package settings

import (
	"context"
	"errors"
	"fmt"

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

// Store is the PostgreSQL implementation of Repository.
type Store struct {
	pool *pgxpool.Pool
}

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

func (s *Store) Get(ctx context.Context, key string) (string, bool, error) {
	var v string
	err := s.pool.QueryRow(ctx, `SELECT value FROM app_settings WHERE key = $1`, key).Scan(&v)
	if err != nil {
		if errors.Is(err, pgx.ErrNoRows) {
			return "", false, nil
		}
		return "", false, err
	}
	return v, true, nil
}

func (s *Store) Set(ctx context.Context, key, value string) error {
	_, err := s.pool.Exec(ctx,
		`INSERT INTO app_settings (key, value) VALUES ($1, $2)
		 ON CONFLICT (key) DO UPDATE SET value = EXCLUDED.value, updated_at = now()`,
		key, value)
	return err
}

func (s *Store) Ensure(ctx context.Context, key string, generate func() (string, error)) (string, error) {
	if v, ok, err := s.Get(ctx, key); err != nil {
		return "", err
	} else if ok {
		return v, nil
	}
	v, err := generate()
	if err != nil {
		return "", err
	}
	if _, err := s.pool.Exec(ctx,
		`INSERT INTO app_settings (key, value) VALUES ($1, $2) ON CONFLICT (key) DO NOTHING`,
		key, v); err != nil {
		return "", err
	}
	got, ok, err := s.Get(ctx, key)
	if err != nil {
		return "", err
	}
	if !ok {
		return "", fmt.Errorf("settings: %q missing after insert", key)
	}
	return got, nil
}