/**
 * Http管理器
 * 
 */

import { sys } from "cc";
import SubManager from "../../Sub/SubManager";

export class HttpManager {
    private static _I: HttpManager | null = null;
    public static get I(): HttpManager {
        if (!HttpManager._I) HttpManager._I = new HttpManager();
        return HttpManager._I;
    }

    private constructor() {}

    /**
     * 发送请求
     * @param url 接口地址
     * @param data 消息字符串 (json格式)
     * @param method 请求方式
     * @param bLock 是否锁定屏幕
     * @param formData 是否formData
     * @returns 
     */
    public async send(url: string, data: any, method: "GET" | "POST" | "PUT" = "GET") {
        console.log("[Http] 请求Url:",url, " 方式:", method, " 数据:", data);
        var xhr = new XMLHttpRequest();
        xhr.timeout = 10000;
        if (method == 'GET') {
            url = url + encodeURI(this.jsonToQueryString(data));
            xhr.open(method, url, true);
            if (sys.isNative) {
                xhr.setRequestHeader("Accept-Encoding", "gzip,deflate");
                xhr.setRequestHeader("content-type", "text/html;charset=utf-8");
            }
        } else {
            xhr.open(method, url, true);
            xhr.setRequestHeader("Content-type", "application/json");
        }
        let self = this;
        return new Promise((resolve, reason) => {
            self.quest(xhr, method, data).then(value => {
                resolve(value);
            }).catch(err => {
                resolve(null);
            });
        });

    } 
    
    /**
     * 把对象转 ?a=1&b=2 的查询串
     */    
    private jsonToQueryString(json: any) {
        var str = '';
        if (typeof json == "object") {
            str = "?";
            for (var k in json) {
                if (str != "?") {
                    str += "&";
                }
                str += encodeURIComponent(k) + "=" + encodeURIComponent(json[k]);
            }
        }
        return str;
    }      

    /**
     * 统一封装 XHR 的发送与状态回调
     */       
    private async quest(xhr: XMLHttpRequest, method: "GET" | "POST" | "PUT" = "GET", data: Object) {
        return new Promise((resolve, reason) => {
            xhr.onreadystatechange = () => {
                if (xhr.readyState == 4) {
                    if (xhr.status >= 200 && xhr.status < 300) {
                        console.log("[Http] 返回", xhr.response);
                        try {
                            resolve(JSON.parse(xhr.response));
                        } catch (e) {
                            reason(e);
                        }                                        
                    } else {
                        reason(xhr.status)
                    }
                }
            };
            xhr.onerror = (error) => {
                console.error("http request onerror");
                SubManager.ShowPrompt("网络错误，请检查网络连接");
                reason(error)
            };
            xhr.ontimeout = (e) => {
                console.error("http request timeout");
                SubManager.ShowPrompt("网络错误，请检查网络连接");
                reason(e)
            }
            //根据POST和GET方式，选择是否发送msg数据
            if (method == 'POST') {
                xhr.send(JSON.stringify(data));
            } else if (method == 'PUT') {
                xhr.send(JSON.stringify(data));
            } else {
                xhr.send();
            }
        });
    }
}