package postgres

import (
	"context"
	"fmt"
	"time"
)

// RateLimitStore manages distributed rate limit counters in Postgres.
// v0.32.0: fixed-window counter — upsert per-second bucket, check burst.
type RateLimitStore struct{}

func NewRateLimitStore() *RateLimitStore { return &RateLimitStore{} }

func (s *RateLimitStore) Allow(ctx context.Context, key string, rate float64, burst int) (bool, error) {
	// Upsert the current-second window counter and return the new token count.
	var tokens float64
	err := DB.QueryRowContext(ctx, `
		INSERT INTO rate_limit_counters (key, window_start, tokens)
		VALUES ($1, date_trunc('second', NOW()), 1)
		ON CONFLICT (key, window_start)
		DO UPDATE SET tokens = rate_limit_counters.tokens + 1
		RETURNING tokens`, key).Scan(&tokens)
	if err != nil {
		return false, fmt.Errorf("rate limit upsert: %w", err)
	}
	return tokens <= float64(burst), nil
}

func (s *RateLimitStore) Cleanup(ctx context.Context, maxAge time.Duration) error {
	_, err := DB.ExecContext(ctx, `
		DELETE FROM rate_limit_counters
		WHERE window_start < NOW() - $1 * INTERVAL '1 second'`,
		int(maxAge.Seconds()))
	return err
}