<?php

namespace SilverStripe\Assets;

use SilverStripe\Assets\Storage\AssetContainer;
use SilverStripe\Assets\Storage\AssetNameGenerator;
use SilverStripe\Assets\Storage\AssetStore;
use SilverStripe\Control\Controller;
use SilverStripe\Core\Injector\Injector;
use SilverStripe\Core\Object;
use SilverStripe\ORM\DataObject;
use SilverStripe\Security\Member;
use InvalidArgumentException;
use Exception;

/**
 * Manages uploads via HTML forms processed by PHP,
 * uploads to Silverstripe's default upload directory,
 * and either creates a new or uses an existing File-object
 * for syncing with the database.
 *
 * <b>Validation</b>
 *
 * By default, a user can upload files without extension limitations,
 * which can be a security risk if the webserver is not properly secured.
 * Use {@link setAllowedExtensions()} to limit this list,
 * and ensure the "assets/" directory does not execute scripts
 * (see http://doc.silverstripe.org/secure-development#filesystem).
 * {@link File::$allowed_extensions} provides a good start for a list of "safe" extensions.
 *
 * @todo Allow for non-database uploads
 */
class Upload extends Controller {

	private static $allowed_actions = array(
		'index',
		'load'
	);

	/**
	 * A dataobject (typically {@see File}) which implements {@see AssetContainer}
	 *
	 * @var AssetContainer
	 */
	protected $file;

	/**
	 * Validator for this upload field
	 *
	 * @var Upload_Validator
	 */
	protected $validator;

	/**
	 * Information about the temporary file produced
	 * by the PHP-runtime.
	 *
	 * @var array
	 */
	protected $tmpFile;

	/**
	 * Replace an existing file rather than renaming the new one.
	 *
	 * @var boolean
	 */
	protected $replaceFile = false;

	/**
	 * Processing errors that can be evaluated,
	 * e.g. by Form-validation.
	 *
	 * @var array
	 */
	protected $errors = array();

	/**
	 * Default visibility to assign uploaded files
	 *
	 * @var string
	 */
	protected $defaultVisibility = AssetStore::VISIBILITY_PROTECTED;

	/**
	 * A foldername relative to /assets,
	 * where all uploaded files are stored by default.
	 *
	 * @config
	 * @var string
	 */
	private static $uploads_folder = "Uploads";

	/**
	 * A prefix for the version number added to an uploaded file
	 * when a file with the same name already exists.
	 * Example using no prefix: IMG001.jpg becomes IMG2.jpg
	 * Example using '-v' prefix: IMG001.jpg becomes IMG001-v2.jpg
	 *
	 * @config
	 * @var string
	 */
	private static $version_prefix = '-v';

	public function __construct() {
		parent::__construct();
		$this->validator = Injector::inst()->create('SilverStripe\\Assets\\Upload_Validator');
		$this->replaceFile = self::config()->replaceFile;
	}

	public function index() {
		return $this->httpError(404); // no-op
	}

	/**
	 * Get current validator
	 *
	 * @return Upload_Validator $validator
	 */
	public function getValidator() {
		return $this->validator;
	}

	/**
	 * Set a different instance than {@link Upload_Validator}
	 * for this upload session.
	 *
	 * @param object $validator
	 */
	public function setValidator($validator) {
		$this->validator = $validator;
	}


	/**
	 * Get an asset renamer for the given filename.
	 *
	 * @param string $filename Path name
	 * @return AssetNameGenerator
	 */
	protected function getNameGenerator($filename){
		return Injector::inst()->createWithArgs('AssetNameGenerator', array($filename));
	}

	/**
	 *
	 * @return AssetStore
	 */
	protected function getAssetStore() {
		return Injector::inst()->get('AssetStore');
	}

	/**
	 * Save an file passed from a form post into the AssetStore directly
	 *
	 * @param array $tmpFile Indexed array that PHP generated for every file it uploads.
	 * @param string|bool $folderPath Folder path relative to /assets
	 * @return array|false Either the tuple array, or false if the file could not be saved
	 */
	public function load($tmpFile, $folderPath = false) {
		// Validate filename
		$filename = $this->getValidFilename($tmpFile, $folderPath);
		if(!$filename) {
			return false;
		}

		// Save file into backend
		$result = $this->storeTempFile($tmpFile, $filename, $this->getAssetStore());

		//to allow extensions to e.g. create a version after an upload
		$this->extend('onAfterLoad', $result, $tmpFile);
		return $result;
	}

	/**
	 * Save an file passed from a form post into this object.
	 * File names are filtered through {@link FileNameFilter}, see class documentation
	 * on how to influence this behaviour.
	 *
	 * @param array $tmpFile
	 * @param AssetContainer $file
	 * @param string|bool $folderPath
	 * @return bool True if the file was successfully saved into this record
	 * @throws Exception
	 */
	public function loadIntoFile($tmpFile, $file = null, $folderPath = false) {
		$this->file = $file;

		// Validate filename
		$filename = $this->getValidFilename($tmpFile, $folderPath);
		if(!$filename) {
			return false;
		}
		$filename = $this->resolveExistingFile($filename);

		// Save changes to underlying record (if it's a DataObject)
		$this->storeTempFile($tmpFile, $filename, $this->file);
		if($this->file instanceof DataObject) {
			$this->file->write();
		}

		//to allow extensions to e.g. create a version after an upload
		$this->file->extend('onAfterUpload');
		$this->extend('onAfterLoadIntoFile', $this->file);
		return true;
	}

	/**
	 * Assign this temporary file into the given destination
	 *
	 * @param array $tmpFile
	 * @param string $filename
	 * @param AssetContainer|AssetStore $container
	 * @return array
	 */
	protected function storeTempFile($tmpFile, $filename, $container) {
		// Save file into backend
		$conflictResolution = $this->replaceFile
			? AssetStore::CONFLICT_OVERWRITE
			: AssetStore::CONFLICT_RENAME;
		$config = array(
			'conflict' => $conflictResolution,
			'visibility' => $this->getDefaultVisibility()
		);
		return $container->setFromLocalFile($tmpFile['tmp_name'], $filename, null, null, $config);
	}

	/**
	 * Given a temporary file and upload path, validate the file and determine the
	 * value of the 'Filename' tuple that should be used to store this asset.
	 *
	 * @param array $tmpFile
	 * @param string $folderPath
	 * @return string|false Value of filename tuple, or false if invalid
	 */
	protected function getValidFilename($tmpFile, $folderPath = null) {
		if(!is_array($tmpFile)) {
			throw new InvalidArgumentException(
				"Upload::load() Not passed an array.  Most likely, the form hasn't got the right enctype"
			);
		}

		// Validate
		$this->clearErrors();
		$valid = $this->validate($tmpFile);
		if(!$valid) {
			return false;
		}

		// Clean filename
		if(!$folderPath) {
			$folderPath = $this->config()->uploads_folder;
		}
		$nameFilter = FileNameFilter::create();
		$file = $nameFilter->filter($tmpFile['name']);
		$filename = basename($file);
		if($folderPath) {
			$filename = File::join_paths($folderPath, $filename);
		}
		return $filename;
	}

	/**
	 * Given a file and filename, ensure that file renaming / replacing rules are satisfied
	 *
	 * If replacing, this method may replace $this->file with an existing record to overwrite.
	 * If renaming, a new value for $filename may be returned
	 *
	 * @param string $filename
	 * @return string $filename A filename safe to write to
	 * @throws Exception
	 */
	protected function resolveExistingFile($filename) {
		// Create a new file record (or try to retrieve an existing one)
		if(!$this->file) {
			$fileClass = File::get_class_for_file_extension(
				File::get_file_extension($filename)
			);
			$this->file = Object::create($fileClass);
		}

		// Skip this step if not writing File dataobjects
		if(! ($this->file instanceof File) ) {
			return $filename;
		}

		// Check there is if existing file
		$existing = File::find($filename);

		// If replacing (or no file exists) confirm this filename is safe
		if($this->replaceFile || !$existing) {
			// If replacing files, make sure to update the OwnerID
			if(!$this->file->ID && $this->replaceFile && $existing) {
				$this->file = $existing;
				$this->file->OwnerID = Member::currentUserID();
			}
			// Filename won't change if replacing
			return $filename;
		}

		// if filename already exists, version the filename (e.g. test.gif to test-v2.gif, test-v2.gif to test-v3.gif)
		$renamer = $this->getNameGenerator($filename);
		foreach($renamer as $newName) {
			if(!File::find($newName)) {
				return $newName;
			}
		}

		// Fail
		$tries = $renamer->getMaxTries();
		throw new Exception("Could not rename {$filename} with {$tries} tries");
	}

	/**
	 * @param bool $replace
	 */
	public function setReplaceFile($replace) {
		$this->replaceFile = $replace;
	}

	/**
	 * @return bool
	 */
	public function getReplaceFile() {
		return $this->replaceFile;
	}

	/**
	 * Container for all validation on the file
	 * (e.g. size and extension restrictions).
	 * Is NOT connected to the {Validator} classes,
	 * please have a look at {FileField->validate()}
	 * for an example implementation of external validation.
	 *
	 * @param array $tmpFile
	 * @return boolean
	 */
	public function validate($tmpFile) {
		$validator = $this->validator;
		$validator->setTmpFile($tmpFile);
		$isValid = $validator->validate();
		if($validator->getErrors()) {
			$this->errors = array_merge($this->errors, $validator->getErrors());
		}
		return $isValid;
	}

	/**
	 * Get file-object, either generated from {load()},
	 * or manually set.
	 *
	 * @return AssetContainer
	 */
	public function getFile() {
		return $this->file;
	}

	/**
	 * Set a file-object (similiar to {loadIntoFile()})
	 *
	 * @param AssetContainer $file
	 */
	public function setFile(AssetContainer $file) {
		$this->file = $file;
	}

	/**
	 * Clear out all errors (mostly set by {loadUploaded()})
	 * including the validator's errors
	 */
	public function clearErrors() {
		$this->errors = array();
		$this->validator->clearErrors();
	}

	/**
	 * Determines wether previous operations caused an error.
	 *
	 * @return boolean
	 */
	public function isError() {
		return (count($this->errors));
	}

	/**
	 * Return all errors that occurred while processing so far
	 * (mostly set by {loadUploaded()})
	 *
	 * @return array
	 */
	public function getErrors() {
		return $this->errors;
	}

	/**
	 * Get default visibility for uploaded files. {@see AssetStore}
	 * One of the values of AssetStore::VISIBILITY_* constants
	 *
	 * @return string
	 */
	public function getDefaultVisibility() {
		return $this->defaultVisibility;
	}

	/**
	 * Assign default visibility for uploaded files. {@see AssetStore}
	 * One of the values of AssetStore::VISIBILITY_* constants
	 *
	 * @param string $visibility
	 * @return $this
	 */
	public function setDefaultVisibility($visibility) {
		$this->defaultVisibility = $visibility;
		return $this;
	}

}