package notifications

import (
	"context"
	"encoding/json"
	"errors"

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

	"shared-album/internal/models"
)

var ErrNotFound = errors.New("not found")

type Store struct {
	pool *pgxpool.Pool
}

func NewStore(pool *pgxpool.Pool) *Store { return &Store{pool: pool} }

func (s *Store) Create(ctx context.Context, n *models.Notification) error {
	payload, err := json.Marshal(n.PayloadJSON)
	if err != nil {
		return err
	}
	return s.pool.QueryRow(ctx,
		`INSERT INTO notifications (id, user_id, type, payload_json)
		 VALUES ($1, $2, $3, $4)
		 RETURNING created_at`,
		n.ID, n.UserID, n.Type, payload,
	).Scan(&n.CreatedAt)
}

func (s *Store) List(ctx context.Context, userID string, limit int) ([]models.Notification, error) {
	if limit <= 0 || limit > 200 {
		limit = 100
	}
	rows, err := s.pool.Query(ctx,
		`SELECT id, user_id, type, payload_json, read_at, created_at
		 FROM notifications
		 WHERE user_id = $1
		 ORDER BY created_at DESC
		 LIMIT $2`, userID, limit)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	out := []models.Notification{}
	for rows.Next() {
		var n models.Notification
		var payload []byte
		if err := rows.Scan(&n.ID, &n.UserID, &n.Type, &payload, &n.ReadAt, &n.CreatedAt); err != nil {
			return nil, err
		}
		_ = json.Unmarshal(payload, &n.PayloadJSON)
		out = append(out, n)
	}
	return out, rows.Err()
}

func (s *Store) MarkRead(ctx context.Context, id, userID string) error {
	tag, err := s.pool.Exec(ctx,
		`UPDATE notifications SET read_at = now() WHERE id = $1 AND user_id = $2 AND read_at IS NULL`,
		id, userID)
	if err != nil {
		return err
	}
	if tag.RowsAffected() == 0 {
		var exists bool
		if err := s.pool.QueryRow(ctx, `SELECT true FROM notifications WHERE id = $1 AND user_id = $2`, id, userID).Scan(&exists); err != nil {
			if errors.Is(err, pgx.ErrNoRows) {
				return ErrNotFound
			}
			return err
		}
	}
	return nil
}