package harness_test

import (
	"context"
	"io"
	"testing"

	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
	"golang.org/x/xerrors"

	"github.com/coder/coder/scaletest/harness"
)

const testPanicMessage = "expected test panic"

type panickingExecutionStrategy struct{}

var _ harness.ExecutionStrategy = panickingExecutionStrategy{}

func (panickingExecutionStrategy) Run(_ context.Context, _ []harness.TestFn) ([]error, error) {
	panic(testPanicMessage)
}

type erroringExecutionStrategy struct {
	err error
}

var _ harness.ExecutionStrategy = erroringExecutionStrategy{}

func (e erroringExecutionStrategy) Run(_ context.Context, _ []harness.TestFn) ([]error, error) {
	return []error{}, e.err
}

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

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

		expectedErr := xerrors.New("expected error")

		h := harness.NewTestHarness(harness.LinearExecutionStrategy{}, harness.LinearExecutionStrategy{})
		r1 := h.AddRun("test", "1", fakeTestFns(nil, nil))
		r2 := h.AddRun("test", "2", fakeTestFns(expectedErr, nil))

		err := h.Run(context.Background())
		require.NoError(t, err)

		res := h.Results()
		require.Equal(t, 2, res.TotalRuns)
		require.Equal(t, 1, res.TotalPass)
		require.Equal(t, 1, res.TotalFail)
		require.Equal(t, map[string]harness.RunResult{
			r1.FullID(): r1.Result(),
			r2.FullID(): r2.Result(),
		}, res.Runs)

		err = h.Cleanup(context.Background())
		require.NoError(t, err)
	})

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

		expectedErr := xerrors.New("expected error")

		h := harness.NewTestHarness(erroringExecutionStrategy{err: expectedErr}, harness.LinearExecutionStrategy{})
		_ = h.AddRun("test", "1", fakeTestFns(nil, nil))

		err := h.Run(context.Background())
		require.Error(t, err)
		require.ErrorIs(t, err, expectedErr)
	})

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

		h := harness.NewTestHarness(panickingExecutionStrategy{}, harness.LinearExecutionStrategy{})
		_ = h.AddRun("test", "1", fakeTestFns(nil, nil))

		err := h.Run(context.Background())
		require.Error(t, err)
		require.ErrorContains(t, err, "panic")
		require.ErrorContains(t, err, testPanicMessage)
	})

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

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

			expectedErr := xerrors.New("expected error")

			h := harness.NewTestHarness(harness.LinearExecutionStrategy{}, harness.LinearExecutionStrategy{})
			_ = h.AddRun("test", "1", fakeTestFns(nil, expectedErr))

			err := h.Run(context.Background())
			require.NoError(t, err)

			err = h.Cleanup(context.Background())
			require.Error(t, err)
			require.ErrorContains(t, err, expectedErr.Error())
		})

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

			h := harness.NewTestHarness(harness.LinearExecutionStrategy{}, harness.LinearExecutionStrategy{})
			_ = h.AddRun("test", "1", testFns{
				RunFn: func(_ context.Context, _ string, _ io.Writer) error {
					return nil
				},
				CleanupFn: func(_ context.Context, _ string) error {
					panic(testPanicMessage)
				},
			})

			err := h.Run(context.Background())
			require.NoError(t, err)

			err = h.Cleanup(context.Background())
			require.Error(t, err)
			require.ErrorContains(t, err, "panic")
			require.ErrorContains(t, err, testPanicMessage)
		})

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

			expectedErr := xerrors.New("expected error")

			h := harness.NewTestHarness(harness.LinearExecutionStrategy{}, erroringExecutionStrategy{err: expectedErr})
			_ = h.AddRun("test", "1", fakeTestFns(nil, nil))

			err := h.Run(context.Background())
			require.NoError(t, err)

			err = h.Cleanup(context.Background())
			require.Error(t, err)
			require.ErrorIs(t, err, expectedErr)
		})

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

			h := harness.NewTestHarness(harness.LinearExecutionStrategy{}, panickingExecutionStrategy{})
			_ = h.AddRun("test", "1", testFns{
				RunFn: func(_ context.Context, _ string, _ io.Writer) error {
					return nil
				},
				CleanupFn: func(_ context.Context, _ string) error {
					return nil
				},
			})

			err := h.Run(context.Background())
			require.NoError(t, err)

			err = h.Cleanup(context.Background())
			require.Error(t, err)
			require.ErrorContains(t, err, "panic")
			require.ErrorContains(t, err, testPanicMessage)
		})
	})

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

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

			h := harness.NewTestHarness(harness.LinearExecutionStrategy{}, harness.LinearExecutionStrategy{})
			_ = h.Run(context.Background())

			require.Panics(t, func() {
				_ = h.AddRun("test", "1", fakeTestFns(nil, nil))
			})
		})

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

			h := harness.NewTestHarness(harness.LinearExecutionStrategy{}, harness.LinearExecutionStrategy{})

			name, id := "test", "1"
			_ = h.AddRun(name, id, fakeTestFns(nil, nil))

			require.Panics(t, func() {
				_ = h.AddRun(name, id, fakeTestFns(nil, nil))
			})
		})

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

			h := harness.NewTestHarness(harness.LinearExecutionStrategy{}, harness.LinearExecutionStrategy{})
			h.Run(context.Background())

			require.Panics(t, func() {
				h.Run(context.Background())
			})
		})

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

			h := harness.NewTestHarness(harness.LinearExecutionStrategy{}, harness.LinearExecutionStrategy{})

			require.Panics(t, func() {
				h.Results()
			})
		})

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

			var (
				started    = make(chan struct{})
				endRun     = make(chan struct{})
				testsEnded = make(chan struct{})
			)
			h := harness.NewTestHarness(harness.LinearExecutionStrategy{}, harness.LinearExecutionStrategy{})
			_ = h.AddRun("test", "1", testFns{
				RunFn: func(_ context.Context, _ string, _ io.Writer) error {
					close(started)
					<-endRun
					return nil
				},
			})
			go func() {
				defer close(testsEnded)
				err := h.Run(context.Background())
				assert.NoError(t, err)
			}()

			<-started
			require.Panics(t, func() {
				h.Results()
			})
			close(endRun)

			<-testsEnded
			_ = h.Results()
		})

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

			h := harness.NewTestHarness(harness.LinearExecutionStrategy{}, harness.LinearExecutionStrategy{})

			require.Panics(t, func() {
				h.Cleanup(context.Background())
			})
		})

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

			var (
				started    = make(chan struct{})
				endRun     = make(chan struct{})
				testsEnded = make(chan struct{})
			)
			h := harness.NewTestHarness(harness.LinearExecutionStrategy{}, harness.LinearExecutionStrategy{})
			_ = h.AddRun("test", "1", testFns{
				RunFn: func(_ context.Context, _ string, _ io.Writer) error {
					close(started)
					<-endRun
					return nil
				},
			})
			go func() {
				defer close(testsEnded)
				err := h.Run(context.Background())
				assert.NoError(t, err)
			}()

			<-started
			require.Panics(t, func() {
				h.Cleanup(context.Background())
			})
			close(endRun)

			<-testsEnded
			err := h.Cleanup(context.Background())
			require.NoError(t, err)
		})
	})
}

func fakeTestFns(err, cleanupErr error) testFns {
	return testFns{
		RunFn: func(_ context.Context, _ string, _ io.Writer) error {
			return err
		},
		CleanupFn: func(_ context.Context, _ string) error {
			return cleanupErr
		},
	}
}