<?php

require_once 'DBSchema/Generic.php';

class MTrackDBSchema_SQLite extends MTrackDBSchema_Generic {

  function determineVersion() {
    /* older versions did not have a schema version table, so we dance
     * around a little bit, but only for sqlite, as those older versions
     * didn't support other databases */
    try {
      $q = $this->db->query('select version from mtrack_schema');
      if ($q) {
        foreach ($q as $row) {
          return $row[0];
        }
      }
    } catch (Exception $e) {
    }

    /* do we have any tables at all? if we do, we treat that as schema
     * version 0 */
    foreach ($this->db->query('select count(*) from sqlite_master') as $row) {
      if ($row[0] > 0) {
        $this->db->exec(
          'create table mtrack_schema (version integer not null)');
        return 0;
      }
    }
    return null;
  }

  var $typemap = array(
    'autoinc' => 'INTEGER PRIMARY KEY AUTOINCREMENT',
    'longtext' => 'text'
  );

  function createTable(MTrackDBSchema_Table $table)
  {
    parent::createTable($table);
  }

  function alterTable(MTrackDBSchema_Table $from, MTrackDBSchema_Table $to)
  {
    $tname = $from->name . '_' . uniqid();

    $sql = array();
    foreach ($to->fields as $f) {
      if ($f->type == 'autoinc') {
        $pri_key = $f->name;
      }
      $str = $this->computeFieldCreate($f);
      $sql[] = $str;
    }

    $sql = "CREATE TEMPORARY TABLE $tname (\n" .
      join(",\n", $sql) .
      ")\n";

    $this->db->exec($sql);

    /* copy old data into this table */
    $sql = "INSERT INTO $tname (";
    $new_names = array();
    $old_names = array();
    foreach ($from->fields as $f) {
        
        if (!isset($to->fields[$f->name])) {
            // to_field does not exist in new schema.
            // look for it.
            foreach( $to->fields as $tf) {
                if (!empty($tf->oldname) && $tf->oldname == $f->name) {
                    $new_names[] = $f->name;
                    $old_names[] = $f->oldname;
                    break;
                }
            }
            continue;
        }
        $new_names[] = $f->name;
        $old_names[] = $f->name;
    }
    $sql .= join(', ', $new_names);
    $sql .= ") SELECT " . join(', ', $names) . " from $from->name";

    #echo "$sql\n";
    $this->db->exec($sql);

    $this->db->exec("DROP TABLE $from->name");
    $this->createTable($to);
    $sql = "INSERT INTO $from->name (";
    $names = array();
    foreach ($from->fields as $f) {
      if (!isset($to->fields[$f->name])) continue;
      $names[] = $f->name;
    }
    $sql .= join(', ', $names);
    $sql .= ") SELECT " . join(', ', $names) . " from $tname";
    #echo "$sql\n";
    $this->db->exec($sql);
    $this->db->exec("DROP TABLE $tname");
  }


}