<?php
class DB {
    public function __construct() {
        $dbdriver = 'mysql';
        $dbhost = Config::get('mysql.host');
        $dbuser = Config::get('mysql.username');
        $dbpass = Config::get('mysql.password');
        $dbname = Config::get('mysql.db');

        # $sqlitedb = $this->config['sqlitedb'];

        $options = [
            PDO::ATTR_PERSISTENT => true,
            PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION
        ];

        try {
            switch($dbdriver) {
                case 'sqlite':
                    $conn = "sqlite:{$sqlitedb}";
                    break;
                case 'mysql':
                    $conn = "mysql:host={$dbhost};dbname={$dbname}";
                    break;
                default:
                    echo "Unsuportted DB Driver! Check the configuration.";
                    exit(1);
            }

            $this->db = new PDO($conn, $dbuser, $dbpass, $options);

        } catch(PDOException $e) {
            echo $e->getMessage(); exit(1);
        }
    }

    public function run($sql, $bind=array()) {
        $sql = trim($sql);

        try {

            $result = $this->db->prepare($sql);
            $result->execute($bind);
            return $result;

        } catch (PDOException $e) {
            echo $e->getMessage();
            exit(1);
        }
    }

    public function create($table, $data) {
        $fields = $this->filter($table, $data);

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

        $bind = array();
        foreach($fields as $field)
            $bind[":$field"] = $data[$field];

        $result = $this->run($sql, $bind);
        return $this->db->lastInsertId();
    }

    public function read($table, $where="", $bind=array(), $fields="*") {
        $sql = "SELECT " . $fields . " FROM " . $table;
        if(!empty($where))
            $sql .= " WHERE " . $where;
        $sql .= ";";

        $result = $this->run($sql, $bind);
        $result->setFetchMode(PDO::FETCH_ASSOC);

        $rows = array();
        while($row = $result->fetch()) {
            $rows[] = $row;
        }

        return $rows;
    }

    public function update($table, $data, $where, $bind=array()) {
        $fields = $this->filter($table, $data);
        $fieldSize = sizeof($fields);

        $sql = "UPDATE " . $table . " SET ";
        for($f = 0; $f < $fieldSize; ++$f) {
            if($f > 0)
                $sql .= ", ";
            $sql .= $fields[$f] . " = :update_" . $fields[$f];
        }
        $sql .= " WHERE " . $where . ";";

        foreach($fields as $field)
            $bind[":update_$field"] = $data[$field];

        $result = $this->run($sql, $bind);
        return $result->rowCount();
    }

    function delete($table, $where, $bind="") {
        $sql = "DELETE FROM " . $table . " WHERE " . $where . ";";
        $result = $this->run($sql, $bind);
        return $result->rowCount();
    }

    private function filter($table, $data) {
        $driver = $this->config['dbdriver'];

        if($driver == 'sqlite') {
            $sql = "PRAGMA table_info('" . $table . "');";
            $key = "name";
        } elseif($driver == 'mysql') {
            $sql = "DESCRIBE " . $table . ";";
            $key = "Field";
        } else {
            $sql = "SELECT column_name FROM information_schema.columns WHERE table_name = '" . $table . "';";
            $key = "column_name";
        }

        if(false !== ($list = $this->run($sql))) {
            $fields = array();
            foreach($list as $record)
                $fields[] = $record[$key];
            return array_values(array_intersect($fields, array_keys($data)));
        }

        return array();
    }
}