<?php

/**

 * Block Serialization Parser

 *

 * @package WordPress

 */

/**

 * Class WP_Block_Parser_Block

 *

 * Holds the block structure in memory

 *

 * @since 3.8.0

 */

class WP_Block_Parser_Block {

	/**

	 * Name of block

	 *

	 * @example "core/paragraph"

	 *

	 * @since 3.8.0

	 * @var string

	 */

	public $blockName;

	/**

	 * Optional set of attributes from block comment delimiters

	 *

	 * @example null

	 * @example array( 'columns' => 3 )

	 *

	 * @since 3.8.0

	 * @var array|null

	 */

	public $attrs;

	/**

	 * List of inner blocks (of this same class)

	 *

	 * @since 3.8.0

	 * @var WP_Block_Parser_Block[]

	 */

	public $innerBlocks;

	/**

	 * Resultant HTML from inside block comment delimiters

	 * after removing inner blocks

	 *

	 * @example "...Just <!-- wp:test /--> testing..." -> "Just testing..."

	 *

	 * @since 3.8.0

	 * @var string

	 */

	public $innerHTML;

	/**

	 * List of string fragments and null markers where inner blocks were found

	 *

	 * @example array(

	 *   'innerHTML'    => 'BeforeInnerAfter',

	 *   'innerBlocks'  => array( block, block ),

	 *   'innerContent' => array( 'Before', null, 'Inner', null, 'After' ),

	 * )

	 *

	 * @since 4.2.0

	 * @var array

	 */

	public $innerContent;

	/**

	 * Constructor.

	 *

	 * Will populate object properties from the provided arguments.

	 *

	 * @since 3.8.0

	 *

	 * @param string $name         Name of block.

	 * @param array  $attrs        Optional set of attributes from block comment delimiters.

	 * @param array  $innerBlocks  List of inner blocks (of this same class).

	 * @param string $innerHTML    Resultant HTML from inside block comment delimiters after removing inner blocks.

	 * @param array  $innerContent List of string fragments and null markers where inner blocks were found.

	 */

	function __construct( $name, $attrs, $innerBlocks, $innerHTML, $innerContent ) {

		$this->blockName    = $name;

		$this->attrs        = $attrs;

		$this->innerBlocks  = $innerBlocks;

		$this->innerHTML    = $innerHTML;

		$this->innerContent = $innerContent;

	}

}

/**

 * Class WP_Block_Parser_Frame

 *

 * Holds partial blocks in memory while parsing

 *

 * @internal

 * @since 3.8.0

 */

class WP_Block_Parser_Frame {

	/**

	 * Full or partial block

	 *

	 * @since 3.8.0

	 * @var WP_Block_Parser_Block

	 */

	public $block;

	/**

	 * Byte offset into document for start of parse token

	 *

	 * @since 3.8.0

	 * @var int

	 */

	public $token_start;

	/**

	 * Byte length of entire parse token string

	 *

	 * @since 3.8.0

	 * @var int

	 */

	public $token_length;

	/**

	 * Byte offset into document for after parse token ends

	 * (used during reconstruction of stack into parse production)

	 *

	 * @since 3.8.0

	 * @var int

	 */

	public $prev_offset;

	/**

	 * Byte offset into document where leading HTML before token starts

	 *

	 * @since 3.8.0

	 * @var int

	 */

	public $leading_html_start;

	/**

	 * Constructor

	 *

	 * Will populate object properties from the provided arguments.

	 *

	 * @since 3.8.0

	 *

	 * @param WP_Block_Parser_Block $block              Full or partial block.

	 * @param int                   $token_start        Byte offset into document for start of parse token.

	 * @param int                   $token_length       Byte length of entire parse token string.

	 * @param int                   $prev_offset        Byte offset into document for after parse token ends.

	 * @param int                   $leading_html_start Byte offset into document where leading HTML before token starts.

	 */

	function __construct( $block, $token_start, $token_length, $prev_offset = null, $leading_html_start = null ) {

		$this->block              = $block;

		$this->token_start        = $token_start;

		$this->token_length       = $token_length;

		$this->prev_offset        = isset( $prev_offset ) ? $prev_offset : $token_start + $token_length;

		$this->leading_html_start = $leading_html_start;

	}

}

/**

 * Class WP_Block_Parser

 *

 * Parses a document and constructs a list of parsed block objects

 *

 * @since 3.8.0

 * @since 4.0.0 returns arrays not objects, all attributes are arrays

 */

class WP_Block_Parser {

	/**

	 * Input document being parsed

	 *

	 * @example "Pre-text\n<!-- wp:paragraph -->This is inside a block!<!-- /wp:paragraph -->"

	 *

	 * @since 3.8.0

	 * @var string

	 */

	public $document;

	/**

	 * Tracks parsing progress through document

	 *

	 * @since 3.8.0

	 * @var int

	 */

	public $offset;

	/**

	 * List of parsed blocks

	 *

	 * @since 3.8.0

	 * @var WP_Block_Parser_Block[]

	 */

	public $output;

	/**

	 * Stack of partially-parsed structures in memory during parse

	 *

	 * @since 3.8.0

	 * @var WP_Block_Parser_Frame[]

	 */

	public $stack;

	/**

	 * Empty associative array, here due to PHP quirks

	 *

	 * @since 4.4.0

	 * @var array empty associative array

	 */

	public $empty_attrs;

	/**

	 * Parses a document and returns a list of block structures

	 *

	 * When encountering an invalid parse will return a best-effort

	 * parse. In contrast to the specification parser this does not

	 * return an error on invalid inputs.

	 *

	 * @since 3.8.0

	 *

	 * @param string $document Input document being parsed.

	 * @return WP_Block_Parser_Block[]

	 */

	function parse( $document ) {

		$this->document    = $document;

		$this->offset      = 0;

		$this->output      = array();

		$this->stack       = array();

		$this->empty_attrs = json_decode( '{}', true );

		do {

			// twiddle our thumbs.

		} while ( $this->proceed() );

		return $this->output;

	}

	/**

	 * Processes the next token from the input document

	 * and returns whether to proceed eating more tokens

	 *

	 * This is the "next step" function that essentially

	 * takes a token as its input and decides what to do

	 * with that token before descending deeper into a

	 * nested block tree or continuing along the document

	 * or breaking out of a level of nesting.

	 *

	 * @internal

	 * @since 3.8.0

	 * @return bool

	 */

	function proceed() {

		$next_token = $this->next_token();

		list( $token_type, $block_name, $attrs, $start_offset, $token_length ) = $next_token;

		$stack_depth = count( $this->stack );

		// we may have some HTML soup before the next block.

		$leading_html_start = $start_offset > $this->offset ? $this->offset : null;

		switch ( $token_type ) {

			case 'no-more-tokens':

				// if not in a block then flush output.

				if ( 0 === $stack_depth ) {

					$this->add_freeform();

					return false;

				}

				/*

				 * Otherwise we have a problem

				 * This is an error

				 *

				 * we have options

				 * - treat it all as freeform text

				 * - assume an implicit closer (easiest when not nesting)

				 */

				// for the easy case we'll assume an implicit closer.

				if ( 1 === $stack_depth ) {

					$this->add_block_from_stack();

					return false;

				}

				/*

				 * for the nested case where it's more difficult we'll

				 * have to assume that multiple closers are missing

				 * and so we'll collapse the whole stack piecewise

				 */

				while ( 0 < count( $this->stack ) ) {

					$this->add_block_from_stack();

				}

				return false;

			case 'void-block':

				/*

				 * easy case is if we stumbled upon a void block

				 * in the top-level of the document

				 */

				if ( 0 === $stack_depth ) {

					if ( isset( $leading_html_start ) ) {

						$this->output[] = (array) self::freeform(

							substr(

								$this->document,

								$leading_html_start,

								$start_offset - $leading_html_start

							)

						);

					}

					$this->output[] = (array) new WP_Block_Parser_Block( $block_name, $attrs, array(), '', array() );

					$this->offset   = $start_offset + $token_length;

					return true;

				}

				// otherwise we found an inner block.

				$this->add_inner_block(

					new WP_Block_Parser_Block( $block_name, $attrs, array(), '', array() ),

					$start_offset,

					$token_length

				);

				$this->offset = $start_offset + $token_length;

				return true;

			case 'block-opener':

				// track all newly-opened blocks on the stack.

				array_push(

					$this->stack,

					new WP_Block_Parser_Frame(

						new WP_Block_Parser_Block( $block_name, $attrs, array(), '', array() ),

						$start_offset,

						$token_length,

						$start_offset + $token_length,

						$leading_html_start

					)

				);

				$this->offset = $start_offset + $token_length;

				return true;

			case 'block-closer':

				/*

				 * if we're missing an opener we're in trouble

				 * This is an error

				 */

				if ( 0 === $stack_depth ) {

					/*

					 * we have options

					 * - assume an implicit opener

					 * - assume _this_ is the opener

					 * - give up and close out the document

					 */

					$this->add_freeform();

					return false;

				}

				// if we're not nesting then this is easy - close the block.

				if ( 1 === $stack_depth ) {

					$this->add_block_from_stack( $start_offset );

					$this->offset = $start_offset + $token_length;

					return true;

				}

				/*

				 * otherwise we're nested and we have to close out the current

				 * block and add it as a new innerBlock to the parent

				 */

				$stack_top                        = array_pop( $this->stack );

				$html                             = substr( $this->document, $stack_top->prev_offset, $start_offset - $stack_top->prev_offset );

				$stack_top->block->innerHTML     .= $html;

				$stack_top->block->innerContent[] = $html;

				$stack_top->prev_offset           = $start_offset + $token_length;

				$this->add_inner_block(

					$stack_top->block,

					$stack_top->token_start,

					$stack_top->token_length,

					$start_offset + $token_length

				);

				$this->offset = $start_offset + $token_length;

				return true;

			default:

				// This is an error.

				$this->add_freeform();

				return false;

		}

	}

	/**

	 * Scans the document from where we last left off

	 * and finds the next valid token to parse if it exists

	 *

	 * Returns the type of the find: kind of find, block information, attributes

	 *

	 * @internal

	 * @since 3.8.0

	 * @since 4.6.1 fixed a bug in attribute parsing which caused catastrophic backtracking on invalid block comments

	 * @return array

	 */

	function next_token() {

		$matches = null;

		/*

		 * aye the magic

		 * we're using a single RegExp to tokenize the block comment delimiters

		 * we're also using a trick here because the only difference between a

		 * block opener and a block closer is the leading `/` before `wp:` (and

		 * a closer has no attributes). we can trap them both and process the

		 * match back in PHP to see which one it was.

		 */

		$has_match = preg_match(

			'/<!--\s+(?P<closer>\/)?wp:(?P<namespace>[a-z][a-z0-9_-]*\/)?(?P<name>[a-z][a-z0-9_-]*)\s+(?P<attrs>{(?:(?:[^}]+|}+(?=})|(?!}\s+\/?-->).)*+)?}\s+)?(?P<void>\/)?-->/s',

			$this->document,

			$matches,

			PREG_OFFSET_CAPTURE,

			$this->offset

		);

		// if we get here we probably have catastrophic backtracking or out-of-memory in the PCRE.

		if ( false === $has_match ) {

			return array( 'no-more-tokens', null, null, null, null );

		}

		// we have no more tokens.

		if ( 0 === $has_match ) {

			return array( 'no-more-tokens', null, null, null, null );

		}

		list( $match, $started_at ) = $matches[0];

		$length    = strlen( $match );

		$is_closer = isset( $matches['closer'] ) && -1 !== $matches['closer'][1];

		$is_void   = isset( $matches['void'] ) && -1 !== $matches['void'][1];

		$namespace = $matches['namespace'];

		$namespace = ( isset( $namespace ) && -1 !== $namespace[1] ) ? $namespace[0] : 'core/';

		$name      = $namespace . $matches['name'][0];

		$has_attrs = isset( $matches['attrs'] ) && -1 !== $matches['attrs'][1];

		/*

		 * Fun fact! It's not trivial in PHP to create "an empty associative array" since all arrays

		 * are associative arrays. If we use `array()` we get a JSON `[]`

		 */

		$attrs = $has_attrs

			? json_decode( $matches['attrs'][0], /* as-associative */ true )

			: $this->empty_attrs;

		/*

		 * This state isn't allowed

		 * This is an error

		 */

		if ( $is_closer && ( $is_void || $has_attrs ) ) {

			// we can ignore them since they don't hurt anything.

		}

		if ( $is_void ) {