downloadMethod

let koaRequest = require('koa-request')
let _ = require('lodash')
let qs = require('qs')
let fs = require('fs')
let path = require('path');
let mime = require('mime');
let parse = require('co-body')
let util = require('./util')
const COOKIE = require('../config/config').cookie

// 下载相关
module.exports = {
    /*
     * @param
     * opt{
     *   type {String}
     *   replacement {String}
     *   callback {Function}
     * }
     */
     requestAndWrite: function(opt) {
        return function *(next) {
            const ctx = this

            let XLSX = require('xlsx')
            let requestParam = this.request.query

            if(!requestParam || !_.size(requestParam)) {
                requestParam = yield parse(this, { limit: '100kb' })
            }
            // console.log(requestParam)
            // console.log('====')
            // send request get data.
            let cookie = util.getCookie(this)
            let ticket = this.cookies.get(COOKIE)
            let url = util.getCommonPath({replacement: opt.replacement}, opt.url)

            let requestData = opt.generatorPostParam && opt.generatorPostParam(requestParam)
            if(opt.type != 'POST') {
                url += `?&${qs.stringify(requestData)}`
            }
            // console.log(requestData)
            let config = util.getCommonConfig({
                ticket,
                url,
                cookie,
                method: opt.type || 'GET',
                data: requestData
            })
            // console.log(config)
            let fileName = path.join(process.cwd(), '/exports', (requestParam.title || 'no_name.csv'))
            // 如果没有exports目录则创建目录
            if (!fs.existsSync(process.cwd() + '/exports/')){
                fs.mkdirSync(process.cwd() + '/exports/');
            }
            let response = opt.url ? yield koaRequest(config) : {}
            let fileContent = '';
            // console.log(response.body)
            // console.log('........')
            try {
                fileContent = JSON.parse(response.body)
            } catch(e) {
                fileContent = response.body
            }

            if(opt.formatContent) {
                fileContent = opt.formatContent(fileContent, requestParam)
            }
            // console.log(fileName)
            // console.log(fileContent)
            // console.log('........')
            function readFile(callback) {
                if(fileName.indexOf('.xlsx') >= 0) {
                    XLSX.writeFileAsync(fileName, fileContent, writeCallBack.bind(this, fileName, ctx, callback))
                } else {
                    var buffer = new Buffer([0xEF, 0xBB, 0xBF])
                    fileContent = buffer.toString("utf-8") + fileContent
                    fs.writeFile(fileName, fileContent, writeCallBack.bind(this, fileName, ctx, callback))
                }
            }
            this.body = yield readFile;
            yield * next;
        }
     },
     // 浏览器出post请求，携带大量数据，node写入后返回文件给浏览器端。
     postDataWrite: function(opt) {
        return function *(next) {
            const ctx = this;

            let XLSX = require('xlsx')
            let fileContent = ''
            let postData = yield parse(this, { limit: '20kb' });
            let fileName = 'exports/' + (postData.title || 'noname.xlsx')

            // 如果没有exports目录则创建目录
            if (!fs.existsSync(process.cwd() + '/exports/')){
                fs.mkdirSync(process.cwd() + '/exports/');
            }

            try {
                fileContent = JSON.parse(postData.content)
            } catch (e) {
                fileContent = postData.content
            }

            function saveFile(callback) {
                if(fileName.indexOf('.xlsx') >= 0) {
                    XLSX.writeFileAsync(fileName, fileContent, writeCallBack.bind(this, fileName, ctx, callback))
                } else {
                    var buffer = new Buffer([0xEF, 0xBB, 0xBF])
                    fileContent = buffer.toString("utf-8") + fileContent
                    fs.writeFile(fileName, fileContent, writeCallBack.bind(this, fileName, ctx, callback))
                }
            }
            this.body = yield saveFile;

            yield * next;
        }
     }
}

// helpers
function writeCallBack(fileName, ctx, callback, error) {
    // writeFileAsync MD, 说好的回调呢，执行这里的时候文件还没写好....
    setTimeout(function() {
        ctx.set('Content-disposition', 'attachment;filename=' + encodeURIComponent(path.basename(fileName)));
        ctx.type = mime.lookup(fileName);
        ctx.body = fs.createReadStream(fileName);

        fs.readFile(fileName, function (err, data) {
            if (err) throw err;

            // 过5s删除本文件，防止Node服务器磁盘爆了
            setTimeout(function() {
                fs.unlinkSync(fileName, function (err) {
                if (err) throw err;
                });
            }, 5 * 1000);
            callback(null, data);
        });
    }, 1000)
}