package public

import (
	"context"
	"errors"
	"fmt"
	"log"
	"strconv"
	"strings"
	"time"

	"velox-bot/internal/db/repos/ticketrepo"
	"velox-bot/internal/tickets"

	"github.com/bwmarrin/discordgo"
)

// The session must provide everything the ticket flows call.
var _ tickets.Discord = (*discordgo.Session)(nil)

// Repo is the full ticket store, including the admin calls that only the
// slash commands make. Set by Init.
var Repo *ticketrepo.Repo

func Init(r *ticketrepo.Repo) {
	Repo = r
	tickets.Init(r)
}

var (
	manageGuild   = int64(discordgo.PermissionManageGuild)
	guildOnly     = &[]discordgo.InteractionContextType{discordgo.InteractionContextGuild}
	textChannels  = []discordgo.ChannelType{discordgo.ChannelTypeGuildText}
	opTimeout     = 2 * time.Minute
	genericFailed = "Something went wrong. Try again in a moment, and tell an admin if it keeps happening."
)

// Tickets is the admin command for setting the system up.
var Tickets = &discordgo.ApplicationCommand{
	Name:                     "tickets",
	Description:              "Set up support tickets",
	DefaultMemberPermissions: &manageGuild,
	Contexts:                 guildOnly,
	Options: []*discordgo.ApplicationCommandOption{
		{
			Type:        discordgo.ApplicationCommandOptionSubCommand,
			Name:        "setup",
			Description: "Choose where tickets are opened and where closed tickets are logged",
			Options: []*discordgo.ApplicationCommandOption{
				{Type: discordgo.ApplicationCommandOptionChannel, Name: "channel", Description: "Where the panel goes and ticket threads are created", Required: true, ChannelTypes: textChannels},
				{Type: discordgo.ApplicationCommandOptionChannel, Name: "log-channel", Description: "Where closed tickets and their transcripts are posted", ChannelTypes: textChannels},
				{Type: discordgo.ApplicationCommandOptionRole, Name: "staff-role", Description: "Creates a Support category handled by this role, if there are no categories yet"},
			},
		},
		{
			Type:        discordgo.ApplicationCommandOptionSubCommandGroup,
			Name:        "category",
			Description: "Manage ticket categories",
			Options: []*discordgo.ApplicationCommandOption{
				{
					Type:        discordgo.ApplicationCommandOptionSubCommand,
					Name:        "add",
					Description: "Add a category (one button on the panel)",
					Options: []*discordgo.ApplicationCommandOption{
						{Type: discordgo.ApplicationCommandOptionString, Name: "name", Description: "e.g. Support, Report, Appeal", Required: true, MaxLength: 40},
						{Type: discordgo.ApplicationCommandOptionRole, Name: "staff-role", Description: "Who handles these tickets"},
						{Type: discordgo.ApplicationCommandOptionString, Name: "emoji", Description: "Shown on the button", MaxLength: 64},
						{Type: discordgo.ApplicationCommandOptionString, Name: "description", Description: "Shown on the panel", MaxLength: 200},
					},
				},
				{
					Type:        discordgo.ApplicationCommandOptionSubCommand,
					Name:        "remove",
					Description: "Remove a category",
					Options: []*discordgo.ApplicationCommandOption{
						{Type: discordgo.ApplicationCommandOptionString, Name: "name", Description: "The category's name", Required: true},
					},
				},
				{Type: discordgo.ApplicationCommandOptionSubCommand, Name: "list", Description: "Show the categories"},
			},
		},
		{
			Type:        discordgo.ApplicationCommandOptionSubCommand,
			Name:        "panel",
			Description: "Post the ticket panel, or update it after changing categories",
		},
	},
}

// Ticket is used inside a ticket thread.
var Ticket = &discordgo.ApplicationCommand{
	Name:        "ticket",
	Description: "Manage the ticket you're in",
	Contexts:    guildOnly,
	Options: []*discordgo.ApplicationCommandOption{
		{
			Type: discordgo.ApplicationCommandOptionSubCommand, Name: "add", Description: "Add someone to this ticket",
			Options: []*discordgo.ApplicationCommandOption{{Type: discordgo.ApplicationCommandOptionUser, Name: "user", Description: "Who to add", Required: true}},
		},
		{
			Type: discordgo.ApplicationCommandOptionSubCommand, Name: "remove", Description: "Remove someone from this ticket (staff only)",
			Options: []*discordgo.ApplicationCommandOption{{Type: discordgo.ApplicationCommandOptionUser, Name: "user", Description: "Who to remove", Required: true}},
		},
		{Type: discordgo.ApplicationCommandOptionSubCommand, Name: "claim", Description: "Take this ticket (staff only)"},
		{
			Type: discordgo.ApplicationCommandOptionSubCommand, Name: "close", Description: "Close this ticket",
			Options: []*discordgo.ApplicationCommandOption{{Type: discordgo.ApplicationCommandOptionString, Name: "reason", Description: "Why it's being closed", MaxLength: 300}},
		},
	},
}

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

func deferReply(s *discordgo.Session, i *discordgo.InteractionCreate) bool {
	err := s.InteractionRespond(i.Interaction, &discordgo.InteractionResponse{
		Type: discordgo.InteractionResponseDeferredChannelMessageWithSource,
		Data: &discordgo.InteractionResponseData{Flags: discordgo.MessageFlagsEphemeral},
	})
	return err == nil
}

func edit(s *discordgo.Session, i *discordgo.InteractionCreate, msg string) {
	_, _ = s.InteractionResponseEdit(i.Interaction, &discordgo.WebhookEdit{Content: &msg, AllowedMentions: &discordgo.MessageAllowedMentions{}})
}

// message turns an error into what the user sees; unexpected ones are logged.
func message(where string, err error) string {
	var ue tickets.UserError
	if errors.As(err, &ue) {
		return string(ue)
	}
	log.Printf("tickets: %s: %v", where, err)
	return genericFailed
}

func actor(i *discordgo.InteractionCreate) tickets.Actor {
	a := tickets.Actor{Member: i.Member}
	if i.Member != nil {
		a.Perms = i.Member.Permissions
	}
	return a
}

func guildID(i *discordgo.InteractionCreate) int64 {
	n, _ := strconv.ParseInt(i.GuildID, 10, 64)
	return n
}

func TicketsHandler(s *discordgo.Session, i *discordgo.InteractionCreate) {
	if Repo == nil {
		reply(s, i, "Tickets aren't available right now.")
		return
	}
	data := i.ApplicationCommandData()
	if len(data.Options) == 0 {
		return
	}
	sub := data.Options[0]
	switch sub.Name {
	case "setup":
		handleSetup(s, i, sub.Options)
	case "panel":
		handlePanel(s, i)
	case "category":
		if len(sub.Options) == 0 {
			return
		}
		switch sub.Options[0].Name {
		case "add":
			handleCategoryAdd(s, i, sub.Options[0].Options)
		case "remove":
			handleCategoryRemove(s, i, sub.Options[0].Options)
		case "list":
			handleCategoryList(s, i)
		}
	}
}

func opts(o []*discordgo.ApplicationCommandInteractionDataOption) map[string]*discordgo.ApplicationCommandInteractionDataOption {
	m := map[string]*discordgo.ApplicationCommandInteractionDataOption{}
	for _, x := range o {
		m[x.Name] = x
	}
	return m
}

// permissionWarning names what the bot is missing in a channel, or "".
func permissionWarning(s *discordgo.Session, channelID string, need int64, what string) string {
	have, err := s.UserChannelPermissions(s.State.User.ID, channelID)
	if err != nil {
		return ""
	}
	if missing := tickets.MissingPerms(have, need); len(missing) > 0 {
		return fmt.Sprintf("\n⚠️ I'm missing these permissions in <#%s> (%s): %s.", channelID, what, strings.Join(missing, ", "))
	}
	return ""
}

func handleSetup(s *discordgo.Session, i *discordgo.InteractionCreate, o []*discordgo.ApplicationCommandInteractionDataOption) {
	ctx, cancel := context.WithTimeout(context.Background(), opTimeout)
	defer cancel()
	args := opts(o)
	g := guildID(i)

	ch := args["channel"].ChannelValue(nil).ID
	var logID int64
	logMention := "none"
	if l, ok := args["log-channel"]; ok {
		lc := l.ChannelValue(nil).ID
		logID, _ = strconv.ParseInt(lc, 10, 64)
		logMention = "<#" + lc + ">"
	}
	chID, _ := strconv.ParseInt(ch, 10, 64)
	if err := Repo.SetChannels(ctx, g, chID, logID); err != nil {
		reply(s, i, message("setup", err))
		return
	}

	cats, err := Repo.ListCategories(ctx, g)
	if err != nil {
		reply(s, i, message("setup", err))
		return
	}
	created := ""
	if r, ok := args["staff-role"]; ok && len(cats) == 0 {
		role := r.RoleValue(nil, i.GuildID)
		roleID, _ := strconv.ParseInt(role.ID, 10, 64)
		if _, err := Repo.AddCategory(ctx, ticketrepo.Category{GuildID: g, Name: "Support", Emoji: "🎫", StaffRoleID: roleID}); err != nil {
			reply(s, i, message("setup", err))
			return
		}
		created = fmt.Sprintf("\nCreated a **Support** category handled by <@&%s>.", role.ID)
		cats = append(cats, ticketrepo.Category{Name: "Support"})
	}

	msg := fmt.Sprintf("Tickets will open as private threads in <#%s>. Closed tickets are logged to %s.%s", ch, logMention, created)
	msg += permissionWarning(s, ch, tickets.NeedTicketChannel, "ticket channel")
	if logID != 0 {
		msg += permissionWarning(s, strconv.FormatInt(logID, 10), tickets.NeedLogChannel, "log channel")
	}
	if len(cats) == 0 {
		msg += "\nNext: add a category with `/tickets category add`, then post the panel with `/tickets panel`."
	} else {
		msg += "\nNext: post the panel with `/tickets panel`."
	}
	msg += "\nTip: give your staff role **Manage Threads** in that channel so they can see every ticket, even ones they weren't pinged in."
	reply(s, i, msg)
}

func handlePanel(s *discordgo.Session, i *discordgo.InteractionCreate) {
	if !deferReply(s, i) {
		return
	}
	ctx, cancel := context.WithTimeout(context.Background(), opTimeout)
	defer cancel()
	msg, err := tickets.PostPanel(ctx, s, Repo, guildID(i))
	if err != nil {
		edit(s, i, message("panel", err))
		return
	}
	edit(s, i, fmt.Sprintf("The ticket panel is up: https://discord.com/channels/%s/%s/%s", i.GuildID, msg.ChannelID, msg.ID))
}

func handleCategoryAdd(s *discordgo.Session, i *discordgo.InteractionCreate, o []*discordgo.ApplicationCommandInteractionDataOption) {
	ctx, cancel := context.WithTimeout(context.Background(), opTimeout)
	defer cancel()
	args := opts(o)
	g := guildID(i)

	cats, err := Repo.ListCategories(ctx, g)
	if err != nil {
		reply(s, i, message("category add", err))
		return
	}
	name := strings.TrimSpace(args["name"].StringValue())
	for _, c := range cats {
		if strings.EqualFold(c.Name, name) {
			reply(s, i, fmt.Sprintf("There's already a category called **%s**.", c.Name))
			return
		}
	}
	if len(cats) >= 25 {
		reply(s, i, "A panel can hold at most 25 categories.")
		return
	}

	c := ticketrepo.Category{GuildID: g, Name: name}
	if r, ok := args["staff-role"]; ok {
		c.StaffRoleID, _ = strconv.ParseInt(r.RoleValue(nil, i.GuildID).ID, 10, 64)
	}
	if e, ok := args["emoji"]; ok {
		c.Emoji = strings.TrimSpace(e.StringValue())
	}
	if d, ok := args["description"]; ok {
		c.Description = strings.TrimSpace(d.StringValue())
	}
	if _, err := Repo.AddCategory(ctx, c); err != nil {
		reply(s, i, message("category add", err))
		return
	}
	reply(s, i, fmt.Sprintf("Added **%s**. Run `/tickets panel` to show it on the panel.", name))
}

func handleCategoryRemove(s *discordgo.Session, i *discordgo.InteractionCreate, o []*discordgo.ApplicationCommandInteractionDataOption) {
	ctx, cancel := context.WithTimeout(context.Background(), opTimeout)
	defer cancel()
	name := strings.TrimSpace(opts(o)["name"].StringValue())
	ok, err := Repo.DeleteCategoryByName(ctx, guildID(i), name)
	switch {
	case err != nil:
		reply(s, i, message("category remove", err))
	case !ok:
		reply(s, i, fmt.Sprintf("There's no category called **%s**.", name))
	default:
		reply(s, i, fmt.Sprintf("Removed **%s**. Open tickets keep working. Run `/tickets panel` to update the panel.", name))
	}
}

func handleCategoryList(s *discordgo.Session, i *discordgo.InteractionCreate) {
	ctx, cancel := context.WithTimeout(context.Background(), opTimeout)
	defer cancel()
	cats, err := Repo.ListCategories(ctx, guildID(i))
	if err != nil {
		reply(s, i, message("category list", err))
		return
	}
	if len(cats) == 0 {
		reply(s, i, "No categories yet. Add one with `/tickets category add`.")
		return
	}
	var b strings.Builder
	for _, c := range cats {
		line := "• "
		if c.Emoji != "" {
			line += c.Emoji + " "
		}
		line += "**" + c.Name + "**"
		if c.StaffRoleID != 0 {
			line += fmt.Sprintf(" → <@&%d>", c.StaffRoleID)
		} else {
			line += " → no staff role (only Manage Threads)"
		}
		if c.Description != "" {
			line += ": " + c.Description
		}
		b.WriteString(line + "\n")
	}
	reply(s, i, b.String())
}

func TicketHandler(s *discordgo.Session, i *discordgo.InteractionCreate) {
	if Repo == nil {
		reply(s, i, "Tickets aren't available right now.")
		return
	}
	data := i.ApplicationCommandData()
	if len(data.Options) == 0 {
		return
	}
	sub := data.Options[0]
	args := opts(sub.Options)
	ctx, cancel := context.WithTimeout(context.Background(), opTimeout)
	defer cancel()

	switch sub.Name {
	case "add", "remove":
		user := args["user"].UserValue(nil)
		if user == nil {
			return
		}
		if !deferReply(s, i) {
			return
		}
		var err error
		if sub.Name == "add" {
			err = tickets.AddMember(ctx, s, Repo, i.ChannelID, actor(i), user.ID)
		} else {
			err = tickets.RemoveMember(ctx, s, Repo, i.ChannelID, actor(i), user.ID)
		}
		if err != nil {
			edit(s, i, message("ticket "+sub.Name, err))
			return
		}
		edit(s, i, "Done.")
	case "claim":
		claim(s, i)
	case "close":
		reason := ""
		if r, ok := args["reason"]; ok {
			reason = r.StringValue()
		}
		closeTicket(s, i, reason)
	}
}

func claim(s *discordgo.Session, i *discordgo.InteractionCreate) {
	if !deferReply(s, i) {
		return
	}
	ctx, cancel := context.WithTimeout(context.Background(), opTimeout)
	defer cancel()
	if err := tickets.Claim(ctx, s, Repo, i.ChannelID, actor(i)); err != nil {
		edit(s, i, message("claim", err))
		return
	}
	edit(s, i, "You're handling this ticket now.")
}

func closeTicket(s *discordgo.Session, i *discordgo.InteractionCreate, reason string) {
	if !deferReply(s, i) {
		return
	}
	ctx, cancel := context.WithTimeout(context.Background(), opTimeout)
	defer cancel()
	if err := tickets.Close(ctx, s, Repo, i.ChannelID, actor(i), reason); err != nil {
		edit(s, i, message("close", err))
		return
	}
	edit(s, i, "Ticket closed.")
}

// HandleComponent handles the panel buttons and dropdown and the Claim and
// Close buttons in a ticket.
func HandleComponent(s *discordgo.Session, i *discordgo.InteractionCreate) {
	if Repo == nil {
		reply(s, i, "Tickets aren't available right now.")
		return
	}
	data := i.MessageComponentData()
	switch {
	case strings.HasPrefix(data.CustomID, "tickets:open:"):
		showOpenForm(s, i, strings.TrimPrefix(data.CustomID, "tickets:open:"))
	case data.CustomID == "tickets:select" && len(data.Values) > 0:
		showOpenForm(s, i, data.Values[0])
	case data.CustomID == "tickets:claim":
		claim(s, i)
	case data.CustomID == "tickets:close":
		ctx, cancel := context.WithTimeout(context.Background(), opTimeout)
		defer cancel()
		if err := tickets.CheckCanClose(ctx, Repo, i.ChannelID, actor(i)); err != nil {
			reply(s, i, message("close", err))
			return
		}
		_ = s.InteractionRespond(i.Interaction, tickets.CloseForm())
	}
}

func showOpenForm(s *discordgo.Session, i *discordgo.InteractionCreate, rawCategory string) {
	catID, err := strconv.ParseInt(rawCategory, 10, 64)
	if err != nil || i.Member == nil || i.Member.User == nil {
		return
	}
	ctx, cancel := context.WithTimeout(context.Background(), opTimeout)
	defer cancel()
	userID, _ := strconv.ParseInt(i.Member.User.ID, 10, 64)
	_, cat, err := tickets.CheckCanOpen(ctx, Repo, guildID(i), userID, catID)
	if err != nil {
		reply(s, i, message("open", err))
		return
	}
	_ = s.InteractionRespond(i.Interaction, tickets.OpenForm(cat))
}

func field(data discordgo.ModalSubmitInteractionData, name string) string {
	for _, row := range data.Components {
		r, ok := row.(*discordgo.ActionsRow)
		if !ok {
			continue
		}
		for _, c := range r.Components {
			if in, ok := c.(*discordgo.TextInput); ok && in.CustomID == name {
				return strings.TrimSpace(in.Value)
			}
		}
	}
	return ""
}

// HandleModalSubmit handles the opening and closing forms.
func HandleModalSubmit(s *discordgo.Session, i *discordgo.InteractionCreate) {
	if Repo == nil {
		reply(s, i, "Tickets aren't available right now.")
		return
	}
	data := i.ModalSubmitData()
	switch {
	case strings.HasPrefix(data.CustomID, "tickets:openform:"):
		catID, err := strconv.ParseInt(strings.TrimPrefix(data.CustomID, "tickets:openform:"), 10, 64)
		if err != nil || i.Member == nil || i.Member.User == nil {
			return
		}
		if !deferReply(s, i) {
			return
		}
		ctx, cancel := context.WithTimeout(context.Background(), opTimeout)
		defer cancel()
		thread, err := tickets.Open(ctx, s, Repo, tickets.OpenRequest{
			GuildID: guildID(i), CategoryID: catID, User: i.Member.User,
			Subject: field(data, "subject"), Details: field(data, "details"),
		})
		if err != nil {
			edit(s, i, message("open", err))
			return
		}
		edit(s, i, fmt.Sprintf("Your ticket is open: <#%s>. The staff will be with you there.", thread.ID))
	case data.CustomID == "tickets:closeform":
		closeTicket(s, i, field(data, "reason"))
	}
}