package tickets

import (
	"context"
	"fmt"
	"regexp"
	"strconv"
	"strings"

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

	"github.com/bwmarrin/discordgo"
)

// Custom IDs. Everything starts with "tickets:" so the interaction router can
// hand it to this package.
const (
	idOpenPrefix     = "tickets:open:"     // older panels: one button per category, + category ID
	idSelect         = "tickets:select"    // panel dropdown
	idCreate         = "tickets:create"    // panel "Create ticket" button
	idOpenFormPrefix = "tickets:openform:" // opening form, + category ID
	idClaim          = "tickets:claim"
	idClose          = "tickets:close"
	idCloseForm      = "tickets:closeform"

	fieldSubject = "subject"
	fieldDetails = "details"
	fieldReason  = "reason"
)

var customEmojiRe = regexp.MustCompile(`^<(a?):(\w+):(\d+)>$`)

// parseEmoji accepts a Unicode emoji or a custom one written as <:name:id>.
func parseEmoji(s string) *discordgo.ComponentEmoji {
	s = strings.TrimSpace(s)
	if s == "" {
		return nil
	}
	if m := customEmojiRe.FindStringSubmatch(s); m != nil {
		return &discordgo.ComponentEmoji{Name: m[2], ID: m[3], Animated: m[1] == "a"}
	}
	return &discordgo.ComponentEmoji{Name: s}
}

// BuildPanel is the message members open tickets from: an embed with the
// guild's text and each category's description, a dropdown to pick the
// category, and a Create ticket button that opens the form for that pick.
func BuildPanel(s *ticketrepo.Settings, cats []ticketrepo.Category) (*discordgo.MessageEmbed, []discordgo.MessageComponent) {
	embed := &discordgo.MessageEmbed{
		Title:       clip(s.PanelTitle, 256),
		Description: clip(s.PanelDescription, 4000),
		Color:       accent,
	}
	if len(cats) > maxCategories {
		cats = cats[:maxCategories]
	}

	opts := make([]discordgo.SelectMenuOption, 0, len(cats))
	for _, c := range cats {
		opts = append(opts, discordgo.SelectMenuOption{
			Label:       clip(c.Name, 100),
			Value:       id(c.ID),
			Description: clip(c.Description, 100),
			Emoji:       parseEmoji(c.Emoji),
		})
		if c.Description != "" {
			embed.Fields = append(embed.Fields, &discordgo.MessageEmbedField{Name: clip(c.Name, 256), Value: clip(c.Description, 1024)})
		}
	}
	return embed, []discordgo.MessageComponent{
		discordgo.ActionsRow{Components: []discordgo.MessageComponent{
			discordgo.SelectMenu{CustomID: idSelect, Placeholder: "Choose what you need help with", Options: opts},
		}},
		discordgo.ActionsRow{Components: []discordgo.MessageComponent{
			discordgo.Button{Label: "Create ticket", Style: discordgo.PrimaryButton, CustomID: idCreate, Emoji: &discordgo.ComponentEmoji{Name: "🎫"}},
		}},
	}
}

// PostPanel posts the panel in the ticket channel, or updates the one it
// posted before, and returns where it ended up.
func PostPanel(ctx context.Context, d Discord, st Store, guildID int64) (*discordgo.Message, error) {
	s, err := st.GetSettings(ctx, guildID)
	if err != nil {
		return nil, err
	}
	if s.ChannelID == 0 {
		return nil, ErrNotSetUp
	}
	cats, err := st.ListCategories(ctx, guildID)
	if err != nil {
		return nil, err
	}
	if len(cats) == 0 {
		return nil, ErrNoCategories
	}
	embed, comps := BuildPanel(s, cats)

	if s.PanelMessageID != 0 {
		embeds := []*discordgo.MessageEmbed{embed}
		msg, err := d.ChannelMessageEditComplex(&discordgo.MessageEdit{
			Channel:    id(s.ChannelID),
			ID:         id(s.PanelMessageID),
			Embeds:     &embeds,
			Components: &comps,
		})
		if err == nil {
			return msg, nil
		}
		// The old panel was deleted or the channel changed: post a new one.
	}

	msg, err := d.ChannelMessageSendComplex(id(s.ChannelID), &discordgo.MessageSend{
		Embeds:     []*discordgo.MessageEmbed{embed},
		Components: comps,
	})
	if err != nil {
		return nil, fmt.Errorf("posting the panel: %w", err)
	}
	if mid, err := strconv.ParseInt(msg.ID, 10, 64); err == nil {
		if err := st.SetPanelMessage(ctx, guildID, mid); err != nil {
			return msg, fmt.Errorf("saving the panel message: %w", err)
		}
	}
	return msg, nil
}

// OpenForm is the short form shown after a member picks a category.
func OpenForm(cat *ticketrepo.Category) *discordgo.InteractionResponse {
	return &discordgo.InteractionResponse{
		Type: discordgo.InteractionResponseModal,
		Data: &discordgo.InteractionResponseData{
			CustomID: idOpenFormPrefix + id(cat.ID),
			Title:    clip("Open a ticket: "+cat.Name, 45),
			Components: []discordgo.MessageComponent{
				discordgo.ActionsRow{Components: []discordgo.MessageComponent{discordgo.TextInput{
					CustomID:    fieldSubject,
					Label:       "What do you need help with?",
					Style:       discordgo.TextInputShort,
					Placeholder: "A short summary",
					Required:    true,
					MinLength:   3,
					MaxLength:   maxSubject,
				}}},
				discordgo.ActionsRow{Components: []discordgo.MessageComponent{discordgo.TextInput{
					CustomID:    fieldDetails,
					Label:       "Details",
					Style:       discordgo.TextInputParagraph,
					Placeholder: "Anything the staff should know (optional)",
					Required:    false,
					MaxLength:   maxDetails,
				}}},
			},
		},
	}
}

// CloseForm asks for an optional reason before closing.
func CloseForm() *discordgo.InteractionResponse {
	return &discordgo.InteractionResponse{
		Type: discordgo.InteractionResponseModal,
		Data: &discordgo.InteractionResponseData{
			CustomID: idCloseForm,
			Title:    "Close this ticket",
			Components: []discordgo.MessageComponent{
				discordgo.ActionsRow{Components: []discordgo.MessageComponent{discordgo.TextInput{
					CustomID:  fieldReason,
					Label:     "Reason (optional)",
					Style:     discordgo.TextInputParagraph,
					Required:  false,
					MaxLength: maxReason,
				}}},
			},
		},
	}
}