package inference

import (
	"testing"
	"time"
)

func TestBreakerTripsAndRecovers(t *testing.T) {
	b := newBreaker(3, 10*time.Second)
	now := time.Unix(1000, 0)
	b.now = func() time.Time { return now }

	// Three consecutive failures trip the breaker.
	for i := 0; i < 3; i++ {
		if !b.allow() {
			t.Fatalf("attempt %d should be allowed while closed", i)
		}
		b.record(false)
	}
	if b.allow() {
		t.Fatal("breaker should be open after the failure threshold, failing fast")
	}

	// Before the cooldown elapses it stays open.
	now = now.Add(9 * time.Second)
	if b.allow() {
		t.Fatal("breaker should still be open before the cooldown elapses")
	}

	// After the cooldown one probe is allowed (half open).
	now = now.Add(2 * time.Second)
	if !b.allow() {
		t.Fatal("breaker should allow a single probe after the cooldown")
	}
	// A second concurrent probe is refused.
	if b.allow() {
		t.Fatal("breaker must allow only one probe at a time while half open")
	}
	// A successful probe closes the breaker.
	b.record(true)
	if !b.allow() {
		t.Fatal("a successful probe should close the breaker")
	}
}

func TestBreakerProbeFailureReopens(t *testing.T) {
	b := newBreaker(1, 5*time.Second)
	now := time.Unix(2000, 0)
	b.now = func() time.Time { return now }
	b.allow()
	b.record(false) // trips immediately (threshold 1)
	now = now.Add(6 * time.Second)
	if !b.allow() {
		t.Fatal("probe should be allowed after cooldown")
	}
	b.record(false) // probe fails
	if b.allow() {
		t.Fatal("a failed probe must reopen the breaker, not close it")
	}
}