<?php

/*
* This file is part of the symfony package.
* (c) Fabien Potencier <fabien.potencier@symfony-project.com>
* (c) Francois Zaninotto <francois.zaninotto@symfony-project.com>
*
* For the full copyright and license information, please view the LICENSE
* file that was distributed with this source code.
*/

/**
 * Manages propel database schemas as YAML and XML.
 *
 * @package    symfony
 * @subpackage propel
 * @author     Fabien Potencier <fabien.potencier@symfony-project.com>
 * @author     François Zaninotto <francois.zaninotto@symfony-project.com>
 * @version    SVN: $Id: sfPropelDatabaseSchema.class.php 24392 2009-11-25 18:35:39Z FabianLange $
 */
class sfPropelDatabaseSchema
{
  protected $connection_name = '';
  protected $database        = array();

  /**
   * Dumps schema as array
   *
   * @return array
   */
  public function asArray()
  {
    return array($this->connection_name => $this->database);
  }

  /**
   * Load schema from array
   *
   * @param array $schema_array
   */
  public function loadArray($schema_array)
  {
    if (is_array($schema_array) && !empty($schema_array))
    {
      $database = array();
      $connection_name = '';

      if (isset($schema_array['classes']))
      {
        // New schema syntax
        $schema_array = $this->convertNewToOldYaml($schema_array);
      }

      if (count($schema_array) > 1)
      {
        throw new sfException('A schema.yml must only contain 1 database entry.');
      }

      $tmp = array_keys($schema_array);
      $connection_name = array_shift($tmp);

      if ($connection_name)
      {
        $database = $schema_array[$connection_name];
      }

      $this->connection_name = $connection_name;
      $this->database = $database;

      $this->fixYAMLDatabase();
      $this->fixYAMLI18n();
      $this->fixYAMLColumns();
    }
  }

  /**
   * Load schema from YAML file
   *
   * @param string $file
   */
  public function loadYAML($file)
  {
    $schema_array = sfYaml::load($file);

    if (!is_array($schema_array))
    {
      return; // No defined schema here, skipping
    }

    if (!isset($schema_array['classes']))
    {
      // Old schema syntax: we convert it
      $schema_array = $this->convertOldToNewYaml($schema_array);
    }

    $this->loadArray($schema_array);
  }

  /**
   * Converts old yaml format schema to new yaml schema
   *
   * @param array $schema
   *
   * @return array
   */
  public function convertOldToNewYaml($schema)
  {
    if (is_array($schema) && !empty($schema))
    {
      $new_schema = array();

      $tmp = array_keys($schema);
      $connection_name = array_shift($tmp);

      if (!empty($connection_name) && isset($schema[$connection_name]))
      {
        $new_schema['connection'] = $connection_name;

        $classes = array();
        foreach($schema[$connection_name] as $table => $table_params)
        {
          if ($table == '_attributes')
          {
            // Database attributes
            $new_schema = array_merge($new_schema, $table_params);
          }
          else if ('_propel_behaviors' == $table)
          {
            // Database behaviors
            $new_schema['propel_behaviors'] = $table_params;
          }
          else
          {
            // Table
            $phpName = sfInflector::camelize($table);
            if (isset($table_params['_attributes']))
            {
              $table_attributes = $table_params['_attributes'];
              unset($table_params['_attributes']);
              if (isset($table_attributes['phpName']))
              {
                $phpName = $table_attributes['phpName'];
                unset($table_attributes['phpName']);
              }
            }
            else
            {
              $table_attributes = array();
            }
            $classes[$phpName] = $table_attributes;
            $classes[$phpName]['tableName'] = $table;
            $classes[$phpName]['columns'] = array();
            foreach($table_params as $column => $column_params)
            {
              switch($column)
              {
                case '_behaviors':
                  $classes[$phpName]['behaviors'] = $column_params;
                  break;
                case '_propel_behaviors':
                  $classes[$phpName]['propel_behaviors'] = $column_params;
                  break;
                case '_inheritance':
                  $classes[$phpName]['inheritance'] = $column_params;
                  break;
                case '_nestedSet':
                  $classes[$phpName]['nestedSet'] = $column_params;
                  break;
                case '_foreignKeys':
                  $classes[$phpName]['foreignKeys'] = $column_params;
                  break;
                case '_indexes':
                  $classes[$phpName]['indexes'] = $column_params;
                  break;
                case '_uniques':
                  $classes[$phpName]['uniques'] = $column_params;
                  break;
                case '_vendor':
                  $classes[$phpName]['vendor'] = $column_params;
                  break;
                default:
                  $classes[$phpName]['columns'][$column] = $column_params;
              }
            }
          }
        }

        $new_schema['classes'] = $classes;

      }

      return $new_schema;
    }
  }

  /**
   * Converts new yaml schema format to old yaml schema
   *
   * @param array $schema
   *
   * @return array
   */
  public function convertNewToOldYaml($schema)
  {
    if (isset($schema['connection']))
    {
      $connection_name = $schema['connection'];
      unset($schema['connection']);
    }
    else
    {
      $connection_name = 'propel';
    }

    $database = array();

    // Tables
    if (isset($schema['classes']))
    {
      $tables = array();
      foreach ($schema['classes'] as $className => $classParams)
      {
        $tableParams = array();

        // Columns
        if (isset($classParams['columns']))
        {
          $tableParams = array_merge($classParams['columns'], $tableParams);
          unset($classParams['columns']);
        }

        // Indexes and foreign keys
        if (isset($classParams['indexes']))
        {
          $tableParams['_indexes'] = $classParams['indexes'];
          unset($classParams['indexes']);
        }
        if (isset($classParams['uniques']))
        {
          $tableParams['_uniques'] = $classParams['uniques'];
          unset($classParams['uniques']);
        }
        if (isset($classParams['foreignKeys']))
        {
          $tableParams['_foreignKeys'] = $classParams['foreignKeys'];
          unset($classParams['foreignKeys']);
        }

        // Behaviors
        if (isset($classParams['behaviors']))
        {
          $tableParams['_behaviors'] = $classParams['behaviors'];
          unset($classParams['behaviors']);
        }
        if (isset($classParams['propel_behaviors']))
        {
          $tableParams['_propel_behaviors'] = $classParams['propel_behaviors'];
          unset($classParams['propel_behaviors']);
        }

        // Inheritance
        if (isset($classParams['inheritance']))
        {
          $tableParams['_inheritance'] = $classParams['inheritance'];
          unset($classParams['inheritance']);
        }

        // Nested sets
        if (isset($classParams['nestedSet']))
        {
          $tableParams['_nestedSet'] = $classParams['nestedSet'];
          unset($classParams['nestedSet']);
        }

        if (isset($classParams['vendor']))
        {
          $tableParams['_vendor'] = $classParams['vendor'];
          unset($classParams['vendor']);
        }

        // Table attributes
        $tableAttributes = array();
        if (isset($classParams['tableName']))
        {
          $tableName = $classParams['tableName'];
          unset($classParams['tableName']);
        }
        else
        {
          $tableName = sfInflector::underscore($className);
        }

        if (sfInflector::camelize($tableName) != $className)
        {
          $tableAttributes['phpName'] = $className;
        }

        if ($tableAttributes || $classParams)
        {
          $tableParams['_attributes'] = array_merge($tableAttributes, $classParams);
        }

        $tables[$tableName] = $tableParams;
      }
      $database = array_merge($database, $tables);
      unset($schema['classes']);
    }

    // Database behaviors
    if (isset($schema['propel_behaviors']))
    {
      $database['_propel_behaviors'] = $schema['propel_behaviors'];
      unset($schema['propel_behaviors']);
    }

    // Database attributes
    if ($schema)
    {
      $database['_attributes'] = $schema;
    }

    return array($connection_name => $database);
  }

  /**
   * Dumps schema as propel xml
   *
   * @return unknown
   */
  public function asXML()
  {
    $xml = "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n";

    $xml .= "<database name=\"$this->connection_name\"".$this->getAttributesFor($this->database).">\n";

    if (isset($this->database['_propel_behaviors']))
    {
      foreach ($this->database['_propel_behaviors'] as $name => $parameters)
      {
        $xml .= "\n  <behavior name=\"$name\"";
        if (is_array($parameters) && count($parameters))
        {
          $xml .= ">\n";
          foreach ($parameters as $key => $value)
          {
            $value = is_array($value) ? implode(', ', $value) : $this->fixXMLBoolean($value);
            $xml .= "    <parameter name=\"$key\" value=\"$value\"/>\n";
          }
          $xml .= "  </behavior>\n";
        }
        else
        {
          $xml .= "/>\n";
        }
      }
    }

    // tables
    foreach ($this->getChildren($this->database) as $tb_name => $table)
    {
      // capture nested set config for this table
      if ($isNestedSet = isset($table['_nestedSet']))
      {
        $treeConfig = $table['_nestedSet'];
        if (
          !isset($treeConfig['left'])
          ||
          !isset($treeConfig['right'])
          ||
          !isset($table[$treeConfig['left']])
          ||
          !isset($table[$treeConfig['right']])
          ||
          (isset($treeConfig['scope']) && !isset($table[$treeConfig['scope']]))
        )
        {
          throw new sfException(sprintf('Incorrect NestedSet configuration for "%s" table.', $tb_name));
        }
      }

      $xml .= "\n  <table name=\"$tb_name\"".$this->getAttributesFor($table);
      if ($isNestedSet)
      {
        $xml .= ' treeMode="NestedSet"';
      }
      if (isset($table['_behaviors']))
      {
        $xml .= sprintf(" behaviors=\"%s\"", htmlspecialchars(serialize($table['_behaviors'])), ENT_QUOTES, sfConfig::get('sf_charset'));
      }
      $xml .= ">\n";

      // behaviors
      if (isset($table['_propel_behaviors']))
      {
        foreach ($table['_propel_behaviors'] as $behavior_name => $parameters)
        {
          if ($parameters)
          {
            $xml .= "    <behavior name=\"$behavior_name\">\n";
            foreach ($parameters as $param_name => $param_value)
            {
              $param_value = is_array($param_value) ? implode(', ', $param_value) : $this->fixXMLBoolean($param_value);
              $xml .= "      <parameter name=\"$param_name\" value=\"$param_value\"/>\n";
            }
            $xml .= "    </behavior>\n";
          }
          else
          {
            $xml .= "    <behavior name=\"$behavior_name\" />\n";
          }
        }
      }

      // columns
      foreach ($this->getChildren($table) as $col_name => $column)
      {
        // inheritance
        if (
          isset($table['_inheritance'])
          &&
          isset($table['_inheritance']['column'])
          &&
          $col_name == $table['_inheritance']['column']
          &&
          isset($table['_inheritance']['classes'])
          &&
          is_array($table['_inheritance']['classes'])
        )
        {
          $column['inheritance'] = $table['_inheritance']['classes'];
          unset($table['_inheritance']);
        }

        // add nested set attributes to this column
        if ($isNestedSet && in_array($col_name, $treeConfig))
        {
          if ($col_name == $treeConfig['left'])
          {
            $column['nestedSetLeftKey'] = 'true';
          }
          elseif ($col_name == $treeConfig['right'])
          {
            $column['nestedSetRightKey'] = 'true';
          }
          elseif (isset($treeConfig['scope']) && $col_name == $treeConfig['scope'])
          {
            $column['treeScopeKey'] = 'true';
          }
        }

        $xml .= "    <column name=\"$col_name\"".$this->getAttributesForColumn($tb_name, $col_name, $column);
      }

      // indexes
      if (isset($table['_indexes']))
      {
        foreach ($table['_indexes'] as $index_name => $index)
        {
          $xml .= "    <index name=\"$index_name\">\n";
          foreach ($index as $index_column)
          {
            preg_match('/^(.+?)\(([\d]+)\)$/', $index_column, $matches);
            if (isset($matches[2]))
            {
              $xml .= "      <index-column name=\"{$matches[1]}\" size=\"{$matches[2]}\" />\n";
            }
            else
            {
              $xml .= "      <index-column name=\"$index_column\" />\n";
            }
          }
          $xml .= "    </index>\n";
        }
      }

      // uniques
      if (isset($table['_uniques']))
      {
        foreach ($table['_uniques'] as $unique_name => $index)
        {
          $xml .= "    <unique name=\"$unique_name\">\n";
          foreach ($index as $unique_column)
          {
            preg_match('/^(.+?)\(([\d]+)\)$/', $unique_column, $matches);
            if (isset($matches[2]))
            {
              $xml .= "      <unique-column name=\"{$matches[1]}\" size=\"{$matches[2]}\" />\n";
            }
            else
            {
              $xml .= "      <unique-column name=\"$unique_column\" />\n";
            }
          }
          $xml .= "    </unique>\n";
        }
      }

      // foreign-keys
      if (isset($table['_foreignKeys']))
      {
        foreach ($table['_foreignKeys'] as $fkey_name => $fkey)
        {
          if (!isset($fkey['foreignTable']))
          {
            if (
              !isset($fkey['foreignClass'])
              ||
              !$fkey['foreignTable'] = $this->findTable($fkey['foreignClass'])
            )
            {
              throw new sfException(sprintf('Unable to resolve foreign table for foreign key "%s": %s', $fkey_name, var_export($fkey, true)));
            }
          }
          unset($fkey['foreignClass']);

          $xml .= '    <foreign-key';

          // foreign key name
          if (!is_numeric($fkey_name))
          {
            $xml .= " name=\"$fkey_name\"";
          }

          // other attributes
          foreach ($fkey as $attribute_name => $attribute_value)
          {
            if (is_string($attribute_value))
            {
              $xml .= " $attribute_name=\"$attribute_value\"";
            }
          }

          $xml .= ">\n";

          // references
          if (isset($fkey['references']))
          {
            foreach ($fkey['references'] as $reference)
            {
              $xml .= "      <reference local=\"{$reference['local']}\" foreign=\"{$reference['foreign']}\" />\n";
            }
          }
          $xml .= "    </foreign-key>\n";
        }
      }

      // vendor
      if (isset($table['_vendor']))
      {
        $xml .= "    <vendor type=\"mysql\">\n";
        foreach ($table['_vendor'] as $vendor_name => $vendor_value)
        {
          $xml .= "    <parameter name=\"$vendor_name\" value=\"$vendor_value\" />\n";
        }
        $xml .= "    </vendor>\n";
      }


      $xml .= "  </table>\n";
    }
    $xml .= "\n</database>\n";

    return $xml;
  }

  /**
   * Fixes databases in yaml shorthand schema
   *
   */
  protected function fixYAMLDatabase()
  {
    if (!isset($this->database['_attributes']))
    {
      $this->database['_attributes'] = array();
    }

    // conventions for database attributes
    $this->setIfNotSet($this->database['_attributes'], 'defaultIdMethod', 'native');
    $this->setIfNotSet($this->database['_attributes'], 'package', 'lib.model');
  }

  /**
   * Fixes i18n tables in yaml shorthand schema
   *
   */
  protected function fixYAMLI18n()
  {
    foreach ($this->getTables() as $i18n_table => $columns)
    {
      $pos = strpos($i18n_table, '_i18n');

      $has_primary_key = false;
      foreach ($columns as $column => $attributes)
      {
        if (is_array($attributes) && array_key_exists('primaryKey', $attributes))
        {
          $has_primary_key = true;
        }
      }

      if ($pos > 0 && $pos == strlen($i18n_table) - 5 && !$has_primary_key)
      {
        // i18n table without primary key
        $main_table = $this->findTable(substr($i18n_table, 0, $pos));

        if ($main_table)
        {
          // set i18n attributes for main table
          $this->setIfNotSet($this->database[$main_table]['_attributes'], 'isI18N', 1);
          $this->setIfNotSet($this->database[$main_table]['_attributes'], 'i18nTable', $i18n_table);

          // set id and culture columns for i18n table
          $this->setIfNotSet($this->database[$i18n_table], 'id', array(
            'type'             => 'integer',
            'required'         => true,
            'primaryKey'       => true,
            'foreignTable'     => $main_table,
            'foreignReference' => 'id',
            'onDelete'         => 'cascade',
          ));
          $this->setIfNotSet($this->database[$i18n_table], 'culture', array(
            'isCulture'  => true,
            'type'       => 'varchar',
            'size'       => '7',
            'required'   => true,
            'primaryKey' => true,
          ));
        }
        else
        {
          throw new sfException(sprintf('Missing main table for internationalized table "%s".', $i18n_table));
        }
      }
    }
  }

  /**
   * Fixes columns in yaml shorthand schema
   *
   */
  protected function fixYAMLColumns()
  {
    foreach ($this->getTables() as $table => $columns)
    {
      $has_primary_key = false;

      foreach ($columns as $column => $attributes)
      {
        if ($attributes == null)
        {
          // conventions for null attributes
          if ($column == 'created_at' || $column == 'updated_at')
          {
            // timestamp convention
            $this->database[$table][$column]['type']= 'timestamp';
          }

          if ($column == 'id')
          {
            // primary key convention
            $this->database[$table]['id'] = array(
            'type'          => 'integer',
            'required'      => true,
            'primaryKey'    => true,
            'autoIncrement' => true
            );
            $has_primary_key = true;
          }

          $pos = strpos($column, '_id');
          if ($pos > 0 && $pos == strlen($column) - 3)
          {
            // foreign key convention
            $foreign_table = $this->findTable(substr($column, 0, $pos));
            if ($foreign_table)
            {
              $this->database[$table][$column] = array(
                'type'             => 'integer',
                'foreignTable'     => $foreign_table,
                'foreignReference' => 'id',
              );
            }
            else
            {
              throw new sfException(sprintf('Unable to resolve foreign table for column "%s".', $column));
            }
          }

        }
        else
        {
          if (!is_array($attributes))
          {
            // compact type given as single attribute
            $this->database[$table][$column] = $this->getAttributesFromCompactType($attributes);
          }
          else
          {
            if (isset($attributes['type']))
            {
              // compact type given as value of the type attribute
              $this->database[$table][$column] = array_merge($this->database[$table][$column], $this->getAttributesFromCompactType($attributes['type']));
            }
            if (isset($attributes['primaryKey']))
            {
              $has_primary_key = true;
            }
          }
        }
      }

      if (!$has_primary_key && !isset($this->database[$table]['_propel_behaviors']['concrete_inheritance']))
      {
        // convention for tables without primary key
        $this->database[$table]['id'] = array(
        'type'          => 'integer',
        'required'      => true,
        'primaryKey'    => true,
        'autoIncrement' => true
        );
      }
    }
  }

  /**
   * Returns attributes for compact type
   *
   * @param string $type
   *
   * @return array The attributes for type
   */
  protected function getAttributesFromCompactType($type)
  {
    preg_match('/varchar\(([\d]+)\)/', $type, $matches);
    if (isset($matches[1]))
    {
      return array('type' => 'varchar', 'size' => $matches[1]);
    }
    else
    {
      return array('type' => $type);
    }
  }

  /**
   * Sets entry if not set
   *
   * @param string $entry
   * @param string $key
   * @param string $value
   */
  protected function setIfNotSet(&$entry, $key, $value)
  {
    if (!isset($entry[$key]))
    {
      $entry[$key] = $value;
    }
  }

  /**
   * Find table by name
   *
   * @param string $table_name
   *
   * @return array
   */
  protected function findTable($table_name)
  {
    // find a table from a phpName or a name
    $table_match = false;
    foreach ($this->getTables() as $tb_name => $table)
    {
      if (
      ($tb_name == $table_name)
      || (isset($table['_attributes']['phpName']) &&
      (
      $table['_attributes']['phpName'] == sfInflector::camelize($table_name)
      || $table['_attributes']['phpName'] == $table_name
      )
      || (sfInflector::underscore($table_name) == $tb_name))
      )
      {
        $table_match = $tb_name;
        break;
      }
    }

    return $table_match;
  }

  /**
   * Get attributes for column
   *
   * @param string $tb_name
   * @param string $col_name
   * @param string $column
   *
   * @return array
   */
  protected function getAttributesForColumn($tb_name, $col_name, $column)
  {
    $attributes_string = '';
    if (is_array($column))
    {
      foreach ($column as $key => $value)
      {
        if (!in_array($key, array('foreignClass', 'foreignTable', 'foreignReference', 'fkPhpName', 'fkRefPhpName', 'fkSkipSql', 'onDelete', 'onUpdate', 'index', 'unique', 'sequence', 'inheritance', 'vendor')))
        {
          $attributes_string .= " $key=\"".htmlspecialchars($this->getCorrectValueFor($key, $value), ENT_QUOTES, sfConfig::get('sf_charset'))."\"";
        }
      }
      if (!isset($column['inheritance']) && !isset($column['vendor']))
      {
        $attributes_string .= " />\n";
      }
      else
      {
        if (isset($column['inheritance']))
        {
          $attributes_string .= ' inheritance="single">'."\n";
          $extended_package = isset($this->database[$tb_name]['_attributes']['package']) ? $this->database[$tb_name]['_attributes']['package'] : $this->database['_attributes']['package'];
          $extended_class   = isset($this->database[$tb_name]['_attributes']['phpName']) ? $this->database[$tb_name]['_attributes']['phpName'] : sfInflector::camelize($tb_name);

          foreach ($column['inheritance'] as $key => $class)
          {
            // each inheritance class can have its own package
            $package = null;
            if (is_array($class))
            {
              $package = isset($class['package']) ? $class['package'] : null;
              $class   = $class['phpName'];
            }

            $attributes_string .= vsprintf('      <inheritance extends="%s.%s" key="%s" class="%s"%s />', array(
              $extended_package,
              $extended_class,
              $key,
              $class,
              $package ? " package=\"$package\"" : '',
            ))."\n";
          }
        }
        if (isset($column['vendor']))
        {
          if (!isset($column['inheritance']))
          {
            $attributes_string .= '>'."\n";
          }
          $attributes_string .= '      <vendor type="mysql">'."\n";
          foreach ($column['vendor'] as $key => $class)
          {
            $attributes_string .= vsprintf('        <parameter name="%s" value="%s" />', array($key, $class))."\n";
          }
          $attributes_string .= '      </vendor>'."\n";
        }
        $attributes_string .= '    </column>'."\n";
      }
    }
    else
    {
      throw new sfException(sprintf('Incorrect settings for column "%s" of table "%s".', $col_name, $tb_name));
    }

    // conventions for foreign key attributes
    if (is_array($column) && (isset($column['foreignTable']) || isset($column['foreignClass'])))
    {
      if (isset($column['foreignTable']))
      {
        $attributes_string .= "    <foreign-key foreignTable=\"{$column['foreignTable']}\"";
      }
      else
      {
        $foreignTable = $this->findTable($column['foreignClass']);
        if (!$foreignTable)
        {
          // Let's assume that the class given is from another schema
          // We have no access to the other schema's phpNames
          // So our last guess is to try to underscore the class name
          $foreignTable = sfInflector::underscore($column['foreignClass']);
        }
        $attributes_string .= "    <foreign-key foreignTable=\"".$foreignTable."\"";
      }

      if (isset($column['onDelete']))
      {
        $attributes_string .= " onDelete=\"{$column['onDelete']}\"";
      }
      if (isset($column['onUpdate']))
      {
        $attributes_string .= " onUpdate=\"{$column['onUpdate']}\"";
      }
      if (isset($column['fkPhpName']))
      {
        $attributes_string .= " phpName=\"{$column['fkPhpName']}\"";
      }
      if (isset($column['fkRefPhpName']))
      {
        $attributes_string .= " refPhpName=\"{$column['fkRefPhpName']}\"";
      }
      if (isset($column['fkSkipSql']))
      {
        $attributes_string .= " skipSql=\"" . $this->getCorrectValueFor('fkSkipSql', $column['fkSkipSql']) . "\"";
      }
      $attributes_string .= ">\n";
      $attributes_string .= "      <reference local=\"$col_name\" foreign=\"{$column['foreignReference']}\" />\n";
      $attributes_string .= "    </foreign-key>\n";
    }

    // conventions for index and unique index attributes
    if (is_array($column) && isset($column['index']))
    {
      if ($column['index'] === 'unique')
      {
        $attributes_string .= "    <unique>\n";
        $attributes_string .= "      <unique-column name=\"$col_name\" />\n";
        $attributes_string .= "    </unique>\n";
      }
      else
      {
        $attributes_string .= "    <index>\n";
        $attributes_string .= "      <index-column name=\"$col_name\" />\n";
        $attributes_string .= "    </index>\n";
      }
    }

    // conventions for sequence name attributes
    // required for databases using sequences for auto-increment columns (e.g. PostgreSQL or Oracle)
    if (is_array($column) && isset($column['sequence']))
    {
      $attributes_string .= "    <id-method-parameter value=\"{$column['sequence']}\" />\n";
    }

    return $attributes_string;
  }

  /**
   * Returns attributes for a tag
   *
   * @param string $tag
   *
   * @return string
   */
  protected function getAttributesFor($tag)
  {
    if (!isset($tag['_attributes']))
    {
      return '';
    }
    $attributes = $tag['_attributes'];
    $attributes_string = '';
    foreach ($attributes as $key => $value)
    {
      $attributes_string .= ' '.$key.'="'.htmlspecialchars($this->getCorrectValueFor($key, $value), ENT_QUOTES, sfConfig::get('sf_charset')).'"';
    }

    return $attributes_string;
  }

  protected function getCorrectValueFor($key, $value)
  {
    $booleans = array('required', 'primaryKey', 'autoincrement', 'autoIncrement', 'isI18N', 'isCulture', 'fkSkipSql');
    if (in_array($key, $booleans))
    {
      return $value == 1 ? 'true' : 'false';
    }
    $acceptStringBoolean = array('default');
    if (in_array($key, $acceptStringBoolean))
    {
      if ($value === true)
      {
        return 'true';
      }
      if ($value === false)
      {
        return 'false';
      }
    }
    return null === $value ? 'null' : $value;
  }

  /**
   * Returns the tables for database
   *
   * @return array
   */
  public function getTables()
  {
    return $this->getChildren($this->database);
  }

  /**
   * Returns the children for a given hash
   *
   * @param string $hash
   *
   * @return array
   */
  public function getChildren($hash)
  {
    foreach ($hash as $key => $value)
    {
      // ignore special children (starting with _)
      if ($key[0] == '_')
      {
        unset($hash[$key]);
      }
    }

    return $hash;
  }

  /**
   * Loads propel xml schema
   *
   * @param string $file The path to the propel xml schema
   */
  public function loadXML($file)
  {
    $schema = simplexml_load_file($file);
    $database = array();

    // database
    list($database_name, $database_attributes) = $this->getNameAndAttributes($schema->attributes());
    if ($database_name)
    {
      $this->connection_name = $database_name;
    }
    else
    {
      throw new sfException('The database tag misses a name attribute.');
    }
    if ($database_attributes)
    {
      $database['_attributes'] = $database_attributes;
    }

    // tables
    foreach ($schema as $table)
    {
      list($table_name, $table_attributes) = $this->getNameAndAttributes($table->attributes());
      if ($table_name)
      {
        $database[$table_name] = array();
      }
      else
      {
        throw new sfException('A table tag misses the name attribute.');
      }
      if ($table_attributes)
      {
        $database[$table_name]['_attributes'] = $table_attributes;
      }

      // columns
      foreach ($table->xpath('column') as $column)
      {
        list($column_name, $column_attributes) = $this->getNameAndAttributes($column->attributes());
        if ($column_name)
        {
          $database[$table_name][$column_name] = $column_attributes;
        }
        else
        {
          throw new sfException('A column tag misses the name attribute.');
        }
      }

      // foreign-keys
      $database[$table_name]['_foreignKeys'] = array();
      foreach ($table->xpath('foreign-key') as $foreign_key)
      {
        $foreign_key_table = array();

        // foreign key attributes
        if (isset($foreign_key['foreignTable']))
        {
          $foreign_key_table['foreignTable'] = (string) $foreign_key['foreignTable'];
        }
        else
        {
          throw new sfException('A foreign key misses the foreignTable attribute.');
        }
        if (isset($foreign_key['onDelete']))
        {
          $foreign_key_table['onDelete'] = (string) $foreign_key['onDelete'];
        }
        if (isset($foreign_key['onUpdate']))
        {
          $foreign_key_table['onUpdate'] = (string) $foreign_key['onUpdate'];
        }

        // foreign key references
        $foreign_key_table['references'] = array();
        foreach ($foreign_key->xpath('reference') as $reference)
        {
          $reference_attributes = array();
          foreach ($reference->attributes() as $reference_attribute_name => $reference_attribute_value)
          {
            $reference_attributes[$reference_attribute_name] = strval($reference_attribute_value);
          }
          $foreign_key_table['references'][] = $reference_attributes;
        }

        if (isset($foreign_key['name']))
        {
          $database[$table_name]['_foreignKeys'][(string)$foreign_key['name']] = $foreign_key_table;
        }
        else
        {
          $database[$table_name]['_foreignKeys'][] = $foreign_key_table;
        }

      }
      $this->removeEmptyKey($database[$table_name], '_foreignKeys');

      // indexes
      $database[$table_name]['_indexes'] = array();
      foreach ($table->xpath('index') as $index)
      {
        $index_keys = array();
        foreach ($index->xpath('index-column') as $index_key)
        {
          $index_keys[] = strval($index_key['name']);
        }
        $database[$table_name]['_indexes'][strval($index['name'])] = $index_keys;
      }
      $this->removeEmptyKey($database[$table_name], '_indexes');

      // unique indexes
      $database[$table_name]['_uniques'] = array();
      foreach ($table->xpath('unique') as $index)
      {
        $unique_keys = array();
        foreach ($index->xpath('unique-column') as $unique_key)
        {
          $unique_keys[] = strval($unique_key['name']);
        }
        $database[$table_name]['_uniques'][strval($index['name'])] = $unique_keys;
      }
      $this->removeEmptyKey($database[$table_name], '_uniques');
    }
    $this->database = $database;

    $this->fixXML();
  }

  /**
   * Fixed xml for using short hand syntax
   *
   * @return void
   */
  public function fixXML()
  {
    $this->fixXMLForeignKeys();
    $this->fixXMLIndexes();
    // $this->fixXMLColumns();
  }

  /**
   * Fixes xml foreign keys
   *
   * @return void
   */
  protected function fixXMLForeignKeys()
  {
    foreach ($this->getTables() as $table => $columns)
    {
      if (isset($this->database[$table]['_foreignKeys']))
      {
        $foreign_keys = $this->database[$table]['_foreignKeys'];
        foreach ($foreign_keys as $foreign_key_name => $foreign_key_attributes)
        {
          // Only single foreign keys can be simplified
          if (count($foreign_key_attributes['references']) == 1)
          {
            $reference = $foreign_key_attributes['references'][0];

            // set simple foreign key
            $this->database[$table][$reference['local']]['foreignTable'] = $foreign_key_attributes['foreignTable'];
            $this->database[$table][$reference['local']]['foreignReference'] = $reference['foreign'];
            if (isset($foreign_key_attributes['onDelete']))
            {
              $this->database[$table][$reference['local']]['onDelete'] = $foreign_key_attributes['onDelete'];
            }
            if (isset($foreign_key_attributes['onUpdate']))
            {
              $this->database[$table][$reference['local']]['onUpdate'] = $foreign_key_attributes['onUpdate'];
            }

            // remove complex foreign key
            unset($this->database[$table]['_foreignKeys'][$foreign_key_name]);
          }

          $this->removeEmptyKey($this->database[$table], '_foreignKeys');
        }
      }
    }
  }

  /**
   * Fixes xml indices
   *
   * @return void
   */
  protected function fixXMLIndexes()
  {
    foreach ($this->getTables() as $table => $columns)
    {
      if (isset($this->database[$table]['_indexes']))
      {
        $indexes = $this->database[$table]['_indexes'];
        foreach ($indexes as $index => $references)
        {
          // Only single indexes can be simplified
          if (count($references) == 1 && false !== substr($index, 0, strlen($index) - 6) && array_key_exists(substr($index, 0, strlen($index) - 6), $columns))
          {
            $reference = $references[0];

            // set simple index
            $this->database[$table][$reference]['index'] = 'true';

            // remove complex index
            unset($this->database[$table]['_indexes'][$index]);
          }

          $this->removeEmptyKey($this->database[$table], '_indexes');
        }
      }
      if (isset($this->database[$table]['_uniques']))
      {
        $uniques = $this->database[$table]['_uniques'];
        foreach ($uniques as $index => $references)
        {
          // Only single unique indexes can be simplified
          if (count($references) == 1 && false !== substr($index, 0, strlen($index) - 7) && array_key_exists(substr($index, 0, strlen($index) - 7), $columns))
          {
            $reference = $references[0];

            // set simple index
            $this->database[$table][$reference]['index'] = 'unique';

            // remove complex unique index
            unset($this->database[$table]['_uniques'][$index]);
          }

          $this->removeEmptyKey($this->database[$table], '_uniques');
        }
      }
    }
  }

  /**
   * Fixes xml columns
   *
   * @return void
   */
  protected function fixXMLColumns()
  {
    foreach ($this->getTables() as $table => $columns)
    {
      foreach ($columns as $column => $attributes)
      {
        if ($column == 'id' && !array_diff($attributes, array('type' => 'integer', 'required' => 'true', 'primaryKey' => 'true', 'autoIncrement' => 'true')))
        {
          // simplify primary keys
          $this->database[$table]['id'] = null;
        }

        if (($column == 'created_at') || ($column == 'updated_at') && !array_diff($attributes, array('type' => 'timestamp')))
        {
          // simplify timestamps
          $this->database[$table][$column] = null;
        }

        $pos                 = strpos($column, '_id');
        $has_fk_name         = $pos > 0 && $pos == strlen($column) - 3;
        $is_foreign_key      = isset($attributes['type']) && $attributes['type'] == 'integer' && isset($attributes['foreignReference']) && $attributes['foreignReference'] == 'id';
        $has_foreign_table   = isset($attributes['foreignTable']) && array_key_exists($attributes['foreignTable'], $this->getTables());
        $has_other_attribute = isset($attributes['onDelete']);
        if ($has_fk_name && $has_foreign_table && $is_foreign_key && !$has_other_attribute)
        {
          // simplify foreign key
          $this->database[$table][$column] = null;
        }
      }
    }
  }

  protected function fixXMLBoolean($value)
  {
    switch (true)
    {
      case true === $value:
        return 'true';
      case false === $value:
        return 'false';
      default:
        return $value;
    }
  }

  /**
   * Dumps schema as yaml
   *
   * @return string
   */
  public function asYAML()
  {
    return sfYaml::dump(array($this->connection_name => $this->database), 3);
  }

  /**
   * Returns name and attributes from given hash
   *
   * @param string $hash
   * @param string $name_attribute
   *
   * @return array
   */
  protected function getNameAndAttributes($hash, $name_attribute = 'name')
  {
    // tag name
    $name = '';
    if (isset($hash[$name_attribute]))
    {
      $name = strval($hash[$name_attribute]);
      unset($hash[$name_attribute]);
    }

    // tag attributes
    $attributes = array();
    foreach ($hash as $attribute => $value)
    {
      $value = (string) $value;
      if (in_array($value, array('true', 'on')))
      {
        $value = true;
      }
      elseif (in_array($value, array('false', 'off')))
      {
        $value = false;
      }
      $attributes[$attribute] = $value;
    }

    return array($name, $attributes);
  }

  protected function removeEmptyKey(&$hash, $key)
  {
    if (isset($hash[$key]) && !$hash[$key])
    {
      unset($hash[$key]);
    }
  }
}
