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<?php

/**
 * MvcCore
 *
 * This source file is subject to the BSD 3 License
 * For the full copyright and license information, please view
 * the LICENSE.md file that are distributed with this source code.
 *
 * @copyright   Copyright (c) 2016 Tom Flidr (https://github.com/mvccore)
 * @license     https://mvccore.github.io/docs/mvccore/5.0.0/LICENCE.md
 */

namespace MvcCore\Ext\Views\Helpers;

/**
 * Responsibility - get any file content by given relative or absolute path in data URL format: `data:image/png;base64,iVBOR..`.
 * - Path could be relative from currently rendered view,
 *   relative from application root or absolute path to file.
 * @see https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/Data_URIs
 * @method \MvcCore\Ext\Views\Helpers\DataUrlHelper GetInstance()
 */
class DataUrlHelper implements \MvcCore\Ext\Views\Helpers\IHelper {

    /**
     * MvcCore Extension - View Helper - Assets - version:
     * Comparison by PHP function version_compare();
     * @see http://php.net/manual/en/function.version-compare.php
     */
    const VERSION = '5.0.0';

    /**
     * Currently rendered view instance.
     * @var \MvcCore\View|NULL
     */
    protected $view = NULL;

    /**
     * Application root path on hard drive.
     * Example: `"C:/www/my/development/directory/www"`
     * @var string|NULL
     */
    protected $appRoot = NULL;

    /**
     * Create view helper instance, every time new instance.
     * @static
     * @return \MvcCore\Ext\Views\Helpers\DataUrlHelper
     */
    public static function & GetInstance () {
        $instance = new static;
        return $instance;
    }

    /**
     * Set currently rendered view instance every time this helper
     * is called and the rendered view instance is changed.
     * This method sets these protected object references:
     * - `DataUrlHelper::$view`     as `\MvcCore\View|\MvcCore\IView`
     * - `DataUrlHelper::$request`  as `\MvcCore\Request|\MvcCore\IRequest`
     * @param \MvcCore\View $view
     * @return \MvcCore\Ext\Views\Helpers\DataUrlHelper
     */
    public function SetView (\MvcCore\IView $view) {
        $this->view = $view;
        $this->appRoot = $view->GetController()->GetRequest()->GetAppRoot();
        return $this;
    }

    /**
     * Return any file content by given relative or absolute path in data url.
     * Path could be relative from currently rendered view,
     * relative from application root or absolute path to file.
     * @see https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/Data_URIs
     * @param string $relativeOrAbsolutePath
     * @throws \InvalidArgumentException If file not found by given path in any searched place.
     * @return string Data URL value like: `data:image/png;base64,iVBORw0KGgoAAAANSUhEUgA...`
     */
    public function DataUrl ($relativeOrAbsolutePath) {
        $currentDirFullPath = $this->view->GetCurrentViewDirectory();
        $searchedPaths = [];
        // first - try to find file relatively from currently rendered view
        array_unshift($searchedPaths, $currentDirFullPath . '/' . $relativeOrAbsolutePath);
        if (!file_exists($searchedPaths[0])) {
            // second - try to find file relatively from application root
            array_unshift($searchedPaths, $this->appRoot . '/' . ltrim($relativeOrAbsolutePath, '/'));
            if (!file_exists($searchedPaths[0])) {
                // third - try to find file absolutely
                array_unshift($searchedPaths, $relativeOrAbsolutePath);
                if (!file_exists($searchedPaths[0])) 
                    // throw an error at last
                    throw new \InvalidArgumentException(
                        "[".get_class()."] File not found in paths: '".implode("', '", array_reverse($searchedPaths))."'."
                    );
            }
        }
        // get last searched path
        $fileFullPath = $searchedPaths[0];
        // Read image path, convert to base64 encoding
        $imageData = base64_encode(file_get_contents($fileFullPath));
        // Format the image SRC:  data:{mime};base64,{data};
        $result = 'data: '.mime_content_type($fileFullPath).';base64,'.$imageData;
        return $result;
    }
}