<?php

class gmeDB
{
  const OPT_FORCE_STMT = 0x1;
  const OPT_NASSOC     = 0x4;

  public $config = array();

  private $conn = null;

  public $db_host;
  public $db_port = null;
  public $db_sock = null;
  public $db_user;
  public $db_pass;
  public $db_name;
  public $db_pconn = false;
  public $db_charset = null;

  function __construct(array $conf)
  {
    $this->config = $conf;
    foreach($this->config as $k => $v)
      $this->$k = $v;

    $this->conn = null;
  }

  function getConnection()
  {
    if(!$this->conn)
      $this->connect();
    return $this->conn;
  }

  function connect()
  {
    $this->conn = mysqli_connect(
      ($this->db_pconn ? 'p:'.$this->db_host : $this->db_host), 
       $this->db_user, 
       $this->db_pass, 
       $this->db_name, 
       $this->db_port,
       $this->db_sock
    );
    if(!$this->conn)
      throw new Exception("Could not connect to mysql server");

    if($this->db_charset !== null && !mysqli_set_charset($this->conn, $this->db_charset))
      $this->_raise("Charset setup error");
  }

  function disconnect()
  {
    if(!$this->conn)
      return;
    mysqli_close($this->conn);
    $this->conn = null;
  }

  function fetch($sql, array $args = array(), $opts = 0, &$meta = array())
  {
    if($args || ($opts & self::OPT_FORCE_STMT))
    {
      $stmt = $this->_newStatement($sql, $args);
      $res = $this->_fetchStatement($stmt, $opts, $meta);
    }
    else
      $res = $this->_fetchQuery($sql, $opts, $meta);

    return $res;
  }

  function fetchRow($sql, array $args = array(), $opts = 0, &$meta = array())
  {
    $rows = $this->fetch($sql, $args, $opts, $meta);
    if(isset($rows[0]))
      return $rows[0];
  }

  function fetchOne($sql, array $args = array(), $opts = 0)
  {
    $row = $this->fetchRow($sql, $args, $opts | self::OPT_NASSOC);
    if(!$row || !isset($row[0]))
      return NULL;
    return $row[0];
  }

  function execute($sql, array $args = array())
  {
    if($args)
      $this->_newStatement($sql, $args);
    else
      $this->_newQuery($sql);
  }

  function sanify($what)
  {
    if(is_string($what))
      return $this->escape($what);
    if(is_null($what))
      return "NULL";
    if(is_array($what))
    {
      foreach($what as $k => &$v)
        $v = $this->sanify($v);
      return $what;
    }
    return 1*$what;
  }

  function escape($what, $quote = true)
  {  
    if(is_null($what))
      return "NULL"; 
    $what = mysqli_escape_string($this->getConnection(), $what);
    return $quote ? "'" . $what . "'" : $what;
  }

  function lastInsertId()
  {
    return mysqli_insert_id($this->getConnection());
  }

  function affectedRows()
  {
    return mysqli_affected_rows($this->getConnection());
  }

  function getLastError()
  {
    return array(mysqli_errno($this->conn), mysqli_error($this->conn));
  }

  private function _newQuery($sql)
  {
    if(!$this->conn)
      $this->connect();

    if(!$result = mysqli_query($this->conn, $sql))
      $this->_raise("Query error: $sql");

    return $result;
  }
  
  private function _fetchQuery($sql, $opts = 0, &$meta = array())
  {
    $result = $this->_newQuery($sql);

    $rows = array(); 
    if($opts & self::OPT_NASSOC)
    {
      while($row = $result->fetch_row())
        $rows[] = $row;
    }
    else
    {
      while($row = $result->fetch_assoc())
        $rows[] = $row;
    }

    $result->free();
    return $rows;
  }

  private function _newStatement($sql, array $args = array())
  {
    if(!$this->conn)
      $this->connect();

    $stmt = mysqli_prepare($this->conn, $sql);
    if(!$stmt)
      $this->_raise("Stmt prepare error: $sql");

    if($args)
      $this->_bindArgs($stmt, $args);

    if(!mysqli_stmt_execute($stmt))
      $this->_raise("Stmt exec error: $sql");

    return $stmt;
  }

  private function _fetchStatement($stmt, $opts = 0, &$meta = array())
  {
    $rows = array();
    $res_meta = mysqli_stmt_result_metadata($stmt);
    $fields = array();
    $out = array();

    $fields[0] = &$stmt;
    $count = 1;

    while($field = mysqli_fetch_field($res_meta)) 
    {
      $fields[$count++] = &$out[$field->name];
      $meta[$field->name] = $field;
    }

    mysqli_stmt_store_result($stmt);
    call_user_func_array('mysqli_stmt_bind_result', $fields);
    if($opts & self::OPT_NASSOC)
    {
      while(mysqli_stmt_fetch($stmt))
      {
        $out_deref = array();
        foreach($out as $v)
          $out_deref[] = $v;
        $rows[] = $out_deref;
      } 
    }
    else
    {
      while(mysqli_stmt_fetch($stmt))
      {
        $out_deref = array();
        foreach($out as $k => $v)
          $out_deref[$k] = $v;
        $rows[] = $out_deref;
      } 
    }

    mysqli_stmt_free_result($stmt);
    mysqli_stmt_close($stmt);

    return $rows;
  }
  
  private function _bindArgs($stmt, array $args)
  {
    $types = '';
    $blob = null;
    $blob_pos = -1;
    $c = 0;
    foreach($args as $key => $arg)
    {
      if(is_string($key))
      {
        $types .= $key;

        //NOTE: supporting exactly one blob special case
        if($key === 'b')
        {
          $blob = &$args[$key];
          $blob_pos = $c;
        }
      }
      else
      {
        if(is_string($arg) || is_null($arg))
          $types .= 's';
        else if(is_int($arg) || is_bool($arg))
          $types .= 'i';
        else if(is_float($arg))
          $types .= 'd';
        else 
          throw new Exception("Unknown type of variable '" . serialize($arg) . "'");
      }
      ++$c;
    }

    $res = call_user_func_array('mysqli_stmt_bind_param', array_merge(array($stmt, $types), $this->_refValues($args)));
    if(!$res)
      $this->_raise("Stmt bind error");

    if($blob !== null)
    {
      if(!mysqli_stmt_send_long_data($stmt, $blob_pos, $blob))
        $this->_raise("Stmt blob send error");
    }
  }

  private function _refValues(array $arr)
  {
    $refs = array(); 
    foreach($arr as $key => $value) 
      $refs[$key] = &$arr[$key]; 
    return $refs; 
  }

  private function _raise($err)
  {
    throw new Exception($err . ", MySQLi error:" . mysqli_error($this->conn));
  }
}

function gme_db_insert_or_update_sql_ex($table, array $fields, array $rows)
{
  $update = array();
  foreach($fields as $field)
    $update[] = $field.'=VALUES('.$field.')';

  $sql = '';
  $sql .= 'INSERT INTO '.$table.' ('.implode(',', $fields).') VALUES ';

  foreach($rows as $row)
    $sql .= '('.implode(',', $row).'),';
  $sql = rtrim($sql, ',');
  
  $sql .= 'ON DUPLICATE KEY UPDATE '.implode(',', $update);

  return $sql;
}

function gme_db_insert_or_update_sql($table, array $row)
{
  return gme_db_insert_or_update_sql_ex($table, array_keys($row), array($row));
}

function gme_db_insert_sql_ex($table, array $fields, array $rows, $delayed = false, $replace = false)
{
  $sql = '';
  $sql .= $replace ? 'REPLACE ' : 'INSERT ';
  $sql .= $delayed ? ' DELAYED ' : '';
  $sql .= 'INTO '.$table.' ('.implode(',', $fields).') VALUES ';

  foreach($rows as $row)
    $sql .= '('.implode(',', $row).'),';
  $sql = rtrim($sql, ',');

  return $sql;
}

function gme_db_insert_sql($table, array $row, $delayed = false)
{
  return gme_db_insert_sql_ex($table, array_keys($row), array($row), $delayed);
}

function gme_db_replace_sql_ex($table, array $fields, array $rows, $delayed = false)
{
  return gme_db_insert_sql_ex($table, $fields, $rows, $delayed, true/*replace*/);
}

function gme_db_replace_sql($table, array $row, $delayed = false)
{
  return gme_db_insert_sql_ex($table, array_keys($row), array($row), $delayed, true/*replace*/);
}