<?php

namespace OCA\UPschooling\Service;

use Aryess\PhpMatrixSdk\Exceptions\MatrixException;
use Aryess\PhpMatrixSdk\Exceptions\MatrixHttpLibException;
use Aryess\PhpMatrixSdk\Exceptions\MatrixRequestException;
use Aryess\PhpMatrixSdk\Exceptions\ValidationException;
use Aryess\PhpMatrixSdk\MatrixClient;
use Aryess\PhpMatrixSdk\Room;
use OCA\UPschooling\Db\MatrixUser;
use OCA\UPschooling\Exceptions\RoomNotFoundException;
use OCP\IConfig;
use Psr\Log\LoggerInterface;

class MatrixService
{

	/** @var LoggerInterface */
	private $logger;

	/** @var IConfig */
	private $config;

	/** @var MatrixClient */
	private $client;

	/** @var string */
	private $registrationSecret;

	/** @var string Matrix server URL */
	private $serverUrl;

	/** @var string Matrix server part */
	private $server;

	/** @var string Matrix admin user */
	private $superuser;

	/** @var string Matrix authentication token */
	private $token;

	/**
	 * @throws MatrixRequestException
	 * @throws MatrixHttpLibException
	 * @throws ValidationException
	 * @throws MatrixException
	 */
	public function __construct(IConfig $config, LoggerInterface $logger)
	{
		$this->logger = $logger;
		$this->config = $config;
		$this->registrationSecret = $this->config->getSystemValueString(
			"upschooling.matrix_registration_secret",
			"oyYh_iEJ7Aim.iB+ye.Xk;Gl3iHFab5*8K,zv~IulT85P=c-38"
		);
		$this->serverUrl = $this->config->getSystemValueString(
			"upschooling.matrix_server_url",
			"http://localhost:8008"
		);
		$this->server = $this->config->getSystemValueString(
			"upschooling.matrix_server",
			"synapse"
		);
		$this->superuser = $this->config->getSystemValueString(
			"upschooling.matrix_superuser",
			"upschooling"
		);
		$this->token = $this->config->getSystemValueString("upschooling.matrix_auth_token");
		if ($this->token != "") {
			$this->client = new MatrixClient($this->serverUrl, $this->token);
			$this->logger->debug("Using previous login as " . $this->superuser . " on server " . $this->serverUrl);
		} else {
			$this->client = new MatrixClient($this->serverUrl);
			$token = $this->client->login($this->superuser, "secret", true);
			$this->logger->debug("Logged in as " . $this->superuser . " on server " . $this->serverUrl);
			$this->config->setSystemValue("upschooling.matrix_auth_token", $token);
		}

		$this->checkRateLimit();
	}

	/**
	 * @param string $roomId a room id of an existing and joined room.
	 * @param string $eventType a unique property identifier with reverse domain notation, e.g. com.example.property.
	 * @param array $content the contents as a JSON serializable array.
	 * @throws RoomNotFoundException
	 * @throws MatrixException
	 */
	public function setProperty(string $roomId, string $eventType, array $content)
	{
		$room = $this->findRoom($roomId);
		$room->sendStateEvent($eventType, $content);
		$this->logger->debug(
			"Set property " . $eventType . " on room " . $roomId,
			array("room" => $roomId, "key" => $eventType, "value" => $content)
		);
	}

	/**
	 * @param string $roomId a room id of an existing and joined room.
	 * @param string $eventType a unique property identifier with reverse domain notation, e.g. com.example.property.
	 * @return array the contents of the room state.
	 * @throws MatrixException
	 * @throws RoomNotFoundException
	 */
	public function getProperty(string $roomId, string $eventType): array
	{
		$this->findRoom($roomId); // make sure the room exists/is joined
		$content = $this->client->api()->getStateEvent($roomId, $eventType);
		$this->logger->debug(
			"Got property " . $eventType . " from room " . $roomId,
			array("room" => $roomId, "key" => $eventType, "value" => $content)
		);
		return $content;
	}

	/**
	 * @param string $roomId a room id of an existing and joined room.
	 * @throws RoomNotFoundException
	 * @returns int the origin server timestamp of the most recent event.
	 */
	public function getLastEventDate(string $roomId): int
	{
		$room = $this->findRoom($roomId);
		$events = $room->getEvents();
		if (count($events) === 0) {
			$this->logger->debug("Did not have any events for room " . $roomId);
			return 0;
		} else {
			$timestamp = array_get($events[0], 'origin_server_ts', 1);
			if ($timestamp === 1) {
				$this->logger->debug("Could not find origin_server_ts in last event of room " . $roomId);
			} else {
				$this->logger->debug("Last event in room " . $roomId . " was at " . $timestamp);
			}
			return $timestamp;
		}
	}

	/**
	 * Registers a new matrix user with the local matrix server.
	 *
	 * @throws MatrixException
	 * @throws MatrixHttpLibException
	 * @throws MatrixRequestException
	 * @return MatrixUser user object without id or Nextcloud user id set.
	 */
	public function registerNewUser(): MatrixUser
	{
		$nonceResponse = $this->client->api()->send(
			'GET',
			'/register',
			null,
			[],
			[],
			'/_synapse/admin/v1',
			true
		);
		$randUsername = trim(str_replace(["/", "+"], ".", base64_encode(random_bytes(6))), "=");
		$username = "upschooling_" . $randUsername;
		$password = base64_encode(random_bytes(32));
		$hmacData = $nonceResponse["nonce"] . "\x00" . $username . "\x00" . $password . "\x00notadmin";
		$hmac = hash_hmac("sha1", $hmacData, $this->registrationSecret, false);
		$registrationResponse = $this->client->api()->send(
			'POST',
			'/register',
			array(
				"nonce" => $nonceResponse["nonce"],
				"username" => $username,
				"password" => $password,
				"displayname" => "UPschooling Support User " . $randUsername,
				"admin" => false,
				"mac" => $hmac,
			),
			[],
			[],
			'/_synapse/admin/v1',
			true
		);

		$matrixUser = new MatrixUser();
		$matrixUser->setMatrixUser($registrationResponse["user_id"]);
		$matrixUser->setMatrixToken($registrationResponse["access_token"]);
		$this->logger->debug("Created a new user: " . $matrixUser->getMatrixUser());
		return $matrixUser;
	}

	/**
	 * @param string $roomId a room id of an existing and joined room.
	 * @throws RoomNotFoundException
	 * @returns Room the room object, if found.
	 */
	private function findRoom(string $roomId): Room
	{
		foreach ($this->client->getRooms() as $room) {
			if ($room->getRoomId() === $roomId) {
				$this->logger->debug("Found room " . $roomId . " on matrix client");
				return $room;
			}
		}
		$this->logger->error("Room " . $roomId . " was not found on matrix client");
		throw new RoomNotFoundException();
	}

	/**
	 * Creates a new room.
 	 *
	 * @throws MatrixException
	 * @return string the room id of the newly created room.
	 */
	public function createRoom(): string
	{
		$roomId = $this->client->createRoom()->getRoomId();
		$this->logger->debug("Created a new room: " . $roomId);
		return $roomId;
	}

	/**
	 * @return string the public matrix server url.
	 */
	public function getServerUrl(): string
	{
		return $this->serverUrl;
	}

	private function checkRateLimit()
	{
		$fullSuperuserId = "@" . $this->superuser . ":" . $this->server;
		$rateLimitResponse = $this->client->api()->send(
			'GET',
			'/users/' . rawurlencode($fullSuperuserId) . '/override_ratelimit',
			null,
			[],
			[],
			'/_synapse/admin/v1',
			true
		);
		if (array_has($rateLimitResponse, "messages_per_second") &&
			array_has($rateLimitResponse, "burst_count")) {
			$this->logger->debug("Ratelimit setting found for " . $this->superuser);
		} else {
			$this->client->api()->send(
				'POST',
				'/users/' . rawurlencode($fullSuperuserId) . '/override_ratelimit',
				array(
					"messages_per_second" => 0,
					"burst_count" => 0,
				),
				[],
				[],
				'/_synapse/admin/v1',
				true
			);
			$this->logger->debug("No ratelimiting for " . $this->superuser);
		}
	}
}