package backendexecutor

import (
	"bytes"
	"context"
	"errors"
	"io"
	"log/slog"
	"net/http"
	"os"
	"path/filepath"
	"slices"
	"strings"
	"sync"
	"testing"

	"yms-daemon/internal/containerengine"
	"yms-daemon/internal/transaction"
)

const (
	testDigest      = "sha256:aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
	testRepository  = "harbor.ymswell.asia/ymswell/glory-ymswell"
	healthyResponse = `{"status":"UP","components":{"db":{"status":"UP"},"diskSpace":{"status":"UP"},"ping":{"status":"UP"},"redis":{"status":"UP"}}}`
)

func TestExecutorPreservesOpaqueImageTagsAndReachesSwitching(t *testing.T) {
	tags := []string{
		"20260814-093609-d7ed70f0-v1.1.8.1",
		"20260814-093609-d7ed70f0",
	}
	for _, tag := range tags {
		tag := tag
		t.Run(tag, func(t *testing.T) {
			ctx := context.Background()
			store, coordinator := testTransactionKernel(t)
			imageReference := testRepository + ":" + tag
			request := testRequest(t, imageReference)
			engine := newFakeEngine(request)
			executor := testExecutor(t, store, coordinator, engine, healthyResponse)
			record := createTransaction(t, store, "opaque-"+tag)

			if err := executor.Run(ctx, record.ID, request); err != nil {
				t.Fatalf("run backend executor: %v", err)
			}
			current, err := store.Transaction(ctx, record.ID)
			if err != nil {
				t.Fatalf("read completed preparation: %v", err)
			}
			if current.State != transaction.StateSwitching {
				t.Fatalf("unexpected transaction state: %s", current.State)
			}
			pending, err := store.PendingSteps(ctx, record.ID)
			if err != nil || len(pending) != 0 {
				t.Fatalf("unexpected pending steps: steps=%+v err=%v", pending, err)
			}

			engine.mu.Lock()
			if engine.lastCreateSpec.ImageReference != imageReference {
				engine.mu.Unlock()
				t.Fatalf("image reference changed: got %q want %q", engine.lastCreateSpec.ImageReference, imageReference)
			}
			if !slices.Contains(engine.lastCreateSpec.Environment, "SERVER_PORT=8081") || !slices.Contains(engine.lastCreateSpec.Environment, "SPRING_CONFIG_LOCATION=file:/app/config/yms.yaml") {
				engine.mu.Unlock()
				t.Fatalf("missing explicit port environment: %+v", engine.lastCreateSpec.Environment)
			}
			initialCalls := engine.callCounts()
			engine.mu.Unlock()

			if err := executor.Run(ctx, record.ID, request); err != nil {
				t.Fatalf("repeat executor at switching state: %v", err)
			}
			engine.mu.Lock()
			repeatedCalls := engine.callCounts()
			engine.mu.Unlock()
			if repeatedCalls != initialCalls {
				t.Fatalf("switching state repeated engine calls: before=%+v after=%+v", initialCalls, repeatedCalls)
			}
		})
	}
}

func TestExecutorRecoversRecordedCreateIntentWithoutRepeatingCreate(t *testing.T) {
	ctx := context.Background()
	store, coordinator := testTransactionKernel(t)
	request := testRequest(t, testRepository+":20260814-093609-d7ed70f0-v1.1.8.1")
	engine := newFakeEngine(request)
	engine.imageAvailable = true
	engine.containers[request.ContainerName] = engine.containerFromSpec(containerSpec(request), false)
	executor := testExecutor(t, store, coordinator, engine, healthyResponse)
	record := createTransaction(t, store, "recover-create")
	transitionToPrepared(t, store, record.ID)

	loadStep := loadIntent(request)
	if _, _, err := store.RecordStepIntent(ctx, record.ID, loadStep); err != nil {
		t.Fatalf("record completed image intent: %v", err)
	}
	if _, err := store.CompleteStep(ctx, record.ID, loadStep.Key, transaction.StepSucceeded, []byte(`{"loaded":true}`), ""); err != nil {
		t.Fatalf("complete image step: %v", err)
	}
	removeStep := removeIntent(request)
	if _, _, err := store.RecordStepIntent(ctx, record.ID, removeStep); err != nil {
		t.Fatalf("record completed remove intent: %v", err)
	}
	if _, err := store.CompleteStep(ctx, record.ID, removeStep.Key, transaction.StepSucceeded, []byte(`{"absent":true}`), ""); err != nil {
		t.Fatalf("complete remove step: %v", err)
	}
	createStep := createIntent(request, engine.loadedImage.ID)
	if _, _, err := store.RecordStepIntent(ctx, record.ID, createStep); err != nil {
		t.Fatalf("record crash-window create intent: %v", err)
	}

	if err := executor.Run(ctx, record.ID, request); err != nil {
		t.Fatalf("recover backend executor: %v", err)
	}
	engine.mu.Lock()
	calls := engine.callCounts()
	engine.mu.Unlock()
	if calls.load != 0 || calls.remove != 0 || calls.create != 0 || calls.start != 1 {
		t.Fatalf("unexpected recovery calls: %+v", calls)
	}
	current, err := store.Transaction(ctx, record.ID)
	if err != nil || current.State != transaction.StateSwitching {
		t.Fatalf("unexpected recovered state: record=%+v err=%v", current, err)
	}
}

func TestExecutorMarksValidationFailureTerminal(t *testing.T) {
	ctx := context.Background()
	store, coordinator := testTransactionKernel(t)
	request := testRequest(t, testRepository+":20260814-093609-d7ed70f0")
	request.Port = 9090
	engine := newFakeEngine(request)
	executor := testExecutor(t, store, coordinator, engine, healthyResponse)
	record := createTransaction(t, store, "invalid-port")

	if err := executor.Run(ctx, record.ID, request); err == nil {
		t.Fatal("expected validation failure")
	}
	current, err := store.Transaction(ctx, record.ID)
	if err != nil || current.State != transaction.StateFailed {
		t.Fatalf("unexpected failed transaction: record=%+v err=%v", current, err)
	}
}

func TestExecutorReplacesInactiveContainerWithConflictingImage(t *testing.T) {
	ctx := context.Background()
	store, coordinator := testTransactionKernel(t)
	request := testRequest(t, testRepository+":20260814-093609-d7ed70f0")
	engine := newFakeEngine(request)
	engine.imageAvailable = true
	conflicting := engine.containerFromSpec(containerSpec(request), false)
	conflicting.ImageID = "sha256:bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb"
	engine.containers[request.ContainerName] = conflicting
	executor := testExecutor(t, store, coordinator, engine, healthyResponse)
	record := createTransaction(t, store, "container-conflict")

	if err := executor.Run(ctx, record.ID, request); err != nil {
		t.Fatalf("replace inactive container: %v", err)
	}
	current, readErr := store.Transaction(ctx, record.ID)
	if readErr != nil || current.State != transaction.StateSwitching {
		t.Fatalf("replacement did not reach switching: record=%+v err=%v", current, readErr)
	}
	engine.mu.Lock()
	calls := engine.callCounts()
	engine.mu.Unlock()
	if calls.remove != 1 || calls.create != 1 {
		t.Fatalf("inactive replacement calls mismatch: %+v", calls)
	}
}

func TestExecutorRejectsChangedRecoveryRequestWithoutChangingState(t *testing.T) {
	ctx := context.Background()
	store, coordinator := testTransactionKernel(t)
	request := testRequest(t, testRepository+":20260814-093609-d7ed70f0-v1.1.8.1")
	engine := newFakeEngine(request)
	engine.imageAvailable = true
	executor := testExecutor(t, store, coordinator, engine, healthyResponse)
	record := createTransaction(t, store, "changed-recovery-request")
	transitionToPrepared(t, store, record.ID)
	if err := executor.prepare(ctx, record.ID, request); err != nil {
		t.Fatalf("prepare original request: %v", err)
	}
	if _, err := store.Transition(ctx, record.ID, transaction.StateStarting, "test starting"); err != nil {
		t.Fatalf("transition to starting: %v", err)
	}

	changed := request
	changed.ImageReference = testRepository + ":20260814-093609-d7ed70f0"
	err := executor.Run(ctx, record.ID, changed)
	if !errors.Is(err, transaction.ErrStepConflict) {
		t.Fatalf("expected persisted intent conflict, got %v", err)
	}
	current, readErr := store.Transaction(ctx, record.ID)
	if readErr != nil || current.State != transaction.StateStarting {
		t.Fatalf("changed recovery request altered transaction: record=%+v err=%v", current, readErr)
	}
}

func TestImageMatchesRequiresDigestEvidenceAndExactPlatform(t *testing.T) {
	t.Parallel()
	platform := containerengine.Platform{OS: "linux", Architecture: "arm64"}
	image := containerengine.Image{
		ID:          "sha256:cccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc",
		RepoDigests: []string{testRepository + "@" + testDigest},
		Platform:    platform,
	}
	matched, err := imageMatches(image, testDigest, platform)
	if err != nil || !matched {
		t.Fatalf("expected exact image match: matched=%t err=%v", matched, err)
	}
	image.RepoDigests = nil
	matched, err = imageMatches(image, testDigest, platform)
	if err != nil || matched {
		t.Fatalf("image ID alone must not satisfy manifest digest: matched=%t err=%v", matched, err)
	}
	image.DescriptorDigest = testDigest
	matched, err = imageMatches(image, testDigest, containerengine.Platform{OS: "linux", Architecture: "amd64"})
	if err != nil || matched {
		t.Fatalf("platform mismatch accepted: matched=%t err=%v", matched, err)
	}
}

func testRequest(t *testing.T, imageReference string) Request {
	t.Helper()
	directory := t.TempDir()
	archivePath := filepath.Join(directory, "backend-image.tar")
	configPath := filepath.Join(directory, "yms.yaml")
	if err := os.WriteFile(archivePath, []byte("image archive"), 0o600); err != nil {
		t.Fatalf("write image archive: %v", err)
	}
	if err := os.WriteFile(configPath, []byte("server: {}\n"), 0o600); err != nil {
		t.Fatalf("write backend configuration: %v", err)
	}
	return Request{
		ImageAcquisition:     ImageAcquisitionLoad,
		ArchivePath:          archivePath,
		ImageReference:       imageReference,
		ExpectedImageDigest:  testDigest,
		Platform:             containerengine.Platform{OS: "linux", Architecture: "amd64"},
		ContainerName:        "explicit-backend-8081",
		Port:                 8081,
		PortEnvironmentKey:   "SERVER_PORT",
		ConfigSource:         configPath,
		ConfigTarget:         "/app/config/yms.yaml",
		TmpSource:            directory,
		TmpTarget:            "/home/yms/tmp",
		ConfigEnvironmentKey: "SPRING_CONFIG_LOCATION",
		ConfigLocation:       "file:/app/config/yms.yaml",
		RestartPolicy:        containerengine.RestartPolicy{Name: "unless-stopped"},
		HealthEndpoint:       "http://127.0.0.1:8081/yms/actuator/health",
	}
}

func testTransactionKernel(t *testing.T) (*transaction.Store, *transaction.Coordinator) {
	t.Helper()
	store, err := transaction.OpenStore(context.Background(), filepath.Join(t.TempDir(), "transactions.db"))
	if err != nil {
		t.Fatalf("open transaction store: %v", err)
	}
	t.Cleanup(func() { _ = store.Close() })
	coordinator, err := transaction.NewCoordinator(store, slog.New(slog.NewTextHandler(io.Discard, nil)))
	if err != nil {
		t.Fatalf("create transaction coordinator: %v", err)
	}
	return store, coordinator
}

func testExecutor(t *testing.T, store *transaction.Store, coordinator *transaction.Coordinator, engine containerengine.Engine, body string) *Executor {
	t.Helper()
	client := &http.Client{Transport: roundTripFunc(func(*http.Request) (*http.Response, error) {
		return &http.Response{StatusCode: http.StatusOK, Header: make(http.Header), Body: io.NopCloser(bytes.NewBufferString(body))}, nil
	})}
	executor, err := New(store, coordinator, engine, client)
	if err != nil {
		t.Fatalf("create backend executor: %v", err)
	}
	return executor
}

func createTransaction(t *testing.T, store *transaction.Store, suffix string) transaction.Transaction {
	t.Helper()
	record, _, err := store.CreateTransaction(context.Background(), transaction.CreateRequest{
		ID:             "backend-" + suffix,
		IdempotencyKey: "backend-request-" + suffix,
		Source:         "test",
		Service:        "backend",
	})
	if err != nil {
		t.Fatalf("create backend transaction: %v", err)
	}
	return record
}

func transitionToPrepared(t *testing.T, store *transaction.Store, transactionID string) {
	t.Helper()
	ctx := context.Background()
	if _, err := store.Transition(ctx, transactionID, transaction.StateValidating, "test validating"); err != nil {
		t.Fatalf("transition to validating: %v", err)
	}
	if _, err := store.Transition(ctx, transactionID, transaction.StatePrepared, "test prepared"); err != nil {
		t.Fatalf("transition to prepared: %v", err)
	}
}

type roundTripFunc func(*http.Request) (*http.Response, error)

func (f roundTripFunc) RoundTrip(request *http.Request) (*http.Response, error) {
	return f(request)
}

type engineCalls struct {
	ping    int
	load    int
	inspect int
	create  int
	start   int
	remove  int
}

type fakeEngine struct {
	mu             sync.Mutex
	request        Request
	loadedImage    containerengine.Image
	imageAvailable bool
	containers     map[string]containerengine.Container
	lastCreateSpec containerengine.ContainerSpec
	pingCalls      int
	loadCalls      int
	inspectCalls   int
	createCalls    int
	startCalls     int
	removeCalls    int
}

func newFakeEngine(request Request) *fakeEngine {
	return &fakeEngine{
		request: request,
		loadedImage: containerengine.Image{
			ID:          "sha256:cccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc",
			RepoDigests: []string{testRepository + "@" + testDigest},
			Platform:    request.Platform,
		},
		containers: make(map[string]containerengine.Container),
	}
}

func (e *fakeEngine) Ping(context.Context) error {
	e.mu.Lock()
	defer e.mu.Unlock()
	e.pingCalls++
	return nil
}

func (e *fakeEngine) LoadImage(_ context.Context, input io.Reader) error {
	e.mu.Lock()
	defer e.mu.Unlock()
	e.loadCalls++
	if _, err := io.ReadAll(input); err != nil {
		return err
	}
	e.imageAvailable = true
	return nil
}

func (e *fakeEngine) PullImage(context.Context, string) error {
	e.mu.Lock()
	defer e.mu.Unlock()
	e.loadCalls++
	e.imageAvailable = true
	return nil
}

func (e *fakeEngine) InspectImage(context.Context, string) (containerengine.Image, error) {
	e.mu.Lock()
	defer e.mu.Unlock()
	e.inspectCalls++
	if !e.imageAvailable {
		return containerengine.Image{}, containerengine.ErrNotFound
	}
	return e.loadedImage, nil
}

func (e *fakeEngine) CreateContainer(_ context.Context, spec containerengine.ContainerSpec) (containerengine.Container, error) {
	e.mu.Lock()
	defer e.mu.Unlock()
	e.createCalls++
	e.lastCreateSpec = spec
	if _, exists := e.containers[spec.Name]; exists {
		return containerengine.Container{}, errors.New("container name already exists")
	}
	record := e.containerFromSpec(spec, false)
	e.containers[spec.Name] = record
	return record, nil
}

func (e *fakeEngine) StartContainer(_ context.Context, name string) error {
	e.mu.Lock()
	defer e.mu.Unlock()
	e.startCalls++
	record, exists := e.containers[name]
	if !exists {
		return containerengine.ErrNotFound
	}
	record.Running = true
	record.Status = "running"
	e.containers[name] = record
	return nil
}

func (e *fakeEngine) ContainerLogs(context.Context, string) (io.ReadCloser, error) {
	return io.NopCloser(strings.NewReader("")), nil
}

func (e *fakeEngine) StopContainer(_ context.Context, name string) error {
	e.mu.Lock()
	defer e.mu.Unlock()
	record, exists := e.containers[name]
	if !exists {
		return containerengine.ErrNotFound
	}
	record.Running = false
	record.Status = "exited"
	e.containers[name] = record
	return nil
}

func (e *fakeEngine) InspectContainer(_ context.Context, name string) (containerengine.Container, error) {
	e.mu.Lock()
	defer e.mu.Unlock()
	record, exists := e.containers[name]
	if !exists {
		return containerengine.Container{}, containerengine.ErrNotFound
	}
	return record, nil
}

func (e *fakeEngine) RemoveContainer(_ context.Context, name string, _ bool) error {
	e.mu.Lock()
	defer e.mu.Unlock()
	e.removeCalls++
	if _, exists := e.containers[name]; !exists {
		return containerengine.ErrNotFound
	}
	delete(e.containers, name)
	return nil
}

func (e *fakeEngine) Close() error { return nil }

func (e *fakeEngine) containerFromSpec(spec containerengine.ContainerSpec, running bool) containerengine.Container {
	return containerengine.Container{
		ID:                 "container-id-" + spec.Name,
		Name:               spec.Name,
		ImageID:            e.loadedImage.ID,
		ImageReference:     spec.ImageReference,
		Platform:           spec.Platform.OS + "/" + spec.Platform.Architecture,
		Running:            running,
		Status:             "created",
		Environment:        append([]string(nil), spec.Environment...),
		NetworkMode:        spec.NetworkMode,
		RestartPolicy:      spec.RestartPolicy,
		Mounts:             append([]containerengine.Mount(nil), spec.Mounts...),
		User:               spec.User,
		StopTimeoutSeconds: spec.StopTimeoutSeconds,
	}
}

func (e *fakeEngine) callCounts() engineCalls {
	return engineCalls{
		ping:    e.pingCalls,
		load:    e.loadCalls,
		inspect: e.inspectCalls,
		create:  e.createCalls,
		start:   e.startCalls,
		remove:  e.removeCalls,
	}
}

var _ containerengine.Engine = (*fakeEngine)(nil)