<?php
/**
 * Functions and hooks to process the Interactivity API directives in the
 * server.
 *
 * @package Gutenberg
 * @subpackage Interactivity API
 */

/**
 * Marks the block as a root block. Checks that there is already a root block in
 * order not to mark template-parts or synced patterns as root blocks, where the
 * parent is null.
 *
 * @param array $parsed_block The parsed block.
 * @param array $source_block The source block.
 * @param array $parent_block The parent block.
 *
 * @return array The parsed block.
 */
function gutenberg_interactivity_mark_root_blocks( $parsed_block, $source_block, $parent_block ) {
	if ( ! isset( $parent_block ) && ! WP_Directive_Processor::has_root_block() ) {
		WP_Directive_Processor::mark_root_block( $parsed_block );
	}

	return $parsed_block;
}
add_filter( 'render_block_data', 'gutenberg_interactivity_mark_root_blocks', 10, 3 );

/**
 * Processes the directives in the root blocks.
 *
 * @param string $block_content The block content.
 * @param array  $block         The full block.
 *
 * @return string Filtered block content.
 */
function gutenberg_process_directives_in_root_blocks( $block_content, $block ) {
	if ( WP_Directive_Processor::is_marked_as_root_block( $block ) ) {
		WP_Directive_Processor::unmark_root_block();

		// Parse our own block delimiters for interactive and non-interactive blocks.
		$parsed_blocks     = parse_blocks( $block_content );
		$context           = new WP_Directive_Context();
		$processed_content = '';
		$namespace_stack   = array();

		foreach ( $parsed_blocks as $parsed_block ) {
			if ( 'core/interactivity-wrapper' === $parsed_block['blockName'] ) {
				$processed_content .= gutenberg_process_interactive_block( $parsed_block, $context, $namespace_stack );
			} elseif ( 'core/non-interactivity-wrapper' === $parsed_block['blockName'] ) {
				$processed_content .= gutenberg_process_non_interactive_block( $parsed_block, $context, $namespace_stack );
			} else {
				$processed_content .= $parsed_block['innerHTML'];
			}
		}
		return $processed_content;
	}

	return $block_content;
}
add_filter( 'render_block', 'gutenberg_process_directives_in_root_blocks', 20, 2 );

/**
 * Marks the block as a children of an interactive block.
 *
 * @param array    $parsed_block The parsed block.
 * @param array    $source_block The source block.
 * @param WP_Block $parent_block The parent block.
 */
function gutenberg_mark_chidren_of_interactive_block( $parsed_block, $source_block, $parent_block ) {
	if (
		isset( $parent_block ) &&
		isset( $parent_block->block_type->supports['interactivity'] ) &&
		$parent_block->block_type->supports['interactivity']
	) {
		WP_Directive_Processor::mark_children_of_interactive_block( $source_block );
	}
	return $parsed_block;
}
add_filter( 'render_block_data', 'gutenberg_mark_chidren_of_interactive_block', 100, 3 );

/**
 * Adds a comment delimiter to mark if the block is interactive or not.
 *
 * @param string   $block_content The block content.
 * @param array    $block The full block, including name and attributes.
 * @param WP_Block $block_instance The block instance.
 */
function gutenberg_mark_block_interactivity( $block_content, $block, $block_instance ) {
	if (
		isset( $block_instance->block_type->supports['interactivity'] ) &&
		$block_instance->block_type->supports['interactivity']
	) {
		// Wraps the interactive block with a comment delimiter to be able to
		// process it later.
		return get_comment_delimited_block_content(
			'core/interactivity-wrapper',
			array(),
			$block_content
		);
	} elseif ( WP_Directive_Processor::is_marked_as_children_of_interactive_block( $block ) ) {
		// Wraps the non-interactive block with a comment delimiter to be able to
		// skip it later.
		return get_comment_delimited_block_content(
			'core/non-interactivity-wrapper',
			array(),
			$block_content
		);
	}
	return $block_content;
}
add_filter( 'render_block', 'gutenberg_mark_block_interactivity', 10, 3 );

/**
 * Traverses the HTML of an interactive block, searching for Interactivity API
 * directives and processing them. For the inner blocks, it calls the
 * corresponding function depending on the wrapper type.
 *
 * @param array                $interactive_block The interactive block to process.
 * @param WP_Directive_Context $context The context to use when processing.
 * @param array                $namespace_stack Stack of namespackes passed by reference.
 *
 * @return string The processed HTML.
 */
function gutenberg_process_interactive_block( $interactive_block, $context, &$namespace_stack ) {
	$block_index              = 0;
	$content                  = '';
	$interactive_inner_blocks = array();

	foreach ( $interactive_block['innerContent'] as $inner_content ) {
		if ( is_string( $inner_content ) ) {
			$content .= $inner_content;
		} else {
			// This is an inner block. It may be an interactive block or a
			// non-interactive block.
			$content                   .= '<wp-inner-blocks-' . $block_index . '></wp-inner-blocks-' . $block_index . '>';
			$interactive_inner_blocks[] = $interactive_block['innerBlocks'][ $block_index++ ];
		}
	}

	return gutenberg_process_interactive_html( $content, $context, $interactive_inner_blocks, $namespace_stack );
}

/**
 * Returns the HTML of a non-interactive block without processing the
 * directives. For the inner blocks, it calls the corresponding function
 * depending on the wrapper type.
 *
 * @param array                $non_interactive_block The non-interactive block to process.
 * @param WP_Directive_Context $context The context to use when processing.
 * @param array                $namespace_stack Stack of namespackes passed by reference.
 *
 * @return string The processed HTML.
 */
function gutenberg_process_non_interactive_block( $non_interactive_block, $context, &$namespace_stack ) {
	$block_index = 0;
	$content     = '';
	foreach ( $non_interactive_block['innerContent'] as $inner_content ) {
		if ( is_string( $inner_content ) ) {
			// This content belongs to a non interactive block and therefore it cannot
			// contain directives. We add the HTML directly to the final output.
			$content .= $inner_content;
		} else {
			// This is an inner block. It may be an interactive block or a
			// non-interactive block.
			$inner_block = $non_interactive_block['innerBlocks'][ $block_index++ ];

			if ( 'core/interactivity-wrapper' === $inner_block['blockName'] ) {
				$content .= gutenberg_process_interactive_block( $inner_block, $context, $namespace_stack );
			} elseif ( 'core/non-interactivity-wrapper' === $inner_block['blockName'] ) {
				$content .= gutenberg_process_non_interactive_block( $inner_block, $context, $namespace_stack );
			}
		}
	}
	return $content;
}

/**
 * Processes interactive HTML by applying directives to the HTML tags.
 *
 * It uses the WP_Directive_Processor class to parse the HTML and apply the
 * directives. If a tag contains a 'WP-INNER-BLOCKS' string and there are inner
 * blocks to process, the function processes these inner blocks and replaces the
 * 'WP-INNER-BLOCKS' tag in the HTML with those blocks.
 *
 * @param string $html The HTML to process.
 * @param mixed  $context The context to use when processing.
 * @param array  $inner_blocks The inner blocks to process.
 * @param array  $namespace_stack Stack of namespackes passed by reference.
 *
 * @return string The processed HTML.
 */
function gutenberg_process_interactive_html( $html, $context, $inner_blocks = array(), &$namespace_stack = array() ) {
	static $directives = array(
		'data-wp-interactive' => 'gutenberg_interactivity_process_wp_interactive',
		'data-wp-context'     => 'gutenberg_interactivity_process_wp_context',
		'data-wp-bind'        => 'gutenberg_interactivity_process_wp_bind',
		'data-wp-class'       => 'gutenberg_interactivity_process_wp_class',
		'data-wp-style'       => 'gutenberg_interactivity_process_wp_style',
		'data-wp-text'        => 'gutenberg_interactivity_process_wp_text',
	);

	$tags                   = new WP_Directive_Processor( $html );
	$prefix                 = 'data-wp-';
	$tag_stack              = array();
	$inner_processed_blocks = array();
	$inner_blocks_index     = 0;
	while ( $tags->next_tag( array( 'tag_closers' => 'visit' ) ) ) {
		$tag_name = $tags->get_tag();

		// Processes the inner blocks.
		if ( str_contains( $tag_name, 'WP-INNER-BLOCKS' ) && ! empty( $inner_blocks ) && ! $tags->is_tag_closer() ) {
			if ( 'core/interactivity-wrapper' === $inner_blocks[ $inner_blocks_index ]['blockName'] ) {
				$inner_processed_blocks[ strtolower( $tag_name ) ] = gutenberg_process_interactive_block( $inner_blocks[ $inner_blocks_index++ ], $context, $namespace_stack );
			} elseif ( 'core/non-interactivity-wrapper' === $inner_blocks[ $inner_blocks_index ]['blockName'] ) {
				$inner_processed_blocks[ strtolower( $tag_name ) ] = gutenberg_process_non_interactive_block( $inner_blocks[ $inner_blocks_index++ ], $context, $namespace_stack );
			}
		}
		if ( $tags->is_tag_closer() ) {
			if ( 0 === count( $tag_stack ) ) {
				continue;
			}
			list( $latest_opening_tag_name, $attributes ) = end( $tag_stack );
			if ( $latest_opening_tag_name === $tag_name ) {
				array_pop( $tag_stack );
				// If the matching opening tag didn't have any directives, we move on.
				if ( 0 === count( $attributes ) ) {
					continue;
				}
			}
		} else {
			$attributes = array();
			foreach ( $tags->get_attribute_names_with_prefix( $prefix ) as $name ) {
				/*
				 * Removes the part after the double hyphen before looking for
				 * the directive processor inside `$directives`, e.g., "wp-bind"
				 * from "wp-bind--src" and "wp-context" from "wp-context" etc...
				 */
				list( $type ) = $tags::parse_attribute_name( $name );
				if ( array_key_exists( $type, $directives ) ) {
					$attributes[] = $type;
				}
			}

			/*
			 * If this is an open tag, and if it either has directives, or if
			 * we're inside a tag that does, take note of this tag and its
			 * directives so we can call its directive processor once we
			 * encounter the matching closing tag.
			 */
			if (
				! $tags::is_html_void_element( $tag_name ) &&
				( 0 !== count( $attributes ) || 0 !== count( $tag_stack ) )
			) {
				$tag_stack[] = array( $tag_name, $attributes );
			}
		}

		// Extract all directive names. They'll be used later on.
		$directive_names     = array_keys( $directives );
		$directive_names_rev = array_reverse( $directive_names );

		/*
		 * Sort attributes by the order they appear in the `$directives`
		 * argument, considering it as the priority order in which
		 * directives should be processed. Note that the order is reversed
		 * for tag closers.
		 */
		$sorted_attrs = array_intersect(
			$tags->is_tag_closer()
				? $directive_names_rev
				: $directive_names,
			$attributes
		);

		foreach ( $sorted_attrs as $attribute ) {
			call_user_func_array(
				$directives[ $attribute ],
				array(
					$tags,
					$context,
					end( $namespace_stack ),
					&$namespace_stack,
				)
			);
		}
	}

	$processed_html = $tags->get_updated_html();

	// Replaces the inner block tags with the content of each inner block
	// processed.
	if ( ! empty( $inner_processed_blocks ) ) {
		foreach ( $inner_processed_blocks as $inner_block_tag => $inner_block_content ) {
			if ( str_contains( $processed_html, $inner_block_tag ) ) {
				$processed_html = str_replace( '<' . $inner_block_tag . '></' . $inner_block_tag . '>', $inner_block_content, $processed_html );
			}
		}
	}

	return $processed_html;
}

/**
 * Resolves the passed reference from the store and the context under the given
 * namespace.
 *
 * A reference could be either a single path or a namespace followed by a path,
 * separated by two colons, i.e, `namespace::path.to.prop`. If the reference
 * contains a namespace, that namespace overrides the one passed as argument.
 *
 * @param string $reference Reference value.
 * @param string $ns Inherited namespace.
 * @param array  $context Context data.
 * @return mixed Resolved value.
 */
function gutenberg_interactivity_evaluate_reference( $reference, $ns, array $context = array() ) {
	// Extract the namespace from the reference (if present).
	list( $ns, $path ) = WP_Directive_Processor::parse_attribute_value( $reference, $ns );

	$store = array(
		'state'   => WP_Interactivity_Initial_State::get_state( $ns ),
		'context' => $context[ $ns ] ?? array(),
	);

	/*
	 * Checks first if the directive path is preceded by a negator operator (!),
	 * indicating that the value obtained from the Interactivity Store (or the
	 * passed context) using the subsequent path should be negated.
	 */
	$should_negate_value = '!' === $path[0];
	$path                = $should_negate_value ? substr( $path, 1 ) : $path;
	$path_segments       = explode( '.', $path );
	$current             = $store;
	foreach ( $path_segments as $p ) {
		if ( isset( $current[ $p ] ) ) {
			$current = $current[ $p ];
		} else {
			return null;
		}
	}

	/*
	 * Checks if $current is an anonymous function or an arrow function, and if
	 * so, call it passing the store. Other types of callables are ignored on
	 * purpose, as arbitrary strings or arrays could be wrongly evaluated as
	 * "callables".
	 *
	 * E.g., "file" is an string and a "callable" (the "file" function exists).
	 */
	if ( $current instanceof Closure ) {
		/*
		 * TODO: Figure out a way to implement derived state without having to
		 * pass the store as argument:
		 *
		 * $current = call_user_func( $current );
		 */
	}

	// Returns the opposite if it has a negator operator (!).
	return $should_negate_value ? ! $current : $current;
}