<?php

  class mw_pdo_sqlite{

    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"] : "content/data/sqlite";
      $this->base = isset($params["base"]) ? $params["base"] : "mtweb.db";
      $this->user = isset($params["user"]) ? $params["user"] : "";
      $this->password = isset($params["password"]) ? $params["password"] : "";
      $this->EXTENTION_OK = (extension_loaded("pdo") && extension_loaded("pdo_sqlite"));
    }

    public function get_link(){
      return $this->link;
    }

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

    public function authentication_required(){
      return false;
    }

    public function sgbd_name(){
      return "PDO SQLite";
    }

    public function connect($host, $base, $user, $password){
      if($host) $host .= substr($host, -1) != "/" ? "/" : "";
      try{
        $this->link = null;
        $this->link = new PDO("sqlite:".$host.$base);
        $this->link->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
        $this->link->query("PRAGMA encoding = 'UTF-8'");
      }
      catch(PDOException $e){
        throw new Exception($this->exception_out("Impossible d'etablir une connection au serveur"));
      }
      return true;
    }

    public function select_db($db_name){
      $this->base = $db_name;
      return $this->connect($this->host, $this->base, $this->user, $this->password);
    }

    public function desc_table($table_name){
      if(strpos($table_name, "'") !== false){
        throw new Exception($this->exception_out("nom de table avec un simple quote"));
      }
      $desc = array(
        "name" => $table_name,
        "attributs" => array()
      );
      $sql = "PRAGMA table_info(".$table_name.")";
      try{
        $rst = $this->query($sql);
        while($v_rst = $this->fetch_assoc($rst)){
          $desc["attributs"][$v_rst["name"]] = array(
            "name" => $v_rst["name"],
            "prymary_key" => isset($v_rst["pk"]) && $v_rst["pk"] ? true : false
          );
        }
        $this->free_result($rst);
      }
      catch(Exception $e){
        throw new Exception($this->exception_out("impossible de lire les champs de la table ".$table_name));
      }
      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 = $this->query("SELECT name FROM sqlite_master WHERE type='table'");
        while($v_rst = $rst->fetch()){
          if($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, $this->password);
      if(!($result = $this->link->query($query_string))){
        throw new Exception($this->exception_out("Syntaxe invalide dans une requete"));
      }
      return $result;
    }

    public function fetch_assoc($rst){
      if(!$this->link){
        throw new Exception($this->exception_out("fetch_assoc sans connexion"));
      }
      if(!$rst){
        throw new Exception($this->exception_out("fetch_assoc sans result handler"));
      }
      try{
        $tuple = $rst->fetch(PDO::FETCH_ASSOC);
      }
      catch(Exception $e){
        throw new Exception($this->exception_out("erreur fetch_assoc"));
      }
      return $tuple;
    }

    public function insert_id(){
      if(!$this->link){
        throw new Exception($this->exception_out("insert_id sans connexion"));
      }
      try{
        $id = $this->link->lastInsertId();
      }
      catch(Exception $e){
        throw new Exception($this->exception_out("erreur insert_id"));
      }
      return $id;
    }

    public function free_result($rst){
      if(!$this->link){
        throw new Exception($this->exception_out("free_result sans connexion"));
      }
      if(!$rst){
        throw new Exception($this->exception_out("free_result sans result handler"));
      }
      try{
        $rst->closeCursor();
        $rst = null;
      }
      catch(Exception $e){
        throw new Exception($this->exception_out("erreur free_result"));
      }
      return true;
    }

    public function close(){
      $this->link = null;
      return true;
    }

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

  }