<?php
namespace AdvancedAddons;

use WP_Error;

/**
 * Server-side helper to insert or replace blocks in the current post.
 *
 * Staged results can be fetched and applied explicitly by the editor, similar
 * to the MCP update_selection ability.
 */
class Block_Updater {

	/**
	 * Insert blocks into a post.
	 *
	 * @param int         $post_id      Post to update.
	 * @param array       $blocks       Block data arrays to insert.
	 * @param string      $position     'end' (default), 'start', 'before_selection', or 'after_selection'.
	 * @param string|null $page_content Optional live page content from the editor. When provided,
	 *                                  used instead of the database post_content for resolving
	 *                                  selection-relative positions, ensuring indices match.
	 * @param bool        $stage_result Whether to stage the result for explicit editor application.
	 * @param array|null  $selection    Live selection supplied by the active request.
	 * @return array|WP_Error Result data or error.
	 */
	public static function insert_blocks( int $post_id, array $blocks, string $position = 'end', ?string $page_content = null, bool $stage_result = true, ?array $selection = null ) {
		if ( ! Security::can_edit_post( $post_id ) ) {
			return new WP_Error(
				'edit_forbidden',
				__( 'Sorry, you are not allowed to edit this post.', 'advanced-animation' )
			);
		}

		$post = get_post( $post_id );
		if ( ! $post ) {
			return new WP_Error( 'invalid_post', __( 'Post not found.', 'advanced-animation' ) );
		}

		$raw_content    = $page_content ?? $post->post_content ?? '';
		$existing_blocks = parse_blocks( $raw_content );

		$index = self::resolve_insert_index( $position, $existing_blocks, $selection );
		if ( is_wp_error( $index ) ) {
			return $index;
		}

		array_splice( $existing_blocks, $index, 0, $blocks );

		$new_content = serialize_blocks( BlocksToHtml::normalize_blocks( $existing_blocks ) );

		// $updated = wp_update_post(
		// 	array(
		// 		'ID'           => $post_id,
		// 		'post_content' => $new_content,
		// 	),
		// 	true
		// );

		// if ( is_wp_error( $updated ) ) {
		// 	return $updated;
		// }

		$result_html      = BlocksToHtml::convert_blocks( $blocks );
		$replacement_html = serialize_blocks( BlocksToHtml::normalize_blocks( $blocks ) );

		$result = array(
			'action'           => 'insert',
			'editor'           => 'gutenberg',
			'position'         => $position,
			'insert_index'     => $index,
			'post_id'          => $post_id,
			'blocks'           => $blocks,
			'html'             => $result_html,
			'replacement_html' => $replacement_html,
			'post_content'     => $new_content,
		);

		if ( $stage_result ) {
			SelectionBridge::store_result( $result );
		}

		return array_merge( $result, array(
			'success'          => true,
			'message'          => self::insert_success_message( $position ),
		) );
	}

	/**
	 * Resolve the absolute top-level index where new blocks should be inserted.
	 *
	 * @param string  $position        Requested position.
	 * @param array   $existing_blocks Current top-level blocks.
	 * @param array|null $selection    Live selection supplied by the active request.
	 * @return int|WP_Error Absolute index (0..count) or error when a required
	 *                      selection is missing.
	 */
	private static function resolve_insert_index( string $position, array $existing_blocks, ?array $selection = null ) {
		$count = count( $existing_blocks );

		if ( 'start' === $position ) {
			return 0;
		}

		if ( 'end' === $position || '' === $position ) {
			return $count;
		}

		if ( 'before_selection' === $position || 'after_selection' === $position ) {
			if ( ! $selection ) {
				$selection = SelectionBridge::read_selection();
				if ( $selection && ! SelectionBridge::is_fresh( $selection ) ) {
					$selection = null;
				}
			}
			if ( ! $selection || empty( $selection['indices'] ) ) {
				return new WP_Error(
					'no_selection',
					__( 'No block selected in the editor. Select a block to use as the anchor, then ask again to insert before/after it.', 'advanced-animation' )
				);
			}

			$indices = array_filter(
				array_map( 'intval', (array) $selection['indices'] ),
				function ( $i ) use ( $count ) {
					return $i >= 0 && $i < $count;
				}
			);

			if ( empty( $indices ) ) {
				return new WP_Error(
					'invalid_selection',
					__( 'The selected block could not be located on this page. Please reselect a block and try again.', 'advanced-animation' )
				);
			}

			if ( 'before_selection' === $position ) {
				return min( $indices );
			}

			return max( $indices ) + 1;
		}

		// Unknown position falls back to the end.
		return $count;
	}

	/**
	 * Human-friendly success message for the chosen position.
	 */
	private static function insert_success_message( string $position ): string {
		switch ( $position ) {
			case 'start':
				return __( 'Blocks added at the top of the page.', 'advanced-animation' );
			case 'before_selection':
				return __( 'Blocks added before the selected block.', 'advanced-animation' );
			case 'after_selection':
				return __( 'Blocks added after the selected block.', 'advanced-animation' );
			default:
				return __( 'Blocks added to the page.', 'advanced-animation' );
		}
	}

	/**
	 * Replace the currently selected blocks with new blocks.
	 *
	 * @param array       $blocks        Block data arrays to insert in place of the selection.
	 * @param string|null $page_content  Optional live page content from the editor. When provided,
	 *                                   used instead of the database post_content for resolving
	 *                                   selection indices, ensuring they match the editor state.
	 * @param bool        $stage_result  Whether to stage the result for explicit editor application.
	 * @param array|null  $selection     Live selection supplied by the active request.
	 * @return array|WP_Error Result data or error.
	 */
	public static function replace_selection( array $blocks, ?string $page_content = null, bool $stage_result = true, ?array $selection = null ) {
		if ( ! $selection ) {
			$selection = SelectionBridge::read_selection();
			if ( $selection && ! SelectionBridge::is_fresh( $selection ) ) {
				$selection = null;
			}
		}
		if ( ! $selection ) {
			return new WP_Error(
				'no_selection',
				__( 'No blocks selected. Please select one or more blocks in the editor to replace them.', 'advanced-animation' )
			);
		}

		$post_id = intval( $selection['post_id'] ?? 0 );
		$indices = $selection['indices'] ?? array();
		$client_ids = $selection['clientIds'] ?? array();

		if ( ! $post_id ) {
			return new WP_Error( 'invalid_post', __( 'Selection is missing a post ID.', 'advanced-animation' ) );
		}

		if ( ! Security::can_edit_post( $post_id ) ) {
			return new WP_Error(
				'edit_forbidden',
				__( 'Sorry, you are not allowed to edit this post.', 'advanced-animation' )
			);
		}

		$post = get_post( $post_id );
		if ( ! $post ) {
			return new WP_Error( 'post_not_found', __( 'Post not found.', 'advanced-animation' ) );
		}

		$raw_content     = $page_content ?? $post->post_content ?? '';
		$existing_blocks = parse_blocks( $raw_content );

		if ( empty( $existing_blocks ) ) {
			$existing_blocks = $blocks;
		} elseif ( ! empty( $indices ) ) {
			sort( $indices, SORT_NUMERIC );
			$indices = array_reverse( $indices );

			foreach ( $indices as $idx ) {
				if ( isset( $existing_blocks[ $idx ] ) ) {
					array_splice( $existing_blocks, $idx, 1, $blocks );
					break;
				}
			}

			if ( ! in_array( $blocks, $existing_blocks, true ) ) {
				$first_idx = min( $indices );
				if ( isset( $existing_blocks[ $first_idx ] ) ) {
					array_splice( $existing_blocks, $first_idx, count( $indices ), $blocks );
				}
			}
		} else {
			$existing_blocks = $blocks;
		}

		$new_content = serialize_blocks( BlocksToHtml::normalize_blocks( $existing_blocks ) );

		// $updated = wp_update_post(
		// 	array(
		// 		'ID'           => $post_id,
		// 		'post_content' => $new_content,
		// 	),
		// 	true
		// );

		// if ( is_wp_error( $updated ) ) {
		// 	return $updated;
		// }

		$result_html      = BlocksToHtml::convert_blocks( $blocks );
		$replacement_html = serialize_blocks( BlocksToHtml::normalize_blocks( $blocks ) );

		$result = array(
			'action'           => 'replace',
			'editor'           => 'gutenberg',
			'post_id'          => $post_id,
			'clientIds'        => $client_ids,
			'blocks'           => $blocks,
			'html'             => $result_html,
			'indices'          => $indices,
			'post_content'     => $new_content,
			'replacement_html' => $replacement_html,
		);

		if ( $stage_result ) {
			SelectionBridge::store_result( $result );
		}

		return array_merge( $result, array(
			'success' => true,
			'message' => __( 'Selected blocks replaced.', 'advanced-animation' ),
		) );
	}
}