const net = require("net")
const User = require("../src/user.js")
const Channel = require("../src/channel.js")

const RPL_WELCOME = '001'
const ERR_NOSUCHNICK = '401'
const ERR_NOSUCHCHANNEL = '403'
const ERR_CANNOTSENDTOCHAN = '404'
const ERR_UNKNOWNCOMMAND = '421'
const ERR_ERRONEUSNICKNAME = '432'
const ERR_NONICKNAMEGIVEN = '431'
const ERR_NICKNAMEINUSE = '433'
const ERR_NEEDMOREPARAMS = '461'


let server = {}

server.create = function create(config = {}) {
    let password
    if (config.password) {
        password = config.password
    }
    let userlist = {}
    let channellist = {}
    let server = net.createServer((socket) => {
        const user = new User(socket, !config.password)
        socket.on('data', function (data) {
            data.toString("ascii").split("\r\n").forEach(function (commandline) {
                if (commandline == "") {
                    return
                }
                let splitted = commandline.split(" ")
                let tokenized = []
                let lastParam = -1
                for (let i = 0; i < splitted.length; i++) {
                    if (lastParam > 0) {
                        tokenized[lastParam] = tokenized[lastParam] + " " + splitted[i]
                    } else if (splitted[i].charAt(0) == ":" && i > 0) {
                        lastParam = i
                        tokenized[lastParam] = splitted[i].slice(1)
                    } else {
                        tokenized[i] = splitted[i]
                    }
                }
                let command = tokenized[0].toUpperCase()
                switch (command) {
                    case  "PING":
                        if (tokenized[1] && tokenized[1] === "irc.example.com") {
                            socket.write("PONG irc.example.com\r\n")
                        }
                        break;
                    case "NICK":
                        if (tokenized[1]) {
                            let nickname = tokenized[1]
                            // nick collision test
                            if (!Object.keys(userlist).includes(nickname)) {
                                user.setNickname(nickname)
                                userlist[user.nickname] = user
                            } else {
                                socket.write(`:irc.example.com ${ERR_NICKNAMEINUSE} ${nickname} :Nickname is already in use`, 'ascii')
                            }


                        } else {
                            socket.write(`:irc.example.com ${ERR_NONICKNAMEGIVEN} :No nickname given`, 'ascii')
                        }

                        break;

                    case "USER":
                        // ignoring servername and hostname, not useful these days
                        user.register(tokenized[1], tokenized[4])
                        let address = user.getAddress()
                        socket.write(`:irc.example.com 001 ${user.nickname} :Welcome to the example IRC Project ${user.nickname}!~${user.username}@${address}\r\n`, "ascii")
                        break;
                    case "PRIVMSG":
                        let target
                        let message = tokenized[2]
                        if (typeof tokenized[1] === 'string' && tokenized[1].charAt(0) === "#") {
                            target = channellist[tokenized[1]]
                        } else {
                            let targetUser = userlist[tokenized[1]]
                            if (targetUser && targetUser.registered) {
                                target = targetUser
                            }
                        }
                        if (target) {
                            target.sendMsg(user, message)
                        } else {
                            user.sendRaw(`:irc.example.com ${ERR_NOSUCHNICK} ${target} no such nick/channel`)
                        }

                        break;
                    case "JOIN":
                        if (!(tokenized[1].charAt(0) === "#")) {
                            socket.write(`:irc.example.com ${ERR_CANNOTSENDTOCHAN}: invalid channel name`)
                            break;
                        }
                        let channelname = tokenized[1]

                        if (Object.keys(channellist).includes(channelname)) {
                          channellist[channelname].join(user)
                        } else {
                          let channel = new Channel(channelname)
                          channel.join(user)
                          channellist[channelname] = channel
                        }

                        break;
                    case "QUIT":
                        server.closeConnection(user.nickname)
                        break;
                    case "PASS":
                        if (tokenized[1] === config.password) {
                            user.authenticated = true
                        } else {
                            user.closeConnection()
                        }
                        break;

                    default:
                        console.error(`Unknown command: ${command}`);
                }
            });
        }).on('error', (err) => {
            console.error(err);
        })
    }).on('error', (err) => {
        console.error(err);
        throw err;
    });

    server.getUserlist = function () {
        return userlist
    }

    server.closeConnection = function (user_nickname) {
        let user = userlist[user_nickname]
        user.closeConnection()
        delete userlist[user_nickname];
    }

    return server
}


module.exports = server