<?php
// PHP 7.4 compatible. No Composer. No build step. WordPress coding standards.
// THE value-source layer (PRD -4.3). Templates never read meta directly -
// they always receive values through this loader.

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

class SLBUILD_SectionLoader {

	private static $instance = null;

	// Active $section context for the currently-rendering section instance.
	private $current_section = array();

	// Active block context for slbuild_block_field() calls inside a block loop.
	private $current_block = array();

	private function __construct() {}

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

	/**
	 * Render all section instances for a page, in layout order.
	 *
	 * @param int|null $post_id Null = current queried post.
	 */
	public function render_page( $post_id = null ): void {
		$ctx      = SLBUILD_Resolver::instance()->resolve( $post_id );
		$store    = new SLBUILD_DataStore();
		$parser   = new SLBUILD_SchemaParser();
		$post_id  = $ctx['post_id'];
		$value_source = $ctx['value_source'] ?? '';
		if ( 'draft_meta' === $value_source ) {
			$layout = $store->get_draft_layout( $post_id );
		} else {
			$layout = $store->get_layout( $post_id );
		}

		foreach ( $layout as $item ) {
			if ( empty( $item['instance'] ) || empty( $item['type'] ) ) {
				continue;
			}
			// Skip hidden sections.
			if ( ! empty( $item['hidden'] ) ) {
				continue;
			}
			// Skip sections excluded from this page.
			if ( $post_id && ! empty( $item['excluded_pages'] ) && is_array( $item['excluded_pages'] ) ) {
				if ( in_array( (int) $post_id, array_map( 'intval', $item['excluded_pages'] ), true ) ) {
					continue;
				}
			}
			$this->render_instance( $item['instance'], $item['type'], $post_id, $ctx );
		}
	}

	/**
	 * Render all section instances for a named global region (header, footer, etc.).
	 *
	 * @param string $region  Region slug e.g. 'header', 'footer'.
	 */
	public function render_global_region( string $region ): void {
		$ctx       = SLBUILD_Resolver::instance()->resolve( null );
		$store     = new SLBUILD_DataStore();
		$raw       = $store->get_global( $region );
		$layout    = is_array( $raw ) && isset( $raw['layout'] )    ? $raw['layout']    : array();
		$instances = is_array( $raw ) && isset( $raw['instances'] ) ? $raw['instances'] : array();

		foreach ( $layout as $item ) {
			if ( empty( $item['instance'] ) || empty( $item['type'] ) ) {
				continue;
			}
			// Pass saved settings + blocks directly from the global region blob.
			$inst_data = $instances[ $item['instance'] ] ?? array();
			$saved     = $inst_data['settings'] ?? array();
			$blocks    = $inst_data['blocks']   ?? array();
			$this->render_instance_with_values( $item['instance'], $item['type'], $saved, $blocks, $ctx );
		}
	}

	/**
	 * Render a section instance using pre-supplied values (bypasses DataStore lookup).
	 * Used for global regions where values live in wp_options, not post meta.
	 */
	private function render_instance_with_values( string $instance_id, string $section_type, array $saved, array $blocks, array $ctx ): void {
		$parser = new SLBUILD_SchemaParser();

		$file = trailingslashit( $ctx['sections_dir'] ) . $section_type . '.php';
		if ( ! file_exists( $file ) && ! empty( $ctx['starter_sections_dir'] ) ) {
			$file = trailingslashit( $ctx['starter_sections_dir'] ) . $section_type . '.php';
		}
		if ( ! file_exists( $file ) ) {
			return;
		}

		$schema   = $parser->parse_file( $file );
		$defaults = array();
		if ( $schema && ! empty( $schema['settings'] ) ) {
			foreach ( $schema['settings'] as $field ) {
				if ( isset( $field['id'] ) && isset( $field['default'] ) ) {
					$defaults[ $field['id'] ] = $field['default'];
				}
			}
		}
		$values = array_merge( $defaults, $saved );

		$this->current_section = array(
			'instance_id' => $instance_id,
			'type'        => $section_type,
			'values'      => $values,
			'blocks'      => $blocks,
			'post_id'     => 0,
			'schema'      => $schema ?: array(),
		);

		include $file;

		$this->current_section = array();
	}

	/**
	 * Render a single section instance.
	 *
	 * @param string   $instance_id
	 * @param string   $section_type  Section slug (matches filename without .php)
	 * @param int      $post_id
	 * @param array    $ctx           Resolved context from Resolver.
	 */
	public function render_instance( $instance_id, $section_type, $post_id, $ctx ): void {
		$store = new SLBUILD_DataStore();
		$parser = new SLBUILD_SchemaParser();

		// Theme /sections/ takes priority; fall back to plugin starter-sections.
		$file = trailingslashit( $ctx['sections_dir'] ) . $section_type . '.php';
		if ( ! file_exists( $file ) && ! empty( $ctx['starter_sections_dir'] ) ) {
			$file = trailingslashit( $ctx['starter_sections_dir'] ) . $section_type . '.php';
		}

		if ( ! file_exists( $file ) ) {
			return;
		}

		$value_source = $ctx['value_source'] ?? '';
		if ( 'draft_meta' === $value_source ) {
			$saved  = $store->get_draft_instance_values( $post_id, $instance_id );
			$blocks = $store->get_draft_instance_blocks( $post_id, $instance_id );
		} else {
			$saved  = $store->get_instance_values( $post_id, $instance_id );
			$blocks = $store->get_instance_blocks( $post_id, $instance_id );
		}

		// Merge schema defaults under saved values so templates always get a value.
		$schema  = $parser->parse_file( $file );
		$defaults = array();
		if ( $schema && ! empty( $schema['settings'] ) ) {
			foreach ( $schema['settings'] as $field ) {
				if ( isset( $field['id'] ) && isset( $field['default'] ) ) {
					$defaults[ $field['id'] ] = $field['default'];
				}
			}
		}
		$values = array_merge( $defaults, $saved );

		// Advanced CSS overrides - wrap section output only when values are set.
		// Sanitize spacing values: only CSS spacing characters allowed (digits, dots, spaces,
		// unit letters, %) to prevent CSS property injection via the style attribute.
		$sanitize_spacing = static function( $val ) {
			return preg_replace( '/[^0-9a-zA-Z.% ]/', '', (string) $val );
		};
		$adv_margin  = isset( $values['slbuild_margin'] )  && $values['slbuild_margin'] !== ''  ? $sanitize_spacing( $values['slbuild_margin'] )  : '';
		$adv_padding = isset( $values['slbuild_padding'] ) && $values['slbuild_padding'] !== '' ? $sanitize_spacing( $values['slbuild_padding'] ) : '';
		$adv_z_index = isset( $values['slbuild_z_index'] ) && $values['slbuild_z_index'] !== '' ? (int) $values['slbuild_z_index'] : '';
		$has_advanced = $adv_margin !== '' || $adv_padding !== '' || $adv_z_index !== '';

		// Set the context so slbuild_field() / slbuild_raw() / slbuild_meta() resolve correctly.
		$this->current_section = array(
			'instance_id' => $instance_id,
			'type'        => $section_type,
			'values'      => $values,
			'blocks'      => $blocks,
			'post_id'     => $post_id,
			'schema'      => $schema ?: array(),
		);

		if ( $has_advanced ) {
			$style_parts = array();
			if ( $adv_margin !== '' )  $style_parts[] = 'margin:' . esc_attr( $adv_margin );
			if ( $adv_padding !== '' ) $style_parts[] = 'padding:' . esc_attr( $adv_padding );
			if ( $adv_z_index !== '' ) {
				$style_parts[] = 'position:relative';
				$style_parts[] = 'z-index:' . $adv_z_index;
			}
			ob_start();
			include $file;
			$html = ob_get_clean();
			// phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped
			echo '<div style="' . implode( ';', $style_parts ) . '">' . $html . '</div>';
		} else {
			include $file;
		}

		$this->current_section = array();
	}

	/**
	 * Get the value of a field in the currently-rendering section.
	 * Returns the raw stored value (escaping is the caller's job via helpers).
	 *
	 * @param string $field_id
	 * @return mixed
	 */
	public function get_field_value( $field_id ) {
		return $this->current_section['values'][ $field_id ] ?? null;
	}

	/**
	 * Get the parsed schema array for the currently-rendering section.
	 * Used by slbuild_meta() to read schema-level keys (heading_level, above_fold, etc.).
	 *
	 * @return array
	 */
	public function get_schema(): array {
		return $this->current_section['schema'] ?? array();
	}

	/**
	 * Get the blocks array for the currently-rendering section.
	 *
	 * @return array
	 */
	public function get_blocks(): array {
		return $this->current_section['blocks'] ?? array();
	}

	/**
	 * Set the active block context (called inside a block loop in a template).
	 *
	 * @param array $block_data Single block instance: [ 'block' => id, 'type' => type, 'settings' => [] ]
	 */
	public function set_current_block( $block_data ): void {
		$this->current_block = $block_data;
	}

	public function clear_current_block(): void {
		$this->current_block = array();
	}

	/**
	 * Get the value of a field in the currently-active block.
	 *
	 * @param string $field_id
	 * @return mixed
	 */
	public function get_block_field_value( $field_id ) {
		return $this->current_block['settings'][ $field_id ] ?? null;
	}

	/**
	 * Enqueue scripts and styles declared in section schemas for the current page's layout.
	 * Hooked to wp_enqueue_scripts at priority 20 - fires before template output, after theme assets.
	 * WP's enqueue system deduplicates by handle, so repeated section types enqueue once.
	 */
	public function maybe_enqueue_assets(): void {
		$post_id = get_queried_object_id();
		if ( ! $post_id ) {
			return;
		}
		$ctx          = SLBUILD_Resolver::instance()->resolve( $post_id );
		$store        = new SLBUILD_DataStore();
		$value_source = $ctx['value_source'] ?? '';
		if ( 'draft_meta' === $value_source ) {
			$layout = $store->get_draft_layout( $post_id );
		} else {
			$layout = $store->get_layout( $post_id );
		}
		if ( empty( $layout ) ) {
			return;
		}

		$parser    = new SLBUILD_SchemaParser();
		$theme_uri = get_stylesheet_directory_uri();
		$seen      = array();

		foreach ( $layout as $item ) {
			$slug = $item['type'] ?? '';
			if ( ! $slug || isset( $seen[ $slug ] ) ) {
				continue;
			}
			$seen[ $slug ] = true;

			$file = trailingslashit( $ctx['sections_dir'] ) . $slug . '.php';
			if ( ! file_exists( $file ) && ! empty( $ctx['starter_sections_dir'] ) ) {
				$file = trailingslashit( $ctx['starter_sections_dir'] ) . $slug . '.php';
			}
			if ( ! file_exists( $file ) ) {
				continue;
			}

			$schema = $parser->parse_file( $file );
			if ( ! $schema || empty( $schema['assets'] ) ) {
				continue;
			}

			foreach ( $schema['assets']['scripts'] ?? array() as $s ) {
				if ( empty( $s['handle'] ) || empty( $s['src'] ) ) {
					continue;
				}
				wp_enqueue_script(
					$s['handle'],
					str_replace( '{{theme}}', $theme_uri, $s['src'] ),
					$s['deps'] ?? array(),
					$s['version'] ?? false,
					! empty( $s['footer'] )
				);
			}

			foreach ( $schema['assets']['styles'] ?? array() as $s ) {
				if ( empty( $s['handle'] ) || empty( $s['src'] ) ) {
					continue;
				}
				wp_enqueue_style(
					$s['handle'],
					str_replace( '{{theme}}', $theme_uri, $s['src'] ),
					$s['deps'] ?? array(),
					$s['version'] ?? false
				);
			}
		}
	}
}