// Package betacmd is /beta, the bot owner's control over the beta program.
// It is a command you use in a direct message with the bot, so it exists in no
// server's command menu, and only the owner of the Discord application can run
// it (the owner is looked up from the application, so there is nothing to
// configure). It chooses the beta server and the Beta Tester role, and
// removes servers from the beta; a server's own owner opts it in with
// /config beta-features. Nothing about the beta needs a dashboard.
package betacmd

import (
	"context"
	"fmt"
	"log"
	"regexp"
	"strconv"
	"strings"
	"sync"
	"time"

	"velox-bot/internal/beta"
	"velox-bot/internal/db/services"

	"github.com/bwmarrin/discordgo"
)

var (
	ownerIDs sync.Map // user ID -> struct{}, filled once from the application
	loadOnce sync.Mutex
	loaded   bool

	snowflake = regexp.MustCompile(`^[0-9]{1,20}$`)
	dmOnly    = &[]discordgo.InteractionContextType{discordgo.InteractionContextBotDM}
)

var Beta = &discordgo.ApplicationCommand{
	Name:        "beta",
	Description: "Manage the beta program (bot owner, in a DM with the bot)",
	Contexts:    dmOnly,
	Options: []*discordgo.ApplicationCommandOption{
		{Type: discordgo.ApplicationCommandOptionSubCommand, Name: "status", Description: "Show how beta access is set up"},
		{
			Type: discordgo.ApplicationCommandOptionSubCommand, Name: "set", Description: "Choose the beta server and the Beta Tester role",
			Options: []*discordgo.ApplicationCommandOption{
				{Type: discordgo.ApplicationCommandOptionString, Name: "server-id", Description: "The beta server's ID (the bot must be in it)", Required: true, MaxLength: 20},
				{Type: discordgo.ApplicationCommandOptionString, Name: "role-id", Description: "The Beta Tester role's ID in that server", Required: true, MaxLength: 20},
			},
		},
		{Type: discordgo.ApplicationCommandOptionSubCommand, Name: "off", Description: "Turn beta features off for everyone (clears the role)"},
		{Type: discordgo.ApplicationCommandOptionSubCommand, Name: "servers", Description: "List the servers that opted in to beta features"},
		{
			Type: discordgo.ApplicationCommandOptionSubCommand, Name: "remove-server", Description: "Take a server out of the beta",
			Options: []*discordgo.ApplicationCommandOption{
				{Type: discordgo.ApplicationCommandOptionString, Name: "server-id", Description: "The server's ID", Required: true, MaxLength: 20},
			},
		},
	},
}

// isOwner reports whether the user owns the bot's Discord application (or is
// on its team). If the application can't be read, nobody is the owner.
func isOwner(s *discordgo.Session, userID string) bool {
	if userID == "" {
		return false
	}
	loadOnce.Lock()
	if !loaded {
		app, err := s.Application("@me")
		if err == nil && app != nil {
			if app.Owner != nil {
				ownerIDs.Store(app.Owner.ID, struct{}{})
			}
			if app.Team != nil {
				ownerIDs.Store(app.Team.OwnerID, struct{}{})
				for _, m := range app.Team.Members {
					if m != nil && m.User != nil {
						ownerIDs.Store(m.User.ID, struct{}{})
					}
				}
			}
			loaded = true
		}
	}
	loadOnce.Unlock()
	_, ok := ownerIDs.Load(userID)
	return ok
}

func reply(s *discordgo.Session, i *discordgo.InteractionCreate, msg string) {
	_ = s.InteractionRespond(i.Interaction, &discordgo.InteractionResponse{
		Type: discordgo.InteractionResponseChannelMessageWithSource,
		Data: &discordgo.InteractionResponseData{Content: msg, AllowedMentions: &discordgo.MessageAllowedMentions{}},
	})
}

func guildName(s *discordgo.Session, id string) string {
	if g, err := s.State.Guild(id); err == nil && g != nil && g.Name != "" {
		return g.Name
	}
	if g, err := s.Guild(id); err == nil && g != nil {
		return g.Name
	}
	return "unknown server"
}

func Handler(s *discordgo.Session, i *discordgo.InteractionCreate) {
	userID := ""
	switch {
	case i.User != nil:
		userID = i.User.ID
	case i.Member != nil && i.Member.User != nil:
		userID = i.Member.User.ID
	}
	if !isOwner(s, userID) {
		reply(s, i, "Only the bot's owner can use this command.")
		return
	}
	if i.GuildID != "" {
		reply(s, i, "Use this command in a direct message with me, not in a server.")
		return
	}
	svc := services.Global
	if svc == nil || svc.BetaSettings == nil {
		reply(s, i, "Beta settings aren't available right now.")
		return
	}
	data := i.ApplicationCommandData()
	if len(data.Options) == 0 {
		return
	}
	sub := data.Options[0]
	args := map[string]*discordgo.ApplicationCommandInteractionDataOption{}
	for _, o := range sub.Options {
		args[o.Name] = o
	}
	ctx, cancel := context.WithTimeout(context.Background(), 20*time.Second)
	defer cancel()
	fail := func(err error) {
		reply(s, i, "Something went wrong. Try again in a moment.")
		log.Printf("beta %s: %v", sub.Name, err)
	}

	switch sub.Name {
	case "status":
		guildID, roleID, err := svc.BetaSettings.Get(ctx)
		if err != nil {
			fail(err)
			return
		}
		opted, _ := svc.BetaSettings.OptedIn(ctx)
		var b strings.Builder
		switch {
		case guildID == "":
			b.WriteString("No beta server is set. Choose one with `/beta set`.\n")
		case roleID == "":
			fmt.Fprintf(&b, "Beta server: **%s** (`%s`).\nNo Beta Tester role is set, so beta features are locked for everyone. Set one with `/beta set`.\n", guildName(s, guildID), guildID)
		default:
			fmt.Fprintf(&b, "Beta server: **%s** (`%s`).\nBeta Tester role: `%s`. Members of the beta server who have it are testers.\n", guildName(s, guildID), guildID, roleID)
		}
		fmt.Fprintf(&b, "%d other server(s) opted in. The bot is using: server `%s`, %d opted-in server(s).", len(opted), beta.GuildID(), len(beta.Servers()))
		reply(s, i, b.String())
	case "set":
		guildArg, roleArg := strings.TrimSpace(args["server-id"].StringValue()), strings.TrimSpace(args["role-id"].StringValue())
		if !snowflake.MatchString(guildArg) || !snowflake.MatchString(roleArg) {
			reply(s, i, "Both IDs must be numbers. In Discord, turn on Developer Mode, then right-click the server or role and choose Copy ID.")
			return
		}
		roles, err := s.GuildRoles(guildArg)
		if err != nil {
			reply(s, i, "I couldn't read that server. Check the ID, and that I'm in it.")
			return
		}
		found := false
		for _, r := range roles {
			if r.ID == roleArg && r.ID != guildArg && !r.Managed {
				found = true
			}
		}
		if !found {
			reply(s, i, "That role isn't a normal role of that server.")
			return
		}
		g, _ := strconv.ParseInt(guildArg, 10, 64)
		r, _ := strconv.ParseInt(roleArg, 10, 64)
		by, _ := strconv.ParseInt(userID, 10, 64)
		if err := svc.BetaSettings.SetServer(ctx, g, r, by); err != nil {
			fail(err)
			return
		}
		reply(s, i, fmt.Sprintf("Saved. **%s** is the beta server, and members with the role `%s` are beta testers. The bot picks this up within 30 seconds.", guildName(s, guildArg), roleArg))
	case "off":
		guildID, _, err := svc.BetaSettings.Get(ctx)
		if err != nil {
			fail(err)
			return
		}
		if guildID == "" {
			reply(s, i, "No beta server is set, so beta features are already off.")
			return
		}
		g, _ := strconv.ParseInt(guildID, 10, 64)
		by, _ := strconv.ParseInt(userID, 10, 64)
		if err := svc.BetaSettings.SetServer(ctx, g, 0, by); err != nil {
			fail(err)
			return
		}
		reply(s, i, "Beta features are off for everyone. Choose a role again with `/beta set` to turn them back on.")
	case "servers":
		opted, err := svc.BetaSettings.OptedIn(ctx)
		if err != nil {
			fail(err)
			return
		}
		if len(opted) == 0 {
			reply(s, i, "No other server has opted in. A server's owner does that with `/config beta-features`.")
			return
		}
		var b strings.Builder
		for _, id := range opted {
			fmt.Fprintf(&b, "• %s (`%s`)\n", guildName(s, id), id)
		}
		out := b.String()
		if r := []rune(out); len(r) > 1900 {
			out = string(r[:1899]) + "…"
		}
		reply(s, i, "**Servers in the beta**\n"+out)
	case "remove-server":
		id := strings.TrimSpace(args["server-id"].StringValue())
		if !snowflake.MatchString(id) {
			reply(s, i, "The ID must be a number.")
			return
		}
		g, _ := strconv.ParseInt(id, 10, 64)
		by, _ := strconv.ParseInt(userID, 10, 64)
		if err := svc.BetaSettings.SetOptedIn(ctx, g, by, false); err != nil {
			fail(err)
			return
		}
		reply(s, i, "Removed. Its beta commands disappear within a minute. Only that server's owner can put it back.")
	}
}