<?php
/**
 * 从数据库操作类.
 *
 * [WeEngine System] Copyright (c) 2014 W7.CC
 */
defined('IN_IA') or exit('Access Denied');
load()->classs('db');

class SlaveDb extends DB {
	private $weight;
	private $slavequery = 0;
	private $slaveid = null;

	public function prepare($sql) {
		$this->init_connect($sql);

		return parent::prepare($sql);
	}

	public function query($sql, $params = array()) {
		$starttime = microtime();
		if (!empty($params)) {
			return parent::query($sql, $params);
		}
		$this->init_connect($sql);
		$result = $this->pdo->exec($sql);
		if (PDO_DEBUG) {
			$info = array();
			$info['sql'] = $sql;
			$info['error'] = $this->pdo->errorInfo();
			$this->debug(false, $info);
		}

		return $result;
	}

	public function slave_connect() {
		$this->slave_choose();
		if ($this->slaveid) {
			if (!isset($this->link[$this->slaveid])) {
				$this->connect($this->slaveid);
			}
			++$this->slavequery ;
			$this->pdo = $this->link[$this->slaveid];
		}

		return true;
	}

	protected function slave_choose() {
		if (!isset($this->weight)) {
			foreach ($this->cfg['slave'] as $key => $value) {
				$this->weight .= str_repeat($key, 1 + intval($value['weight']));
			}
		}
		$sid = $this->weight[mt_rand(0, strlen($this->weight) - 1)];
		$this->slaveid = 'slave_' . $sid;
		if (!isset($this->cfg[$this->slaveid])) {
			$this->cfg[$this->slaveid] = $this->cfg['slave'][$sid];
		}
	}

	public function init_connect($sql) {
		if (!(true == $this->cfg['slave_status'] && !empty($this->cfg['slave']))) {
			$this->master_connect();
		} else {
			$sql = trim($sql);
			$sql_lower = strtolower($sql);
			$slave_except = false;
			if (!strexists($sql_lower, 'where ')) {
				$tablename = substr($sql_lower, strpos($sql_lower, 'from ') + 5);
			} else {
				$tablename = substr($sql_lower, strpos($sql_lower, 'from ') + 5, strpos($sql_lower, ' where') - strpos($sql_lower, 'from ') - 5);
			}
			$tablename = trim($tablename, '`');
			$tablename = str_replace($this->tablepre, '', $tablename);
			if (!empty($this->cfg['common']['slave_except_table']) && in_array(strtolower($tablename), $this->cfg['common']['slave_except_table'])) {
				$slave_except = true;
			}
			if (!(!$slave_except && 'SELECT' === strtoupper(substr($sql, 0, 6)) && $this->slave_connect())) {
				$this->master_connect();
			}
		}

		return true;
	}

	public function master_connect() {
		if (!isset($this->link['master'])) {
			$this->connect('master');
		}
		$this->pdo = $this->link['master'];
	}

	public function insertid() {
		$this->master_connect();

		return parent::insertid();
	}

	public function begin() {
		$this->master_connect();

		return parent::begin();
	}

	public function commit() {
		$this->master_connect();

		return parent::commit();
	}

	public function rollback() {
		$this->master_connect();

		return parent::rollback();
	}
}
