package main

import (
	"github.com/bwmarrin/discordgo"
	"regexp"
	"strconv"
	"strings"
)

// ParseForCommands parses input for Commands, returns message if no command specified, else return is empty
func ParseForCommands(line string) string {
	if len(line) < 2 {
		return line
	}

	switch line[:2] {
	case "s/":
		// `s/X/Y/` replace X with Y in the last message sent
		r := regexp.MustCompile(`s/([^/]+)/([^/]*)/$`)
		n := r.FindStringSubmatchIndex(line)
		if len(n) < 1 {
			return ""
		}
		i := 0
		var m *discordgo.Message
		for i = len(State.Messages) - 1; i >= 0; i-- {
			m = State.Messages[i]
			if m.ChannelID == State.Channel.ID && m.GuildID == State.Guild.ID && m.Author.ID == Session.User.ID {
				break
			}
		}
		if i == 0 || !strings.Contains(m.Content, line[n[2]:n[3]]) {
			return ""
		}
		r, err := regexp.Compile("(" + line[n[2]:n[3]] + ")")
		if err != nil {
			Msg(ErrorMsg, "%s - invalid regex\n", line)
		}
		rep := r.ReplaceAllString(m.Content, line[n[4]:n[5]])
		newm := discordgo.NewMessageEdit(m.ChannelID, m.ID)
		newm = newm.SetContent(rep)
		_, err = State.Session.DiscordGo.ChannelMessageEditComplex(newm)
		if err != nil {
			Msg(ErrorMsg, "%s\n", err)
			return ""
		}
		Msg(TextMsg, "%s → %s\n", m.Content, rep)
		return ""

	case ":?":
		// Show help menu
		Msg(TextMsg, "Commands: \n")
		Msg(TextMsg, "s/X/Y/ - Replace X with Y in the last message\n")
		Msg(TextMsg, "[:g] - Open guild menu\n")
		Msg(TextMsg, "[:p] - Open private message menu\n")
		Msg(TextMsg, "[:c] - Open guild channel menu\n")
		Msg(TextMsg, "[:c ?] - List guild channels\n")
		Msg(TextMsg, "[:c <num>] - Go directly to channel <num>\n")
		Msg(TextMsg, "[:m <num>] - Display last <num> messages\n")
		Msg(TextMsg, "[:n <name>] - Change username to <name>\n")
		Msg(TextMsg, "[:!] - Print current server information\n")
		Msg(TextMsg, "[:?] - Print this menu\n")
		return ""

	case ":g":
		// Choose a server (guild)
		SelectGuild()
		return ""

	case ":p":
		// Enter DM menu
		SelectPrivate()
		return ""

	case ":c":
		// Choose a channel within the server
		opts := strings.Split(line, " ")
		if len(opts) == 1 {
			SelectChannel()
			return ""
		}
		selectID := 0
		if opts[1] == "?" {
			for _, channel := range State.Channels {
				if channel.Type == 0 {
					Msg(TextMsg, "[%d] %s\n", selectID, channel.Name)
					selectID++
				}
			}
			return ""
		}
		selectMap := make(map[int]*discordgo.Channel)
		for _, channel := range State.Channels {
			if channel.Type == 0 {
				selectMap[selectID] = channel
				selectID++
			}
		}
		selection, err := strconv.Atoi(opts[1])
		if err != nil {
			Msg(ErrorMsg, "[:c] Argument Error: %s\n", err)
			return ""
		}
		if len(State.Channels) < selection || selection < 0 {
			Msg(ErrorMsg, "[:c] Argument Error: Out of bounds\n")
			return ""
		}
		channel := selectMap[selection]
		State.SetChannel(channel.ID)
		ShowContent()
		return ""

	case ":m":
		// Load message backlog -- TODO ­ currently does not retrieve more than n messages
		AmountStr := strings.Split(line, " ")
		if len(AmountStr) < 2 {
			Msg(ErrorMsg, "[:m] No Arguments \n")
			return ""
		}

		Amount, err := strconv.Atoi(AmountStr[1])
		if err != nil {
			Msg(ErrorMsg, "[:m] Argument Error: %s \n", err)
			return ""
		}

		Msg(InfoMsg, "Printing last %d messages!\n", Amount)
		State.RetrieveMessages(Amount)
		PrintMessages(Amount)
		return ""

	case ":n":
		// Change nickname
		session := State.Session
		user := session.User
		oldName := user.Username
		newName := strings.TrimPrefix(line, ":n ")
		_, err := State.Session.DiscordGo.UserUpdate(user.Email, session.Password, newName, user.Avatar, "")
		if err != nil {
			Msg(ErrorMsg, "[:n] Argument Error: %s\n", err)
			return ""
		}
		Msg(TextMsg, "%s → %s\n", oldName, newName)
		return ""

	case ":!":
		// Print current server information
		Msg(TextMsg, GuildInfo(State.Guild))
		return ""
	}

	return line
}

//SelectGuild selects a new Guild
func SelectGuild() {
	State.Enabled = false
	SelectGuildMenu()
	// Segfaults would happen here
	SelectChannelMenu()
	State.Enabled = true
	ShowContent()
}

//AddUserChannel moves a user to a private channel with another user.
func AddUserChannel() {
	State.Enabled = false
	AddUserChannelMenu()
	State.Enabled = true
	ShowContent()
}

//SelectChannel selects a new Channel
func SelectChannel() {
	State.Enabled = false
	SelectChannelMenu()
	State.Enabled = true
	ShowContent()
}

//SelectPrivate a private channel
func SelectPrivate() {
	State.Enabled = false
	SelectPrivateMenu()
	State.Enabled = true
	ShowContent()
}

//SelectDeletePrivate a private channel
func SelectDeletePrivate() {
	State.Enabled = false
	SelectDeletePrivateMenu()
	State.Enabled = true
	ShowContent()
}