File: class-hook-buffer.php

<?php

/ * Description * * @author MarekA */

if (!class_exists( 'HookBuffer' ) ) :

class HookBuffer {

private static $buffers = [];
    
private $buffer_name = '';
private $buffer = '';
private $buffer_status = 'waiting';
    
private $priority1;
private $priority2;
private $remove_actions_priority;
    
private $tag1;
private $tag2;
    
private $output=FALSE;
private $all_hook_lock=FALSE;

public function __construct( $buffer_name, $tag1='', $tag2='' ) {
	if ( !( function_exists( 'add_action' ) 
		&&  function_exists( 'remove_action' ) )
		|| self::buffer_exists( $buffer_name ) ) {
		throw new Exception;
	}
	$this->buffer_name = (string)$buffer_name;
	$this->tag1 = (string)$tag1;
	$this->tag2 = (string)$tag2;
            
	if ( in_array( 'next', [ $tag1, $tag2 ] ) ) {
		$this->all_hook_lock = TRUE;
		if ( !$tag1 ) {	$this->start_buffering(); }
		add_action( 'all', [ $this, 'init_in_all_hook' ], 10, 1 );
	} else {
		$this->init();
	}
            
	self::$buffers[$buffer_name] = $this;
}

public static function buffer_exists( $buffer_name ) {
	return array_key_exists((string)$buffer_name, self::$buffers);
}

public static function buffer_ready( $buffer_name ) {
	$b = self::b( (string)$buffer_name );
	return ( $b !== FALSE && $b->get_status() === 'finished' ) ? TRUE : FALSE;
}

public static function b( $buffer_name ) {
	$buffer_name = (string)$buffer_name;
	return self::buffer_exists($buffer_name) ? 
			self::$buffers[$buffer_name] : FALSE;
}

private function init() {
	$tag1 = $this->tag1;
	$tag2 = $this->tag2; 
	
	if ( $tag1 ) {
		if ( $tag2 ) {
			$this->add_actions( 'last', 'first' );
		} else {
			$this->tag2 = $tag1;
			$this->add_actions( 'first', 'last' );
		}
	} else {
		if ( $tag2 ) {
			$this->tag1 = NULL;
			$this->add_actions( NULL, 'first' );
			if ( !$this->all_hook_lock ) { $this->start_buffering( ); }
		} else {
			return;
		}
	}
}
    
public function init_in_all_hook( $tag ) {
	if ( !$this->all_hook_lock ) {
		return;
	}

	remove_action( 'all', [ $this, 'init_in_all_hook' ], 10 );

	if ( $this->tag1 === 'next' ) {
		$this->tag1 = $tag;
	}

	if ( $this->tag2 === 'next' ) {
		$this->tag2 = $tag;
	}

	$this->init();
	$this->all_hook_lock = FALSE;
}

private function init_priorities( $position1, $position2 ) {

	if ( $position1 === 'first' ) {
		$this->priority1 = -9999;
	} elseif ( $position1 === 'last' ) {
		$this->priority1 = 10000;
	} else {
		$this->priority1 = NULL;
	}
	
	if ( $position2 === 'first' ) {
		$this->priority2 = -10000;
	} elseif ( $position2 === 'last' ) {
		$this->priority2 = 9999;
	} else {
		$this->priority2 = NULL;
	}
	
	$this->remove_actions_priority = 10001;
}

private function add_actions( $position1, $position2 ) {
	$this->init_priorities($position1, $position2);
	
	if ( $this->tag1 ) {
		add_action( 
			$this->tag1,
			[ $this, 'start_buffering' ],
			$this->priority1 );
	}
	
	if ( $this->tag2 ) {
		add_action(
			$this->tag2, 
			[ $this, 'stop_buffering' ],
			$this->priority2 );
		add_action(
			$this->tag2,
			[ $this, 'remove_actions' ],
			$this->remove_actions_priority );
	}
	
	return $this;
}

public function start_buffering( $var=NULL ) {
	if ( $this->get_status() === 'waiting' ) {
		$this->buffer_status = 'buffering';
		ob_start();
	}	
	return $var;
}

public function stop_buffering( $var=NULL ) {
	if ( $this->get_status() === 'buffering' ) {
		$this->buffer = ob_get_contents();
		ob_end_clean();
		$this->buffer_status = 'finished';
		if ( $this->output ) {
			$this->output();
		}
	} else {
		$this->buffer_status = 'finished';
	}
	return $var;
}

public function get_status() {
	return $this->buffer_status;
}

public function get() {
	return $this->get_status() === 'finished' ? $this->filter() : FALSE;
}

protected function filter() {
	return $this->buffer;
}

public function output() {
	if ( $this->get_status() === 'finished' ) {
		echo $this->get();
	} else {
		$this->output = TRUE;
	}
	
	return $this;
}

public function remove_actions() {
	if ( current_filter() !== $this->tag2 ) {
		return;
	} 
	
	remove_action( 
			$this->tag1,
			[ $this, 'start_buffering' ],
			$this->priority1 );
	remove_action(
			$this->tag2, 
			[ $this, 'stop_buffering' ],
			$this->priority2 );
	remove_action( 
			$this->tag2,
			[ $this, 'remove_actions' ],
			$this->remove_actions_priority );
	
	return $this;
}
    
    public function destroy() {
        $this->stop_buffering();
        $this->remove_actions();
        $this->buffer = '';
        unset( self::$buffers[ $this->buffer_name ] );
    }

}

endif;