user)
			.await
			.unwrap_or_else(|_| user.localpart().to_owned());

		let ctx = PushConditionRoomCtx {
			room_id: room_id.to_owned(),
			member_count: room_joined_count,
			user_id: user.to_owned(),
			user_display_name,
			power_levels: Some(power_levels),
		};

		ruleset.get_actions(pdu, &ctx)
	}

	#[tracing::instrument(skip(self, unread, pusher, tweaks, event))]
	async fn send_notice(
		&self,
		unread: UInt,
		pusher: &Pusher,
		tweaks: Vec<Tweak>,
		event: &PduEvent,
	) -> Result {
		// TODO: email
		match &pusher.kind {
			| PusherKind::Http(http) => {
				let url = &http.url;
				let url = url::Url::parse(&http.url).map_err(|e| {
					err!(Request(InvalidParam(
						warn!(%url, "HTTP pusher URL is not a valid URL: {e}")
					)))
				})?;

				if ["http", "https"]
					.iter()
					.all(|&scheme| scheme != url.scheme().to_lowercase())
				{
					return Err!(Request(InvalidParam(
						warn!(%url, "HTTP pusher URL is not a valid HTTP/HTTPS URL")
					)));
				}

				if let Ok(ip) =
					IPAddress::parse(url.host_str().expect("URL previously validated"))
				{
					if !self.services.client.valid_cidr_range(&ip) {
						return Err!(Request(InvalidParam(
							warn!(%url, "HTTP pusher URL is a forbidden remote address")
						)));
					}
				}

				// TODO (timo): can pusher/devices have conflicting formats
				let event_id_only = http.format == Some(PushFormat::EventIdOnly);

				let mut device =
					Device::new(pusher.ids.app_id.clone(), pusher.ids.pushkey.clone());
				device.data.data.clone_from(&http.data);
				device.data.format.clone_from(&http.format);

				// Tweaks are only added if the format is NOT event_id_only
				if !event_id_only {
					device.tweaks.clone_from(&tweaks);
				}

				let d = vec![device];
				let mut notifi = Notification::new(d);

				notifi.event_id = Some((*event.event_id).to_owned());
				notifi.room_id = Some((*event.room_id).to_owned());
				if http
					.data
					.get("org.matrix.msc4076.disable_badge_count")
					.is_none() && http.data.get("disable_badge_count").is_none()
				{
					notifi.counts = NotificationCounts::new(unread, uint!(0));
				} else {
					// counts will not be serialised if it's the default (0, 0)
					// skip_serializing_if = "NotificationCounts::is_default"
					notifi.counts = NotificationCounts::default();
				}

				if event_id_only {
					self.send_request(
						&http.url,
						send_event_notification::v1::Request::new(notifi),
					)
					.await?;
				} else {
					if event.kind == TimelineEventType::RoomEncrypted
						|| tweaks
							.iter()
							.any(|t| matches!(t, Tweak::Highlight(true) | Tweak::Sound(_)))
					{
						notifi.prio = NotificationPriority::High;
					} else {
						notifi.prio = NotificationPriority::Low;
					}
					notifi.sender = Some(event.sender.clone());
					notifi.event_type = Some(event.kind.clone());
					notifi.content = serde_json::value::to_raw_value(&event.content).ok();

					if event.kind == TimelineEventType::RoomMember {
						notifi.user_is_target =
							event.state_key.as_deref() == Some(event.sender.as_str());
					}

					notifi.sender_display_name =
						self.services.users.displayname(&event.sender).await.ok();

					notifi.room_name = self
						.services
						.state_accessor
						.get_name(&event.room_id)
						.await
						.ok();

					notifi.room_alias = self
						.services
						.state_accessor
						.get_canonical_alias(&event.room_id)
						.await
						.ok();

					self.send_request(
						&http.url,
						send_event_notification::v1::Request::new(notifi),
					)
					.await?;
				}

				Ok(())
			},
			// TODO: Handle email
			//PusherKind::Email(_) => Ok(()),
			| _ => Ok(()),
		}
	}
}