package events

import (
	"context"
	"log"
	"strconv"

	"velox-bot/internal/db/repos/schedulerepo"
	"velox-bot/internal/db/services"

	"github.com/bwmarrin/discordgo"
)

// HandleMessageReactionAdd reacts to emoji on schedule DM messages:
// ✅ accept, ❌ decline, 🔁 request reschedule.
func HandleMessageReactionAdd(s *discordgo.Session, r *discordgo.MessageReactionAdd, svc *services.Services) {
	if svc == nil || svc.Schedule == nil {
		return
	}
	if r == nil || r.UserID == "" || r.MessageID == "" {
		return
	}

	// Ignore bot reactions.
	if r.Member != nil && r.Member.User != nil && r.Member.User.Bot {
		return
	}

	msgID64, err := strconv.ParseInt(r.MessageID, 10, 64)
	if err != nil || msgID64 == 0 {
		return
	}

	ctx := context.Background()
	sch, err := svc.Schedule.GetByMessageID(ctx, msgID64)
	if err != nil || sch == nil {
		return
	}

	// Only invitee can react to change status.
	if r.UserID != strconv.FormatInt(sch.InviteeID, 10) {
		return
	}

	// Only pending can be transitioned by reaction.
	if sch.Status != schedulerepo.StatusPending {
		return
	}

	var newStatus schedulerepo.ScheduleStatus
	switch r.Emoji.Name {
	case "✅":
		newStatus = schedulerepo.StatusAccepted
	case "❌":
		newStatus = schedulerepo.StatusDeclined
	case "🔁":
		newStatus = schedulerepo.StatusRescheduleRequested
	default:
		return
	}

	if err := svc.Schedule.UpdateStatus(ctx, sch.ID, newStatus); err != nil {
		log.Printf("schedule: failed to update status id=%d: %v", sch.ID, err)
		return
	}

	statusText := map[schedulerepo.ScheduleStatus]string{
		schedulerepo.StatusAccepted:            "accepted ✅",
		schedulerepo.StatusDeclined:            "declined ❌",
		schedulerepo.StatusRescheduleRequested: "requested rescheduling 🔁",
	}[newStatus]

	utcStr := sch.ScheduledAt.UTC().Format("2006-01-02 15:04")

	// Notify requester with local time if configured.
	if svc.UserSettings != nil {
		loc, zone, _, err := svc.UserSettings.GetTimezone(ctx, sch.RequesterID)
		if err != nil {
			loc = sch.ScheduledAt.UTC().Location()
			zone = "UTC"
		}
		localStr := sch.ScheduledAt.In(loc).Format("2006-01-02 15:04")
		content := "Your session request with <@" + strconv.FormatInt(sch.InviteeID, 10) + "> for " +
			utcStr + " UTC (" + localStr + " " + zone + ") has been " + statusText + "."

		requesterID := strconv.FormatInt(sch.RequesterID, 10)
		dmCh, err := s.UserChannelCreate(requesterID)
		if err == nil {
			if _, err := s.ChannelMessageSend(dmCh.ID, content); err != nil {
				log.Printf("schedule: failed to DM requester about status change: %v", err)
			}
		}
	}
}