<?php
/**
 * Downloader class - Handles fetching icons from CDN and storing locally.
 *
 * @package MapleIcons
 */

if ( ! defined( 'ABSPATH' ) ) {
    exit;
}

/**
 * Class MI_Downloader
 *
 * Downloads icon sets from CDN and stores them locally.
 */
class MI_Downloader {

    /**
     * Allowed SVG elements for sanitization.
     *
     * @var array
     */
    private static $allowed_svg_elements = array(
        'svg'      => array(
            'xmlns'           => true,
            'viewbox'         => true,
            'width'           => true,
            'height'          => true,
            'fill'            => true,
            'stroke'          => true,
            'stroke-width'    => true,
            'stroke-linecap'  => true,
            'stroke-linejoin' => true,
            'class'           => true,
            'aria-hidden'     => true,
            'role'            => true,
            'focusable'       => true,
            'style'           => true,
        ),
        'path'     => array(
            'd'               => true,
            'fill'            => true,
            'stroke'          => true,
            'stroke-width'    => true,
            'stroke-linecap'  => true,
            'stroke-linejoin' => true,
            'fill-rule'       => true,
            'clip-rule'       => true,
            'opacity'         => true,
            'fill-opacity'    => true,
            'stroke-opacity'  => true,
        ),
        'circle'   => array(
            'cx'              => true,
            'cy'              => true,
            'r'               => true,
            'fill'            => true,
            'stroke'          => true,
            'stroke-width'    => true,
            'opacity'         => true,
        ),
        'rect'     => array(
            'x'               => true,
            'y'               => true,
            'width'           => true,
            'height'          => true,
            'rx'              => true,
            'ry'              => true,
            'fill'            => true,
            'stroke'          => true,
            'stroke-width'    => true,
            'opacity'         => true,
        ),
        'line'     => array(
            'x1'              => true,
            'y1'              => true,
            'x2'              => true,
            'y2'              => true,
            'stroke'          => true,
            'stroke-width'    => true,
            'stroke-linecap'  => true,
            'opacity'         => true,
        ),
        'polyline' => array(
            'points'          => true,
            'fill'            => true,
            'stroke'          => true,
            'stroke-width'    => true,
            'stroke-linecap'  => true,
            'stroke-linejoin' => true,
            'opacity'         => true,
        ),
        'polygon'  => array(
            'points'          => true,
            'fill'            => true,
            'stroke'          => true,
            'stroke-width'    => true,
            'opacity'         => true,
        ),
        'ellipse'  => array(
            'cx'              => true,
            'cy'              => true,
            'rx'              => true,
            'ry'              => true,
            'fill'            => true,
            'stroke'          => true,
            'stroke-width'    => true,
            'opacity'         => true,
        ),
        'g'        => array(
            'fill'            => true,
            'stroke'          => true,
            'stroke-width'    => true,
            'transform'       => true,
            'opacity'         => true,
        ),
        'defs'     => array(),
        'clippath' => array(
            'id' => true,
        ),
        'use'      => array(
            'href'       => true,
            'xlink:href' => true,
        ),
    );

    /**
     * Download an entire icon set.
     *
     * @param string        $slug              Icon set slug.
     * @param callable|null $progress_callback Optional progress callback.
     * @return array|WP_Error Download results or error.
     */
    public function download_set( $slug, $progress_callback = null ) {
        // Validate slug.
        if ( ! MI_Icon_Sets::is_valid_slug( $slug ) ) {
            return new WP_Error(
                'invalid_set',
                __( 'Invalid icon set.', 'maple-icons' )
            );
        }

        $set_config = MI_Icon_Sets::get( $slug );
        $manifest   = MI_Icon_Sets::load_manifest( $slug );

        if ( is_wp_error( $manifest ) ) {
            return $manifest;
        }

        // Create base directory.
        $base_dir = MI_ICONS_DIR . $slug;
        if ( ! $this->ensure_directory( $base_dir ) ) {
            return new WP_Error(
                'directory_error',
                __( 'Could not create icon directory.', 'maple-icons' )
            );
        }

        // Create style directories.
        foreach ( $set_config['styles'] as $style_slug => $style_config ) {
            $style_dir = $base_dir . '/' . $style_slug;
            if ( ! $this->ensure_directory( $style_dir ) ) {
                return new WP_Error(
                    'directory_error',
                    __( 'Could not create style directory.', 'maple-icons' )
                );
            }
        }

        $icons         = isset( $manifest['icons'] ) ? $manifest['icons'] : array();
        $total_icons   = count( $icons );
        $downloaded    = 0;
        $failed        = 0;
        $errors        = array();
        $total_to_download = 0;

        // Calculate total icons to download (icon × styles).
        foreach ( $icons as $icon ) {
            $icon_styles = isset( $icon['styles'] ) ? $icon['styles'] : array_keys( $set_config['styles'] );
            $total_to_download += count( $icon_styles );
        }

        // Initialize progress transient.
        set_transient(
            'mi_download_progress_' . $slug,
            array(
                'completed' => 0,
                'total'     => $total_to_download,
                'status'    => 'downloading',
            ),
            HOUR_IN_SECONDS
        );

        $current = 0;

        // Download each icon.
        foreach ( $icons as $icon ) {
            $icon_name   = $icon['name'];
            $icon_styles = isset( $icon['styles'] ) ? $icon['styles'] : array_keys( $set_config['styles'] );

            foreach ( $icon_styles as $style ) {
                if ( ! isset( $set_config['styles'][ $style ] ) ) {
                    continue;
                }

                $result = $this->download_icon( $slug, $style, $icon_name );

                if ( is_wp_error( $result ) ) {
                    $failed++;
                    $errors[] = sprintf( '%s/%s: %s', $style, $icon_name, $result->get_error_message() );
                } else {
                    $downloaded++;
                }

                $current++;

                // Update progress.
                set_transient(
                    'mi_download_progress_' . $slug,
                    array(
                        'completed' => $current,
                        'total'     => $total_to_download,
                        'status'    => 'downloading',
                    ),
                    HOUR_IN_SECONDS
                );

                // Call progress callback if provided.
                if ( is_callable( $progress_callback ) ) {
                    call_user_func( $progress_callback, $current, $total_to_download );
                }

                // Allow some breathing room for the server.
                if ( 0 === $current % MI_DOWNLOAD_BATCH_SIZE ) {
                    usleep( 100000 ); // 100ms pause every batch.
                }
            }
        }

        // Clear progress transient.
        delete_transient( 'mi_download_progress_' . $slug );

        return array(
            'success'    => $failed === 0,
            'downloaded' => $downloaded,
            'failed'     => $failed,
            'total'      => $total_to_download,
            'errors'     => $errors,
        );
    }

    /**
     * Download a single icon from CDN.
     *
     * @param string $slug  Icon set slug.
     * @param string $style Style slug.
     * @param string $name  Icon name.
     * @return string|WP_Error Local file path or error.
     */
    public function download_icon( $slug, $style, $name ) {
        // Validate inputs.
        if ( ! MI_Icon_Sets::is_valid_slug( $slug ) ) {
            return new WP_Error( 'invalid_set', __( 'Invalid icon set.', 'maple-icons' ) );
        }

        if ( ! MI_Icon_Sets::is_valid_style( $slug, $style ) ) {
            return new WP_Error( 'invalid_style', __( 'Invalid icon style.', 'maple-icons' ) );
        }

        // Validate icon name (only allow alphanumeric, hyphens, underscores).
        if ( ! preg_match( '/^[a-z0-9\-_]+$/i', $name ) ) {
            return new WP_Error( 'invalid_name', __( 'Invalid icon name.', 'maple-icons' ) );
        }

        $cdn_url    = MI_Icon_Sets::get_cdn_url( $slug, $style, $name );
        $local_path = MI_Icon_Sets::get_local_path( $slug, $style, $name );

        // Check if already downloaded.
        if ( file_exists( $local_path ) ) {
            return $local_path;
        }

        // Fetch from CDN.
        $response = wp_remote_get(
            $cdn_url,
            array(
                'timeout'   => MI_DOWNLOAD_TIMEOUT,
                'sslverify' => true,
            )
        );

        if ( is_wp_error( $response ) ) {
            return $response;
        }

        $status_code = wp_remote_retrieve_response_code( $response );
        if ( 200 !== $status_code ) {
            return new WP_Error(
                'cdn_error',
                sprintf(
                    /* translators: %d: HTTP status code */
                    __( 'CDN returned status %d.', 'maple-icons' ),
                    $status_code
                )
            );
        }

        $svg_content = wp_remote_retrieve_body( $response );
        if ( empty( $svg_content ) ) {
            return new WP_Error( 'empty_response', __( 'Empty response from CDN.', 'maple-icons' ) );
        }

        // Get set config for normalization.
        $set_config = MI_Icon_Sets::get( $slug );

        // Normalize and sanitize SVG.
        $svg_content = $this->normalize_svg( $svg_content, $set_config );
        $svg_content = $this->sanitize_svg( $svg_content );

        if ( empty( $svg_content ) ) {
            return new WP_Error( 'invalid_svg', __( 'Invalid or empty SVG content.', 'maple-icons' ) );
        }

        // Ensure directory exists.
        $dir = dirname( $local_path );
        if ( ! $this->ensure_directory( $dir ) ) {
            return new WP_Error( 'directory_error', __( 'Could not create directory.', 'maple-icons' ) );
        }

        // Write file.
        global $wp_filesystem;
        if ( empty( $wp_filesystem ) ) {
            require_once ABSPATH . 'wp-admin/includes/file.php';
            WP_Filesystem();
        }

        if ( ! $wp_filesystem->put_contents( $local_path, $svg_content, FS_CHMOD_FILE ) ) {
            return new WP_Error( 'write_error', __( 'Could not write SVG file.', 'maple-icons' ) );
        }

        return $local_path;
    }

    /**
     * Normalize SVG content based on set configuration.
     *
     * @param string $svg        SVG content.
     * @param array  $set_config Icon set configuration.
     * @return string Normalized SVG content.
     */
    private function normalize_svg( $svg, $set_config ) {
        // Strip XML declaration.
        $svg = preg_replace( '/<\?xml[^>]*\?>/i', '', $svg );

        // Strip DOCTYPE.
        $svg = preg_replace( '/<!DOCTYPE[^>]*>/i', '', $svg );

        // Strip comments.
        $svg = preg_replace( '/<!--.*?-->/s', '', $svg );

        // Strip title and desc elements.
        $svg = preg_replace( '/<title[^>]*>.*?<\/title>/is', '', $svg );
        $svg = preg_replace( '/<desc[^>]*>.*?<\/desc>/is', '', $svg );

        // Normalize viewBox for Phosphor (256 → 24).
        if ( ! empty( $set_config['normalize'] ) ) {
            $svg = preg_replace(
                '/viewBox=["\']0\s+0\s+256\s+256["\']/i',
                'viewBox="0 0 24 24"',
                $svg
            );
        }

        // Fix hardcoded colors for Material.
        if ( ! empty( $set_config['color_fix'] ) ) {
            // Replace hardcoded hex colors.
            $svg = preg_replace( '/fill=["\']#[0-9a-fA-F]{3,6}["\']/', 'fill="currentColor"', $svg );
            $svg = preg_replace( '/fill=["\']black["\']/', 'fill="currentColor"', $svg );
            $svg = preg_replace( '/fill=["\']rgb\([^)]+\)["\']/', 'fill="currentColor"', $svg );

            // Same for stroke.
            $svg = preg_replace( '/stroke=["\']#[0-9a-fA-F]{3,6}["\']/', 'stroke="currentColor"', $svg );
            $svg = preg_replace( '/stroke=["\']black["\']/', 'stroke="currentColor"', $svg );
        }

        // Remove width/height attributes (let CSS control size).
        $svg = preg_replace( '/\s(width|height)=["\'][^"\']*["\']/i', '', $svg );

        // Ensure there's no leading/trailing whitespace.
        $svg = trim( $svg );

        return $svg;
    }

    /**
     * Sanitize SVG content to remove potentially dangerous elements.
     *
     * @param string $svg SVG content.
     * @return string Sanitized SVG content.
     */
    private function sanitize_svg( $svg ) {
        // Remove script tags.
        $svg = preg_replace( '/<script\b[^>]*>.*?<\/script>/is', '', $svg );

        // Remove event handlers.
        $svg = preg_replace( '/\s+on\w+\s*=/i', ' data-removed=', $svg );

        // Remove javascript: URLs.
        $svg = preg_replace( '/javascript:/i', 'removed:', $svg );

        // Remove data: URLs (except for certain safe uses).
        $svg = preg_replace( '/data:[^"\'>\s]+/i', 'removed:', $svg );

        // Use WordPress kses with our allowed tags.
        $svg = wp_kses( $svg, self::$allowed_svg_elements );

        // Verify it's still a valid SVG.
        if ( strpos( $svg, '<svg' ) === false || strpos( $svg, '</svg>' ) === false ) {
            return '';
        }

        return $svg;
    }

    /**
     * Ensure a directory exists, creating it if necessary.
     *
     * @param string $dir Directory path.
     * @return bool True if directory exists or was created.
     */
    private function ensure_directory( $dir ) {
        if ( file_exists( $dir ) ) {
            return is_dir( $dir );
        }

        return wp_mkdir_p( $dir );
    }

    /**
     * Delete all icons for a set.
     *
     * @param string $slug Icon set slug.
     * @return bool True on success.
     */
    public function delete_set( $slug ) {
        if ( ! MI_Icon_Sets::is_valid_slug( $slug ) ) {
            return false;
        }

        $set_dir = MI_ICONS_DIR . $slug;

        // Validate the path is within our icons directory.
        $real_path    = realpath( $set_dir );
        $allowed_base = realpath( MI_ICONS_DIR );

        if ( false === $real_path || false === $allowed_base ) {
            // Directory doesn't exist, nothing to delete.
            return true;
        }

        if ( strpos( $real_path, $allowed_base ) !== 0 ) {
            // Path traversal attempt.
            return false;
        }

        // Recursively delete the directory.
        return $this->delete_directory( $set_dir );
    }

    /**
     * Recursively delete a directory.
     *
     * @param string $dir Directory path.
     * @return bool True on success.
     */
    private function delete_directory( $dir ) {
        if ( ! is_dir( $dir ) ) {
            return true;
        }

        $files = array_diff( scandir( $dir ), array( '.', '..' ) );

        foreach ( $files as $file ) {
            $path = $dir . '/' . $file;
            if ( is_dir( $path ) ) {
                $this->delete_directory( $path );
            } else {
                wp_delete_file( $path );
            }
        }

        return rmdir( $dir );
    }

    /**
     * Get download progress for a set.
     *
     * @param string $slug Icon set slug.
     * @return array|false Progress data or false if not downloading.
     */
    public function get_progress( $slug ) {
        return get_transient( 'mi_download_progress_' . $slug );
    }
}