package bot

import (
	"context"
	"log"
	"strings"
	"time"

	"github.com/gissleh/irc"
	"git.aiterp.net/rpdata/logbot3/internal/config"
	"git.aiterp.net/rpdata/logbot3/internal/models/channels"
	"git.aiterp.net/rpdata/logbot3/internal/models/logs"
	"git.aiterp.net/rpdata/logbot3/internal/models/posts"
)

// A Channel represents a handler for a single channel that takes care of the logging and such.
type Channel struct {
	ctx    context.Context
	cancel context.CancelFunc
	ch     chan ChannelPost

	lastPostSessionID string
	lastPostTime      time.Time

	name      string
	parentCtx context.Context
	parent    *Bot
	client    *irc.Client
}

func newChannel(parent *Bot, name string, client *irc.Client) *Channel {
	ctx, cancel := context.WithCancel(parent.ctx)

	return &Channel{
		name:      name,
		parent:    parent,
		parentCtx: parent.ctx,
		client:    client,
		ch:        make(chan ChannelPost, 8),

		ctx:    ctx,
		cancel: cancel,
	}
}

func (channel *Channel) loop() {
	queue := make([]ChannelPost, 0, 8)
	minutely := time.NewTicker(time.Minute)

	defer channel.cancel()
	defer minutely.Stop()

	// In case of a crash, it should take ownership of sessions when rejoining.
	session, err := logs.FindOpen(channel.parentCtx, channel.name)
	if err == nil {
		minsUntilDeadline := 1 + int(((time.Hour * 2) - time.Since(session.LatestTime())).Minutes())
		if minsUntilDeadline < 1 {
			minsUntilDeadline = 1
		}

		channel.client.Sayf(channel.name, "Session https://aiterp.net/logs/%s will be closed in %d min if there are no new posts.", session.ID, minsUntilDeadline)

		channel.lastPostSessionID = session.ID
		channel.lastPostTime = session.LatestTime()
	}

	// If the bot is op, run the commands from the configuration.
	go func() {
		time.Sleep(time.Second)

		commands := config.Get().Commands.OnJoinOp
		target := channel.client.Channel(channel.name)

		if len(commands) > 0 && target != nil {
			me, ok := target.UserList().User(channel.client.Nick())
			if ok && strings.ContainsRune(me.Modes, 'o') {
				channel.parent.runCommands(commands, target, map[string]string{
					"chan": channel.name,
				})
			}
		}
	}()

	for {
		select {
		case post := <-channel.ch:
			{
				// Handle bot commands, or add to queue otherwise.
				if cmd := post.botCommand(); cmd != nil {
					switch cmd.Verb {
					case "end", "ends", "endsession":
						{
							session, err := logs.FindOpen(channel.parentCtx, channel.name)
							if err == logs.ErrNoneOpen {
								channel.client.Say(channel.name, "No open session found. Mission accomplished, I guess?")
								break
							} else if err != nil {
								log.Println("Could not find session:", err)
								break
							}

							_, err = logs.SetOpen(channel.parentCtx, session, false)
							if err != nil {
								channel.client.Say(channel.name, "Something went wrong when closing the log, please use the website instead.")
								log.Println("Could not set open:", err)
							}
						}
					case "tag", "event":
						{
							if cmd.Text == "" {
								channel.client.Say(channel.name, "Usage: !tag <Event Name>")
							}

							session, err := logs.FindOpen(channel.parentCtx, channel.name)
							if err == logs.ErrNoneOpen {
								channel.client.Say(channel.name, "No open session found. You can edit closed logs on the website.")
								break
							} else if err != nil {
								log.Println("Could not find session:", err)
								break
							}

							_, err = logs.SetEventName(channel.parentCtx, session, cmd.Text)
							if err != nil {
								channel.client.Say(channel.name, "Something went wrong when setting the event name, please use the website instead.")
								log.Println("Could not set event name:", err)
							}
						}
					case "register":
						{
							target := channel.client.Channel(channel.name)
							if target != nil {
								me, ok := target.UserList().User(channel.client.Nick())
								if !ok || !strings.ContainsRune(me.Modes, 'o') {
									channel.client.Say(channel.name, "This unit has insufficient privileges.")
									break
								}

								chanServNick := config.Get().Names.ChanServ
								if chanServNick == "" {
									channel.client.Say(channel.name, "This function is not enabled.")
									break
								}

								channel.client.Sayf(chanServNick, "REGISTER %s", target.Name())
							}
						}
					}
				} else {
					queue = append(queue, post)

					if post.Time.After(channel.lastPostTime) {
						channel.lastPostTime = post.Time
					}
				}

				// Posts after here aren't going to be bot commands, so log its reception.
				log.Printf("Received %s post from %s", post.Kind, post.Nick)

				// Stop here if there's nothing to post.
				if len(queue) == 0 {
					break
				}

				// Buffer up posts close to one another.
				deadline := time.After(time.Second * 3)
				buffering := true
				for buffering {
					select {
					case post := <-channel.ch:
						{
							queue = append(queue, post)
						}
					case <-deadline:
						{
							buffering = false
						}
					}
				}

				// Select session.
				session, err := logs.FindOpen(channel.parentCtx, channel.name)
				if err == logs.ErrNoneOpen {
					eventName := ""
					channelData, err := channels.Find(channel.parentCtx, channel.name)
					if err == nil {
						eventName = channelData.EventName
					}

					session, err = logs.Add(channel.parentCtx, channel.name, queue[0].Time, true, eventName)
					if err != nil {
						channel.client.Say(channel.name, "This unit failed to open session: "+err.Error())
						log.Println("Failed to open session:", err)
					}
				} else if err != nil {
					channel.client.Say(channel.name, "This unit is unable to check active sessions: "+err.Error())
					break
				}
				log.Println("Selected session:", session.ID)

				// Remember which session was last posted to.
				channel.lastPostSessionID = session.ID

				// Post posts
				lastSuccess := -1
				for i, channelPost := range queue {
					post, err := posts.Add(channel.parentCtx, session, channelPost.Time, channelPost.Kind, channelPost.Nick, channelPost.Text)
					if err != nil {
						log.Println("Failed to post:", err)
						break
					}

					summary := ""
					for _, ru := range post.Text {
						summary += string(ru)
						if len(summary) > 30 {
							summary += "..."
							break
						}
					}

					log.Printf("Posted (id=%s, kind=%s, nick=%s, delay=%s): %s", post.ID, post.Kind, post.Nick, time.Since(post.Time), summary)
					lastSuccess = i
				}
				if lastSuccess >= 0 {
					copy(queue, queue[lastSuccess:])
					queue = queue[:len(queue)-(lastSuccess+1)]
				}
			}

		case now := <-minutely.C:
			if !channel.lastPostTime.IsZero() && now.Sub(channel.lastPostTime) > (time.Hour*2) {
				session, err := logs.FindOpen(channel.parentCtx, channel.name)
				if err == logs.ErrNoneOpen {
					log.Println(channel.name, "Log already closed.")
					channel.lastPostTime = time.Time{}
					channel.lastPostSessionID = ""
					break
				} else if err != nil {
					log.Println(channel.name, "Could not find session:", err)
					break
				}

				if session.ID != channel.lastPostSessionID {
					log.Println("Aborted auto-close in", channel.name, "due to session change.")
					channel.lastPostTime = time.Time{}
					channel.lastPostSessionID = ""
					break
				}

				if now.Sub(session.LatestTime()) < (time.Hour * 2) {
					log.Println("Aborted auto-close in", channel.name, "due to session being more recent.")
					channel.lastPostTime = session.LatestTime()
					break
				}

				_, err = logs.SetOpen(channel.parentCtx, session, false)
				if err != nil {
					log.Println("Could not set open:", err)
					break
				}

				channel.client.Sayf(channel.name, "Log session closed after 2+ hours of inactivity. See log at https://aiterp.net/logs/%s", channel.lastPostSessionID)

				channel.lastPostTime = time.Time{}
				channel.lastPostSessionID = ""
			}

		case <-channel.ctx.Done():
			{
				// Time to pack up shop.
				return
			}
		}
	}
}

func (channel *Channel) wait(ctx context.Context) error {
	select {
	case <-ctx.Done():
		return ctx.Err()
	case <-channel.ctx.Done():
		return nil
	}
}

// A ChannelPost is a post made to a channel.
type ChannelPost struct {
	Kind    string
	Time    time.Time
	Nick    string
	Text    string
	Account string
}

func (post *ChannelPost) botCommand() *botCommand {
	if !strings.HasPrefix(post.Text, "!") {
		return nil
	}

	split := strings.SplitN(post.Text, " ", 2)

	if len(split) == 1 {
		return &botCommand{Verb: strings.ToLower(split[0][1:]), Text: ""}
	}
	return &botCommand{Verb: strings.ToLower(split[0][1:]), Text: split[1]}
}

type botCommand struct {
	Verb string
	Text string
}