package main

import (
	"bufio"
	"fmt"
	"log"
	"net"
	"net/textproto"
	"strings"
)

const (
	JOIN    = "JOIN"
	NICK    = "NICK"
	PART    = "PART"
	PRIVMSG = "PRIVMSG"
	QUIT    = "QUIT"
	USER    = "USER"
)

type Message struct {
	Prefix   string
	Command  string
	Params   []string
	Trailing []string
}

func (m *Message) Parse(line string) {
	prefixEnd, trailingStart := -1, len(line)
	m.Prefix, m.Command = "", ""
	if strings.HasPrefix(line, ":") {
		prefixEnd = strings.Index(line, " ")
		m.Prefix = line[1:prefixEnd]
	}
	trailingStart = strings.Index(line, " :")
	if trailingStart >= 0 {
		m.Trailing = strings.Fields(line[trailingStart+2:])
	} else {
		trailingStart = len(line) - 1
	}
	cmdAndParams := strings.Fields(line[(prefixEnd + 1) : trailingStart+1])
	if len(cmdAndParams) > 0 {
		m.Command = cmdAndParams[0]
	}
	if len(cmdAndParams) > 1 {
		m.Params = cmdAndParams[1:]
	}
}

func NewMessage() *Message {
	m := new(Message)
	return m
}

type Bot struct {
	Server   string
	Port     int
	Channels []string
	User     string
	Nick     string
	Password string
	Conn     net.Conn
	Reader   *textproto.Reader
	Writer   *textproto.Writer
	Handlers map[string]string
}

func (bot *Bot) Connect() error {
	conn, err := net.Dial("tcp", bot.url())
	if err != nil {
		return err
	}
	bot.Conn = conn
	bot.Reader = textproto.NewReader(bufio.NewReader(bot.Conn))
	bot.Writer = textproto.NewWriter(bufio.NewWriter(bot.Conn))
	bot.Writer.PrintfLine("%s %s 8 * :%s", USER, bot.User, bot.User)
	bot.Writer.PrintfLine("%s %s", NICK, bot.Nick)
	return nil
}

func (bot *Bot) HandleActions() {
	message := NewMessage()
	for {
		line, err := bot.Reader.ReadLine()
		if err != nil {
			log.Fatal(err)
		}
		fmt.Printf("%s\n", line)
		message.Parse(line)
		if response, ok := bot.Handlers[message.Trailing[0]]; ok {
			bot.Writer.PrintfLine("%s %s %s", PRIVMSG, message.Params[0], response)
		}
	}
}

func (bot *Bot) Ident() {
	if bot.Password != "" {
		bot.Writer.PrintfLine("%s NickServ :identify %s %s", PRIVMSG, bot.Nick, bot.Password)
	}
}

func (bot *Bot) Join() {
	for _, channel := range bot.Channels {
		bot.Writer.PrintfLine("%s %s", JOIN, channel)
	}
}

func (bot *Bot) url() string {
	return fmt.Sprintf("%s:%d", bot.Server, bot.Port)
}

func NewBot(server string, port int, channels []string, user, nick, password string) *Bot {
	bot := &Bot{
		Server:   server,
		Port:     port,
		Channels: channels,
		User:     user,
		Nick:     nick,
		Password: password,
		Handlers: make(map[string]string),
	}
	return bot
}

func main() {
	server := "irc.freenode.net"
	port := 6667
	channels := []string{"#bottestchannel"}
	user := "bottestuser"
	nick := "bottestnick"
	password := ""
	ircbot := NewBot(server, port, channels, user, nick, password)
	ircbot.Handlers["!test"] = fmt.Sprintf("passed!")
	ircbot.Connect()
	ircbot.Join()
	ircbot.HandleActions()
	defer ircbot.Conn.Close()
}