package tickets

import (
	"context"
	"fmt"
	"log"
	"strconv"

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

	"github.com/bwmarrin/discordgo"
)

// CheckCanOpen runs before the form is shown, so a member who can't open a
// ticket finds out before typing anything.
func CheckCanOpen(ctx context.Context, st Store, guildID, userID, categoryID int64) (*ticketrepo.Settings, *ticketrepo.Category, error) {
	s, err := st.GetSettings(ctx, guildID)
	if err != nil {
		return nil, nil, err
	}
	if !s.Configured || s.ChannelID == 0 {
		return nil, nil, ErrNotSetUp
	}
	if !s.Enabled {
		return nil, nil, ErrDisabled
	}
	cat, err := st.GetCategory(ctx, guildID, categoryID)
	if err != nil {
		return nil, nil, err
	}
	if cat == nil {
		return nil, nil, ErrUnknownCategory
	}
	open, err := st.CountOpenByOpener(ctx, guildID, userID)
	if err != nil {
		return nil, nil, err
	}
	if open >= s.MaxOpenPerUser {
		if s.MaxOpenPerUser == 1 {
			return nil, nil, UserError("You already have an open ticket. Close it before opening another one.")
		}
		return nil, nil, UserError(fmt.Sprintf("You already have %d open tickets, the most this server allows. Close one before opening another.", open))
	}
	return s, cat, nil
}

type OpenRequest struct {
	GuildID    int64
	CategoryID int64
	User       *discordgo.User
	Subject    string
	Details    string
}

// IntroComponents are the Claim and Close buttons under a ticket's first
// message, disabled as the ticket moves on.
func IntroComponents(claimed, closed bool) []discordgo.MessageComponent {
	claimLabel := "Claim"
	if claimed {
		claimLabel = "Claimed"
	}
	return []discordgo.MessageComponent{discordgo.ActionsRow{Components: []discordgo.MessageComponent{
		discordgo.Button{Label: claimLabel, Style: discordgo.SuccessButton, CustomID: idClaim, Disabled: claimed || closed, Emoji: &discordgo.ComponentEmoji{Name: "🙋"}},
		discordgo.Button{Label: "Close", Style: discordgo.DangerButton, CustomID: idClose, Disabled: closed, Emoji: &discordgo.ComponentEmoji{Name: "🔒"}},
	}}}
}

// IntroEmbed describes the ticket at the top of its thread.
func IntroEmbed(t *ticketrepo.Ticket, details string) *discordgo.MessageEmbed {
	desc := "**" + clip(t.Subject, maxSubject) + "**"
	if details != "" {
		desc += "\n\n" + clip(details, maxDetails)
	}
	claimed := "Nobody yet"
	if t.ClaimedBy != 0 {
		claimed = "<@" + id(t.ClaimedBy) + ">"
	}
	e := &discordgo.MessageEmbed{
		Title:       fmt.Sprintf("Ticket #%04d · %s", t.Number, clip(t.CategoryName, 60)),
		Description: desc,
		Color:       accent,
		Fields: []*discordgo.MessageEmbedField{
			{Name: "Opened by", Value: "<@" + id(t.OpenerID) + ">", Inline: true},
			{Name: "Claimed by", Value: claimed, Inline: true},
		},
		Footer: &discordgo.MessageEmbedFooter{Text: "Staff can claim this ticket. Anyone here can close it once it's sorted."},
	}
	if t.Status == ticketrepo.StatusClosed {
		e.Footer.Text = "This ticket is closed."
	}
	return e
}

// Open creates the ticket: a private thread in the ticket channel with the
// opener added, a first message that mentions the category's staff role
// (which adds that role's members to the thread), and the database row.
func Open(ctx context.Context, d Discord, st Store, req OpenRequest) (*discordgo.Channel, error) {
	s, cat, err := CheckCanOpen(ctx, st, req.GuildID, mustID(req.User.ID), req.CategoryID)
	if err != nil {
		return nil, err
	}

	number, err := st.NextNumber(ctx, req.GuildID)
	if err != nil {
		return nil, err
	}

	name := req.User.GlobalName
	if name == "" {
		name = req.User.Username
	}
	thread, err := d.ThreadStartComplex(id(s.ChannelID), &discordgo.ThreadStart{
		Name:                ThreadName(cat.Name, number, name),
		Type:                discordgo.ChannelTypeGuildPrivateThread,
		AutoArchiveDuration: autoArchiveWeek,
		Invitable:           false, // only staff can add people
	})
	if err != nil {
		return nil, fmt.Errorf("creating the thread: %w", err)
	}
	// From here on a failure leaves an empty thread behind unless it's removed.
	fail := func(err error) (*discordgo.Channel, error) {
		if _, derr := d.ChannelDelete(thread.ID); derr != nil {
			log.Printf("tickets: removing thread %s after a failed open: %v", thread.ID, derr)
		}
		return nil, err
	}

	if err := d.ThreadMemberAdd(thread.ID, req.User.ID); err != nil {
		return fail(fmt.Errorf("adding the opener: %w", err))
	}

	t := &ticketrepo.Ticket{
		GuildID:      req.GuildID,
		Number:       number,
		CategoryID:   cat.ID,
		CategoryName: cat.Name,
		OpenerID:     mustID(req.User.ID),
		Subject:      clip(req.Subject, maxSubject),
		Status:       ticketrepo.StatusOpen,
	}
	content := "<@" + req.User.ID + ">"
	mentions := &discordgo.MessageAllowedMentions{Users: []string{req.User.ID}}
	if cat.StaffRoleID != 0 {
		content += " <@&" + id(cat.StaffRoleID) + ">"
		mentions.Roles = []string{id(cat.StaffRoleID)}
	}
	intro, err := d.ChannelMessageSendComplex(thread.ID, &discordgo.MessageSend{
		Content:         content,
		Embeds:          []*discordgo.MessageEmbed{IntroEmbed(t, req.Details)},
		Components:      IntroComponents(false, false),
		AllowedMentions: mentions,
	})
	if err != nil {
		return fail(fmt.Errorf("posting the first message: %w", err))
	}

	t.ThreadID = mustID(thread.ID)
	t.IntroMessage = mustID(intro.ID)
	if _, err := st.CreateTicket(ctx, *t); err != nil {
		return fail(fmt.Errorf("saving the ticket: %w", err))
	}
	return thread, nil
}

// mustID parses a snowflake that came from Discord; those are always valid.
func mustID(s string) int64 {
	n, _ := strconv.ParseInt(s, 10, 64)
	return n
}