<?php

namespace Driver\SQL;

abstract class SQL {

  protected $lastError;
  protected $connection;
  protected $connectionData;
  protected $lastInsertId;

  public function __construct($connectionData) {
    $this->connection = NULL;
    $this->lastError = 'Not connected';
    $this->connectionData = $connectionData;
    $this->lastInsertId = 0;
  }

  public function isConnected() {
    return !is_null($this->connection);
  }

  public function getLastError() {
    return trim($this->lastError);
  }

  public function createTable($tableName) {
    return new Query\CreateTable($this, $tableName);
  }

  public function insert($tableName, $columns=array()) {
    return new Query\Insert($this, $tableName, $columns);
  }

  public function select(...$columNames) {
    return new Query\Select($this, $columNames);
  }

  public function truncate($table) {
    return new Query\Truncate($this, $table);
  }

  public function delete($table) {
    return new Query\Delete($this, $table);
  }

  public function update($table) {
    return new Query\Update($this, $table);
  }

  // ####################
  // ### ABSTRACT METHODS
  // ####################

  // Misc
  public abstract function checkRequirements();
  public abstract function getDriverName();

  // Connection Managment
  public abstract function connect();
  public abstract function disconnect();

  // Querybuilder
  public abstract function executeCreateTable($query);
  public abstract function executeInsert($query);
  public abstract function executeSelect($query);
  public abstract function executeDelete($query);
  public abstract function executeTruncate($query);
  public abstract function executeUpdate($query);
  protected abstract function getColumnDefinition($column);
  protected abstract function getConstraintDefinition($constraint);
  protected abstract function getValueDefinition($val);
  protected abstract function addValue($val, &$params);

  // Special Keywords and functions
  public abstract function currentTimestamp();

  // Statements
  protected abstract function execute($query, $values=NULL, $returnValues=false);

  protected function buildCondition($condition, &$params) {
    if ($condition instanceof \Driver\SQL\Condition\CondOr) {
      $conditions = array();
      foreach($condition->getConditions() as $cond) {
        $conditions[] = $this->buildCondition($cond, $params);
      }
      return "(" . implode(" OR ", $conditions) . ")";
    } else if ($condition instanceof \Driver\SQL\Condition\Compare) {
      $column = $condition->getColumn();
      $value = $condition->getValue();
      $operator = $condition->getOperator();
      return $column . $operator . $this->addValue($value, $params);
    } else if ($condition instanceof \Driver\SQL\Condition\CondBool) {
      return $condition->getValue();
    } else if (is_array($condition)) {
      if (count($condition) == 1) {
        return $this->buildCondition($condition[0], $params);
      } else {
        $conditions = array();
        foreach($condition as $cond) {
          $conditions[] = $this->buildCondition($cond, $params);
        }
        return implode(" AND ", $conditions);
      }
    }
  }

  public function setLastError($str) {
    $this->lastError = $str;
  }

  public function getLastInsertId() {
    return $this->lastInsertId;
  }

  public function close() {
    $this->disconnect();
    $this->connection = NULL;
  }

  public static function createConnection($connectionData) {
    $type = $connectionData->getProperty("type");
    if ($type === "mysql") {
      $sql = new MySQL($connectionData);
    } else if ($type === "postgres") {
      $sql = new PostgreSQL($connectionData);
    /*} else if ($type === "oracle") {
      // $sql = new OracleSQL($connectionData);
    */
    } else {
      return "Unknown database type";
    }

    if ($sql->checkRequirements()) {
      $sql->connect();
    }

    return $sql;
  }
}

?>