<?php

class Query {
    protected $db;
    protected $table;
    protected $join = array();
    protected $where = array();
    protected $order = array();
    protected $limit;
    protected $offset;
    protected $values = array();

    public function __construct($table)
    {
        $this->db = DB::db();
        $this->table = $table;
    }

    public function select($cols = '*', $alias = null)
    {
        $sql = "SELECT {$cols} FROM " .
            $this->table . ($alias ? " AS $alias" : "") .
            $this->getJoin() .
            $this->getWhere() .
            $this->getOrder() .
            $this->getLimit();
        // print dump($this);
        $stmt = $this->db->prepare($sql);
        $stmt->execute($this->values);
        return $stmt;
    }

    public function row($cols = '*', $alias = null)
    {
        $stmt = $this->select($cols, $alias);
        return $stmt->fetch(PDO::FETCH_ASSOC);
    }

    public function rows($cols = '*', $alias = null)
    {
        $stmt = $this->select($cols, $alias);
        return $stmt->fetchAll(PDO::FETCH_ASSOC);
    }

    public function one($field, $colnum = 0)
    {
        $stmt = $this->select($field);
        return $stmt->fetchColumn($colnum);
    }

    public function count($field = '*')
    {
        $stmt = $this->select("COUNT($field)");
        return $stmt->fetchColumn($colnum);
    }

    public function insert($row)
    {
        $row = (array) $row;
        $sql = 'INSERT INTO ' . $this->table;
        $values = array_values($row);

        if ($values != $row) {
            $sql .= ' (' . join(',', array_keys($row)) . ')';
        }

        $sql .= ' VALUES(' . rtrim(str_repeat('?,', count($row)), ',') . ')';
        $stmt = $this->db->prepare($sql);
        $stmt->execute($values);
        return $this->db->lastInsertId();
    }

    public function update($data)
    {
        $data = (array) $data;
        $sql = "UPDATE {$this->table} SET ";
        $parts = array();

        foreach (array_keys($data) as $v) {
            $parts[] = "$v=?";
        }

        $sql .= implode(',', $parts) .
            $this->getWhere();
        $values = array_merge(array_values($data), $this->values);
        $stmt = $this->db->prepare($sql);
        $stmt->execute($values);
        return $stmt->rowCount();
    }

    public static function delete()
    {
        $sql = 'DELETE FROM ' .
            $this->table .
            $this->getWhere();
        $stmt = $this->db->prepare($sql);
        $stmt->execute($this->values);
        return $stmt->rowCount();
    }

    public function join($table, $alias, $field1, $field2, $type = null) {
        $this->join[] = ($type ? "$type " : "") . "JOIN $table AS $alias ON $field1=$field2";
        return $this;
    }

    public function where($field, $val, $op = '=')
    {
        $this->where[] = "$field $op ?";
        $this->values[] = $val;
        return $this;
    }

    public function order($field, $type = null)
    {
        $this->order[] = $field . ($type ? " $type" : "");
        return $this;
    }

    public function limit($limit, $offset = null)
    {
        $this->limit = $limit;
        $this->offset = $offset;
        return $this;
    }

    public function page($page, $per_page)
    {
        $page = (int) $page;
        $per_page = (int) $per_page;
        $offset = $per_page * $page - $per_page;
        $this->limit($per_page, $offset);
        return $this;
    }

    protected function getJoin()
    {
        return count($this->join) ? ' ' . implode(' ', $this->join) : '';
    }

    protected function getWhere()
    {
        return count($this->where) ? ' WHERE ' . implode(' AND ', $this->where) : '';
    }

    protected function getOrder()
    {
        return count($this->order) ? ' ORDER BY ' . implode(',', $this->order) : '';
    }

    protected function getLimit()
    {
        $l = (int) $this->limit;
        $o = (int) $this->offset;
        return $l || $o ? " LIMIT " . ($o ? "$o, " : "") . $l : "";
    }
}