package worker_test

import (
	"sync/atomic"
	"testing"

	"github.com/gruntwork-io/terragrunt/internal/worker"

	"errors"

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

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

	wp := worker.NewWorkerPool(5)
	defer wp.Stop()

	var counter int32

	// Submit 10 tasks that increment a counter
	for range 10 {
		wp.Submit(func() error {
			atomic.AddInt32(&counter, 1)
			return nil
		})
	}

	// Wait for all tasks to complete
	errs := wp.Wait()
	require.NoError(t, errs)

	if atomic.LoadInt32(&counter) != 10 {
		t.Errorf("expected counter to be 10, got %d", counter)
	}
}

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

	wp := worker.NewWorkerPool(10)
	defer wp.Stop()

	var counter int32

	for range 5 {
		wp.Submit(func() error {
			atomic.AddInt32(&counter, 1)
			return nil
		})
	}

	// Wait for all tasks to complete
	errs := wp.Wait()
	require.NoError(t, errs)

	if atomic.LoadInt32(&counter) != 5 {
		t.Errorf("expected counter to be 5, got %d", counter)
	}
}

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

	wp := worker.NewWorkerPool(3)
	defer wp.Stop()

	var successCount int32

	// Submit tasks, half of which return an error
	for i := range 10 {
		wp.Submit(func() error {
			if i%2 == 0 {
				return errors.New("mock error")
			}

			atomic.AddInt32(&successCount, 1)

			return nil
		})
	}

	errs := wp.Wait()
	require.Error(t, errs)

	unwrapper, ok := errs.(interface{ Unwrap() []error })
	require.True(t, ok, "expected joined error, got %T", errs)
	require.Len(t, unwrapper.Unwrap(), 5, "expected exactly 5 errors, got %d", len(unwrapper.Unwrap()))

	if atomic.LoadInt32(&successCount) != 5 {
		t.Errorf("expected successCount to be 5, got %d", successCount)
	}
}

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

	wp := worker.NewWorkerPool(2)

	var counter int32

	// Submit some tasks
	for range 5 {
		wp.Submit(func() error {
			atomic.AddInt32(&counter, 1)
			return nil
		})
	}

	// Wait for all tasks to complete and stop the pool
	err := wp.Wait()
	require.NoError(t, err)
	wp.Stop()

	finalCount := atomic.LoadInt32(&counter)
	require.Equal(t, int32(5), finalCount, "expected counter to be 5")

	// Create a new worker pool instead of assuming restart
	wp = worker.NewWorkerPool(2)
	defer wp.Stop()

	// Submit new tasks
	for range 3 {
		wp.Submit(func() error {
			atomic.AddInt32(&counter, 1)
			return nil
		})
	}

	errs := wp.Wait()
	require.NoError(t, errs)

	finalCountAfterRestart := atomic.LoadInt32(&counter)
	require.Equal(t, int32(8), finalCountAfterRestart, "expected counter to be 8")
}
func TestParallelSubmitsAndWaits(t *testing.T) {
	t.Parallel()

	wp := worker.NewWorkerPool(4)

	t.Cleanup(func() { wp.Stop() })

	var totalCount int32

	t.Run("parallelTaskSubmit1", func(t *testing.T) {
		t.Parallel()

		localWp := worker.NewWorkerPool(4) // Create a new worker pool per subtest
		defer localWp.Stop()

		for range 10 {
			localWp.Submit(func() error {
				atomic.AddInt32(&totalCount, 1)
				return nil
			})
		}

		err := localWp.Wait()
		require.NoError(t, err)
	})

	t.Run("parallelTaskSubmit2", func(t *testing.T) {
		t.Parallel()

		localWp := worker.NewWorkerPool(4) // Create another fresh worker pool
		defer localWp.Stop()

		for range 15 {
			localWp.Submit(func() error {
				atomic.AddInt32(&totalCount, 1)
				return nil
			})
		}

		err := localWp.Wait()
		require.NoError(t, err)
	})
}

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

	wp := worker.NewWorkerPool(1)
	defer wp.Stop()

	var totalCount int32

	// Submit 5 tasks
	for range 5 {
		wp.Submit(func() error {
			atomic.AddInt32(&totalCount, 1)
			return nil
		})
	}

	errs := wp.Wait()
	require.NoError(t, errs)

	if atomic.LoadInt32(&totalCount) != 5 {
		t.Errorf("expected totalCount to be 5, got %d", totalCount)
	}
}
