package api

import (
	"bytes"
	"encoding/json"
	"fmt"
	"log/slog"
	"time"

	"github.com/sandrodach/mindsift/internal/domain"
)

// --- MULTI-CHANNEL ALARM DISPATCHER (EMAIL, DISCORD, CUSTOM WEBHOOK) ---

func (s *Server) sendEmailNotification(toEmail, subject, bodyText string) error {
	if s.cfg.DemoMode {
		return errDemoOutgoing
	}
	cfg, err := s.smtpSettings()
	if err != nil {
		return err
	}
	if err := sendMail(cfg, toEmail, subject, bodyText); err != nil {
		step := ""
		if se, ok := err.(*smtpStepError); ok {
			step = se.Step
		}
		slog.Warn("E-Mail-Versand fehlgeschlagen", "smtp_step", step, "host", cfg.Host, "port", cfg.Port, "to", toEmail, "error", err)
		return err
	}
	return nil
}

func (s *Server) sendDiscordNotification(webhookURL, title, description, dueDate, priority string) error {
	if s.cfg.DemoMode {
		return errDemoOutgoing
	}
	allowPrivate := s.allowPrivateWebhooks()
	if err := validateWebhookURL(webhookURL, true, allowPrivate); err != nil {
		return err
	}
	httpClient := guardedClient(allowPrivate)
	payload := map[string]interface{}{
		"content": "⏰ **MindSift Aufgaben-Alarm**",
		"embeds": []map[string]interface{}{
			{
				"title":       title,
				"description": fmt.Sprintf("%s\n\n**Fällig:** %s | **Priorität:** %s", description, dueDate, priority),
				"color":       2450411,
				"footer": map[string]string{
					"text": "MindSift Alarm-System",
				},
			},
		},
	}
	body, err := json.Marshal(payload)
	if err != nil {
		return err
	}
	resp, err := httpClient.Post(webhookURL, "application/json", bytes.NewReader(body))
	if err != nil {
		return err
	}
	defer resp.Body.Close()
	if resp.StatusCode >= 400 {
		return fmt.Errorf("HTTP Status %d", resp.StatusCode)
	}
	return nil
}

func (s *Server) sendCustomWebhookNotification(webhookURL, event, title, notes, dueDate, priority string) error {
	if s.cfg.DemoMode {
		return errDemoOutgoing
	}
	allowPrivate := s.allowPrivateWebhooks()
	if err := validateWebhookURL(webhookURL, false, allowPrivate); err != nil {
		return err
	}
	httpClient := guardedClient(allowPrivate)
	payload := map[string]interface{}{
		"event":     event,
		"title":     title,
		"notes":     notes,
		"dueDate":   dueDate,
		"priority":  priority,
		"timestamp": domain.NowISO(),
	}
	body, err := json.Marshal(payload)
	if err != nil {
		return err
	}
	resp, err := httpClient.Post(webhookURL, "application/json", bytes.NewReader(body))
	if err != nil {
		return err
	}
	defer resp.Body.Close()
	if resp.StatusCode >= 400 {
		return fmt.Errorf("HTTP Status %d", resp.StatusCode)
	}
	return nil
}

// alarmDue reports whether the alarm for a due date should go out now: from the due time (09:00 for
// all-day tasks) minus the user's lead time on. Unreadable dates never fire.
func alarmDue(dueDate string, notifyBeforeMinutes int, now time.Time) bool {
	at, ok := domain.DueAlarmAt(dueDate, notifyBeforeMinutes, now.Location())
	return ok && !now.Before(at)
}

func (s *Server) startAlarmTicker() {
	ticker := time.NewTicker(60 * time.Second)
	defer ticker.Stop()

	for range ticker.C {
		alarms, err := s.store.GetDueTasksForAlarm()
		if err != nil || len(alarms) == 0 {
			continue
		}

		now := time.Now()

		for _, a := range alarms {
			if !alarmDue(a.DueDate, a.NotifyBeforeMinutes, now) {
				continue
			}
			if len(a.AlarmChannels) == 0 {
				continue
			}

			sentAny := false
			due := domain.HumanDue(a.DueDate)
			desc := a.Notes
			if desc == "" {
				desc = "Aufgabe ist jetzt fällig."
			}

			for _, ch := range a.AlarmChannels {
				switch ch {
				case "discord":
					if a.DiscordWebhookURL != "" {
						if err := s.sendDiscordNotification(a.DiscordWebhookURL, a.Title, desc, due, a.Priority); err == nil {
							sentAny = true
						}
					}
				case "webhook":
					if a.CustomWebhookURL != "" {
						if err := s.sendCustomWebhookNotification(a.CustomWebhookURL, "task_due", a.Title, desc, a.DueDate, a.Priority); err == nil {
							sentAny = true
						}
					}
				case "email":
					if a.AlarmEmail != "" {
						emailBody := fmt.Sprintf("Hallo,\n\ndeine Aufgabe in MindSift ist fällig:\n\nAufgabe: %s\nFällig am: %s\nPriorität: %s\nNotizen: %s\n", a.Title, due, a.Priority, desc)
						if err := s.sendEmailNotification(a.AlarmEmail, "⏰ Aufgabe fällig: "+a.Title, emailBody); err == nil {
							sentAny = true
						}
					}
				}
			}

			if sentAny {
				if err := s.store.MarkTaskAlarmSent(a.TaskID); err != nil {
					slog.Error("Alarm als gesendet markieren fehlgeschlagen (wird erneut gesendet)", "task_id", a.TaskID, "error", err)
				}
			} else if gaveUp, _ := s.store.RecordTaskAlarmFailure(a.TaskID); gaveUp {
				slog.Warn("Aufgaben-Alarm nach 3 Fehlversuchen aufgegeben", "task_id", a.TaskID, "title", a.Title)
			}
		}
	}
}