<?php

declare(strict_types=1);
/**
 * SPDX-FileCopyrightText: 2016-2024 Nextcloud GmbH and Nextcloud contributors
 * SPDX-FileCopyrightText: 2016 ownCloud, Inc.
 * SPDX-License-Identifier: AGPL-3.0-only
 */
namespace OC;

use OCP\AppFramework\QueryException;
use OCP\Capabilities\ICapability;
use OCP\Capabilities\IInitialStateExcludedCapability;
use OCP\Capabilities\IPublicCapability;
use OCP\ILogger;
use Psr\Log\LoggerInterface;

class CapabilitiesManager {
	/**
	 * Anything above 0.1s to load the capabilities of an app qualifies for bad code
	 * and should be cached within the app.
	 */
	public const ACCEPTABLE_LOADING_TIME = 0.1;

	/** @var \Closure[] */
	private array $capabilities = [];

	public function __construct(
		private LoggerInterface $logger,
	) {
	}

	/**
	 * Get an array of all the capabilities that are registered at this manager
	 *
	 * @param bool $public get public capabilities only
	 * @throws \InvalidArgumentException
	 * @return array<string, mixed>
	 */
	public function getCapabilities(bool $public = false, bool $initialState = false) : array {
		$capabilities = [];
		foreach ($this->capabilities as $capability) {
			try {
				$c = $capability();
			} catch (QueryException $e) {
				$this->logger->error('CapabilitiesManager', [
					'exception' => $e,
				]);
				continue;
			}

			if ($c instanceof ICapability) {
				if (!$public || $c instanceof IPublicCapability) {
					if ($initialState && ($c instanceof IInitialStateExcludedCapability)) {
						// Remove less important capabilities information that are expensive to query
						// that we would otherwise inject to every page load
						continue;
					}
					$startTime = microtime(true);
					$capabilities = array_replace_recursive($capabilities, $c->getCapabilities());
					$endTime = microtime(true);
					$timeSpent = $endTime - $startTime;
					if ($timeSpent > self::ACCEPTABLE_LOADING_TIME) {
						$logLevel = match (true) {
							$timeSpent > self::ACCEPTABLE_LOADING_TIME * 16 => ILogger::FATAL,
							$timeSpent > self::ACCEPTABLE_LOADING_TIME * 8 => ILogger::ERROR,
							$timeSpent > self::ACCEPTABLE_LOADING_TIME * 4 => ILogger::WARN,
							$timeSpent > self::ACCEPTABLE_LOADING_TIME * 2 => ILogger::INFO,
							default => ILogger::DEBUG,
						};
						$this->logger->log(
							$logLevel,
							'Capabilities of {className} took {duration} seconds to generate.',
							[
								'className' => get_class($c),
								'duration' => round($timeSpent, 2),
							]
						);
					}
				}
			} else {
				throw new \InvalidArgumentException('The given Capability (' . get_class($c) . ') does not implement the ICapability interface');
			}
		}

		return $capabilities;
	}

	/**
	 * In order to improve lazy loading a closure can be registered which will be called in case
	 * capabilities are actually requested
	 *
	 * $callable has to return an instance of OCP\Capabilities\ICapability
	 *
	 * @param \Closure $callable
	 */
	public function registerCapability(\Closure $callable) {
		$this->capabilities[] = $callable;
	}
}