package tree

import (
	"errors"
	"testing"
	"time"

	"github.com/stretchr/testify/require"
)

func TestCircuitBreaker(t *testing.T) {
	remoteErr := errors.New("service is being synchronized")
	breakDuration := 1 * time.Second
	threshold := 10
	cb := newCircuitBreaker(breakDuration, threshold)

	// Hit threshold
	for i := 0; i < threshold; i++ {
		err := cb.Do(1, func() error { return remoteErr })
		require.ErrorIs(t, err, remoteErr)
	}

	// Different client should not be affected by threshold
	require.NoError(t, cb.Do(2, func() error { return nil }))

	// Immediate request should return circuit breaker error
	require.ErrorIs(t, cb.Do(1, func() error { return nil }), ErrCBClosed)

	// Request after breakDuration should be ok
	time.Sleep(breakDuration)
	require.NoError(t, cb.Do(1, func() error { return nil }))

	// Try hitting threshold one more time after break duration
	for i := 0; i < threshold; i++ {
		err := cb.Do(1, func() error { return remoteErr })
		require.ErrorIs(t, err, remoteErr)
	}

	// Immediate request should return circuit breaker error
	require.ErrorIs(t, cb.Do(1, func() error { return nil }), ErrCBClosed)
}

func TestCircuitBreakerNoBlock(t *testing.T) {
	remoteErr := errors.New("service is being synchronized")
	funcDuration := 200 * time.Millisecond
	threshold := 100
	cb := newCircuitBreaker(10*funcDuration, threshold)

	slowFunc := func() error {
		time.Sleep(funcDuration)
		return remoteErr
	}

	for i := 0; i < threshold; i++ {
		// run in multiple goroutines Do function
		go func() {
			cb.Do(1, slowFunc)
		}()
	}

	time.Sleep(funcDuration)

	// eventually at most after one more func duration circuit breaker will be
	// closed and not blocked by slow func execution under mutex
	require.Eventually(t, func() bool {
		return errors.Is(cb.Do(1, func() error { return nil }), ErrCBClosed)
	}, funcDuration, funcDuration/10)
}