package middleware_test

import (
	"context"
	"testing"
	"time"

	"github.com/cenkalti/backoff/v5"
	"github.com/pkg/errors"
	"github.com/stretchr/testify/assert"

	"github.com/ThreeDotsLabs/watermill"
	"github.com/ThreeDotsLabs/watermill/message"
	"github.com/ThreeDotsLabs/watermill/message/router/middleware"
)

func TestRetry_retry(t *testing.T) {
	retry := middleware.Retry{
		MaxRetries: 1,
	}

	runCount := 0
	producedMessages := message.Messages{message.NewMessage("2", nil)}

	h := retry.Middleware(func(msg *message.Message) (messages []*message.Message, e error) {
		runCount++
		if runCount == 0 {
			return nil, errors.New("foo")
		}

		return producedMessages, nil
	})

	handlerMessages, handlerErr := h(message.NewMessage("1", nil))

	assert.Equal(t, 1, runCount)
	assert.EqualValues(t, producedMessages, handlerMessages)
	assert.NoError(t, handlerErr)
}

func TestRetry_max_retries(t *testing.T) {
	retry := middleware.Retry{
		MaxRetries: 1,
		Logger:     watermill.NewStdLogger(true, true),
	}

	runCount := 0

	h := retry.Middleware(func(msg *message.Message) (messages []*message.Message, e error) {
		runCount++
		return nil, errors.New("foo")
	})

	_, err := h(message.NewMessage("1", nil))

	assert.Equal(t, 2, runCount)
	assert.EqualError(t, err, "foo")
}

func TestRetry_retry_hook(t *testing.T) {
	var retriesFromHook []int

	retry := middleware.Retry{
		MaxRetries: 2,
		OnRetryHook: func(retryNum int, delay time.Duration) {
			retriesFromHook = append(retriesFromHook, retryNum)
		},
	}

	h := retry.Middleware(func(msg *message.Message) (messages []*message.Message, e error) {
		return nil, errors.New("foo")
	})
	_, _ = h(message.NewMessage("1", nil))

	assert.EqualValues(t, []int{1, 2}, retriesFromHook)
}

func TestRetry_retries_exhausted_hook(t *testing.T) {
	var exhaustedParams middleware.RetriesExhaustedParams

	handlerErr := errors.New("foo")

	retry := middleware.Retry{
		MaxRetries: 2,
		OnRetriesExhausted: func(params middleware.RetriesExhaustedParams) {
			exhaustedParams = params
		},
	}

	h := retry.Middleware(func(msg *message.Message) (messages []*message.Message, e error) {
		return nil, handlerErr
	})
	_, _ = h(message.NewMessage("1", nil))

	assert.ErrorIs(t, exhaustedParams.Err, handlerErr)
	// With MaxRetries=2, there are 3 total attempts (1 initial + 2 retries)
	// retryNum is incremented after each attempt, so it's 3 when exhausted
	assert.Equal(t, 3, exhaustedParams.RetryNum)
}

func TestRetry_retries_exhausted_hook_not_called_on_success(t *testing.T) {
	var hookCalled bool

	retry := middleware.Retry{
		MaxRetries: 2,
		OnRetriesExhausted: func(params middleware.RetriesExhaustedParams) {
			hookCalled = true
		},
	}

	h := retry.Middleware(func(msg *message.Message) (messages []*message.Message, e error) {
		return nil, nil
	})
	_, _ = h(message.NewMessage("1", nil))

	assert.False(t, hookCalled, "OnRetriesExhausted should not be called on success")
}

func TestRetry_retries_exhausted_hook_not_called_when_should_retry_returns_false(t *testing.T) {
	var hookCalled bool

	retry := middleware.Retry{
		MaxRetries: 5,
		ShouldRetry: func(params middleware.RetryParams) bool {
			return false
		},
		OnRetriesExhausted: func(params middleware.RetriesExhaustedParams) {
			hookCalled = true
		},
	}

	h := retry.Middleware(func(msg *message.Message) (messages []*message.Message, e error) {
		return nil, errors.New("foo")
	})
	_, _ = h(message.NewMessage("1", nil))

	assert.False(t, hookCalled, "OnRetriesExhausted should not be called when ShouldRetry returns false")
}

func TestRetry_logger(t *testing.T) {
	logger := watermill.NewCaptureLogger()

	retry := middleware.Retry{
		MaxRetries: 2,
		Logger:     logger,
	}

	handlerErr := errors.New("foo")

	h := retry.Middleware(func(msg *message.Message) (messages []*message.Message, e error) {
		return nil, handlerErr
	})
	_, _ = h(message.NewMessage("1", nil))

	assert.True(t, logger.HasError(handlerErr))
}

func TestRetry_ctx_cancel(t *testing.T) {
	retry := middleware.Retry{
		InitialInterval: time.Minute,
	}

	producedMessages := message.Messages{message.NewMessage("2", nil)}

	h := retry.Middleware(func(msg *message.Message) (messages []*message.Message, e error) {
		return producedMessages, errors.New("err")
	})

	msg := message.NewMessage("1", nil)
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()
	msg.SetContext(ctx)

	done := make(chan struct{})

	type handlerResult struct {
		Messages message.Messages
		Err      error
	}
	handlerResultCh := make(chan handlerResult, 1)

	go func() {
		messages, err := h(msg)
		handlerResultCh <- handlerResult{messages, err}
		close(done)
	}()

	select {
	case <-done:
		t.Fatal("handler should be still during retrying")
	default:
		// ok
	}

	cancel()

	select {
	case <-done:
		// ok
	case <-time.After(time.Second):
		t.Fatal("ctx cancelled, retrying should be done")
	}

	handlerResultReceived := <-handlerResultCh

	assert.Error(t, handlerResultReceived.Err)
	// produced messages are nil since ctx is canceling the operation in the middle
	assert.Nil(t, handlerResultReceived.Messages)
}

func TestRetry_max_elapsed(t *testing.T) {
	maxRetries := 10
	sleepInHandler := time.Millisecond * 20

	retry := middleware.Retry{
		MaxElapsedTime: time.Millisecond * 10,
		MaxRetries:     maxRetries,
	}

	runTimeWithoutMaxElapsedTime := sleepInHandler * time.Duration(maxRetries)

	h := retry.Middleware(func(msg *message.Message) (messages []*message.Message, e error) {
		time.Sleep(sleepInHandler)
		return nil, errors.New("foo")
	})

	startTime := time.Now()
	_, _ = h(message.NewMessage("1", nil))
	timeElapsed := time.Since(startTime)

	assert.True(
		t,
		timeElapsed < runTimeWithoutMaxElapsedTime,
		"handler should run less than %s, time elapsed: %s",
		runTimeWithoutMaxElapsedTime,
		timeElapsed,
	)
}

func TestRetry_max_interval(t *testing.T) {
	t.Parallel()

	maxRetries := 10
	backoffTimes := make([]time.Duration, maxRetries)
	maxInterval := time.Millisecond * 30

	retry := middleware.Retry{
		MaxRetries:          maxRetries,
		InitialInterval:     time.Millisecond * 10,
		MaxInterval:         maxInterval,
		Multiplier:          2.0,
		RandomizationFactor: 0,
		OnRetryHook: func(retryNum int, delay time.Duration) {
			backoffTimes[retryNum-1] = delay
		},
	}

	h := retry.Middleware(func(msg *message.Message) (messages []*message.Message, e error) {
		return nil, errors.New("bar")
	})
	_, _ = h(message.NewMessage("2", nil))

	for i, delay := range backoffTimes {
		assert.True(t, delay <= maxInterval, "wait interval %d (%s) exceeds maxInterval (%s)", i, delay, maxInterval)
	}
}

func TestRetry_first_run_no_delay(t *testing.T) {
	t.Parallel()

	initialInterval := time.Millisecond * 100
	retry := middleware.Retry{
		MaxElapsedTime:  initialInterval * 2,
		MaxRetries:      10,
		InitialInterval: initialInterval,
	}

	h := retry.Middleware(func(msg *message.Message) (messages []*message.Message, e error) {
		return nil, nil
	})

	start := time.Now()
	_, _ = h(message.NewMessage("1", nil))
	elapsed := time.Since(start)

	assert.True(t, elapsed < initialInterval, "first retry should not wait, elapsed: %s", elapsed)
}

func TestRetry_should_retry(t *testing.T) {
	errToSkip := errors.New("this should be skipped")

	retry := middleware.Retry{
		MaxRetries: 5,
		ShouldRetry: func(params middleware.RetryParams) bool {
			return !errors.Is(params.Err, errToSkip)
		},
	}

	runCount := 0

	h := retry.Middleware(func(msg *message.Message) (messages []*message.Message, e error) {
		runCount++
		return nil, errToSkip
	})

	handlerMessages, handlerErr := h(message.NewMessage("1", nil))

	assert.Equal(t, 1, runCount)
	assert.Nil(t, handlerMessages)
	assert.ErrorIs(t, handlerErr, errToSkip)

	// to not create any dependency on backoff package
	var backoffPermanentError *backoff.PermanentError
	assert.False(t, errors.As(handlerErr, &backoffPermanentError))
}

// Test that the ShouldRetry function is called on each retry attempt.
// Under the hood, the second attempt goes over a bit different code path,
// so we want to make sure that it works consistently.
func TestRetry_should_retry_second_attempt(t *testing.T) {
	errToSkip := errors.New("this should be skipped")

	retry := middleware.Retry{
		MaxRetries: 5,
		ShouldRetry: func(params middleware.RetryParams) bool {
			return !errors.Is(params.Err, errToSkip)
		},
	}

	runCount := 0

	h := retry.Middleware(func(msg *message.Message) (messages []*message.Message, e error) {
		runCount++

		if runCount == 1 {
			return nil, errors.New("some other error")
		} else {
			return nil, errToSkip
		}
	})

	handlerMessages, handlerErr := h(message.NewMessage("1", nil))

	assert.Equal(t, 2, runCount)
	assert.Nil(t, handlerMessages)
	assert.ErrorIs(t, handlerErr, errToSkip)

	// to not create any dependency on backoff package
	var backoffPermanentError *backoff.PermanentError
	assert.False(t, errors.As(handlerErr, &backoffPermanentError))
}

// Test that if backoff.Permanent error stops the retries.
// For sake of potential future regressions (see Hyrum's Law).
func TestRetry_backoff_backoff_permanent(t *testing.T) {
	errToSkip := errors.New("this should be skipped")

	retry := middleware.Retry{
		MaxRetries: 5,
	}

	runCount := 0

	h := retry.Middleware(func(msg *message.Message) (messages []*message.Message, e error) {
		runCount++
		return nil, backoff.Permanent(errToSkip)
	})

	handlerMessages, handlerErr := h(message.NewMessage("1", nil))

	assert.Equal(t, 1, runCount)
	assert.Nil(t, handlerMessages)
	assert.ErrorIs(t, handlerErr, errToSkip)

	// to not create any dependency on backoff package
	var backoffPermanentError *backoff.PermanentError
	assert.False(t, errors.As(handlerErr, &backoffPermanentError))
}

// TestRetry_uncancel_context checks scenario when context is canceled,
// and we want to retry. More context: https://github.com/ThreeDotsLabs/watermill/issues/467
//
// Message is passed as a pointer, so underlying middlewares or handlers can cancel its context.
// In this scenario, retrying is pointless because context is already canceled, so any operation
// that relies on context will fail immediately.
func TestRetry_uncancel_context(t *testing.T) {
	retry := middleware.Retry{
		MaxRetries:          5,
		ResetContextOnRetry: true,
	}

	num := 0

	var ctxCancelMiddleware = func(h message.HandlerFunc) message.HandlerFunc {
		return func(msg *message.Message) ([]*message.Message, error) {
			num++

			ctx, cancel := context.WithCancel(msg.Context())
			defer func() {
				cancel()
			}()

			if num == 1 {
				t.Log("Run 1: canceling context")
				cancel()
			} else {
				t.Logf("Run %d: context is not canceled", num)
			}

			msg.SetContext(ctx)
			return h(msg)
		}
	}

	h := func(msg *message.Message) (messages []*message.Message, e error) {
		return nil, msg.Context().Err()
	}

	h = ctxCancelMiddleware(h)
	h = retry.Middleware(h)

	_, handlerErr := h(message.NewMessage("1", nil))
	assert.NoError(t, handlerErr)
}