<?php
// dblayer.php

/* Documentation :
The dbLayer provide an abstraction layer on PDO to be easier on all the CRUD
(Create, Read, Update, Delete) operations, accross all the databases engines.
To use it, extends in your code this class, and define the attributes :
- protected $table : name of the table you want to use
- protected $fields : description of all the fields in the database like :
  protected $fields = array (
    "id"=>array ("integer", "not null", "autoincrement"),
    "zone"=>array ("varchar", "255", "not null"),
    "viewname"=>array ("varchar", "255"),
    "viewclients"=>array ("varchar", "255"),
    "comment"=>array ("varchar", "1024"),
    "opendate"=>array ("datetime", "not null"),
    "closedate"=>array ("datetime"),
  );
- protected $primary = "id" ; the primary key of the table (in text). Actually
  the dbLayer abstraction don't supports primary key on multiples columns

Optionnaly, you can add the 
- protected $debug = TRUE : enable the debug on screen (NOT FOR PROD !!)
*/

/** Permit abstraction on the differents SQL databases available */
class dblayer extends PDO
{
  protected $fields = array ();
  protected $primary = null;
  protected $db = null;
  public $debug = FALSE;
  /** Return all the tables available in the database */
  function listTables ()
  {
    $driver = $this->getAttribute(PDO::ATTR_DRIVER_NAME);
    $rc = @include_once ("dbLayer".ucfirst ($driver).".php");
    if ($rc === FALSE)
      throw new Exception ("dbLayer driver $driver not available");
  }

  // TODO !!
  /** Create Table creation from $this->fields with engine abstraction
      Example in sqlite3 id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
              in MySQL   id INTEGER NOT NULL PRIMARY KEY AUTO_INCREMENT, */

  // TODO !!
  /** Create automatic creation of $fields from .schema of sqlite3/
      show create table `NomTable`; for MySQL*/ 

  /** Connection to the database engine
      See http://fr2.php.net/manual/en/pdo.construct.php for the $dsn format */
  function __construct ($dsn, $username=null, $password=null,
                        $driver_options=null)
  {
    $this->db = new PDO ($dsn, $username, $password, $driver_options);
    $this->db->setAttribute (PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
  }

  /** Create a new entry in the table. Datas must be an indexed array */
  function create ($datas)
  {
    if ($this->db === null)
      throw new Exception ("Database not connected");
    $datasOK = array ();
    // Check for missing parameters
    foreach ($this->fields as $key=>$params)
    {
      if (in_array ("autoincrement", $params))
        $datas[$key] = null;
      if (in_array ("not null", $params) && !array_key_exists ($key, $datas))
        throw new Exception ("Mandatory field '$key' not provided");
      // TODO : Check for type inconsistancies before create $datasOK
      if (array_key_exists ($key, $datas))
        $datasOK[$key] = $datas[$key];
    }

    $req = "INSERT INTO `".$this->table."` ";
    $req .= "(".implode (",", array_keys ($datasOK)).")";
    $req .= " VALUES ";
    $req .= "(:".implode (",:", array_keys ($datasOK)).")";
    if ($this->debug) echo "DEBUG : $req\n";
    $st = $this->db->prepare ($req);
    foreach ($datasOK as $key=>$val)
    {
      if ($this->debug) echo "DEBUG BIND : $key->".var_export ($val, TRUE)."\n";
      if ($val === null)
        $st->bindValue (":$key", $val, PDO::PARAM_NULL);
      elseif ($this->fields[$key][0] === "integer")
        $st->bindValue (":$key", $val, PDO::PARAM_INT);
      elseif ($this->fields[$key][0] === "varchar")
        $st->bindValue (":$key", $val, PDO::PARAM_STR);
      elseif ($this->fields[$key][0] === "datetime")
        $st->bindValue (":$key", $val, PDO::PARAM_STR);
      else
        throw new Exception ("TO BE DEVELOPPED : ".$this->fields[$key][0]);
    }

    $st->execute ();
    return $this->db->lastInsertId();
  }

  /** Read all the table or only one line defined by the primary key */
  function read ($selectkey=null)
  {
    if ($this->db === null)
      throw new Exception ("Database not connected");
    $req = "SELECT ";
    $req .= implode (",", array_keys ($this->fields));
    $req .= " FROM `".$this->table."`";
    if ($selectkey !== NULL)
      $req .= " WHERE $this->primary=:primary";

    if ($this->debug) echo "DEBUG : $req\n";
    $st = $this->db->prepare ($req);
    if ($selectkey !== NULL)
    {
      if ($this->debug) echo "DEBUG BIND : primary->".
                             var_export ($selectkey, TRUE)."\n";
      $st->bindValue (":primary", $selectkey);
    }
    $st->execute ();
    $res = array ();
    while ($d = $st->fetch (PDO::FETCH_ASSOC))
      $res[] = $d;
    return $res;
  }

  /** Update the key tuple with the provided datas */
  function update ($updatekey, $datas)
  {
    if ($this->db === null)
      throw new Exception ("Database not connected");
    $datasOK = array ();
    // Check for missing parameters
    foreach ($this->fields as $key=>$params)
    {
      // TODO : Check for type inconsistancies before create $datasOK
      if (array_key_exists ($key, $datas))
        $datasOK[$key] = $datas[$key];
    }

    $req = "UPDATE `".$this->table."` SET ";
    $i = 0;
    foreach ($datasOK as $key=>$val)
    {
      if ($i>0) $req .= ",";
      $req .= "$key=:$key";
      $i++;
    }
    $req .= " WHERE $this->primary=:primary";
    if ($this->debug) echo "DEBUG : $req\n";
    $st = $this->db->prepare ($req);
    if ($this->debug) echo "DEBUG BIND : primary->".
                           var_export ($updatekey, TRUE)."\n";
    $st->bindValue (":primary", $updatekey);
    foreach ($datasOK as $key=>$val)
    {
      if ($this->debug) echo "DEBUG BIND : $key->".var_export ($val, TRUE)."\n";
      if ($val === null)
        $st->bindValue (":$key", $val, PDO::PARAM_NULL);
      elseif ($this->fields[$key][0] === "integer")
        $st->bindValue (":$key", $val, PDO::PARAM_INT);
      elseif ($this->fields[$key][0] === "varchar")
        $st->bindValue (":$key", $val, PDO::PARAM_STR);
      elseif ($this->fields[$key][0] === "datetime")
        $st->bindValue (":$key", $val, PDO::PARAM_STR);
      else
        throw new Exception ("TO BE DEVELOPPED : ".$this->fields[$key][0]);
    }

    $st->execute ();
  }

  /** Delete a tuple identified by its primary key */
  function delete ($deletekey)
  {
    if ($this->db === null)
      throw new Exception ("Database not connected");
    $req = "DELETE FROM `".$this->table."` ";
    $req .= "WHERE $this->primary = :primary";
    $st = $this->db->prepare ($req);
    if ($this->debug) echo "DEBUG : $req\n";
    if ($this->debug) echo "DEBUG BIND : primary->".
                           var_export ($deletekey, TRUE)."\n";
    $st->bindValue (":primary", $deletekey);
    $st->execute ();
  }
}

/** POC :
error_reporting (E_ALL);
require_once  ("domframework/dbLayer.php");
class zone extends dbLayer
{
  // The database must be initialized with 
  // CREATE TABLE `dns_zones` (id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
  //                           zone VARCHAR(255) NOT NULL,
  //                           viewname VARCHAR(255),
  //                           viewclients VARCHAR(255),
  //                           comment VARCHAR(1024),
  //                           opendate DATETIME NOT NULL,
  //                           closedate DATETIME,
  //                           UNIQUE (zone,viewname)); 
  protected $table = "dns_zones";
  protected $fields = array (
    "id"=>array ("integer", "not null", "autoincrement"),
    "zone"=>array ("varchar", "255", "not null"),
    "viewname"=>array ("varchar", "255"),
    "viewclients"=>array ("varchar", "255"),
    "comment"=>array ("varchar", "1024"),
    "opendate"=>array ("datetime", "not null"),
    "closedate"=>array ("datetime"),
  );
  protected $primary = "id";
}

ini_set ("date.timezone", "Europe/Paris");
$zone = new zone ("sqlite:datas/database.db");
$last = $zone->create (array ("zone"=>"testZone", "opendate"=>date("Y-m-d H:i:s")));
//print_r ($zone->read ());
$zone->update (2040, array ("zone"=>"testZone2"));
print_r ($zone->delete ($last));
*/