package irc

import (
	"log"
)

type Channel struct {
	commands  chan<- ChannelCommand
	key       string
	members   ClientSet
	name      string
	noOutside bool
	password  string
	replies   chan<- Reply
	server    *Server
	topic     string
}

type ChannelSet map[*Channel]bool

type ChannelCommand interface {
	Command
	HandleChannel(channel *Channel)
}

// NewChannel creates a new channel from a `Server` and a `name`
// string, which must be unique on the server.
func NewChannel(s *Server, name string) *Channel {
	commands := make(chan ChannelCommand)
	replies := make(chan Reply)
	channel := &Channel{
		name:     name,
		members:  make(ClientSet),
		server:   s,
		commands: commands,
		replies:  replies,
	}
	go channel.receiveCommands(commands)
	go channel.receiveReplies(replies)
	return channel
}

func (channel *Channel) receiveCommands(commands <-chan ChannelCommand) {
	for command := range commands {
		if DEBUG_CHANNEL {
			log.Printf("%s → %s : %s", command.Source(), channel, command)
		}
		command.HandleChannel(channel)
	}
}

func (channel *Channel) receiveReplies(replies <-chan Reply) {
	for reply := range replies {
		if DEBUG_CHANNEL {
			log.Printf("%s ← %s : %s", channel, reply.Source(), reply)
		}
		for client := range channel.members {
			client.replies <- reply
		}
	}
}

func (channel *Channel) IsEmpty() bool {
	return len(channel.members) == 0
}

func (channel *Channel) GetTopic(replier Replier) {
	if channel.topic == "" {
		replier.Replies() <- RplNoTopic(channel)
		return
	}

	replier.Replies() <- RplTopic(channel)
}

func (channel *Channel) GetUsers(replier Replier) {
	replier.Replies() <- NewNamesReply(channel)
}

func (channel *Channel) Nicks() []string {
	nicks := make([]string, len(channel.members))
	i := 0
	for client := range channel.members {
		nicks[i] = client.Nick()
		i += 1
	}
	return nicks
}

func (channel *Channel) Replies() chan<- Reply {
	return channel.replies
}

func (channel *Channel) Id() string {
	return channel.name
}

func (channel *Channel) Nick() string {
	return channel.name
}

func (channel *Channel) PublicId() string {
	return channel.name
}

func (channel *Channel) String() string {
	return channel.Id()
}

func (channel *Channel) Join(client *Client) {
	channel.members[client] = true
	client.channels[channel] = true
	reply := RplJoin(channel, client)
	channel.replies <- reply
	channel.GetTopic(client)
	channel.GetUsers(client)
}

func (channel *Channel) HasMember(client *Client) bool {
	return channel.members[client]
}

//
// commands
//

func (m *JoinCommand) HandleChannel(channel *Channel) {
	client := m.Client()
	if channel.key != m.channels[channel.name] {
		client.replies <- ErrBadChannelKey(channel)
		return
	}

	channel.Join(client)
}

func (m *PartCommand) HandleChannel(channel *Channel) {
	c := m.Client()

	if !channel.HasMember(c) {
		c.replies <- ErrNotOnChannel(channel)
		return
	}

	msg := m.message
	if msg == "" {
		msg = c.Nick()
	}

	channel.replies <- RplPart(channel, c, msg)

	delete(channel.members, c)
	delete(c.channels, channel)

	if channel.IsEmpty() { // TODO persistent channels
		channel.server.DeleteChannel(channel)
	}
}

func (m *TopicCommand) HandleChannel(channel *Channel) {
	client := m.Client()

	if !channel.HasMember(client) {
		client.replies <- ErrNotOnChannel(channel)
		return
	}

	if m.topic == "" {
		channel.GetTopic(client)
		return
	}

	channel.topic = m.topic

	channel.GetTopic(channel)
}

func (m *PrivMsgCommand) HandleChannel(channel *Channel) {
	channel.replies <- RplPrivMsgChannel(channel, m.Client(), m.message)
}