<?php

  class mw_mysql{

    public $link;
    public $host;
    public $base;
    public $user;
    public $password;
    public $EXTENTION_OK;

    public function __construct($params = array()){
      $this->host = isset($params["host"]) ? $params["host"] : "localhost";
      $this->base = isset($params["base"]) ? $params["base"] : "mtweb";
      $this->user = isset($params["user"]) ? $params["user"] : "";
      $this->password = isset($params["password"]) ? $params["password"] : "";
      $this->EXTENTION_OK = function_exists("mysql_connect");
    }

    public function extention_ok(&$env){
      return $this->EXTENTION_OK;
    }

    public function authentication_required(){
      return true;
    }

    public function sgbd_name(){
      return "MySql";
    }

    public function connect($host, $base, $user, $password){
      $this->link = @mysql_connect($host, $user, $password);
      if(!$this->link) throw new Exception($this->exception_out("Impossible d'etablir une connection au serveur"));
      @mysql_query("SET NAMES 'utf8'");
      if($base){
        $connected = @mysql_select_db($base, $this->link);
        if(!$connected) throw new Exception($this->exception_out("Impossible de selectioner la base ".$base));
      }
      return true;
    }

    public function select_db($db_name){
      $this->base = $db_name;
      if(!$this->link) $this->connect($this->host, $this->base, $this->user, $this->password);
      return $this->query("USE ".$db_name);
    }

    public function desc_table($table_name){
      $sql = "SELECT * from information_schema.columns where table_name='".$table_name."'";
      $rst = $this->query($sql);
      $desc = array(
        "name" => $table_name,
        "attributs" => array()
      );
      try{
        while($v_rst = $this->fetch_assoc($rst)){
          $desc["attributs"][$v_rst["COLUMN_NAME"]] = array(
            "name" => $v_rst["COLUMN_NAME"],
            "prymary_key" => $v_rst["COLUMN_KEY"] == "PRI" ? true : false,
            "auto_increment" => $v_rst["EXTRA"] == "auto_increment" ? true : false
          );
        }
        $this->free_result($rst);
      }
      catch(Exception $e){
        throw new Exception($this->exception_out("Impossible de lire la description de la table"));
      }
      return $desc;
    }

    public function table_exists($table_name){
      if(!$this->link) $this->connect($this->host, $this->base, $this->user, $this->password);
      $EXISTS = false;
      try{
        $rst = $this->query("SHOW TABLES");
        while($v_rst = mysql_fetch_row($rst)){
          if($v_rst[0] == $table_name){
            $EXISTS = true;
            break;
          }
        }
        $this->free_result($rst);
      }
      catch(Exception $e){
        throw new Exception($this->exception_out("Impossible de savoir si la table existe"));
      }
      return $EXISTS;
    }

    public function field_exists($table_name, $field_name){
      if(!$this->link) $this->connect($this->host, $this->base, $this->user, $this->password);
      if(!($desc = $this->desc_table($table_name))){
        throw new Exception($this->exception_out("Impossible de lire la description de la table"));
      }
      $EXISTS = false;
      foreach($desc["attributs"] as $attribut_name => $attribut){
        if($field_name == $attribut_name){
          $EXISTS = true;
          break;
        }
      }
      return $EXISTS;
    }

    public function query($query_string){
      if(!$this->link) $this->connect($this->host, $this->base, $this->user, $this->password);
      $result = @mysql_query($query_string, $this->link);
      if(!$result) throw new Exception($this->exception_out("Syntaxe invalide dans une requete"));
      return $result;
    }

    public function fetch_assoc($rst){
      if($this->link){
        if($rst){
          return mysql_fetch_assoc($rst);
        }
        else throw new Exception($this->exception_out("fetch_assoc sans result handler"));
      }
      else throw new Exception($this->exception_out("fetch_assoc sans connexion"));
    }

    public function insert_id(){
      if($this->link){
        return mysql_insert_id($this->link);
      }
      else throw new Exception($this->exception_out("insert_id sans connexion"));
    }

    public function free_result($rst){
      if($this->link){
        if($rst){
          return mysql_free_result($rst);
        }
        else throw new Exception($this->exception_out("free_result sans result handler"));
      }
      else throw new Exception($this->exception_out("free_result sans connexion"));
    }

    public function close(){
      if($this->link) return mysql_close($this->link);
      return true;
    }

    public function exception_out($message){
      return "[erreur] mysql : ".$message;
    }

  }