<?php

/**
 * Created by PhpStorm.
 * User: MisterX
 * Date: 24.05.2016
 * Time: 14:00
 */
class Bin_Db_Builder
{
	const SELECT = 0;
	const DELETE = 1;
	const UPDATE = 2;
	const INSERT = 3;

	/*
     * The builder states.
     */
	const STATE_DIRTY = 0;
	const STATE_CLEAN = 1;

	/**
	 * @var array The array of SQL parts collected.
	 */
	private $sqlParts = array(
		'select'  => array(),
		'from'    => array(),
		'join'    => array(),
		'set'     => array(),
		'where'   => null,
		'groupBy' => array(),
		'having'  => null,
		'orderBy' => array(),
		'values'  => array(),
	);

	protected $connection;

	/**
	 * The complete SQL string for this query.
	 *
	 * @var string
	 */
	private $sql;

	/**
	 * The type of query this is. Can be select, update or delete.
	 *
	 * @var integer
	 */
	private $type = self::SELECT;

	/**
	 * The state of the query object. Can be dirty or clean.
	 *
	 * @var integer
	 */
	private $state = self::STATE_CLEAN;

	public function __construct(Bin_Db $connection)
	{
		$this->connection = $connection;
	}

	public function getSQL()
	{
		if ($this->sql !== null && $this->state === self::STATE_CLEAN) {
			return $this->sql;
		}
		switch ($this->type) {
			case self::INSERT:
				$sql = $this->getSQLForInsert();
				break;
//			case self::DELETE:
//				$sql = $this->getSQLForDelete();
//				break;
//			case self::UPDATE:
//				$sql = $this->getSQLForUpdate();
//				break;
//			case self::SELECT:
//			default:
//				$sql = $this->getSQLForSelect();
//				break;
		}
		$this->state = self::STATE_CLEAN;
		$this->sql = $sql;
		return $sql;
	}

	/**
	 * Either appends to or replaces a single, generic query part.
	 *
	 * The available parts are: 'select', 'from', 'set', 'where',
	 * 'groupBy', 'having' and 'orderBy'.
	 *
	 * @param string  $sqlPartName
	 * @param string  $sqlPart
	 * @param boolean $append
	 *
	 * @return self
	 */
	protected function add($sqlPartName, $sqlPart, $append = false)
	{
		$isArray = is_array($sqlPart);
		$isMultiple = is_array($this->sqlParts[$sqlPartName]);
		if ($isMultiple && !$isArray) {
			$sqlPart = array($sqlPart);
		}
		$this->state = self::STATE_DIRTY;
		if ($append) {
			if ($sqlPartName == "orderBy" || $sqlPartName == "groupBy" || $sqlPartName == "select" || $sqlPartName == "set") {
				foreach ($sqlPart as $part) {
					$this->sqlParts[$sqlPartName][] = $part;
				}
			} elseif ($isArray && is_array($sqlPart[key($sqlPart)])) {
				$key = key($sqlPart);
				$this->sqlParts[$sqlPartName][$key][] = $sqlPart[$key];
			} elseif ($isMultiple) {
				$this->sqlParts[$sqlPartName][] = $sqlPart;
			} else {
				$this->sqlParts[$sqlPartName] = $sqlPart;
			}
			return $this;
		}
		$this->sqlParts[$sqlPartName] = $sqlPart;
		return $this;
	}

	/**
	 * Turns the query being built into an insert query that inserts into
	 * a certain table
	 * @param string $table The table into which the rows should be inserted.
	 * @return $this
	 */
	public function insert($table = null)
	{
		$this->type = self::INSERT;
		if ( ! $table) {
			return $this;
		}
		return $this->add('from', array(
			'table' => $table
		));
	}

	/**
	 * Specifies values for an insert query indexed by column names.
	 * @param array $values The values to specify for the insert query indexed by column names.
	 * @return $this
	 */
	public function values(array $values)
	{
		return $this->add('values', $values);
	}


	/**
	 * Sets a value for a column in an insert query.
	 * @param string $column The column into which the value should be inserted.
	 * @param string $value  The value that should be inserted into the column.
	 * @return $this
	 */
	public function setValue($column, $value)
	{
		$this->sqlParts['values'][$column] = $value;
		return $this;
	}

	public function from($table, $alias = null)
	{
		return $this->add('from', array(
			'table' => $table,
			'alias' => $alias
		), true);
	}

	/**
	 * Converts this instance into an INSERT string in SQL.
	 *
	 * @return string
	 */
	private function getSQLForInsert()
	{
		$table = $this->connection->escapeIdentifier($this->sqlParts['from']['table']);
		$fields = array_map(array($this->connection,'escapeIdentifier'),array_keys($this->sqlParts['values']));
		$values = array_map(array($this->connection,'escapeValue'),$this->sqlParts['values']);
		return 'INSERT INTO ' . $table .' (' . implode(', ', $fields) . ') VALUES (' . implode(', ', $values) . ')';
	}

	public function execute() {
		return $this->connection->query($this->getSQL());
	}

}