package notification

import (
	"context"
	"database/sql"
	"errors"
	"fmt"
	"time"
)

var ErrNotFound = fmt.Errorf("notification not found")

type Notification struct {
	ID          int64     `json:"id"`
	VolunteerID int64     `json:"volunteer_id"`
	Message     string    `json:"message"`
	Read        bool      `json:"read"`
	CreatedAt   time.Time `json:"created_at"`
}

type Store struct {
	db *sql.DB
}

func NewStore(db *sql.DB) *Store {
	return &Store{db: db}
}

func (s *Store) Create(ctx context.Context, volunteerID int64, message string) (*Notification, error) {
	res, err := s.db.ExecContext(ctx,
		`INSERT INTO notifications (volunteer_id, message) VALUES (?, ?)`,
		volunteerID, message,
	)
	if err != nil {
		return nil, fmt.Errorf("insert notification: %w", err)
	}
	id, _ := res.LastInsertId()
	return s.GetByID(ctx, id)
}

func (s *Store) GetByID(ctx context.Context, id int64) (*Notification, error) {
	n := &Notification{}
	var createdAt string
	err := s.db.QueryRowContext(ctx,
		`SELECT id, volunteer_id, message, read, created_at FROM notifications WHERE id = ?`, id,
	).Scan(&n.ID, &n.VolunteerID, &n.Message, &n.Read, &createdAt)
	if errors.Is(err, sql.ErrNoRows) {
		return nil, ErrNotFound
	}
	if err != nil {
		return nil, fmt.Errorf("get notification: %w", err)
	}
	n.CreatedAt, _ = time.Parse("2006-01-02 15:04:05", createdAt)
	return n, nil
}

func (s *Store) ListForVolunteer(ctx context.Context, volunteerID int64) ([]Notification, error) {
	rows, err := s.db.QueryContext(ctx,
		`SELECT id, volunteer_id, message, read, created_at FROM notifications WHERE volunteer_id = ? ORDER BY created_at DESC`,
		volunteerID,
	)
	if err != nil {
		return nil, fmt.Errorf("list notifications: %w", err)
	}
	defer rows.Close()

	var notifications []Notification
	for rows.Next() {
		var n Notification
		var createdAt string
		if err := rows.Scan(&n.ID, &n.VolunteerID, &n.Message, &n.Read, &createdAt); err != nil {
			return nil, err
		}
		n.CreatedAt, _ = time.Parse("2006-01-02 15:04:05", createdAt)
		notifications = append(notifications, n)
	}
	return notifications, rows.Err()
}

func (s *Store) MarkRead(ctx context.Context, id, volunteerID int64) (*Notification, error) {
	result, err := s.db.ExecContext(ctx,
		`UPDATE notifications SET read = 1 WHERE id = ? AND volunteer_id = ?`,
		id, volunteerID,
	)
	if err != nil {
		return nil, fmt.Errorf("mark read: %w", err)
	}
	affected, _ := result.RowsAffected()
	if affected == 0 {
		return nil, ErrNotFound
	}
	return s.GetByID(ctx, id)
}