package channels

import (
	"context"
	"fmt"
	"time"

	"github.com/jackc/pgx/v5/pgxpool"
)

type InAppNotification struct {
	ID         string
	TenantSlug string
	UserID     string
	Title      string
	Body       string
	ReadAt     *time.Time
	CreatedAt  time.Time
}

// InAppStore persistiert In-App-Benachrichtigungen (Akzeptanzkriterium 2).
type InAppStore struct {
	pool *pgxpool.Pool
}

func NewInAppStore(pool *pgxpool.Pool) *InAppStore {
	return &InAppStore{pool: pool}
}

func (s *InAppStore) Create(ctx context.Context, tenantSlug, userID, title, body string) (string, error) {
	var id string
	err := s.pool.QueryRow(ctx, `
		INSERT INTO in_app_notifications (tenant_slug, user_id, title, body)
		VALUES ($1, $2, $3, $4)
		RETURNING id
	`, tenantSlug, userID, title, body).Scan(&id)
	if err != nil {
		return "", fmt.Errorf("in-app-benachrichtigung speichern: %w", err)
	}
	return id, nil
}

// ListForUser liefert alle Benachrichtigungen eines Benutzers (ueber API
// abrufbar, Akzeptanzkriterium 2).
func (s *InAppStore) ListForUser(ctx context.Context, tenantSlug, userID string) ([]InAppNotification, error) {
	rows, err := s.pool.Query(ctx, `
		SELECT id, title, body, read_at, created_at FROM in_app_notifications
		WHERE tenant_slug = $1 AND user_id = $2 ORDER BY created_at DESC
	`, tenantSlug, userID)
	if err != nil {
		return nil, fmt.Errorf("benachrichtigungen auflisten: %w", err)
	}
	defer rows.Close()

	var out []InAppNotification
	for rows.Next() {
		n := InAppNotification{TenantSlug: tenantSlug, UserID: userID}
		if err := rows.Scan(&n.ID, &n.Title, &n.Body, &n.ReadAt, &n.CreatedAt); err != nil {
			return nil, fmt.Errorf("benachrichtigung lesen: %w", err)
		}
		out = append(out, n)
	}
	return out, rows.Err()
}

// MarkRead markiert eine Benachrichtigung als gelesen (Akzeptanzkriterium 2
// / Pruefung 2).
func (s *InAppStore) MarkRead(ctx context.Context, id string) error {
	_, err := s.pool.Exec(ctx, `UPDATE in_app_notifications SET read_at = now() WHERE id = $1`, id)
	if err != nil {
		return fmt.Errorf("als gelesen markieren: %w", err)
	}
	return nil
}