"use strict"

var r2mConsts = require('./Header.js');
var AppErrors = require('../AppErrors.js');

class R2m_Helper {
    constructor(objSocket, objR2mClient) {
        this._ver = r2mConsts.R2M_VERSION;
        this.objR2mClient = objR2mClient;
        this._events = [];

        this.objClient = objSocket.open();
        this.listen();
    }

    listen() {

        let bufData = '';
        this.objClient.on('data', (data) => {
            if (bufData.length == 0) {
                bufData = data;
            } else {
                // 合并包数据
                bufData = Buffer.concat([bufData, data], bufData.length + data.length);
            }
            let response = this.parse(bufData);
            // 重置buf
            bufData = response.buf;

            for (let i = 0; i < response.results.length; i++) {
                let result = response.results[i];
                // 触发数据接收事件
                this._events[result['id']].emit('receive', result);
                this._events[result['id']] = null;
            }
        });

        //this.objClient.setTimeout(10000, () => {
        //    this.objClient.end();
        //});

        this.objClient.on('end', () => {
           this.objR2mClient._objHelper = null;
           console.log('client disconnected');
        });

        this.objClient.on('error', (data) => {
            throw new AppErrors.R2MError(`socket error ${data}`);
        });
    }

    request(conf, cmd, data, id) {
        id = id || 0;
        return this.cmd(conf, cmd, data, id, r2mConsts.CMD_TYPE_REQUEST);
    }

    parse(buf) {
        let response = {buf:'',results:[]};
        let start = 0;
        let buflen = buf.length;
        do {
            let ver = buf.readUInt16BE(start + 0);
            if (!ver) {
                break;
            }
            if (ver != this._ver) {
                this.errMsg = `no match redis2mysql service version. client:${ver}, server:${this._ver}`;
            }

            let cmd = buf.readUInt16BE(start + 2);
            let cmdType = buf.readUInt16BE(start + 4);
            let codeType = buf.readUInt16BE(start + 6);
            let contentType = buf.readUInt16BE(start + 8);
            let id = buf.readUInt32BE(start + 10);
            let length = buf.readUInt32BE(start + 14);

            let content = buf.toString('utf8', start + 18, length + start + 18);
            // 出现分包
            if (length > this.mbStringLength(content)) {
                response['buf'] = buf.slice(start, buflen);
                break;
            }

            start = length + start + 18;

            if (contentType == r2mConsts.CONTENT_TYPE_JSON) {
                content = JSON.parse(content);
            }
            let result = {ver, cmd, cmdType, codeType, contentType, id, content};
            response.results.push(result);
        } while(start < buflen);

        return response;
    }

    cmd(conf, cmd, data, id, cmdType, codeType) {
        id = id || 0;
        cmdType = cmdType || r2mConsts.CMD_TYPE_REQUEST;
        codeType = codeType || r2mConsts.CODE_TYPE_BINARY;

        let contentType = r2mConsts.CONTENT_TYPE_TEXT;
        if (typeof data === "object") {
            contentType = r2mConsts.CONTENT_TYPE_JSON; 
            data = JSON.stringify(data);
        }

        if (conf) {
            var args = JSON.stringify({conf, data});
        } else {
            var args = data;
        }

        let strLength = this.mbStringLength(args);
        let buf = new Buffer(18 + strLength);

        buf.writeUInt16BE(this._ver, 0);
        buf.writeUInt16BE(cmd, 2);
        buf.writeUInt16BE(cmdType, 4);
        buf.writeUInt16BE(codeType, 6);
        buf.writeUInt16BE(contentType, 8);
        buf.writeUInt32BE(id, 10);
        buf.writeUInt32BE(strLength, 14);
        buf.write(args, 18);
        return this.objClient.write(buf);
    }

    mbStringLength(s) { 
        let totalLength = 0; 
        let i; 
        let charCode; 
        for (i = 0; i < s.length; i++) { 
            charCode = s.charCodeAt(i); 
            if (charCode < 0x007f) { 
                totalLength = totalLength + 1; 
            } else if ((0x0080 <= charCode) && (charCode <= 0x07ff)) { 
                totalLength += 2; 
            } else if ((0x0800 <= charCode) && (charCode <= 0xffff)) { 
                totalLength += 3; 
            } 
        } 
        return totalLength; 
    }     

}

module.exports = R2m_Helper;