use std::collections::{BTreeMap, BTreeSet};

use axum::extract::State;
use conduwuit::{
	Err, Result, RoomVersion, debug, debug_info, debug_warn, err, info,
	matrix::{StateKey, pdu::PduBuilder},
	trace, warn,
};
use conduwuit_service::{Services, appservice::RegistrationInfo};
use futures::FutureExt;
use ruma::{
	CanonicalJsonObject, Int, OwnedRoomAliasId, OwnedRoomId, OwnedUserId, RoomId, RoomVersionId,
	api::client::room::{self, create_room},
	events::{
		TimelineEventType,
		invite_permission_config::FilterLevel,
		room::{
			canonical_alias::RoomCanonicalAliasEventContent,
			create::RoomCreateEventContent,
			guest_access::{GuestAccess, RoomGuestAccessEventContent},
			history_visibility::{HistoryVisibility, RoomHistoryVisibilityEventContent},
			join_rules::{JoinRule, RoomJoinRulesEventContent},
			member::{MembershipState, RoomMemberEventContent},
			name::RoomNameEventContent,
			power_levels::RoomPowerLevelsEventContent,
			topic::RoomTopicEventContent,
		},
	},
	int,
	serde::{JsonObject, Raw},
};
use serde_json::{json, value::to_raw_value};

use crate::{Ruma, client::invite_helper};

/// # `POST /_matrix/client/v3/createRoom`
///
/// Creates a new room.
///
/// - Room ID is randomly generated
/// - Create alias if `room_alias_name` is set
/// - Send create event
/// - Join sender user
/// - Send power levels event
/// - Send canonical room alias
/// - Send join rules
/// - Send history visibility
/// - Send guest access
/// - Send events listed in initial state
/// - Send events implied by `name` and `topic`
/// - Send invite events
#[allow(clippy::large_stack_frames)]
#[allow(clippy::cognitive_complexity)]
pub(crate) async fn create_room_route(
	State(services): State<crate::State>,
	body: Ruma<create_room::v3::Request>,
) -> Result<create_room::v3::Response> {
	use create_room::v3::RoomPreset;

	let sender_user = body.sender_user();

	if !services.globals.allow_room_creation()
		&& body.appservice_info.is_none()
		&& !services.users.is_admin(sender_user).await
	{
		return Err!(Request(Forbidden("Room creation has been disabled.",)));
	}

	if services.users.is_suspended(sender_user).await? {
		return Err!(Request(UserSuspended("You cannot perform this action while suspended.")));
	}

	let room_version = match body.room_version.clone() {
		| Some(room_version) =>
			if services.server.supported_room_version(&room_version) {
				room_version
			} else {
				return Err!(Request(UnsupportedRoomVersion(
					"This server does not support that room version."
				)));
			},
		| None => services.server.config.default_room_version.clone(),
	};
	let room_features = RoomVersion::new(&room_version)?;

	let room_id: Option<OwnedRoomId> = if !room_features.room_ids_as_hashes {
		match &body.room_id {
			| Some(custom_room_id) => Some(custom_room_id_check(&services, custom_room_id)?),
			| None => Some(RoomId::new(services.globals.server_name())),
		}
	} else {
		None
	};

	// check if room ID doesn't already exist instead of erroring on auth check
	if let Some(ref room_id) = room_id {
		if services.rooms.short.get_shortroomid(room_id).await.is_ok() {
			return Err!(Request(RoomInUse("Room with that custom room ID already exists",)));
		}
	}

	if body.visibility == room::Visibility::Public
		&& services.server.config.lockdown_public_room_directory
		&& !services.users.is_admin(sender_user).await
		&& body.appservice_info.is_none()
	{
		warn!(
			"Non-admin user {sender_user} tried to publish {room_id:?} to the room directory \
			 while \"lockdown_public_room_directory\" is enabled"
		);

		if services.server.config.admin_room_notices {
			services
				.admin
				.notice(&format!(
					"Non-admin user {sender_user} tried to publish {room_id:?} to the room \
					 directory while \"lockdown_public_room_directory\" is enabled"
				))
				.await;
		}

		return Err!(Request(Forbidden("Publishing rooms to the room directory is not allowed")));
	}

	let mut invitees = BTreeSet::new();

	for recipient_user in &body.invite {
		if !matches!(
			services
				.users
				.invite_filter_level(recipient_user, sender_user)
				.await,
			FilterLevel::Allow
		) {
			// drop invites if the creator has them blocked
			continue;
		}

		// if the recipient of the invite is local and has the sender blocked, error
		// out. if the recipient is remote we can't tell yet, and if they're local and
		// have the sender _ignored_ their invite will be filtered out in
		// the handlers for the individual /sync endpoints
		if services.globals.user_is_local(recipient_user)
			&& matches!(
				services
					.users
					.invite_filter_level(sender_user, recipient_user)
					.await,
				FilterLevel::Block
			) {
			return Err!(Request(InviteBlocked(
				"{recipient_user} has blocked invites from you."
			)));
		}

		invitees.insert(recipient_user.clone());
	}

	let alias: Option<OwnedRoomAliasId> = match body.room_alias_name.as_ref() {
		| Some(alias) =>
			Some(room_alias_check(&services, alias, body.appservice_info.as_ref()).await?),
		| _ => None,
	};

	let create_content = match &body.creation_content {
		| Some(content) => {
			use RoomVersionId::*;

			let mut content = content
				.deserialize_as::<CanonicalJsonObject>()
				.map_err(|e| {
					err!(Request(BadJson(error!(
						"Failed to deserialise content as canonical JSON: {e}"
					))))
				})?;

			match room_version {
				| V1 | V2 | V3 | V4 | V5 | V6 | V7 | V8 | V9 | V10 => {
					content.insert(
						"creator".into(),
						json!(&sender_user).try_into().map_err(|e| {
							err!(Request(BadJson(debug_error!("Invalid creation content: {e}"))))
						})?,
					);
				},
				| _ => {
					// V11+ removed the "creator" key
				},
			}
			content.insert(
				"room_version".into(),
				json!(room_version.as_str())
					.try_into()
					.map_err(|e| err!(Request(BadJson("Invalid creation content: {e}"))))?,
			);
			content
		},
		| None => {
			use RoomVersionId::*;

			let content = match room_version {
				| V1 | V2 | V3 | V4 | V5 | V6 | V7 | V8 | V9 | V10 =>
					RoomCreateEventContent::new_v1(sender_user.to_owned()),
				| V11 => RoomCreateEventContent::new_v11(),
				| _ => RoomCreateEventContent::new_v12(),
			};
			let mut content =
				serde_json::from_str::<CanonicalJsonObject>(to_raw_value(&content)?.get())?;
			content.insert("room_version".into(), json!(room_version.as_str()).try_into()?);
			content
		},
	};

	let state_lock = match room_id.clone() {
		| Some(room_id) => {
			let _short_id = services
				.rooms
				.short
				.get_or_create_shortroomid(&room_id)
				.await;
			services.rooms.state.mutex.lock(&room_id).await
		},
		| None => {
			let temp_room_id = RoomId::new(services.globals.server_name());
			trace!("Locking temporary room state mutex for {temp_room_id}");
			services.rooms.state.mutex.lock(&temp_room_id).await
		},
	};

	// 1. The room create event
	debug!("Creating room create event for {sender_user} in room {room_id:?}");
	let tmp_id = room_id.as_deref();
	let create_event_id = services
		.rooms
		.timeline
		.build_and_append_pdu(
			PduBuilder {
				event_type: TimelineEventType::RoomCreate,
				content: to_raw_value(&create_content)?,
				state_key: Some(StateKey::new()),
				timestamp: body.origin_server_ts,
				..Default::default()
			},
			sender_user,
			tmp_id,
			&state_lock,
		)
		.boxed()
		.await?;
	trace!("Created room create event with ID {}", &create_event_id);
	let room_id = match room_id.clone() {
		| Some(room_id) => room_id,
		| None => {
			let as_room_id = create_event_id.as_str().replace('$', "!");
			trace!("Creating room with v12 room ID {as_room_id}");
			RoomId::parse(&as_room_id)?.to_owned()
		},
	};
	drop(state_lock);
	if let Some(expected_room_id) = body.room_id.as_ref() {
		if expected_room_id.as_str() != room_id.as_str() {
			return Err!(Request(InvalidParam(
				"Custom room ID {expected_room_id} does not match the generated room ID \
				 {room_id}.",
			)));
		}
	}
	debug!("Room created with ID {room_id}");
	let state_lock = services.rooms.state.mutex.lock(&room_id).await;

	// 2. Let the room creator join
	debug_info!("Joining {sender_user} to room {room_id}");
	services
		.rooms
		.timeline
		.build_and_append_pdu(
			PduBuilder::state(sender_user.to_string(), &RoomMemberEventContent {
				displayname: services.users.displayname(sender_user).await.ok(),
				avatar_url: services.users.avatar_url(sender_user).await.ok(),
				blurhash: services.users.blurhash(sender_user).await.ok(),
				is_direct: Some(body.is_direct),
				..RoomMemberEventContent::new(MembershipState::Join)
			}),
			sender_user,
			Some(&room_id),
			&state_lock,
		)
		.boxed()
		.await?;

	// 3. Power levels

	// Figure out preset. We need it for preset specific events
	let preset = body.preset.clone().unwrap_or(match &body.visibility {
		| room::Visibility::Public => RoomPreset::PublicChat,
		| _ => RoomPreset::PrivateChat, // Room visibility should not be custom
	});

	let mut power_levels_to_grant = BTreeMap::from_iter([(sender_user.to_owned(), int!(100))]);

	if preset == RoomPreset::TrustedPrivateChat {
		for recipient_user in &invitees {
			power_levels_to_grant.insert(recipient_user.clone(), int!(100));
		}
	}

	let mut creators: Vec<OwnedUserId> = vec![sender_user.to_owned()];
	// Do we care about additional_creators?
	if room_features.explicitly_privilege_room_creators {
		// Have they been specified?
		if let Some(additional_creators) = create_content.get("additional_creators") {
			// Are they a real array?
			if let Some(additional_creators) = additional_creators.as_array() {
				// Iterate through them
				for creator in additional_creators {
					// Are they a string?
					if let Some(creator) = creator.as_str() {
						// Do they parse into a real user ID?
						if let Ok(creator) = OwnedUserId::parse(creator) {
							// Add them to the power levels and creators
							creators.push(creator.clone());
						}
					}
				}
			}
		}
	} else {
		power_levels_to_grant.insert(sender_user.to_owned(), int!(100));
		creators.clear(); // If this vec is not empty, default_power_levels_content will
		// treat this as a v12 room
	}

	let power_levels_content = default_power_levels_content(
		body.power_level_content_override.as_ref(),
		&body.visibility,
		power_levels_to_grant,
		creators,
	)?;

	services
		.rooms
		.timeline
		.build_and_append_pdu(
			PduBuilder {
				event_type: TimelineEventType::RoomPowerLevels,
				content: to_raw_value(&power_levels_content)?,
				state_key: Some(StateKey::new()),
				..Default::default()
			},
			sender_user,
			Some(&room_id),
			&state_lock,
		)
		.boxed()
		.await?;

	// 4. Canonical room alias
	if let Some(room_alias_id) = &alias {
		services
			.rooms
			.timeline
			.build_and_append_pdu(
				PduBuilder::state(String::new(), &RoomCanonicalAliasEventContent {
					alias: Some(room_alias_id.to_owned()),
					alt_aliases: vec![],
				}),
				sender_user,
				Some(&room_id),
				&state_lock,
			)
			.boxed()
			.await?;
	}

	// 5. Events set by preset

	// 5.1 Join Rules
	services
		.rooms
		.timeline
		.build_and_append_pdu(
			PduBuilder::state(
				String::new(),
				&RoomJoinRulesEventContent::new(match preset {
					| RoomPreset::PublicChat => JoinRule::Public,
					// according to spec "invite" is the default
					| _ => JoinRule::Invite,
				}),
			),
			sender_user,
			Some(&room_id),
			&state_lock,
		)
		.boxed()
		.await?;

	// 5.2 History Visibility
	services
		.rooms
		.timeline
		.build_and_append_pdu(
			PduBuilder::state(
				String::new(),
				&RoomHistoryVisibilityEventContent::new(HistoryVisibility::Shared),
			),
			sender_user,
			Some(&room_id),
			&state_lock,
		)
		.boxed()
		.await?;

	// 5.3 Guest Access
	services
		.rooms
		.timeline
		.build_and_append_pdu(
			PduBuilder::state(
				String::new(),
				&RoomGuestAccessEventContent::new(match preset {
					| RoomPreset::PublicChat => GuestAccess::Forbidden,
					| _ => GuestAccess::CanJoin,
				}),
			),
			sender_user,
			Some(&room_id),
			&state_lock,
		)
		.boxed()
		.await?;

	// 6. Events listed in initial_state
	for event in &body.initial_state {
		let mut pdu_builder = event.deserialize_as::<PduBuilder>().map_err(|e| {
			err!(Request(InvalidParam(warn!("Invalid initial state event: {e:?}"))))
		})?;

		debug_info!("Room creation initial state event: {event:?}");

		// client/appservice workaround: if a user sends an initial_state event with a
		// state event in there with the content of literally `{}` (not null or empty
		// string), let's just skip it over and warn.
		if pdu_builder.content.get().eq("{}") {
			debug_warn!("skipping empty initial state event with content of `{{}}`: {event:?}");
			debug_warn!("content: {}", pdu_builder.content.get());
			continue;
		}

		// Implicit state key defaults to ""
		pdu_builder.state_key.get_or_insert_with(StateKey::new);

		// Silently skip encryption events if they are not allowed
		if pdu_builder.event_type == TimelineEventType::RoomEncryption
			&& !services.config.allow_encryption
		{
			continue;
		}

		services
			.rooms
			.timeline
			.build_and_append_pdu(pdu_builder, sender_user, Some(&room_id), &state_lock)
			.boxed()
			.await?;
	}

	// 7. Events implied by name and topic
	if let Some(name) = &body.name {
		services
			.rooms
			.timeline
			.build_and_append_pdu(
				PduBuilder::state(String::new(), &RoomNameEventContent::new(name.clone())),
				sender_user,
				Some(&room_id),
				&state_lock,
			)
			.boxed()
			.await?;
	}

	if let Some(topic) = &body.topic {
		services
			.rooms
			.timeline
			.build_and_append_pdu(
				PduBuilder::state(String::new(), &RoomTopicEventContent { topic: topic.clone() }),
				sender_user,
				Some(&room_id),
				&state_lock,
			)
			.boxed()
			.await?;
	}

	// 8. Events implied by invite (and TODO: invite_3pid)
	drop(state_lock);
	for recipient_user in &invitees {
		if let Err(e) =
			invite_helper(&services, sender_user, recipient_user, &room_id, None, body.is_direct)
				.boxed()
				.await
		{
			warn!(?e, "Failed to send invite");
		}
	}

	// Homeserver specific stuff
	if let Some(alias) = alias {
		services
			.rooms
			.alias
			.set_alias(&alias, &room_id, sender_user)?;
	}

	if body.visibility == room::Visibility::Public {
		services.rooms.directory.set_public(&room_id);

		if services.server.config.admin_room_notices {
			services
				.admin
				.send_text(&format!(
					"{sender_user} made {} public to the room directory",
					&room_id
				))
				.await;
		}
		info!("{sender_user} made {0} public to the room directory", &room_id);
	}

	info!("{sender_user} created a room with room ID {room_id}");

	Ok(create_room::v3::Response::new(room_id))
}

/// creates the power_levels_content for the PDU builder
fn default_power_levels_content(
	power_level_content_override: Option<&Raw<RoomPowerLevelsEventContent>>,
	visibility: &room::Visibility,
	users: BTreeMap<OwnedUserId, Int>,
	creators: Vec<OwnedUserId>,
) -> Result<serde_json::Value> {
	let mut power_levels_content =
		serde_json::to_value(RoomPowerLevelsEventContent { users, ..Default::default() })
			.expect("event is valid, we just created it");

	// secure proper defaults of sensitive/dangerous permissions that moderators
	// (power level 50) should not have easy access to
	power_levels_content["events"]["m.room.power_levels"] =
		serde_json::to_value(100).expect("100 is valid Value");
	power_levels_content["events"]["m.room.server_acl"] =
		serde_json::to_value(100).expect("100 is valid Value");
	power_levels_content["events"]["m.room.tombstone"] =
		serde_json::to_value(100).expect("100 is valid Value");
	power_levels_content["events"]["m.room.encryption"] =
		serde_json::to_value(100).expect("100 is valid Value");
	power_levels_content["events"]["m.room.history_visibility"] =
		serde_json::to_value(100).expect("100 is valid Value");

	// always allow users to respond (not post new) to polls. this is primarily
	// useful in read-only announcement rooms that post a public poll.
	power_levels_content["events"]["org.matrix.msc3381.poll.response"] =
		serde_json::to_value(0).expect("0 is valid Value");
	power_levels_content["events"]["m.poll.response"] =
		serde_json::to_value(0).expect("0 is valid Value");

	// synapse does this too. clients do not expose these permissions. it prevents
	// default users from calling public rooms, for obvious reasons.
	if *visibility == room::Visibility::Public {
		power_levels_content["events"]["m.call.invite"] =
			serde_json::to_value(50).expect("50 is valid Value");
		power_levels_content["events"]["m.call"] =
			serde_json::to_value(50).expect("50 is valid Value");
		power_levels_content["events"]["m.call.member"] =
			serde_json::to_value(50).expect("50 is valid Value");
		power_levels_content["events"]["org.matrix.msc3401.call"] =
			serde_json::to_value(50).expect("50 is valid Value");
		power_levels_content["events"]["org.matrix.msc3401.call.member"] =
			serde_json::to_value(50).expect("50 is valid Value");
	}

	if let Some(power_level_content_override) = power_level_content_override {
		let json: JsonObject = serde_json::from_str(power_level_content_override.json().get())
			.map_err(|e| err!(Request(BadJson("Invalid power_level_content_override: {e:?}"))))?;

		for (key, value) in json {
			power_levels_content[key] = value;
		}
	}

	if !creators.is_empty() {
		// Raise the default power level of tombstone to 150
		power_levels_content["events"]["m.room.tombstone"] =
			serde_json::to_value(150).expect("150 is valid Value");
		for creator in creators {
			// Omit creators from the power level list altogether
			power_levels_content["users"]
				.as_object_mut()
				.expect("users is an object")
				.remove(creator.as_str());
		}
	}

	Ok(power_levels_content)
}

/// if a room is being created with a room alias, run our checks
async fn room_alias_check(
	services: &Services,
	room_alias_name: &str,
	appservice_info: Option<&RegistrationInfo>,
) -> Result<OwnedRoomAliasId> {
	// Basic checks on the room alias validity
	if room_alias_name.contains(':') {
		return Err!(Request(InvalidParam(
			"Room alias contained `:` which is not allowed. Please note that this expects a \
			 localpart, not the full room alias.",
		)));
	} else if room_alias_name.contains(char::is_whitespace) {
		return Err!(Request(InvalidParam(
			"Room alias contained spaces which is not a valid room alias.",
		)));
	}

	// check if room alias is forbidden
	if services
		.globals
		.forbidden_alias_names()
		.is_match(room_alias_name)
	{
		return Err!(Request(Unknown("Room alias name is forbidden.")));
	}

	let server_name = services.globals.server_name();
	let full_room_alias = OwnedRoomAliasId::parse(format!("#{room_alias_name}:{server_name}"))
		.map_err(|e| {
			err!(Request(InvalidParam(debug_error!(
				?e,
				%room_alias_name,
				"Failed to parse room alias.",
			))))
		})?;

	if services
		.rooms
		.alias
		.resolve_local_alias(&full_room_alias)
		.await
		.is_ok()
	{
		return Err!(Request(RoomInUse("Room alias already exists.")));
	}

	if let Some(info) = appservice_info {
		if !info.aliases.is_match(full_room_alias.as_str()) {
			return Err!(Request(Exclusive("Room alias is not in namespace.")));
		}
	} else if services
		.appservice
		.is_exclusive_alias(&full_room_alias)
		.await
	{
		return Err!(Request(Exclusive("Room alias reserved by appservice.",)));
	}

	debug_info!("Full room alias: {full_room_alias}");

	Ok(full_room_alias)
}

/// if a room is being created with a custom room ID, run our checks against it
fn custom_room_id_check(services: &Services, custom_room_id: &str) -> Result<OwnedRoomId> {
	// apply forbidden room alias checks to custom room IDs too
	if services
		.globals
		.forbidden_alias_names()
		.is_match(custom_room_id)
	{
		return Err!(Request(Unknown("Custom room ID is forbidden.")));
	}

	if custom_room_id.contains(':') {
		return Err!(Request(InvalidParam(
			"Custom room ID contained `:` which is not allowed. Please note that this expects a \
			 localpart, not the full room ID.",
		)));
	} else if custom_room_id.contains(char::is_whitespace) {
		return Err!(Request(InvalidParam(
			"Custom room ID contained spaces which is not valid."
		)));
	}

	let server_name = services.globals.server_name();
	let mut room_id = custom_room_id.to_owned();
	if custom_room_id.contains(':') {
		if !custom_room_id.starts_with('!') {
			return Err!(Request(InvalidParam(
				"Custom room ID contains an unexpected `:` which is not allowed.",
			)));
		}
	} else if custom_room_id.starts_with('!') {
		return Err!(Request(InvalidParam(
			"Room ID is prefixed with !, but is not fully qualified. You likely did not want \
			 this.",
		)));
	} else {
		room_id = format!("!{custom_room_id}:{server_name}");
	}
	OwnedRoomId::parse(room_id)
		.map_err(Into::into)
		.and_then(|full_room_id| {
			if full_room_id
				.server_name()
				.expect("failed to extract server name from room ID")
				!= server_name
			{
				Err!(Request(InvalidParam("Custom room ID must be on this server.",)))
			} else {
				Ok(full_room_id)
			}
		})
		.inspect(|full_room_id| {
			debug_info!(%full_room_id, "Full custom room ID");
		})
		.inspect_err(|e| warn!(?e, %custom_room_id, "Failed to create room with custom room ID",))
}
