<?php
/**
 * Copyright 2010-2013 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License").
 * You may not use this file except in compliance with the License.
 * A copy of the License is located at
 *
 * http://aws.amazon.com/apache2.0
 *
 * or in the "license" file accompanying this file. This file is distributed
 * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
 * express or implied. See the License for the specific language governing
 * permissions and limitations under the License.
 */

namespace Akeeba\Engine\Postproc\Connector\Amazon\Aws\S3\Sync;

use Akeeba\Engine\Postproc\Connector\Amazon\Aws\Common\Exception\RuntimeException;
use Akeeba\Engine\Postproc\Connector\Amazon\Aws\Common\Exception\UnexpectedValueException;
use Akeeba\Engine\Postproc\Connector\Amazon\Aws\Common\Model\MultipartUpload\TransferInterface;
use Akeeba\Engine\Postproc\Connector\Amazon\Aws\S3\S3Client;
use Akeeba\Engine\Postproc\Connector\Amazon\Aws\S3\Iterator\OpendirIterator;
use Akeeba\Engine\Postproc\Connector\Amazon\Guzzle\Common\Event;
use Akeeba\Engine\Postproc\Connector\Amazon\Guzzle\Common\HasDispatcherInterface;
use Akeeba\Engine\Postproc\Connector\Amazon\Guzzle\Iterator\FilterIterator;
use Akeeba\Engine\Postproc\Connector\Amazon\Guzzle\Service\Command\CommandInterface;

abstract class AbstractSyncBuilder
{
    /** @var \Iterator Iterator that returns SplFileInfo objects to upload */
    protected $sourceIterator;

    /** @var S3Client Amazon S3 client used to send requests */
    protected $client;

    /** @var string Bucket used with the transfer */
    protected $bucket;

    /** @var int Number of files that can be transferred concurrently */
    protected $concurrency = 10;

    /** @var array Custom parameters to add to each operation sent while transferring */
    protected $params = array();

    /** @var FilenameConverterInterface */
    protected $sourceConverter;

    /** @var FilenameConverterInterface */
    protected $targetConverter;

    /** @var string Prefix at prepend to each Amazon S3 object key */
    protected $keyPrefix = '';

    /** @var string Directory separator for Amazon S3 keys */
    protected $delimiter = '/';

    /** @var string Base directory to remove from each file path before converting to an object name or file name */
    protected $baseDir;

    /** @var bool Whether or not to only transfer modified or new files */
    protected $forcing = false;

    /** @var bool Whether or not debug output is enable */
    protected $debug;

    /**
     * @return self
     */
    public static function getInstance()
    {
        return new static();
    }

    /**
     * Set the bucket to use with the sync
     *
     * @param string $bucket Amazon S3 bucket name
     *
     * @return self
     */
    public function setBucket($bucket)
    {
        $this->bucket = $bucket;

        return $this;
    }

    /**
     * Set the Amazon S3 client object that will send requests
     *
     * @param S3Client $client Amazon S3 client
     *
     * @return self
     */
    public function setClient(S3Client $client)
    {
        $this->client = $client;

        return $this;
    }

    /**
     * Set a custom iterator that returns \SplFileInfo objects for the source data
     *
     * @param \Iterator $iterator
     *
     * @return self
     */
    public function setSourceIterator(\Iterator $iterator)
    {
        $this->sourceIterator = $iterator;

        return $this;
    }

    /**
     * Set a custom object key provider instead of building one internally
     *
     * @param FileNameConverterInterface $converter Filename to object key provider
     *
     * @return self
     */
    public function setSourceFilenameConverter(FilenameConverterInterface $converter)
    {
        $this->sourceConverter = $converter;

        return $this;
    }

    /**
     * Set a custom object key provider instead of building one internally
     *
     * @param FileNameConverterInterface $converter Filename to object key provider
     *
     * @return self
     */
    public function setTargetFilenameConverter(FilenameConverterInterface $converter)
    {
        $this->targetConverter = $converter;

        return $this;
    }

    /**
     * Set the base directory of the files being transferred. The base directory is removed from each file path before
     * converting the file path to an object key or vice versa.
     *
     * @param string $baseDir Base directory, which will be deleted from each uploaded object key
     *
     * @return self
     */
    public function setBaseDir($baseDir)
    {
        $this->baseDir = $baseDir;

        return $this;
    }

    /**
     * Specify a prefix to prepend to each Amazon S3 object key or the prefix where object are stored in a bucket
     *
     * Can be used to upload files to a pseudo sub-folder key or only download files from a pseudo sub-folder
     *
     * @param string $keyPrefix Prefix for each uploaded key
     *
     * @return self
     */
    public function setKeyPrefix($keyPrefix)
    {
        // Removing leading slash
        $this->keyPrefix = ltrim($keyPrefix, '/');

        return $this;
    }

    /**
     * Specify the delimiter used for the targeted filesystem (default delimiter is "/")
     *
     * @param string $delimiter Delimiter to use to separate paths
     *
     * @return self
     */
    public function setDelimiter($delimiter)
    {
        $this->delimiter = $delimiter;

        return $this;
    }

    /**
     * Specify an array of operation parameters to apply to each operation executed by the sync object
     *
     * @param array $params Associative array of PutObject (upload) GetObject (download) parameters
     *
     * @return self
     */
    public function setOperationParams(array $params)
    {
        $this->params = $params;

        return $this;
    }

    /**
     * Set the number of files that can be transferred concurrently
     *
     * @param int $concurrency Number of concurrent transfers
     *
     * @return self
     */
    public function setConcurrency($concurrency)
    {
        $this->concurrency = $concurrency;

        return $this;
    }

    /**
     * Set to true to force transfers even if a file already exists and has not changed
     *
     * @param bool $force Set to true to force transfers without checking if it has changed
     *
     * @return self
     */
    public function force($force = false)
    {
        $this->forcing = (bool) $force;

        return $this;
    }

    /**
     * Enable debug mode
     *
     * @param bool|resource $enabledOrResource Set to true or false to enable or disable debug output. Pass an opened
     *                                         fopen resource to write to instead of writing to standard out.
     * @return self
     */
    public function enableDebugOutput($enabledOrResource = true)
    {
        $this->debug = $enabledOrResource;

        return $this;
    }

    /**
     * Add a filename filter that uses a regular expression to filter out files that you do not wish to transfer.
     *
     * @param string $search Regular expression search (in preg_match format). Any filename that matches this regex
     *                       will not be transferred.
     * @return self
     */
    public function addRegexFilter($search)
    {
        $this->assertFileIteratorSet();
        $this->sourceIterator = new FilterIterator($this->sourceIterator, function ($i) use ($search) {
            return !preg_match($search, (string) $i);
        });
        $this->sourceIterator->rewind();

        return $this;
    }

    /**
     * Builds a UploadSync or DownloadSync object
     *
     * @return AbstractSync
     */
    public function build()
    {
        $this->validateRequirements();
        $this->sourceConverter = $this->sourceConverter ?: $this->getDefaultSourceConverter();
        $this->targetConverter = $this->targetConverter ?: $this->getDefaultTargetConverter();

        // Only wrap the source iterator in a changed files iterator if we are not forcing the transfers
        if (!$this->forcing) {
            $this->sourceIterator->rewind();
            $this->sourceIterator = new ChangedFilesIterator(
                new \NoRewindIterator($this->sourceIterator),
                $this->getTargetIterator(),
                $this->sourceConverter,
                $this->targetConverter
            );
            $this->sourceIterator->rewind();
        }

        $sync = $this->specificBuild();

        if ($this->params) {
            $this->addCustomParamListener($sync);
        }

        if ($this->debug) {
            $this->addDebugListener($sync, is_bool($this->debug) ? STDOUT : $this->debug);
        }

        return $sync;
    }

    /**
     * Hook to implement in subclasses
     *
     * @return self
     */
    abstract protected function specificBuild();

    /**
     * @return \Iterator
     */
    abstract protected function getTargetIterator();

    /**
     * @return FilenameConverterInterface
     */
    abstract protected function getDefaultSourceConverter();

    /**
     * @return FilenameConverterInterface
     */
    abstract protected function getDefaultTargetConverter();

    /**
     * Add a listener to the sync object to output debug information while transferring
     *
     * @param AbstractSync $sync     Sync object to listen to
     * @param resource     $resource Where to write debug messages
     */
    abstract protected function addDebugListener(AbstractSync $sync, $resource);

    /**
     * Validate that the builder has the minimal requirements
     *
     * @throws RuntimeException if the builder is not configured completely
     */
    protected function validateRequirements()
    {
        if (!$this->client) {
            throw new RuntimeException('No client was provided');
        }
        if (!$this->bucket) {
            throw new RuntimeException('No bucket was provided');
        }
        $this->assertFileIteratorSet();
    }

    /**
     * Ensure that the base file iterator has been provided
     *
     * @throws RuntimeException
     */
    protected function assertFileIteratorSet()
    {
        // Interesting... Need to use isset because: Object of class GlobIterator could not be converted to boolean
        if (!isset($this->sourceIterator)) {
            throw new RuntimeException('A source file iterator must be specified');
        }
    }

    /**
     * Wraps a generated iterator in a filter iterator that removes directories
     *
     * @param \Iterator $iterator Iterator to wrap
     *
     * @return \Iterator
     * @throws UnexpectedValueException
     */
    protected function filterIterator(\Iterator $iterator)
    {
        $f = new FilterIterator($iterator, function ($i) {
            if (!$i instanceof \SplFileInfo) {
                throw new UnexpectedValueException('All iterators for UploadSync must return SplFileInfo objects');
            }
            return $i->isFile();
        });

        $f->rewind();

        return $f;
    }

    /**
     * Add the custom param listener to a transfer object
     *
     * @param HasDispatcherInterface $sync
     */
    protected function addCustomParamListener(HasDispatcherInterface $sync)
    {
        $params = $this->params;
        $sync->getEventDispatcher()->addListener(
            UploadSync::BEFORE_TRANSFER,
            function (Event $e) use ($params) {
                if ($e['command'] instanceof CommandInterface) {
                    $e['command']->overwriteWith($params);
                }
            }
        );
    }

    /**
     * Create an Amazon S3 file iterator based on the given builder settings
     *
     * @return OpendirIterator
     */
    protected function createS3Iterator()
    {
        // Ensure that the stream wrapper is registered
        $this->client->registerStreamWrapper();

        // Calculate the opendir() bucket and optional key prefix location
        $dir = "s3://{$this->bucket}";
        if ($this->keyPrefix) {
            $dir .= '/' . ltrim($this->keyPrefix, '/ ');
        }

        // Use opendir so that we can pass stream context to the iterator
        $dh = opendir($dir, stream_context_create(array(
            's3' => array(
                'delimiter'  => '',
                'listFilter' => function ($obj) {
                    // Ensure that we do not try to download a glacier object.
                    return !isset($obj['StorageClass']) ||
                        $obj['StorageClass'] != 'GLACIER';
                }
            )
        )));

        // Add the trailing slash for the OpendirIterator concatenation
        if (!$this->keyPrefix) {
            $dir .= '/';
        }

        return $this->filterIterator(new \NoRewindIterator(new OpendirIterator($dh, $dir)));
    }
}
