<?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 Psr\Log\LoggerInterface;

class MatrixService
{

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

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

	/** @var string */
	private $registrationSecret = "~d9fJpPKDZIV67A7=tPCvok:=fTBLV;MFf=9FRxtAazW@-GwSo";

	/**
	 * @throws MatrixRequestException
	 * @throws MatrixHttpLibException
	 * @throws ValidationException
	 * @throws MatrixException
	 */
	public function __construct(LoggerInterface $logger)
	{
		$this->logger = $logger;
		$serverUrl = "http://synapse:8008";
		$user = "upschooling";
		$this->client = new MatrixClient($serverUrl);
		$this->client->login($user, "secret", true);
		$this->logger->debug("Logged in as " . $user . " on server " . $serverUrl);
	}

	/**
	 * @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;
	}

}