<?php
/**
* Class for downloading a file from a given URL.
*
* @package Merlin WP
*/

class Merlin_Downloader {
    /**
    * Holds full path to where the files will be saved.
    *
    * @var string
    */
    private $download_directory_path = '';

    /**
    * Constructor method.
    *
    * @param string $download_directory_path Full path to where the files will be saved.
    */
    public function __construct( $download_directory_path = '' ) {
        $this->set_download_directory_path( $download_directory_path );
    }


    /**
    * Download file from a given URL.
    *
    * @param string $url URL of file to download.
    * @param string $filename Filename of the file to save.
    * @return string|WP_Error Full path to the downloaded file or WP_Error object with error message.
    */
    public function download_file( $url, $filename ) {
        $content = $this->get_content_from_url( $url );

        // Check if there was an error and break out.
        if ( is_wp_error( $content ) ) {

            return $content;
        }

        $saved_file = file_put_contents( $this->download_directory_path . $filename, $content );

        if ( ! empty( $saved_file ) ) {
            return $this->download_directory_path . $filename;
        }

        return false;
    }


    /**
    * Helper function: get content from an URL.
    *
    * @param string $url URL to the content file.
    * @return string|WP_Error, content from the URL or WP_Error object with error message.
    */
    private function get_content_from_url( $url ) {
        // Test if the URL to the file is defined.
        if ( empty( $url ) ) {
            return new \WP_Error(
                'missing_url',
                __( 'Missing URL for downloading a file!', 'merlin-wp' )
            );
        }

        // Get file content from the server.
        $response = wp_remote_get(
            $url,
            array( 'timeout' => apply_filters( 'merlin_timeout_for_downloading_import_file', 20 ) )
        );

        // Test if the get request was not successful.
        if ( is_wp_error( $response ) || 200 !== $response['response']['code'] ) {
            // Collect the right format of error data (array or WP_Error).
            $response_error = $this->get_error_from_response( $response );

            return new \WP_Error(
                'download_error',
                sprintf(
                    __( 'An error occurred while fetching file from: %1$s%2$s%3$s!%4$sReason: %5$s - %6$s.', 'merlin-wp' ),
                    '<strong>',
                    $url,
                    '</strong>',
                    '<br>',
                    $response_error['error_code'],
                    $response_error['error_message']
                )
            );
        }

        // Return content retrieved from the URL.
        return wp_remote_retrieve_body( $response );
    }


    /**
    * Helper function: get the right format of response errors.
    *
    * @param array|WP_Error $response Array or WP_Error or the response.
    * @return array Error code and error message.
    */
    private function get_error_from_response( $response ) {
        $response_error = array();

        if ( is_array( $response ) ) {
            $response_error['error_code']    = $response['response']['code'];
            $response_error['error_message'] = $response['response']['message'];
        }
        else {
            $response_error['error_code']    = $response->get_error_code();
            $response_error['error_message'] = $response->get_error_message();
        }

        return $response_error;
    }


    /**
    * Get download_directory_path attribute.
    */
    public function get_download_directory_path() {
        return $this->download_directory_path;
    }


    /**
    * Set download_directory_path attribute.
    * If no valid path is specified, the default WP upload directory will be used.
    *
    * @param string $download_directory_path Path, where the files will be saved.
    */
    public function set_download_directory_path( $download_directory_path ) {
        if ( file_exists( $download_directory_path ) ) {
            $this->download_directory_path = $download_directory_path;
        }
        else {
            $upload_dir = wp_upload_dir();
            $this->download_directory_path = apply_filters( 'merlin_upload_file_path', trailingslashit( $upload_dir['path'] ) );
        }
    }

    /**
    * Check, if the file already exists and return his full path.
    *
    * @param string $filename The name of the file.
    *
    * @return bool|string
    */
    public function fetch_existing_file( $filename ) {
        if ( file_exists( $this->download_directory_path . $filename ) ) {
            return $this->download_directory_path . $filename;
        }

        return false;
    }
}