<?php
// PHP 7.4 compatible. No Composer. No build step. WordPress coding standards.
// THE single source-decision point. Nothing else in the rendering
// path decides where sections or values come from.

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

class SLBUILD_Resolver {

	private static $instance = null;

	// Resolved once per request and cached.
	private $context = null;

	private function __construct() {}

	public static function instance(): self {
		if ( null === self::$instance ) {
			self::$instance = new self();
		}
		return self::$instance;
	}

	/**
	 * Resolve the section source directory and value source for the current request.
	 *
	 * Returns:
	 *   'sections_dir' => absolute path to the sections folder to read from
	 *   'value_source' => 'meta' | 'draft_meta'
	 *   'post_id'      => resolved post ID for value reads
	 *
	 * @param int|null $post_id The page being rendered. Null = current queried post.
	 * @return array
	 */
	public function resolve( $post_id = null ): array {
		if ( null === $post_id ) {
			$post_id = get_queried_object_id();
		}

		// Editor preview (logged-in admin, ?slbuild_preview=1) ? serve from draft meta.
		if ( isset( $_GET['slbuild_preview'] ) && current_user_can( 'edit_pages' ) ) { // phpcs:ignore WordPress.Security.NonceVerification
			return array(
				'sections_dir'         => $this->get_live_sections_dir(),
				'starter_sections_dir' => $this->get_starter_sections_dir(),
				'value_source'         => 'draft_meta',
				'post_id'              => (int) $post_id,
			);
		}

		// Phase 1.5: valid preview token ? live sections + draft content data.
		// Primary use case: share a client-review link showing unsaved content changes
		// before clicking Publish. Section code stays live; only field values are from the draft.
		if ( $this->has_valid_preview_token( (int) $post_id ) ) {
			return array(
				'sections_dir'         => $this->get_live_sections_dir(),
				'starter_sections_dir' => $this->get_starter_sections_dir(),
				'value_source'         => 'draft_meta',
				'post_id'              => (int) $post_id,
			);
		}

		return array(
			'sections_dir'         => $this->get_live_sections_dir(),
			'starter_sections_dir' => $this->get_starter_sections_dir(),
			'value_source'         => 'meta',
			'post_id'              => (int) $post_id,
		);
	}

	/**
	 * Returns true when the request carries a valid slbuild_preview_token for this post.
	 * Works for logged-out users — token is checked against a stored transient only.
	 *
	 * @param int $post_id
	 * @return bool
	 */
	private function has_valid_preview_token( int $post_id ): bool {
		if ( ! $post_id || ! isset( $_GET['slbuild_preview_token'] ) ) { // phpcs:ignore WordPress.Security.NonceVerification
			return false;
		}
		$submitted = sanitize_text_field( wp_unslash( $_GET['slbuild_preview_token'] ) ); // phpcs:ignore WordPress.Security.NonceVerification
		if ( ! $submitted ) {
			return false;
		}
		$stored = get_transient( 'slbuild_preview_' . $post_id );
		return $stored && hash_equals( $stored, $submitted );
	}

	/**
	 * Absolute path to the active theme's live /sections/ directory.
	 *
	 * @return string
	 */
	public function get_live_sections_dir(): string {
		return get_stylesheet_directory() . '/sections';
	}

	/**
	 * Absolute path to the active theme's draft /sections-draft/ directory.
	 * Used in Phase 1.5 preview flow.
	 *
	 * @return string
	 */
	public function get_draft_sections_dir(): string {
		return get_stylesheet_directory() . '/sections-draft';
	}

	/**
	 * Absolute path to the plugin's bundled starter-sections directory.
	 * Theme /sections/ always takes priority over these.
	 *
	 * @return string
	 */
	public function get_starter_sections_dir(): string {
		return rtrim( SLBUILD_PATH, '/\\' ) . '/starter-sections';
	}

	/**
	 * Read and return the active theme's slb-theme.json manifest.
	 * Returns an empty array if the file is absent or malformed.
	 *
	 * @return array
	 */
	public function get_theme_manifest(): array {
		static $manifest = null;
		if ( null === $manifest ) {
			$path = get_stylesheet_directory() . '/slb-theme.json';
			if ( ! file_exists( $path ) ) {
				$manifest = array();
			} else {
				$raw      = file_get_contents( $path ); // phpcs:ignore WordPress.WP.AlternativeFunctions.file_get_contents_file_get_contents
				$decoded  = json_decode( $raw, true );
				$manifest = ( is_array( $decoded ) && ! empty( $decoded['slbuild_theme'] ) ) ? $decoded : array();
			}
		}
		return $manifest;
	}
}