package ratelimit

import (
	"context"
	"testing"
	"time"

	"github.com/alicebob/miniredis/v2"
	"github.com/redis/go-redis/v9"
)

func TestRedisLimiterSharesOneChannelBudget(t *testing.T) {
	mr := miniredis.RunT(t)
	client := redis.NewClient(&redis.Options{Addr: mr.Addr()})
	limiter := NewWithClient(client)

	first, err := limiter.Wait(context.Background(), "channel-a", 20)
	if err != nil {
		t.Fatalf("first wait: %v", err)
	}
	second, err := limiter.Wait(context.Background(), "channel-a", 20)
	if err != nil {
		t.Fatalf("second wait: %v", err)
	}
	if first != 0 {
		t.Fatalf("first delay = %v, want 0", first)
	}
	if second < 40*time.Millisecond {
		t.Fatalf("second delay = %v, want a shared channel delay", second)
	}
}

func TestRedisLimiterUsesIndependentChannelBudgets(t *testing.T) {
	mr := miniredis.RunT(t)
	client := redis.NewClient(&redis.Options{Addr: mr.Addr()})
	limiter := NewWithClient(client)

	if _, err := limiter.Wait(context.Background(), "channel-a", 1); err != nil {
		t.Fatalf("channel a wait: %v", err)
	}
	delay, err := limiter.Wait(context.Background(), "channel-b", 1)
	if err != nil {
		t.Fatalf("channel b wait: %v", err)
	}
	if delay != 0 {
		t.Fatalf("channel b delay = %v, want 0", delay)
	}
}

func TestRedisLimiterConfiguredRateIsAuthoritativeUpperBound(t *testing.T) {
	mr := miniredis.RunT(t)
	client := redis.NewClient(&redis.Options{Addr: mr.Addr()})
	limiter := NewWithClient(client)

	if err := limiter.Configure(context.Background(), "channel-a", 10); err != nil {
		t.Fatalf("configure: %v", err)
	}
	if _, err := limiter.Wait(context.Background(), "channel-a", 1000); err != nil {
		t.Fatalf("first wait: %v", err)
	}
	delay, err := limiter.Wait(context.Background(), "channel-a", 1000)
	if err != nil {
		t.Fatalf("second wait: %v", err)
	}
	if delay < 90*time.Millisecond {
		t.Fatalf("delay = %v, want configured 10 TPS ceiling", delay)
	}
}