<?php

declare(strict_types=1);

namespace Symplify\EasyCodingStandard\ChangedFilesDetector;

use Symfony\Component\Cache\Adapter\TagAwareAdapterInterface;
use Symfony\Component\Cache\CacheItem;
use Symplify\SmartFileSystem\SmartFileInfo;

/**
 * @see \Symplify\EasyCodingStandard\ChangedFilesDetector\Tests\ChangedFilesDetectorTest
 */
final class ChangedFilesDetector
{
    /**
     * @var string
     */
    public const CHANGED_FILES_CACHE_TAG = 'changed_files';

    /**
     * @var string
     */
    private const CONFIGURATION_HASH_KEY = 'configuration_hash';

    /**
     * @var FileHashComputer
     */
    private $fileHashComputer;

    /**
     * @var TagAwareAdapterInterface
     */
    private $tagAwareAdapter;

    public function __construct(FileHashComputer $fileHashComputer, TagAwareAdapterInterface $tagAwareAdapter)
    {
        $this->fileHashComputer = $fileHashComputer;
        $this->tagAwareAdapter = $tagAwareAdapter;
    }

    /**
     * For tests
     */
    public function changeConfigurationFile(string $configurationFile): void
    {
        $this->storeConfigurationDataHash($this->fileHashComputer->compute($configurationFile));
    }

    public function addFileInfo(SmartFileInfo $smartFileInfo): void
    {
        /** @var CacheItem $cacheItem */
        $cacheItem = $this->tagAwareAdapter->getItem($this->fileInfoToKey($smartFileInfo));
        $cacheItem->set($this->fileHashComputer->compute($smartFileInfo->getRealPath()));
        $cacheItem->tag(self::CHANGED_FILES_CACHE_TAG);

        $this->tagAwareAdapter->save($cacheItem);
    }

    public function invalidateFileInfo(SmartFileInfo $smartFileInfo): void
    {
        $this->tagAwareAdapter->deleteItem($this->fileInfoToKey($smartFileInfo));
    }

    public function hasFileInfoChanged(SmartFileInfo $smartFileInfo): bool
    {
        $newFileHash = $this->fileHashComputer->compute($smartFileInfo->getRealPath());

        $cacheItem = $this->tagAwareAdapter->getItem($this->fileInfoToKey($smartFileInfo));
        $oldFileHash = $cacheItem->get();
        return $newFileHash !== $oldFileHash;
    }

    public function clearCache(): void
    {
        // clear cache only for changed files group
        $this->tagAwareAdapter->invalidateTags([self::CHANGED_FILES_CACHE_TAG]);
    }

    /**
     * For cache invalidation
     * @param SmartFileInfo[] $configFileInfos
     */
    public function setUsedConfigs(array $configFileInfos): void
    {
        if (count($configFileInfos) === 0) {
            return;
        }

        // the first config is core to all → if it was changed, just invalidate it
        $firstConfigFileInfo = $configFileInfos[0];
        $this->storeConfigurationDataHash($this->fileHashComputer->compute($firstConfigFileInfo->getRealPath()));
    }

    private function storeConfigurationDataHash(string $configurationHash): void
    {
        $this->invalidateCacheIfConfigurationChanged($configurationHash);

        $cacheItem = $this->tagAwareAdapter->getItem(self::CONFIGURATION_HASH_KEY);
        $cacheItem->set($configurationHash);

        $this->tagAwareAdapter->save($cacheItem);
    }

    private function fileInfoToKey(SmartFileInfo $smartFileInfo): string
    {
        return sha1($smartFileInfo->getRelativeFilePathFromCwd());
    }

    private function invalidateCacheIfConfigurationChanged(string $configurationHash): void
    {
        $cacheItem = $this->tagAwareAdapter->getItem(self::CONFIGURATION_HASH_KEY);

        $oldConfigurationHash = $cacheItem->get();
        if ($configurationHash !== $oldConfigurationHash) {
            $this->clearCache();
        }
    }
}