package processing

import (
	"context"
	"sync"
	"sync/atomic"
	"testing"
	"time"

	"github.com/google/uuid"
)

func TestWaitRateSerializesConcurrentCallers(t *testing.T) {
	t.Parallel()
	c := &OpenAIClient{MinInterval: 30 * time.Millisecond}
	const n = 8
	var wg sync.WaitGroup
	wg.Add(n)
	start := time.Now()
	for i := 0; i < n; i++ {
		go func() {
			defer wg.Done()
			if err := c.waitRate(context.Background()); err != nil {
				t.Errorf("waitRate: %v", err)
			}
		}()
	}
	wg.Wait()
	elapsed := time.Since(start)
	// With reservation under the lock, n callers need ~ (n-1)*MinInterval.
	minExpected := time.Duration(n-2) * c.MinInterval
	if elapsed < minExpected {
		t.Fatalf("elapsed %v too short for %d serialized waits (want >= %v)", elapsed, n, minExpected)
	}
}

func TestStartLimiterAllowConcurrent(t *testing.T) {
	t.Parallel()
	l := NewStartLimiter(10, time.Minute)
	company := uuid.New()
	var allowed atomic.Int64
	var wg sync.WaitGroup
	const n = 40
	wg.Add(n)
	for i := 0; i < n; i++ {
		go func() {
			defer wg.Done()
			if l.Allow(company) {
				allowed.Add(1)
			}
		}()
	}
	wg.Wait()
	if got := allowed.Load(); got != 10 {
		t.Fatalf("allowed=%d want 10", got)
	}
}

func TestStartLimiterSeparateCompanies(t *testing.T) {
	t.Parallel()
	l := NewStartLimiter(3, time.Minute)
	a, b := uuid.New(), uuid.New()
	for i := 0; i < 3; i++ {
		if !l.Allow(a) {
			t.Fatalf("company A start %d should allow", i)
		}
	}
	if l.Allow(a) {
		t.Fatal("company A should be rate limited")
	}
	if !l.Allow(b) {
		t.Fatal("company B should not share A budget")
	}
	if NewStartLimiter(1, time.Minute) == nil {
		t.Fatal("NewStartLimiter must return non-nil")
	}
	var nilLimiter *StartLimiter
	if !nilLimiter.Allow(a) {
		t.Fatal("nil StartLimiter must allow (fail-open)")
	}
}