package bot

import (
	"context"
	"log"
	"sync"
	"time"
	"velox-bot/internal/beta"
	"velox-bot/internal/commands"
	"velox-bot/internal/commands/betacmd"
	"velox-bot/internal/db/repos/musicrepo"
	"velox-bot/internal/db/services"
	"velox-bot/internal/events"
	"velox-bot/internal/music"
	"velox-bot/internal/security"
	"velox-bot/internal/tickets"

	"github.com/bwmarrin/discordgo"
)

type Bot struct {
	Session            *discordgo.Session
	AppID              string
	GuildID            string
	Commands           []*discordgo.ApplicationCommand
	registeredCommands []*discordgo.ApplicationCommand
	Services           *services.Services
	MusicRepo          *musicrepo.Repo
	DBHost             string
	LavalinkHost       string
	LavalinkPass       string
	betaRegistered     map[string]bool // servers where the beta commands are registered right now
	betaRoles          sync.Map        // "guild:user" -> cachedRoles
}

func NewBot(token, appID, guildID, lavalinkHost, lavalinkPass string, cmds []*discordgo.ApplicationCommand, services *services.Services, musicRepo *musicrepo.Repo, dbHost string) (*Bot, error) {
	session, err := discordgo.New("Bot " + token)
	if err != nil {
		return nil, err
	}

	// Intents needed for:
	// - InteractionCreate (slash commands): Guilds
	// - MessageCreate (leveling): GuildMessages
	// - GuildMemberAdd (welcome messages): GuildMembers
	// - VoiceStateUpdate (meeting lobby): GuildVoiceStates
	session.Identify.Intents = discordgo.IntentsGuilds |
		discordgo.IntentsGuildBans |
		discordgo.IntentsGuildMembers |
		discordgo.IntentsGuildMessages |
		discordgo.IntentsMessageContent |
		discordgo.IntentsGuildVoiceStates |
		discordgo.IntentsDirectMessages

	return &Bot{
		betaRegistered: map[string]bool{},
		Session:        session,
		AppID:          appID,
		GuildID:        guildID,
		Commands:       cmds,
		Services:       services,
		MusicRepo:      musicRepo,
		DBHost:         dbHost,
		LavalinkHost:   lavalinkHost,
		LavalinkPass:   lavalinkPass,
	}, nil
}

func (b *Bot) Start() error {
	if err := b.Session.Open(); err != nil {
		return err
	}

	_ = music.Init(b.Session, b.MusicRepo, b.AppID, b.LavalinkHost, b.LavalinkPass)

	go func() {
		if err := music.StartCommandListener(context.Background(), b.DBHost, b.MusicRepo); err != nil {
			log.Printf("music: command listener stopped: %v", err)
		}
	}()

	if st := tickets.Default(); st != nil {
		go func() {
			// The connection can drop (database restart, network blip):
			// reconnect instead of silently ignoring the dashboard from then on.
			for {
				err := tickets.StartCommandListener(context.Background(), b.DBHost, b.Session, st)
				log.Printf("tickets: command listener stopped: %v (retrying in 10s)", err)
				time.Sleep(10 * time.Second)
			}
		}()
	}

	if eng := security.Start(b.Session, b.Session.State.User.ID); eng != nil {
		// Moderators are exempt from heat; their permissions come from the
		// gateway cache so a message never costs an API call.
		eng.ChannelPerms = b.Session.State.UserChannelPermissions
		eng.ResumeRaids(context.Background())
		go eng.WatchRaids(context.Background(), 30*time.Second)
		go eng.WatchSnapshots(context.Background())
		go func() {
			// Reconnect if the database connection drops, instead of
			// silently ignoring the dashboard from then on.
			for {
				err := eng.StartCommandListener(context.Background(), b.DBHost)
				log.Printf("security: command listener stopped: %v (retrying in 10s)", err)
				time.Sleep(10 * time.Second)
			}
		}()
	}

	b.registeredCommands = make([]*discordgo.ApplicationCommand, len(b.Commands))
	for _, cmd := range b.Commands {
		created, err := b.Session.ApplicationCommandCreate(b.AppID, b.GuildID, cmd)
		if err != nil {
			log.Printf("Cannot create '%v' command: %v", cmd.Name, err)
			continue
		}
		b.registeredCommands = append(b.registeredCommands, created)
	}

	b.Session.AddHandler(commands.HandleInteraction)

	b.Session.AddHandler(func(s *discordgo.Session, c *discordgo.ChannelDelete) {
		events.HandleChannelDelete(s, c, b.Services)
	})

	b.Session.AddHandler(func(s *discordgo.Session, m *discordgo.MessageCreate) {
		if eng := security.Default(); eng != nil {
			eng.OnMessage(context.Background(), m)
		}
		events.HandleMessageCreate(s, m, b.Services)
	})

	b.Session.AddHandler(func(s *discordgo.Session, m *discordgo.GuildMemberAdd) {
		events.HandleBotAddedOnGuild(s, m, b.Services)

		// Security runs first: someone it removes (join lock, Join Gate,
		// raid) gets no welcome message or default role.
		if eng := security.Default(); eng != nil && m != nil && m.Member != nil {
			if eng.OnMemberJoin(context.Background(), m.GuildID, m.Member) {
				events.HandleGuildMemberAddLog(s, m, b.Services)
				return
			}
		}

		// Ignore bot members for welcome/log onboarding of normal users.
		if m != nil && m.Member != nil && m.User != nil && m.User.Bot {
			return
		}

		events.HandleGuildMemberAdd(s, m, b.Services)
		events.HandleGuildMemberAddLog(s, m, b.Services)
	})

	// Anti-nuke and unauthorized bot additions read the audit log as it
	// happens (needs the Guild Moderation intent and View Audit Log).
	b.Session.AddHandler(func(s *discordgo.Session, ev *discordgo.GuildAuditLogEntryCreate) {
		if eng := security.Default(); eng != nil && ev.AuditLogEntry != nil {
			eng.OnAuditLogEntry(context.Background(), ev.GuildID, ev.AuditLogEntry)
		}
	})

	b.Session.AddHandler(func(s *discordgo.Session, m *discordgo.GuildMemberRemove) {
		events.HandleGuildMemberRemoveLog(s, m, b.Services)
	})

	b.Session.AddHandler(func(s *discordgo.Session, m *discordgo.GuildMemberUpdate) {
		events.HandleGuildMemberUpdateLog(s, m, b.Services)
	})

	b.Session.AddHandler(func(s *discordgo.Session, m *discordgo.MessageUpdate) {
		events.HandleMessageUpdateLog(s, m, b.Services)
	})

	b.Session.AddHandler(func(s *discordgo.Session, m *discordgo.MessageDelete) {
		events.HandleMessageDeleteLog(s, m, b.Services)
	})

	b.Session.AddHandler(func(s *discordgo.Session, m *discordgo.GuildBanAdd) {
		events.HandleGuildBanAddLog(s, m, b.Services)
	})

	b.Session.AddHandler(func(s *discordgo.Session, m *discordgo.GuildBanRemove) {
		events.HandleGuildBanRemoveLog(s, m, b.Services)
	})

	b.Session.AddHandler(func(s *discordgo.Session, t *discordgo.ThreadDelete) {
		if st := tickets.Default(); st != nil && t.Channel != nil {
			tickets.ThreadDeleted(context.Background(), st, t.ID)
		}
	})

	b.Session.AddHandler(func(s *discordgo.Session, vs *discordgo.VoiceStateUpdate) {
		events.HandleVoiceStateUpdate(s, vs, b.Services)
		music.OnVoiceStateUpdate(vs)
	})

	b.Session.AddHandler(func(s *discordgo.Session, ev *discordgo.VoiceServerUpdate) {
		music.OnVoiceServerUpdate(ev)
	})

	events.StartScheduleReminderLoop(b.Session, b.Services)
	events.StartTwitchLiveLoop(b.Session, b.Services)

	return nil
}

// betaPollEvery is how often the bot looks for a change to the beta settings
// made on the dashboard.
const betaPollEvery = 30 * time.Second

// WatchBeta keeps the bot's idea of who the beta testers are, and which
// servers opted in, in step with the dashboard. When the list of servers
// changes, the beta commands follow: they appear in servers that opted in and
// are removed from servers that opted out. If the settings can't be read, the
// last known ones stay in force (and before the first read, beta stays off).
func (b *Bot) WatchBeta(ctx context.Context, load func(context.Context) (guildID, roleID string, servers []string, err error)) {
	beta.SetRolesLookup(b.betaMemberRoles)
	sync := func() {
		guildID, roleID, servers, err := load(ctx)
		if err != nil {
			log.Printf("beta: cannot read settings, keeping the last ones: %v", err)
			return
		}
		beta.Configure(guildID, roleID, servers)
		b.syncBetaCommands()
	}
	sync()
	go func() {
		t := time.NewTicker(betaPollEvery)
		defer t.Stop()
		for {
			select {
			case <-ctx.Done():
				return
			case <-t.C:
				sync()
			}
		}
	}()
}

type cachedRoles struct {
	roles []string
	at    time.Time
}

// betaRolesTTL is how long a member's roles in the beta server are remembered
// when they had to be fetched from Discord.
const betaRolesTTL = 30 * time.Second

// betaMemberRoles answers beta.SetRolesLookup: someone's roles in the beta
// server. The gateway cache is used when it has them (it is kept current by
// member updates), otherwise Discord is asked, at most once per
// betaRolesTTL per person.
func (b *Bot) betaMemberRoles(guildID, userID string) ([]string, error) {
	if m, err := b.Session.State.Member(guildID, userID); err == nil && m != nil {
		return m.Roles, nil
	}
	key := guildID + ":" + userID
	if v, ok := b.betaRoles.Load(key); ok {
		if c := v.(cachedRoles); time.Since(c.at) < betaRolesTTL {
			return c.roles, nil
		}
	}
	m, err := b.Session.GuildMember(guildID, userID)
	if err != nil {
		return nil, err
	}
	b.betaRoles.Store(key, cachedRoles{roles: m.Roles, at: time.Now()})
	return m.Roles, nil
}

// syncBetaCommands makes the beta commands exist in exactly the servers where
// beta features are on (the beta server and the ones that opted in), and
// nowhere else. A server whose registration failed is retried next time.
func (b *Bot) syncBetaCommands() {
	want := map[string]bool{}
	if g := beta.GuildID(); g != "" {
		want[g] = true
	}
	for _, id := range beta.Servers() {
		want[id] = true
	}
	for id := range b.betaRegistered {
		if !want[id] {
			b.removeBetaCommands(id)
			delete(b.betaRegistered, id)
		}
	}
	for id := range want {
		if !b.betaRegistered[id] && b.addBetaCommands(id) {
			b.betaRegistered[id] = true
		}
	}
}

// addBetaCommands registers the beta commands in a server. In the beta server
// it also removes commands this bot left there that no longer exist (when the
// beta server is also the bot's main server, its regular commands are kept).
// /beta is for the bot's owner and is only registered in the beta server. It
// reports whether everything was registered.
func (b *Bot) addBetaCommands(guildID string) bool {
	isBetaServer := guildID == beta.GuildID()
	keep := map[string]bool{}
	for _, cmd := range b.Commands {
		if b.GuildID == guildID {
			keep[cmd.Name] = true
		}
	}
	ok := true
	for _, cmd := range commands.BetaCommands {
		if cmd.Name == betacmd.Beta.Name && !isBetaServer {
			continue
		}
		keep[cmd.Name] = true
		if _, err := b.Session.ApplicationCommandCreate(b.AppID, guildID, cmd); err != nil {
			log.Printf("beta: cannot create '%v' command in %s: %v", cmd.Name, guildID, err)
			ok = false
		}
	}
	if !isBetaServer {
		return ok
	}
	existing, err := b.Session.ApplicationCommands(b.AppID, guildID)
	if err != nil {
		log.Printf("beta: cannot list commands, leaving stale ones alone: %v", err)
		return ok
	}
	for _, cmd := range existing {
		if keep[cmd.Name] {
			continue
		}
		if err := b.Session.ApplicationCommandDelete(b.AppID, guildID, cmd.ID); err != nil {
			log.Printf("beta: cannot remove stale '%v' command: %v", cmd.Name, err)
		}
	}
	return ok
}

// removeBetaCommands takes the beta commands out of a server that is no longer
// part of the beta, and leaves everything else there alone.
func (b *Bot) removeBetaCommands(guildID string) {
	isBeta := map[string]bool{}
	for _, cmd := range commands.BetaCommands {
		isBeta[cmd.Name] = true
	}
	existing, err := b.Session.ApplicationCommands(b.AppID, guildID)
	if err != nil {
		log.Printf("beta: cannot list commands in %s: %v", guildID, err)
		return
	}
	for _, cmd := range existing {
		if !isBeta[cmd.Name] {
			continue
		}
		if err := b.Session.ApplicationCommandDelete(b.AppID, guildID, cmd.ID); err != nil {
			log.Printf("beta: cannot remove '%v' from %s: %v", cmd.Name, guildID, err)
		}
	}
}

func (b *Bot) Close() error {
	for _, cmd := range b.registeredCommands {
		if err := b.Session.ApplicationCommandDelete(b.AppID, b.GuildID, cmd.ID); err != nil {
			log.Printf("cannot delete '%s' command: %v", cmd.Name, err)
		}
	}
	return b.Session.Close()
}