package storage

import (
	"database/sql"
	"fmt"

	_ "github.com/lib/pq"
)

type postgres struct {
	db *sql.DB
}

func New(dsn string) (Service, error) {
	pool, err := sql.Open("postgres", dsn)
	if err != nil {
		return nil, fmt.Errorf("could not open database connection: %v", err)
	}
	return &postgres{pool}, nil
}

func (s *postgres) Close() error {
	return s.db.Close()
}

func (s *postgres) Subscribe(topic string, sub Subscriber) error {
	_, err := s.db.Exec(
		`INSERT INTO "subscribers" ("topic", "callback", "lease_seconds", "secret", "created") VALUES (?, ?, ?, ?, now())`,
		topic,
		sub.Callback,
		sub.LeaseSeconds,
		sub.Secret,
	)
	return err
}

func (s *postgres) Unsubscribe(topic, callback string) error {
	_, err := s.db.Exec(
		`DELETE FROM "subscribers" WHERE "topic" = ? AND "callback" = ?`,
		topic,
		callback,
	)
	return err
}

func (s *postgres) Subscribers(topic string) ([]Subscriber, error) {
	rows, err := s.db.Query(`SELECT callback, lease_seconds, secret, created FROM "subscribers"`)
	if err != nil {
		return nil, err
	}

	var subscribers []Subscriber
	for rows.Next() {
		var sub Subscriber
		err := rows.Scan(&sub.Callback, &sub.LeaseSeconds, &sub.Secret, &sub.Created)
		if err != nil {
			return nil, err
		}
		subscribers = append(subscribers, sub)
	}
	return subscribers, nil
}