<?php
/**
 * Synced-content processing: H1 title extraction, internal-link translation,
 * and repository image sideloading.
 *
 * @package RobotsTxt\DocumentationMarkdown
 * @since   1.2.0
 */

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

/**
 * Reduce inline Markdown formatting in a single line to plain text.
 *
 * Used to derive a clean post title from an H1 that may contain links,
 * emphasis, inline code, or images.
 *
 * @since 1.2.0
 *
 * @param string $text Inline Markdown text (single line).
 * @return string Sanitized plain text.
 */
function robotstxt_docmd_plain_text_from_inline_markdown( string $text ): string {
	$patterns     = array(
		'/!\[([^\]]*)\]\([^)]*\)/',   // Images -> alt text.
		'/\[([^\]]*)\]\([^)]*\)/',    // Links -> label text.
		'/`([^`]*)`/',                 // Inline code -> contents.
		'/(\*\*|__|~~|\*|_)(.+?)\1/',  // Bold/italic/strikethrough -> contents.
	);
	$replacements = array( '$1', '$1', '$1', '$2' );

	$result = preg_replace( $patterns, $replacements, $text );
	if ( ! is_string( $result ) ) {
		$result = $text;
	}

	return sanitize_text_field( trim( $result ) );
}

/**
 * Extract the post title from the first H1 in the Markdown, and remove that
 * H1 line from the content so it does not duplicate the theme-rendered title.
 *
 * Falls back to $fallback_title when no H1 is present or the extracted text
 * is empty after sanitization.
 *
 * @since 1.2.0
 *
 * @param string $content        Raw Markdown.
 * @param string $fallback_title Fallback title if no H1 is found.
 * @return array{title: string, content: string} {
 *     Extracted title (plain text) and the Markdown with the first H1 removed.
 *
 *     @type string $title   Post title.
 *     @type string $content Markdown with the first H1 line removed.
 * }
 */
function robotstxt_docmd_extract_h1_title( string $content, string $fallback_title ): array {
	if ( preg_match( '/^#[ \t]+(.+)$/m', $content, $matches ) ) {
		$title = robotstxt_docmd_plain_text_from_inline_markdown( trim( $matches[1] ) );
		if ( '' === $title ) {
			$title = $fallback_title;
		}

		$replaced = preg_replace( '/^#[ \t]+.*$/m', '', $content, 1 );
		if ( is_string( $replaced ) ) {
			$content = $replaced;
		}
	} else {
		$title = $fallback_title;
	}

	return array(
		'title'   => $title,
		'content' => $content,
	);
}

/**
 * Resolve a (possibly relative) Markdown link target to a canonical repository
 * path, relative to the file currently being synced.
 *
 * Handles "./file.md", "../file.md", "sub/file.md", and absolute "/file.md"
 * forms. Returns null for empty targets.
 *
 * @since 1.2.0
 *
 * @param string $current_file_path Repository path of the file being synced.
 * @param string $href              Raw link target.
 * @return string|null Canonical repository path, or null if it cannot be resolved.
 */
function robotstxt_docmd_resolve_repo_path( string $current_file_path, string $href ): ?string {
	// Strip any fragment or query string before resolving.
	$path = preg_replace( '/[?#].*$/', '', $href );
	if ( ! is_string( $path ) || '' === $path ) {
		return null;
	}

	if ( 0 === strpos( $path, '/' ) ) {
		// Absolute repository path.
		$base_segments = array();
		$rel_segments  = explode( '/', ltrim( $path, '/' ) );
	} else {
		// Relative to the current file's directory.
		$dir           = dirname( $current_file_path );
		$base_segments = '.' === $dir ? array() : explode( '/', $dir );
		$rel_segments  = explode( '/', $path );
	}

	$result = $base_segments;
	foreach ( $rel_segments as $segment ) {
		if ( '' === $segment || '.' === $segment ) {
			continue;
		}
		if ( '..' === $segment ) {
			array_pop( $result );
			continue;
		}
		$result[] = $segment;
	}

	$normalized = implode( '/', $result );
	if ( '' === $normalized ) {
		return null;
	}

	return $normalized;
}

/**
 * Build a lookup of canonical repository file paths to WordPress permalinks,
 * scoped to the given repository and branch. Only mappings with an existing
 * target post are included.
 *
 * @since 1.2.0
 *
 * @param string $owner  Repository owner.
 * @param string $repo   Repository name.
 * @param string $branch Branch name.
 * @return array<string, string> Map of repository path => permalink.
 */
function robotstxt_docmd_build_link_map( string $owner, string $repo, string $branch ): array {
	$mappings = robotstxt_docmd_get_all_mappings();
	$map      = array();

	foreach ( $mappings as $mapping ) {
		if ( $mapping['repo_owner'] !== $owner || $mapping['repo_name'] !== $repo || $mapping['branch'] !== $branch ) {
			continue;
		}
		if ( empty( $mapping['target_post_id'] ) ) {
			continue;
		}

		$permalink = get_permalink( (int) $mapping['target_post_id'] );
		if ( is_string( $permalink ) && '' !== $permalink ) {
			$map[ $mapping['file_path'] ] = $permalink;
		}
	}

	return $map;
}

/**
 * Get the imported-image asset map for a synced post.
 *
 * @since 1.2.0
 *
 * @param int $post_id Target post ID.
 * @return array<string, int> Map of repository image path => attachment ID.
 */
function robotstxt_docmd_get_asset_map( int $post_id ): array {
	$raw = get_post_meta( $post_id, '_robotstxt_docmd_assets', true );
	if ( ! is_array( $raw ) ) {
		return array();
	}

	$map = array();
	foreach ( $raw as $path => $attachment_id ) {
		if ( is_string( $path ) && ( is_int( $attachment_id ) || ( is_string( $attachment_id ) && ctype_digit( $attachment_id ) ) ) ) {
			$map[ $path ] = (int) $attachment_id;
		}
	}

	return $map;
}

/**
 * Persist the imported-image asset map for a synced post.
 *
 * @since 1.2.0
 *
 * @param int   $post_id Target post ID.
 * @param array $map     Map of repository image path => attachment ID.
 * @phpstan-param array<string, int> $map
 * @return void
 */
function robotstxt_docmd_save_asset_map( int $post_id, array $map ): void {
	update_post_meta( $post_id, '_robotstxt_docmd_assets', $map );
}

/**
 * Return the list of image extensions allowed for sideloading.
 *
 * SVG is intentionally excluded to avoid stored XSS via embedded scripts.
 *
 * @since 1.2.0
 *
 * @return list<string>
 */
function robotstxt_docmd_allowed_image_extensions(): array {
	return array( 'jpg', 'jpeg', 'png', 'gif', 'webp' );
}

/**
 * Download an image from the repository and import it into the Media Library.
 *
 * @since 1.2.0
 *
 * @param string $repo_path       Canonical repository path of the image.
 * @param int    $target_post_id  Post to attach the image to.
 * @param string $owner           Repository owner.
 * @param string $repo            Repository name.
 * @param string $branch          Branch name.
 * @param string $token           Encrypted GitHub token.
 * @return int|WP_Error Attachment ID on success, or WP_Error.
 */
function robotstxt_docmd_sideload_repo_image( string $repo_path, int $target_post_id, string $owner, string $repo, string $branch, string $token ): int|WP_Error {
	$ext     = strtolower( (string) pathinfo( $repo_path, PATHINFO_EXTENSION ) );
	$allowed = robotstxt_docmd_allowed_image_extensions();
	if ( ! in_array( $ext, $allowed, true ) ) {
		return new WP_Error(
			'unsupported_image_type',
			sprintf(
				/* translators: %s: file extension */
				__( 'Unsupported image type .%s. Allowed: jpg, jpeg, png, gif, webp.', 'robotstxt-documentation-markdown' ),
				$ext
			)
		);
	}

	// Fetch image bytes from GitHub.
	$bytes = robotstxt_docmd_get_file_content( $owner, $repo, $repo_path, $branch, $token );
	if ( is_wp_error( $bytes ) ) {
		return $bytes;
	}

	// Size guard (10 MB).
	if ( strlen( $bytes ) > 10 * 1024 * 1024 ) {
		return new WP_Error( 'image_too_large', __( 'Repository image exceeds the 10 MB import limit.', 'robotstxt-documentation-markdown' ) );
	}

	if ( ! function_exists( 'media_handle_sideload' ) ) {
		require_once ABSPATH . 'wp-admin/includes/file.php';
		require_once ABSPATH . 'wp-admin/includes/media.php';
		require_once ABSPATH . 'wp-admin/includes/image.php';
	}

	$filename = sanitize_file_name( basename( $repo_path ) );
	$tmp_name = wp_tempnam( $filename );
	if ( '' === $tmp_name ) {
		return new WP_Error( 'temp_failed', __( 'Could not create a temporary file for image import.', 'robotstxt-documentation-markdown' ) );
	}

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

	if ( ! $wp_filesystem instanceof WP_Filesystem_Base ) {
		wp_delete_file( $tmp_name );
		return new WP_Error( 'fs_failed', __( 'Could not initialize the WordPress filesystem.', 'robotstxt-documentation-markdown' ) );
	}

	if ( ! $wp_filesystem->put_contents( $tmp_name, $bytes, FS_CHMOD_FILE ) ) {
		wp_delete_file( $tmp_name );
		return new WP_Error( 'write_failed', __( 'Could not write image to the temporary file.', 'robotstxt-documentation-markdown' ) );
	}

	$attach_id = media_handle_sideload(
		array(
			'name'     => $filename,
			'tmp_name' => $tmp_name,
		),
		$target_post_id
	);

	if ( is_wp_error( $attach_id ) ) {
		wp_delete_file( $tmp_name );
		return $attach_id;
	}

	return (int) $attach_id;
}

/**
 * Post-process synced HTML: rewrite internal links to mapped permalinks and
 * sideload repository images into the Media Library.
 *
 * Internal-link and image references are parsed with DOMDocument (no regex on
 * HTML). Images already present in $asset_map are reused. Image import errors
 * are non-fatal: the original src is kept and the sync continues.
 *
 * @since 1.2.0
 *
 * @param string $html            Converted HTML content.
 * @param array  $mapping         Mapping being synced.
 * @param int    $target_post_id  Target post ID (for image attachment).
 * @param string $token           Encrypted GitHub token (for image fetch).
 * @param array  $asset_map       Existing imported-image map (path => attach ID).
 * @phpstan-param MappingData $mapping
 * @phpstan-param array<string, int> $asset_map
 * @return array{html: string, assets: array<string, int>} Processed HTML and the updated asset map.
 */
function robotstxt_docmd_process_synced_html( string $html, array $mapping, int $target_post_id, string $token, array $asset_map ): array {
	$dom = new DOMDocument();
	libxml_use_internal_errors( true );
	$dom->loadHTML(
		'<!DOCTYPE html><html><head><meta charset="utf-8"></head><body>' . $html . '</body></html>'
	);
	libxml_clear_errors();

	$link_map = robotstxt_docmd_build_link_map( $mapping['repo_owner'], $mapping['repo_name'], $mapping['branch'] );

	// Rewrite internal anchor hrefs.
	foreach ( $dom->getElementsByTagName( 'a' ) as $link ) {
		$href = $link->getAttribute( 'href' );
		if ( '' === $href ) {
			continue;
		}

		// Skip absolute, protocol-relative, mailto/tel, and anchor-only links.
		if ( preg_match( '~^(https?:|mailto:|tel:|//|#)~', $href ) ) {
			continue;
		}

		$resolved = robotstxt_docmd_resolve_repo_path( $mapping['file_path'], $href );
		if ( null === $resolved ) {
			continue;
		}

		if ( isset( $link_map[ $resolved ] ) ) {
			$link->setAttribute( 'href', $link_map[ $resolved ] );
		}
	}

	// Sideload or reuse repository images.
	foreach ( $dom->getElementsByTagName( 'img' ) as $image ) {
		$src = $image->getAttribute( 'src' );
		if ( '' === $src ) {
			continue;
		}

		// Skip absolute, protocol-relative, and data URIs.
		if ( preg_match( '~^(https?:|//|data:)~', $src ) ) {
			continue;
		}

		$resolved = robotstxt_docmd_resolve_repo_path( $mapping['file_path'], $src );
		if ( null === $resolved ) {
			continue;
		}

		// Reuse an already-imported attachment.
		if ( isset( $asset_map[ $resolved ] ) ) {
			$url = wp_get_attachment_url( (int) $asset_map[ $resolved ] );
			if ( is_string( $url ) && '' !== $url ) {
				$image->setAttribute( 'src', $url );
			}
			continue;
		}

		// Import the image from the repository.
		$attach_id = robotstxt_docmd_sideload_repo_image(
			$resolved,
			$target_post_id,
			$mapping['repo_owner'],
			$mapping['repo_name'],
			$mapping['branch'],
			$token
		);

		if ( is_wp_error( $attach_id ) ) {
			// Keep the original src; do not block the sync.
			continue;
		}

		$asset_map[ $resolved ] = $attach_id;
		$url                    = wp_get_attachment_url( $attach_id );
		if ( is_string( $url ) && '' !== $url ) {
			$image->setAttribute( 'src', $url );
		}
	}

	// Extract the processed body HTML.
	$body = $dom->getElementsByTagName( 'body' )->item( 0 );
	if ( ! $body instanceof DOMElement ) {
		return array(
			'html'   => $html,
			'assets' => $asset_map,
		);
	}

	$output = '';
	foreach ( $body->childNodes as $child ) { // phpcs:ignore WordPress.NamingConventions.ValidVariableName.UsedPropertyNotSnakeCase -- DOMDocument API property.
		$saved = $dom->saveHTML( $child );
		if ( is_string( $saved ) ) {
			$output .= $saved;
		}
	}

	if ( '' === $output ) {
		$output = $html;
	}

	return array(
		'html'   => $output,
		'assets' => $asset_map,
	);
}