package ratelimit

import (
	"testing"
	"time"
)

func TestLimiter_AllowsUnderThreshold(t *testing.T) {
	l := NewLimiter(10, time.Minute)
	for i := range 9 {
		if !l.Allowed("1.2.3.4") {
			t.Fatalf("expected allowed at failure %d", i)
		}
		l.RecordFailure("1.2.3.4")
	}
	if !l.Allowed("1.2.3.4") {
		t.Fatalf("expected allowed after 9 failures")
	}
}

func TestLimiter_BlocksAtThreshold(t *testing.T) {
	l := NewLimiter(10, time.Minute)
	for range 10 {
		l.RecordFailure("1.2.3.4")
	}
	if l.Allowed("1.2.3.4") {
		t.Fatalf("expected blocked after 10 failures")
	}
}

func TestLimiter_BlockedClientStaysThrottledAcrossWindowBoundary(t *testing.T) {
	window := 300 * time.Millisecond
	l := NewLimiter(10, window)

	for range 20 {
		l.RecordFailure("1.2.3.4")
	}
	if l.Allowed("1.2.3.4") {
		t.Fatalf("expected blocked immediately after 20 failures")
	}

	idx := l.windowIndex(time.Now())
	windowEnd := time.Unix(0, (idx+1)*int64(window))
	// Sleep just past the window boundary so the failures roll into the previous
	// bucket, then check that their weighted contribution still blocks the client.
	time.Sleep(time.Until(windowEnd) + window/10)

	if l.Allowed("1.2.3.4") {
		t.Fatalf("expected still blocked shortly after the window boundary")
	}
}

func TestLimiter_ResetsAfterIdlePeriod(t *testing.T) {
	window := 50 * time.Millisecond
	l := NewLimiter(10, window)

	for range 10 {
		l.RecordFailure("1.2.3.4")
	}
	if l.Allowed("1.2.3.4") {
		t.Fatalf("expected blocked immediately after 10 failures")
	}

	time.Sleep(window * 3)

	if !l.Allowed("1.2.3.4") {
		t.Fatalf("expected allowed after idling for 2+ windows")
	}
}

func TestLimiter_Cleanup(t *testing.T) {
	window := 20 * time.Millisecond
	l := NewLimiter(10, window)
	l.RecordFailure("1.2.3.4")

	time.Sleep(window * 4)
	l.Cleanup()

	l.mu.RLock()
	_, ok := l.state["1.2.3.4"]
	l.mu.RUnlock()
	if ok {
		t.Fatalf("expected stale IP to be cleaned up")
	}
}

func TestOverlapFraction(t *testing.T) {
	window := 100 * time.Millisecond
	previousIdx := int64(1000)
	previousWindowEnd := time.Unix(0, (previousIdx+1)*int64(window))

	if got := overlapFraction(previousWindowEnd.Add(-10*time.Millisecond), window, previousIdx); got != 1 {
		t.Fatalf("expected overlap 1 before window end, got %v", got)
	}
	if got := overlapFraction(previousWindowEnd.Add(20*time.Millisecond), window, previousIdx); got < 0.79 || got > 0.81 {
		t.Fatalf("expected overlap ~0.8 at 20ms into next window, got %v", got)
	}
	if got := overlapFraction(previousWindowEnd.Add(200*time.Millisecond), window, previousIdx); got != 0 {
		t.Fatalf("expected overlap 0 once fully elapsed, got %v", got)
	}
}