package server

import (
	"context"
	"errors"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"

	"scm.bstein.dev/bstein/soteria/internal/api"
	"scm.bstein.dev/bstein/soteria/internal/config"
	"scm.bstein.dev/bstein/soteria/internal/k8s"
	"scm.bstein.dev/bstein/soteria/internal/longhorn"

	corev1 "k8s.io/api/core/v1"
)

type restoreTestKubeClient struct {
	*fakeKubeClient
	listPVCsErr      error
	targetExistsErr  error
	resolveErr       error
	createRestoreErr error
}

func (k *restoreTestKubeClient) ListBoundPVCs(ctx context.Context) ([]k8s.PVCSummary, error) {
	if k.listPVCsErr != nil {
		return nil, k.listPVCsErr
	}
	return k.fakeKubeClient.ListBoundPVCs(ctx)
}

func (k *restoreTestKubeClient) PersistentVolumeClaimExists(ctx context.Context, namespace, pvcName string) (bool, error) {
	if k.targetExistsErr != nil {
		return false, k.targetExistsErr
	}
	return k.fakeKubeClient.PersistentVolumeClaimExists(ctx, namespace, pvcName)
}

func (k *restoreTestKubeClient) ResolvePVCVolume(ctx context.Context, namespace, pvcName string) (string, *corev1.PersistentVolumeClaim, *corev1.PersistentVolume, error) {
	if k.resolveErr != nil {
		return "", nil, nil, k.resolveErr
	}
	return k.fakeKubeClient.ResolvePVCVolume(ctx, namespace, pvcName)
}

func (k *restoreTestKubeClient) CreateRestoreJob(ctx context.Context, cfg *config.Config, req api.RestoreTestRequest) (string, string, error) {
	if k.createRestoreErr != nil {
		return "", "", k.createRestoreErr
	}
	return k.fakeKubeClient.CreateRestoreJob(ctx, cfg, req)
}

type restoreTestLonghornClient struct {
	*fakeLonghornClient
	findBackup    *longhorn.Backup
	findErr       error
	getVolume     *longhorn.Volume
	getVolumeErr  error
	createVolErr  error
	createPVCErr  error
	deleteVolErr  error
	deletedVolume string
}

func (l *restoreTestLonghornClient) FindBackup(ctx context.Context, volumeName, snapshot string) (*longhorn.Backup, error) {
	if l.findErr != nil {
		return nil, l.findErr
	}
	if l.findBackup != nil {
		return l.findBackup, nil
	}
	return l.fakeLonghornClient.FindBackup(ctx, volumeName, snapshot)
}

func (l *restoreTestLonghornClient) GetVolume(ctx context.Context, volume string) (*longhorn.Volume, error) {
	if l.getVolumeErr != nil {
		return nil, l.getVolumeErr
	}
	if l.getVolume != nil {
		return l.getVolume, nil
	}
	return l.fakeLonghornClient.GetVolume(ctx, volume)
}

func (l *restoreTestLonghornClient) CreateVolumeFromBackup(ctx context.Context, name, size string, replicas int, backupURL string) (*longhorn.Volume, error) {
	if l.createVolErr != nil {
		return nil, l.createVolErr
	}
	return l.fakeLonghornClient.CreateVolumeFromBackup(ctx, name, size, replicas, backupURL)
}

func (l *restoreTestLonghornClient) CreatePVC(ctx context.Context, volumeName, namespace, pvcName string) error {
	if l.createPVCErr != nil {
		return l.createPVCErr
	}
	return l.fakeLonghornClient.CreatePVC(ctx, volumeName, namespace, pvcName)
}

func (l *restoreTestLonghornClient) DeleteVolume(ctx context.Context, volumeName string) error {
	l.deletedVolume = volumeName
	if l.deleteVolErr != nil {
		return l.deleteVolErr
	}
	return l.fakeLonghornClient.DeleteVolume(ctx, volumeName)
}

func newRestoreTestServer(cfg *config.Config, client kubeClient, longhornClient longhornClient) *Server {
	srv := &Server{
		cfg:      cfg,
		client:   client,
		longhorn: longhornClient,
		metrics:  newTelemetry(),
		policies: map[string]api.BackupPolicy{},
	}
	srv.handler = http.HandlerFunc(srv.route)
	return srv
}

func TestHandleRestoreRejectsInvalidRequests(t *testing.T) {
	srv := newRestoreTestServer(
		&config.Config{AuthRequired: false, BackupDriver: "longhorn"},
		&restoreTestKubeClient{fakeKubeClient: &fakeKubeClient{}},
		&restoreTestLonghornClient{fakeLonghornClient: &fakeLonghornClient{}},
	)

	testCases := []struct {
		name   string
		method string
		body   string
		status int
		want   string
	}{
		{name: "method", method: http.MethodGet, body: "", status: http.StatusMethodNotAllowed, want: "method not allowed"},
		{name: "invalid json", method: http.MethodPost, body: `{"namespace":`, status: http.StatusBadRequest, want: "invalid JSON"},
		{name: "missing namespace", method: http.MethodPost, body: `{"pvc":"data","target_pvc":"restore-data"}`, status: http.StatusBadRequest, want: "namespace is required"},
		{name: "missing pvc", method: http.MethodPost, body: `{"namespace":"apps","target_pvc":"restore-data"}`, status: http.StatusBadRequest, want: "pvc is required"},
		{name: "missing target pvc", method: http.MethodPost, body: `{"namespace":"apps","pvc":"data"}`, status: http.StatusBadRequest, want: "target_pvc is required"},
	}

	for _, tc := range testCases {
		req := httptest.NewRequest(tc.method, "/v1/restores", strings.NewReader(tc.body))
		if tc.method == http.MethodPost {
			req.Header.Set("Content-Type", "application/json")
		}
		res := httptest.NewRecorder()
		srv.Handler().ServeHTTP(res, req)
		if res.Code != tc.status || !strings.Contains(res.Body.String(), tc.want) {
			t.Fatalf("%s: expected %d/%q, got %d %s", tc.name, tc.status, tc.want, res.Code, res.Body.String())
		}
	}
}

func TestHandleRestoreCoversAdditionalValidationBranches(t *testing.T) {
	srv := newRestoreTestServer(
		&config.Config{AuthRequired: false, BackupDriver: "longhorn"},
		&restoreTestKubeClient{fakeKubeClient: &fakeKubeClient{}},
		&restoreTestLonghornClient{fakeLonghornClient: &fakeLonghornClient{}},
	)

	testCases := []struct {
		name string
		body string
		want string
		code int
	}{
		{
			name: "invalid namespace label",
			body: `{"namespace":"Bad_Ns","pvc":"data","target_pvc":"restore-data"}`,
			want: "namespace must be a valid Kubernetes DNS-1123 label",
			code: http.StatusBadRequest,
		},
		{
			name: "invalid pvc label",
			body: `{"namespace":"apps","pvc":"Bad_PVC","target_pvc":"restore-data"}`,
			want: "pvc must be a valid Kubernetes DNS-1123 label",
			code: http.StatusBadRequest,
		},
		{
			name: "invalid target pvc label",
			body: `{"namespace":"apps","pvc":"data","target_pvc":"Bad_Target"}`,
			want: "target_pvc must be a valid Kubernetes DNS-1123 label",
			code: http.StatusBadRequest,
		},
		{
			name: "default target namespace still conflicts",
			body: `{"namespace":"apps","pvc":"data","target_pvc":"data"}`,
			want: "target namespace/pvc must differ from source",
			code: http.StatusConflict,
		},
	}

	for _, tc := range testCases {
		req := httptest.NewRequest(http.MethodPost, "/v1/restores", strings.NewReader(tc.body))
		req.Header.Set("Content-Type", "application/json")
		res := httptest.NewRecorder()
		srv.Handler().ServeHTTP(res, req)
		if res.Code != tc.code || !strings.Contains(res.Body.String(), tc.want) {
			t.Fatalf("%s: expected %d/%q, got %d %s", tc.name, tc.code, tc.want, res.Code, res.Body.String())
		}
	}
}

func TestHandleNamespaceRestoreRejectsInvalidRequestsAndBackendErrors(t *testing.T) {
	t.Run("bad requests", func(t *testing.T) {
		srv := newRestoreTestServer(
			&config.Config{AuthRequired: false, BackupDriver: "longhorn"},
			&restoreTestKubeClient{fakeKubeClient: &fakeKubeClient{}},
			&restoreTestLonghornClient{fakeLonghornClient: &fakeLonghornClient{}},
		)

		testCases := []struct {
			name   string
			method string
			body   string
			status int
			want   string
		}{
			{name: "method", method: http.MethodGet, body: "", status: http.StatusMethodNotAllowed, want: "method not allowed"},
			{name: "invalid json", method: http.MethodPost, body: `{"namespace":`, status: http.StatusBadRequest, want: "invalid JSON"},
			{name: "missing namespace", method: http.MethodPost, body: `{}`, status: http.StatusBadRequest, want: "namespace is required"},
			{name: "invalid namespace", method: http.MethodPost, body: `{"namespace":"Bad_Ns"}`, status: http.StatusBadRequest, want: "namespace must be a valid Kubernetes DNS-1123 label"},
			{name: "invalid target namespace", method: http.MethodPost, body: `{"namespace":"apps","target_namespace":"Bad_Ns"}`, status: http.StatusBadRequest, want: "target_namespace must be a valid Kubernetes DNS-1123 label"},
		}

		for _, tc := range testCases {
			req := httptest.NewRequest(tc.method, "/v1/restores/namespace", strings.NewReader(tc.body))
			if tc.method == http.MethodPost {
				req.Header.Set("Content-Type", "application/json")
			}
			res := httptest.NewRecorder()
			srv.Handler().ServeHTTP(res, req)
			if res.Code != tc.status || !strings.Contains(res.Body.String(), tc.want) {
				t.Fatalf("%s: expected %d/%q, got %d %s", tc.name, tc.status, tc.want, res.Code, res.Body.String())
			}
		}
	})

	t.Run("backend error", func(t *testing.T) {
		srv := newRestoreTestServer(
			&config.Config{AuthRequired: false, BackupDriver: "longhorn"},
			&restoreTestKubeClient{
				fakeKubeClient: &fakeKubeClient{},
				listPVCsErr:    errors.New("list pvcs exploded"),
			},
			&restoreTestLonghornClient{fakeLonghornClient: &fakeLonghornClient{}},
		)

		req := httptest.NewRequest(http.MethodPost, "/v1/restores/namespace", strings.NewReader(`{"namespace":"apps"}`))
		req.Header.Set("Content-Type", "application/json")
		res := httptest.NewRecorder()
		srv.Handler().ServeHTTP(res, req)

		if res.Code != http.StatusBadGateway || !strings.Contains(res.Body.String(), "list pvcs exploded") {
			t.Fatalf("expected namespace restore backend error, got %d %s", res.Code, res.Body.String())
		}
	})
}

func TestHandleNamespaceRestoreDefaultsTargetNamespaceForEmptyResults(t *testing.T) {
	srv := newRestoreTestServer(
		&config.Config{AuthRequired: false, BackupDriver: "longhorn"},
		&restoreTestKubeClient{
			fakeKubeClient: &fakeKubeClient{
				pvcs: []k8s.PVCSummary{
					{Namespace: "other", Name: "cache", VolumeName: "pv-other-cache", Phase: "Bound"},
				},
			},
		},
		&restoreTestLonghornClient{fakeLonghornClient: &fakeLonghornClient{}},
	)

	req := httptest.NewRequest(http.MethodPost, "/v1/restores/namespace", strings.NewReader(`{"namespace":"apps","dry_run":false}`))
	req.Header.Set("Content-Type", "application/json")
	res := httptest.NewRecorder()
	srv.Handler().ServeHTTP(res, req)

	if res.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d: %s", res.Code, res.Body.String())
	}
	if !strings.Contains(res.Body.String(), `"target_namespace":"apps"`) || !strings.Contains(res.Body.String(), `"total":0`) {
		t.Fatalf("expected default target namespace and empty results, got %s", res.Body.String())
	}
}

func TestHandleNamespaceRestoreAggregatesFailures(t *testing.T) {
	srv := newRestoreTestServer(
		&config.Config{AuthRequired: false, BackupDriver: "longhorn"},
		&restoreTestKubeClient{
			fakeKubeClient: &fakeKubeClient{
				pvcs: []k8s.PVCSummary{
					{Namespace: "apps", Name: "cache", VolumeName: "pv-apps-cache", Phase: "Bound"},
				},
				targetExists: true,
			},
		},
		&restoreTestLonghornClient{fakeLonghornClient: &fakeLonghornClient{}},
	)

	req := httptest.NewRequest(http.MethodPost, "/v1/restores/namespace", strings.NewReader(`{"namespace":"apps","target_namespace":"restore"}`))
	req.Header.Set("Content-Type", "application/json")
	res := httptest.NewRecorder()
	srv.Handler().ServeHTTP(res, req)

	if res.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d: %s", res.Code, res.Body.String())
	}
	if !strings.Contains(res.Body.String(), `"failed":1`) || !strings.Contains(res.Body.String(), `"status":"conflict"`) {
		t.Fatalf("expected aggregated failure response, got %s", res.Body.String())
	}
}

func TestExecuteRestoreLonghornErrorAndCleanupPaths(t *testing.T) {
	cfg := &config.Config{AuthRequired: false, BackupDriver: "longhorn"}

	t.Run("target exists lookup error", func(t *testing.T) {
		srv := newRestoreTestServer(
			cfg,
			&restoreTestKubeClient{
				fakeKubeClient:  &fakeKubeClient{},
				targetExistsErr: errors.New("target lookup exploded"),
			},
			&restoreTestLonghornClient{fakeLonghornClient: &fakeLonghornClient{}},
		)
		_, result, err := srv.executeRestore(context.Background(), api.RestoreTestRequest{
			Namespace: "apps", PVC: "data", TargetNamespace: "restore", TargetPVC: "restore-data",
		}, "brad")
		if result != "validation_error" || err == nil || !strings.Contains(err.Error(), "target lookup exploded") {
			t.Fatalf("expected target exists validation error, got result=%q err=%v", result, err)
		}
	})

	t.Run("resolve pvc error", func(t *testing.T) {
		srv := newRestoreTestServer(
			cfg,
			&restoreTestKubeClient{
				fakeKubeClient: &fakeKubeClient{},
				resolveErr:     errors.New("resolve pvc exploded"),
			},
			&restoreTestLonghornClient{fakeLonghornClient: &fakeLonghornClient{}},
		)
		_, result, err := srv.executeRestore(context.Background(), api.RestoreTestRequest{
			Namespace: "apps", PVC: "data", TargetNamespace: "restore", TargetPVC: "restore-data",
		}, "brad")
		if result != "validation_error" || err == nil || !strings.Contains(err.Error(), "resolve pvc exploded") {
			t.Fatalf("expected resolve pvc validation error, got result=%q err=%v", result, err)
		}
	})

	t.Run("find backup error", func(t *testing.T) {
		srv := newRestoreTestServer(
			cfg,
			&restoreTestKubeClient{fakeKubeClient: &fakeKubeClient{}},
			&restoreTestLonghornClient{
				fakeLonghornClient: &fakeLonghornClient{},
				findErr:            errors.New("find backup exploded"),
			},
		)
		_, result, err := srv.executeRestore(context.Background(), api.RestoreTestRequest{
			Namespace: "apps", PVC: "data", TargetNamespace: "restore", TargetPVC: "restore-data",
		}, "brad")
		if result != "validation_error" || err == nil || !strings.Contains(err.Error(), "find backup exploded") {
			t.Fatalf("expected find backup validation error, got result=%q err=%v", result, err)
		}
	})

	t.Run("backup url required", func(t *testing.T) {
		srv := newRestoreTestServer(
			cfg,
			&restoreTestKubeClient{fakeKubeClient: &fakeKubeClient{}},
			&restoreTestLonghornClient{
				fakeLonghornClient: &fakeLonghornClient{},
				findBackup:         &longhorn.Backup{Name: "backup-a", URL: ""},
			},
		)
		_, result, err := srv.executeRestore(context.Background(), api.RestoreTestRequest{
			Namespace: "apps", PVC: "data", TargetNamespace: "restore", TargetPVC: "restore-data",
		}, "brad")
		if result != "validation_error" || err == nil || !strings.Contains(err.Error(), "backup_url is required") {
			t.Fatalf("expected backup_url validation error, got result=%q err=%v", result, err)
		}
	})

	t.Run("get volume backend error", func(t *testing.T) {
		srv := newRestoreTestServer(
			cfg,
			&restoreTestKubeClient{fakeKubeClient: &fakeKubeClient{}},
			&restoreTestLonghornClient{
				fakeLonghornClient: &fakeLonghornClient{},
				findBackup:         &longhorn.Backup{Name: "backup-a", URL: "s3://bucket/backup-a"},
				getVolumeErr:       errors.New("get volume exploded"),
			},
		)
		_, result, err := srv.executeRestore(context.Background(), api.RestoreTestRequest{
			Namespace: "apps", PVC: "data", TargetNamespace: "restore", TargetPVC: "restore-data",
		}, "brad")
		if result != "backend_error" || err == nil || !strings.Contains(err.Error(), "get volume exploded") {
			t.Fatalf("expected get volume backend error, got result=%q err=%v", result, err)
		}
	})

	t.Run("create volume backend error", func(t *testing.T) {
		srv := newRestoreTestServer(
			cfg,
			&restoreTestKubeClient{fakeKubeClient: &fakeKubeClient{}},
			&restoreTestLonghornClient{
				fakeLonghornClient: &fakeLonghornClient{},
				findBackup:         &longhorn.Backup{Name: "backup-a", URL: "s3://bucket/backup-a"},
				getVolume:          &longhorn.Volume{Name: "pv-apps-data", Size: "4096", NumberOfReplicas: 0},
				createVolErr:       errors.New("create volume exploded"),
			},
		)
		_, result, err := srv.executeRestore(context.Background(), api.RestoreTestRequest{
			Namespace: "apps", PVC: "data", TargetNamespace: "restore", TargetPVC: "restore-data",
		}, "brad")
		if result != "backend_error" || err == nil || !strings.Contains(err.Error(), "create volume exploded") {
			t.Fatalf("expected create volume backend error, got result=%q err=%v", result, err)
		}
	})

	t.Run("create pvc cleanup success", func(t *testing.T) {
		longhornClient := &restoreTestLonghornClient{
			fakeLonghornClient: &fakeLonghornClient{},
			findBackup:         &longhorn.Backup{Name: "backup-a", URL: "s3://bucket/backup-a"},
			getVolume:          &longhorn.Volume{Name: "pv-apps-data", Size: "4096", NumberOfReplicas: 1},
			createPVCErr:       errors.New("create pvc exploded"),
		}
		srv := newRestoreTestServer(
			cfg,
			&restoreTestKubeClient{fakeKubeClient: &fakeKubeClient{}},
			longhornClient,
		)
		_, result, err := srv.executeRestore(context.Background(), api.RestoreTestRequest{
			Namespace: "apps", PVC: "data", TargetNamespace: "restore", TargetPVC: "restore-data",
		}, "brad")
		if result != "backend_error" || err == nil || !strings.Contains(err.Error(), "create restore pvc") {
			t.Fatalf("expected create pvc backend error, got result=%q err=%v", result, err)
		}
		if longhornClient.deletedVolume == "" {
			t.Fatalf("expected failed PVC create to trigger volume cleanup")
		}
	})

	t.Run("create pvc cleanup failure", func(t *testing.T) {
		srv := newRestoreTestServer(
			cfg,
			&restoreTestKubeClient{fakeKubeClient: &fakeKubeClient{}},
			&restoreTestLonghornClient{
				fakeLonghornClient: &fakeLonghornClient{},
				findBackup:         &longhorn.Backup{Name: "backup-a", URL: "s3://bucket/backup-a"},
				getVolume:          &longhorn.Volume{Name: "pv-apps-data", Size: "4096", NumberOfReplicas: 1},
				createPVCErr:       errors.New("create pvc exploded"),
				deleteVolErr:       errors.New("cleanup exploded"),
			},
		)
		_, result, err := srv.executeRestore(context.Background(), api.RestoreTestRequest{
			Namespace: "apps", PVC: "data", TargetNamespace: "restore", TargetPVC: "restore-data",
		}, "brad")
		if result != "backend_error" || err == nil || !strings.Contains(err.Error(), "cleanup failed") {
			t.Fatalf("expected cleanup failure to be surfaced, got result=%q err=%v", result, err)
		}
	})
}

func TestExecuteRestoreResticAndHelperFunctions(t *testing.T) {
	t.Run("restic create restore error", func(t *testing.T) {
		srv := newRestoreTestServer(
			&config.Config{AuthRequired: false, BackupDriver: "restic"},
			&restoreTestKubeClient{
				fakeKubeClient:   &fakeKubeClient{},
				createRestoreErr: errors.New("create restore job exploded"),
			},
			&restoreTestLonghornClient{fakeLonghornClient: &fakeLonghornClient{}},
		)
		_, result, err := srv.executeRestore(context.Background(), api.RestoreTestRequest{
			Namespace: "apps", PVC: "data", TargetNamespace: "restore", TargetPVC: "restore-data",
		}, "brad")
		if result != "backend_error" || err == nil || !strings.Contains(err.Error(), "create restore job exploded") {
			t.Fatalf("expected restic backend error, got result=%q err=%v", result, err)
		}
	})

	t.Run("unsupported driver", func(t *testing.T) {
		srv := newRestoreTestServer(
			&config.Config{AuthRequired: false, BackupDriver: "mystery"},
			&restoreTestKubeClient{fakeKubeClient: &fakeKubeClient{}},
			&restoreTestLonghornClient{fakeLonghornClient: &fakeLonghornClient{}},
		)
		_, result, err := srv.executeRestore(context.Background(), api.RestoreTestRequest{
			Namespace: "apps", PVC: "data", TargetNamespace: "restore", TargetPVC: "restore-data",
		}, "brad")
		if result != "unsupported_driver" || err == nil || !strings.Contains(err.Error(), "unsupported backup driver") {
			t.Fatalf("expected unsupported driver error, got result=%q err=%v", result, err)
		}
	})

	t.Run("restic dry run success", func(t *testing.T) {
		srv := newRestoreTestServer(
			&config.Config{AuthRequired: false, BackupDriver: "restic"},
			&restoreTestKubeClient{fakeKubeClient: &fakeKubeClient{}},
			&restoreTestLonghornClient{fakeLonghornClient: &fakeLonghornClient{}},
		)
		response, result, err := srv.executeRestore(context.Background(), api.RestoreTestRequest{
			Namespace: "apps", PVC: "data", TargetNamespace: "restore", TargetPVC: "restore-data", DryRun: true,
		}, "brad")
		if err != nil || result != "dry_run" || response.JobName != "restore-job" || response.Secret != "restore-secret" {
			t.Fatalf("expected restic dry-run success, got response=%#v result=%q err=%v", response, result, err)
		}
	})

	t.Run("restore status code", func(t *testing.T) {
		testCases := map[string]int{
			"validation_error":   http.StatusBadRequest,
			"unsupported_driver": http.StatusBadRequest,
			"conflict":           http.StatusConflict,
			"backend_error":      http.StatusBadGateway,
			"anything-else":      http.StatusInternalServerError,
		}
		for result, want := range testCases {
			if got := restoreStatusCode(result); got != want {
				t.Fatalf("result=%q: expected %d, got %d", result, want, got)
			}
		}
	})

	t.Run("target pvc name", func(t *testing.T) {
		if got := targetPVCName("", "Data_PVC"); got != "restore-data-pvc" {
			t.Fatalf("expected default restore prefix, got %q", got)
		}
		if got := targetPVCName("___", "Data_PVC"); got != "restore-data-pvc" {
			t.Fatalf("expected sanitized-empty prefix to fall back to restore, got %q", got)
		}
		if got := targetPVCName("drill", "cache"); got != "drill-cache" {
			t.Fatalf("expected explicit prefix, got %q", got)
		}
		if got := targetPVCName("drill-", "cache"); got != "drill-cache" {
			t.Fatalf("expected suffix-preserving prefix, got %q", got)
		}
		if got := targetPVCName(strings.Repeat("very-long-prefix-", 8), strings.Repeat("data-", 8)); len(got) > 63 {
			t.Fatalf("expected truncated target pvc name <=63 chars, got %d %q", len(got), got)
		}
	})
}