<?php
declare(strict_types=1);


/**
 * Nextcloud - Social Support
 *
 * This file is licensed under the Affero General Public License version 3 or
 * later. See the COPYING file.
 *
 * @author Maxence Lange <maxence@artificial-owl.com>
 * @copyright 2018, Maxence Lange <maxence@artificial-owl.com>
 * @license GNU AGPL version 3 or any later version
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */


namespace OCA\Social\Service;


use daita\MySmallPhpTools\Traits\TArrayTools;
use OCA\Social\Db\HashtagsRequest;
use OCA\Social\Db\StreamRequest;
use OCA\Social\Exceptions\DateTimeException;
use OCA\Social\Exceptions\HashtagDoesNotExistException;
use OCA\Social\Model\ActivityPub\Object\Note;
use OCA\Social\Model\ActivityPub\Stream;


class HashtagService {


	const TREND_1H = 3600;
	const TREND_12H = 43200;
	const TREND_1D = 86400;
	const TREND_3D = 259200;
	const TREND_10D = 864000;


	use TArrayTools;


	/** @var HashtagsRequest */
	private $hashtagsRequest;

	/** @var StreamRequest */
	private $streamRequest;

	/** @var ConfigService */
	private $configService;

	/** @var MiscService */
	private $miscService;


	/**
	 * ImportService constructor.
	 *
	 * @param HashtagsRequest $hashtagsRequest
	 * @param StreamRequest $streamRequest
	 * @param ConfigService $configService
	 * @param MiscService $miscService
	 */
	public function __construct(
		HashtagsRequest $hashtagsRequest, StreamRequest $streamRequest,
		ConfigService $configService,
		MiscService $miscService
	) {
		$this->hashtagsRequest = $hashtagsRequest;
		$this->streamRequest = $streamRequest;
		$this->configService = $configService;
		$this->miscService = $miscService;
	}

	/*
	 * note: trend is:
	 * [
	 *   '1h' => x,
	 *   '12h' => x,
	 *   '1d' => x,
	 *   '3d' => x,
	 *   '10d' => x
	 * ]
	 */


	/**
	 * @return int
	 * @throws DateTimeException
	 */
	public function manageHashtags(): int {
		$current = $this->hashtagsRequest->getAll();

		$time = time();
		$hashtags = [
			'1h'  => $this->getTrendSince($time - self::TREND_1H),
			'12h' => $this->getTrendSince($time - self::TREND_12H),
			'1d'  => $this->getTrendSince($time - self::TREND_1D),
			'3d'  => $this->getTrendSince($time - self::TREND_3D),
			'10d' => $this->getTrendSince($time - self::TREND_10D)
		];

		$count = 0;
		$formatted = $this->formatTrend($hashtags);
		foreach ($formatted as $hashtag => $trend) {
			$count++;
			try {
				$this->getFromList($current, $hashtag);
				$this->hashtagsRequest->update($hashtag, $trend);
			} catch (HashtagDoesNotExistException $e) {
				$this->hashtagsRequest->save($hashtag, $trend);
			}
		}

		return $count;
	}


	/**
	 * @param string $hashtag
	 *
	 * @return array
	 * @throws HashtagDoesNotExistException
	 */
	public function getHashtag(string $hashtag): array {
		if (substr($hashtag, 0, 1) !== '#') {
			$hashtag = '#' . $hashtag;
		}

		return $this->hashtagsRequest->getHashtag($hashtag);
	}


	/**
	 * @param string $hashtag
	 *
	 * @return array
	 */
	public function searchHashtags(string $hashtag): array {
		return $this->hashtagsRequest->searchHashtags($hashtag);
	}


	/**
	 * @param int $timestamp
	 *
	 * @return Stream[]
	 * @throws DateTimeException
	 */
	private function getTrendSince(int $timestamp): array {
		$result = [];

		$notes = $this->streamRequest->getNoteSince($timestamp);
		foreach ($notes as $note) {
			/** @var Note $note */
			foreach ($note->getHashtags() as $hashtag) {
				if (array_key_exists($hashtag, $result)) {
					$result[$hashtag]++;
				} else {
					$result[$hashtag] = 1;
				}
			}
		}

		return $result;
	}


	/**
	 * @param array $hashtags
	 *
	 * @return array
	 */
	private function formatTrend(array $hashtags): array {
		$trends = [];
		foreach (end($hashtags) as $hashtag => $count) {
			$trends[$hashtag] = [];
		}

		$all = array_keys($trends);
		$periods = array_keys($hashtags);
		foreach ($all as $hashtag) {
			foreach ($periods as $period) {
				$count = $this->countFromList($hashtags[$period], $hashtag);
				$trends[$hashtag][$period] = $count;
			}
		}

		return $trends;
	}


	/**
	 * @param array $list
	 * @param string $hashtag
	 *
	 * @return int
	 */
	private function countFromList(array $list, string $hashtag): int {
		foreach ($list as $key => $count) {
			if ($key === $hashtag) {
				return $count;
			}
		}

		return 0;
	}


	/**
	 * @param array $list
	 * @param string $hashtag
	 *
	 * @return array
	 * @throws HashtagDoesNotExistException
	 */
	private function getFromList(array $list, string $hashtag): array {
		foreach ($list as $item) {
			if ($this->get('hashtag', $item, '') === $hashtag) {
				return $item;
			}
		}

		throw new HashtagDoesNotExistException();
	}
}