Migrate.php

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<?php

namespace Rsi\Fred\Db;

class Migrate extends \Rsi\Fred\Component{

  const ACTION_EXEC = 'exec'; //!< New.
  const ACTION_UNDO = 'undo'; //!< Removed.
  const ACTION_REDO = 'redo'; //!< Changed.
  const ACTION_TEST = 'test'; //!< Testing.

  public $mask = '*.sql'; //!< Format for migration files.
  public $path = null; //!< Directory with migration files (including trailing delimiter).
  public $delimiter = '///// [action]'; //!< Delimiter for the migration file parts ([action] holds the action).
  public $test = false; //!< Execute the 'test' part of the migration file.

  protected $_db = null;
  protected $_currentPath = null; //!< Path with current files (keep out of version control; empty = path + "current/").

  protected $_current = null;

  protected function flatten($sql){
    return md5(preg_replace('/\\s+/','',$sql));
  }
  /**
   * Return all migration files in a directory.
   * @param string $path
   * @return array  Key = migration filename, value = SQL.
   */
  protected function dir($path){
    $dir = [];
    foreach((new \GlobIterator($path . $this->mask,\GlobIterator::NEW_CURRENT_AND_KEY)) as $filename => $info)
      $dir[$filename] = file_get_contents($path . $filename);
    ksort($dir);
    return $dir;
  }
  /**
   * Difference between current database state and desired state based on migration files.
   * @return array  Key = migration filename, value = action.
   */
  public function diff(){
    $diff = array_fill_keys(array_keys($this->current),self::ACTION_UNDO);
    $redo = false;
    foreach($this->dir($this->path) as $filename => $sql) $diff[$filename] = array_key_exists($filename,$this->current)
      ? ($redo || ($redo = $this->flatten($this->current[$filename]) != $this->flatten($sql)) ? self::ACTION_REDO : null) //redo all after first redo
      : self::ACTION_EXEC;
    ksort($diff);
    return array_filter($diff);
  }

  protected function split($sql){
    $parts = [];
    $delimiter = '/(?:$|' . str_replace('\\[action\\]','(' . implode('|',$this->constants('ACTION_')) . ')',preg_quote($this->delimiter,'/')) . ')/';
    $action = self::ACTION_EXEC;
    while(preg_match($delimiter,$sql,$match,PREG_OFFSET_CAPTURE)) switch(count($match)){
      case 1: //last part
        $parts[$action] = $sql;
        break 2;
      case 2:
        $parts[$action] = substr($sql,0,$match[0][1]);
        $sql = substr($sql,$match[1][1] + strlen($action = $match[1][0]));
        break;
    }
    return $parts;
  }
  /**
   * Migrate the database.
   * @return array  Key = migration filename, value = action.
   * @see diff()
   */
  public function execute(){
    $log = $this->component('log');
    if($diff = $this->diff()){
      $this->_db->begin();
      try{
        foreach(array_reverse($diff) as $filename => $action) switch($action){
          case self::ACTION_UNDO:
          case self::ACTION_REDO:
            $log->info("Migrate: undo $filename",__FILE__,__LINE__);
            if(trim($sql = $this->split($this->current[$filename])[$action] ?? null)) $this->_db->execute($sql);
            break;
        }
        foreach($diff as $filename => $action) switch($action){
          case self::ACTION_TEST: if(!$this->test) break;
          case self::ACTION_REDO:
          case self::ACTION_EXEC:
            $log->info("Migrate: $action $filename",__FILE__,__LINE__);
            if(trim($sql = $this->split(file_get_contents($this->path . $filename))[$action] ?? null)) $this->_db->execute($sql);
            break;
        }
        $this->current = $this->dir($this->path);
        $this->_db->commit();
      }
      catch(\Exception $e){
        $this->_db->rollBack();
        throw $e;
      }
    }
    return $diff;
  }

  protected function getCurrent(){
    if($this->_current === null) $this->_current = $this->dir($this->currentPath);
    return $this->_current;
  }

  protected function setCurrent($value){
    foreach($this->dir($this->current) as $filename => $sql) unlink($this->currentPath . $filename);
    foreach(($this->_current = $value) as $filename => $sql) file_put_contents($this->currentPath . $filename,$sql);
  }

  protected function getCurrentPath(){
    return $this->_currentPath ?: $this->path . 'current/';
  }

}