<?php
namespace app\controller\manager;

use think\facade\{Db, Config, Env};
use app\model\{Log as MLog};
use app\service\Tool;

class Backup extends Base
{
    /**
     * 因受mysql 配置参数net_buffer_length和max_allowed_packet大小的限制，因此insert语句改为单条插入
     * show VARIABLES like "%net_buffer_length%" 默认单条sql语句长度16k 
     * show VARIABLES like "%max_allowed_packet%" 默认单个sql文件最大容量
     * sql 文件注释 -- + 空格之后填写注释内容
     * 因根目录文件夹权限限制，因此需要手动创建backup/data目录并赋予权限（www用户组）
     */
    public function back()
    {
        ini_set('max_execution_time', 0);
        ini_set("memory_limit",-1);
        set_time_limit(0);

        $path = Config::get('filesystem.disks.backup.root') . '/';
        $dataBase = Env::get('database.database');
        // 不要使用单引号，双引号中的变量可以解析，单引号就是绝对的字符串
        $eol = "\r\n";
        $eolB = "\r\n\r\n";
        $info = '-- ------------------------------'.$eol;
        $info .= '-- 日期： '.date('Y-m-d H:i:s',time()).$eol;
        $info .= '-- MySQL --Database - '.$dataBase.$eol;
        $info .= '-- ------------------------------'.$eol;

        $info .= 'CREATE DATABASE IF NOT EXISTS `'.$dataBase.'` DEFAULT CHARACTER SET "utf8mb4" COLLATE "utf8mb4_general_ci";'.$eolB;
        $info .= 'USE `'.$dataBase.'`;'.$eol;

        if(is_dir($path)) {
            if(!is_writable($path)) {
                chmod($path, 0755);
            }
        } else {
            mkdir($path, 0755, true);
        }
        $fileName = $path.$dataBase.'_'.date('YmdHis',time()).'.sql';
        if(file_exists($fileName)) {
            @unlink($fileName);
        }
        // 以追加的方式写入
        file_put_contents($fileName, $info, FILE_APPEND);
        $tables = Db::query('show tables');
        foreach ($tables as $table) {
            // 表结构
            $tableName = $table['Tables_in_'.$dataBase];
            $sqlTable = 'SHOW CREATE TABLE '.$tableName;
            $res = Db::query($sqlTable);
            $infoTable = '-- ------------------------------'.$eol;
            $infoTable .= '-- Table structure for `'.$tableName.'`'.$eol;
            $infoTable .= '-- ------------------------------'.$eolB;
            $infoTable .= 'DROP TABLE IF EXISTS `'.$tableName.'`;'.$eolB;
            $infoTable .= $res[0]['Create Table'].';'.$eolB;
            // 表数据
            $infoTable .= '-- ------------------------------'.$eol;
            $infoTable .= '-- Data for the table `'.$tableName.'`'.$eol;
            $infoTable .= '-- ------------------------------'.$eolB;
            file_put_contents($fileName, $infoTable, FILE_APPEND);

            $sqlData = 'select * from '.$tableName;
            $data = Db::query($sqlData);
            $count = count($data);
            if ($count > 0) {
                $dataStr = 'INSERT INTO `'.$tableName.'` VALUE ';
                foreach ($data as $k => $item) {
                    $valStr = '(';
                    foreach ($item as $val) {
                        // 字符串转义
                        $val = addslashes($val);
                        $valStr .= '"'.$val.'", ';
                    }
                    // 去除最后的逗号和空格
                    $valStr = substr($valStr,0,strlen($valStr)-2);
                    // 限制单条sql语句在16K以内（可根据mysql配置条件进行调整）
                    $sqlLength = strlen($dataStr) + strlen($valStr);
                    if($sqlLength >= (1024 * 16 - 10)) {
                        $dataStr .= $valStr.');'.$eol;
                        file_put_contents($fileName, $dataStr, FILE_APPEND);
                        // 提前分段写入后需重置数据语句
                        if ($k <= ($count-1)) {
                            $dataStr = 'INSERT INTO `'.$tableName.'` VALUE ';
                        } else {
                            $dataStr = '';
                        }
                    } else {
                        if ($k < ($count-1)) {
                            $dataStr .= $valStr.'),'.$eol;
                        } else {
                            $dataStr .= $valStr.');'.$eolB;
                        }
                    }
                }
                file_put_contents($fileName, $dataStr, FILE_APPEND);
            }
        }
        clearstatcache();

        $backups = explode('/', $fileName);
        $backupName =  $backups[count($backups)-1];
        $src = Config::get('filesystem.disks.backup.url') . '/';
        return $this->json(0, '备份成功：' . $src . $backupName);
    }


    public function index()
    {
        $path = Config::get('filesystem.disks.backup.root') . '/';
        $src = Config::get('filesystem.disks.backup.url') . '/';
        $items = [];
        if(is_dir($path)) {
            if(!is_readable($path)) {
                chmod($path,0755);
            }
            $files = scandir($path);
            foreach ($files as $file) {
                if($file != '.' && $file != '..') {
                    $ext = substr($file, -4);
                    if ($ext == '.sql') {
                        $creatTime = substr($file, -18, 14);
                        $items[] = [
                            'file' => $file,
                            'path' => $src . $file,
                            'time' =>is_numeric($creatTime) ? date('Y-m-d H:i:s', strtotime($creatTime)) : '',
                        ];
                    }
                }
            }
        }
        clearstatcache();

        $this->data['items'] = $items;
        $this->data['backupPath'] = str_replace('\\','/', $path);
        return $this->view();
    }
    
    public function del()
    {
        if (request()->isPost()) {
            $filePath = input('post.id');
            Tool::delFile($filePath);
            MLog::write('backup', 'del', '删除了备份数据文件，文件路径为：' . $filePath);
            return $this->json();
        } else {
            return $this->json(1, '非法请求');
        }
    }
}