package grpcserver

import (
	"context"
	"encoding/json"
	"log/slog"
	"net"
	"net/http"
	"net/http/httptest"
	"path/filepath"
	"testing"

	"google.golang.org/grpc"
	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/credentials/insecure"
	"google.golang.org/grpc/metadata"
	"google.golang.org/grpc/status"

	mcdslauth "git.wntrmute.dev/kyle/mcdsl/auth"

	pb "git.wntrmute.dev/kyle/mcr/gen/mcr/v1"
	"git.wntrmute.dev/kyle/mcr/internal/db"
)

// mockMCIAS starts a fake MCIAS HTTP server for token validation.
// Recognized tokens:
//   - "admin-token" → valid, username=admin-uuid, roles=[admin]
//   - "user-token"  → valid, username=user-uuid, account_type=human, roles=[user]
//   - "alice-token" → valid, username=alice, account_type=human, roles=[user]
//   - anything else → invalid
func mockMCIAS(t *testing.T) *httptest.Server {
	t.Helper()
	mux := http.NewServeMux()
	mux.HandleFunc("POST /v1/token/validate", func(w http.ResponseWriter, r *http.Request) {
		var req struct {
			Token string `json:"token"`
		}
		if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
			http.Error(w, "bad request", http.StatusBadRequest)
			return
		}
		w.Header().Set("Content-Type", "application/json")
		switch req.Token {
		case "admin-token":
			_ = json.NewEncoder(w).Encode(map[string]interface{}{
				"valid":        true,
				"username":     "admin-uuid",
				"account_type": "human",
				"roles":        []string{"admin"},
			})
		case "user-token":
			_ = json.NewEncoder(w).Encode(map[string]interface{}{
				"valid":        true,
				"username":     "user-uuid",
				"account_type": "human",
				"roles":        []string{"user"},
			})
		case "alice-token":
			_ = json.NewEncoder(w).Encode(map[string]interface{}{
				"valid":        true,
				"username":     "alice",
				"account_type": "human",
				"roles":        []string{"user"},
			})
		default:
			_ = json.NewEncoder(w).Encode(map[string]interface{}{"valid": false})
		}
	})
	srv := httptest.NewServer(mux)
	t.Cleanup(srv.Close)
	return srv
}

// testAuthenticator creates an mcdsl/auth.Authenticator that talks to the given mock MCIAS.
func testAuthenticator(t *testing.T, serverURL string) *mcdslauth.Authenticator {
	t.Helper()
	a, err := mcdslauth.New(mcdslauth.Config{ServerURL: serverURL}, slog.Default())
	if err != nil {
		t.Fatalf("auth.New: %v", err)
	}
	return a
}

// openTestDB creates a temporary test database with migrations applied.
func openTestDB(t *testing.T) *db.DB {
	t.Helper()
	path := filepath.Join(t.TempDir(), "test.db")
	d, err := db.Open(path)
	if err != nil {
		t.Fatalf("Open: %v", err)
	}
	t.Cleanup(func() { _ = d.Close() })
	if err := d.Migrate(); err != nil {
		t.Fatalf("Migrate: %v", err)
	}
	return d
}

// startTestServer creates a gRPC server and client for testing.
func startTestServer(t *testing.T, deps Deps) *grpc.ClientConn {
	t.Helper()

	srv, err := New("", "", deps, slog.Default())
	if err != nil {
		t.Fatalf("New: %v", err)
	}

	lis, err := net.Listen("tcp", "127.0.0.1:0")
	if err != nil {
		t.Fatalf("Listen: %v", err)
	}

	go func() {
		_ = srv.Serve(lis)
	}()
	t.Cleanup(func() { srv.GracefulStop() })

	//nolint:gosec // insecure credentials for testing only
	cc, err := grpc.NewClient(
		lis.Addr().String(),
		grpc.WithTransportCredentials(insecure.NewCredentials()),
		grpc.WithDefaultCallOptions(grpc.ForceCodecV2(pb.JSONCodec{})),
	)
	if err != nil {
		t.Fatalf("Dial: %v", err)
	}
	t.Cleanup(func() { _ = cc.Close() })

	return cc
}

// withAuth adds a bearer token to the outgoing context metadata.
func withAuth(ctx context.Context, token string) context.Context {
	return metadata.AppendToOutgoingContext(ctx, "authorization", "Bearer "+token)
}

func TestHealthBypassesAuth(t *testing.T) {
	mcias := mockMCIAS(t)
	auth := testAuthenticator(t, mcias.URL)
	database := openTestDB(t)

	cc := startTestServer(t, Deps{
		DB:            database,
		Authenticator: auth,
	})

	client := pb.NewAdminServiceClient(cc)
	resp, err := client.Health(context.Background(), &pb.HealthRequest{})
	if err != nil {
		t.Fatalf("Health: %v", err)
	}
	if resp.Status != "ok" {
		t.Fatalf("Health status: got %q, want %q", resp.Status, "ok")
	}
}

func TestAuthInterceptorNoToken(t *testing.T) {
	mcias := mockMCIAS(t)
	auth := testAuthenticator(t, mcias.URL)
	database := openTestDB(t)

	cc := startTestServer(t, Deps{
		DB:            database,
		Authenticator: auth,
	})

	client := pb.NewRegistryServiceClient(cc)
	_, err := client.ListRepositories(context.Background(), &pb.ListRepositoriesRequest{})
	if err == nil {
		t.Fatal("expected error for unauthenticated request")
	}

	st, ok := status.FromError(err)
	if !ok {
		t.Fatalf("expected gRPC status error, got %v", err)
	}
	if st.Code() != codes.Unauthenticated {
		t.Fatalf("code: got %v, want Unauthenticated", st.Code())
	}
}

func TestAuthInterceptorInvalidToken(t *testing.T) {
	mcias := mockMCIAS(t)
	auth := testAuthenticator(t, mcias.URL)
	database := openTestDB(t)

	cc := startTestServer(t, Deps{
		DB:            database,
		Authenticator: auth,
	})

	ctx := withAuth(context.Background(), "bad-token")
	client := pb.NewRegistryServiceClient(cc)
	_, err := client.ListRepositories(ctx, &pb.ListRepositoriesRequest{})
	if err == nil {
		t.Fatal("expected error for invalid token")
	}

	st, ok := status.FromError(err)
	if !ok {
		t.Fatalf("expected gRPC status error, got %v", err)
	}
	if st.Code() != codes.Unauthenticated {
		t.Fatalf("code: got %v, want Unauthenticated", st.Code())
	}
}

func TestAuthInterceptorValidToken(t *testing.T) {
	mcias := mockMCIAS(t)
	auth := testAuthenticator(t, mcias.URL)
	database := openTestDB(t)

	cc := startTestServer(t, Deps{
		DB:            database,
		Authenticator: auth,
	})

	ctx := withAuth(context.Background(), "user-token")
	client := pb.NewRegistryServiceClient(cc)
	resp, err := client.ListRepositories(ctx, &pb.ListRepositoriesRequest{})
	if err != nil {
		t.Fatalf("ListRepositories: %v", err)
	}
	if resp == nil {
		t.Fatal("expected non-nil response")
	}
}

func TestAdminInterceptorDenied(t *testing.T) {
	mcias := mockMCIAS(t)
	auth := testAuthenticator(t, mcias.URL)
	database := openTestDB(t)

	cc := startTestServer(t, Deps{
		DB:            database,
		Authenticator: auth,
	})

	ctx := withAuth(context.Background(), "user-token")

	// Policy RPCs require admin.
	policyClient := pb.NewPolicyServiceClient(cc)
	_, err := policyClient.ListPolicyRules(ctx, &pb.ListPolicyRulesRequest{})
	if err == nil {
		t.Fatal("expected error for non-admin user")
	}

	st, ok := status.FromError(err)
	if !ok {
		t.Fatalf("expected gRPC status error, got %v", err)
	}
	if st.Code() != codes.PermissionDenied {
		t.Fatalf("code: got %v, want PermissionDenied", st.Code())
	}
}

func TestAdminInterceptorAllowed(t *testing.T) {
	mcias := mockMCIAS(t)
	auth := testAuthenticator(t, mcias.URL)
	database := openTestDB(t)

	cc := startTestServer(t, Deps{
		DB:            database,
		Authenticator: auth,
	})

	ctx := withAuth(context.Background(), "admin-token")

	// Admin user should be able to list policy rules.
	policyClient := pb.NewPolicyServiceClient(cc)
	resp, err := policyClient.ListPolicyRules(ctx, &pb.ListPolicyRulesRequest{})
	if err != nil {
		t.Fatalf("ListPolicyRules: %v", err)
	}
	if resp == nil {
		t.Fatal("expected non-nil response")
	}
}

func TestMethodMapCompleteness(t *testing.T) {
	mm := methodMap()

	// Verify that admin-required methods match our security spec.
	expectedAdmin := []string{
		"/mcr.v1.RegistryService/DeleteRepository",
		"/mcr.v1.RegistryService/GarbageCollect",
		"/mcr.v1.RegistryService/GetGCStatus",
		"/mcr.v1.PolicyService/ListPolicyRules",
		"/mcr.v1.PolicyService/CreatePolicyRule",
		"/mcr.v1.PolicyService/GetPolicyRule",
		"/mcr.v1.PolicyService/UpdatePolicyRule",
		"/mcr.v1.PolicyService/DeletePolicyRule",
		"/mcr.v1.AuditService/ListAuditEvents",
	}

	for _, method := range expectedAdmin {
		if !mm.AdminRequired[method] {
			t.Errorf("method %s should require admin but is not in AdminRequired", method)
		}
	}

	if len(mm.AdminRequired) != len(expectedAdmin) {
		t.Errorf("AdminRequired has %d entries, expected %d", len(mm.AdminRequired), len(expectedAdmin))
	}

	// Health is the only public method.
	expectedPublic := []string{
		"/mcr.v1.AdminService/Health",
	}

	for _, method := range expectedPublic {
		if !mm.Public[method] {
			t.Errorf("method %s should be public but is not in Public", method)
		}
	}

	if len(mm.Public) != len(expectedPublic) {
		t.Errorf("Public has %d entries, expected %d", len(mm.Public), len(expectedPublic))
	}

	// Auth-required methods.
	expectedAuth := []string{
		"/mcr.v1.RegistryService/ListRepositories",
		"/mcr.v1.RegistryService/GetRepository",
	}

	for _, method := range expectedAuth {
		if !mm.AuthRequired[method] {
			t.Errorf("method %s should require auth but is not in AuthRequired", method)
		}
	}

	if len(mm.AuthRequired) != len(expectedAuth) {
		t.Errorf("AuthRequired has %d entries, expected %d", len(mm.AuthRequired), len(expectedAuth))
	}
}

func TestDeleteRepoRequiresAdmin(t *testing.T) {
	mcias := mockMCIAS(t)
	auth := testAuthenticator(t, mcias.URL)
	database := openTestDB(t)

	cc := startTestServer(t, Deps{
		DB:            database,
		Authenticator: auth,
	})

	ctx := withAuth(context.Background(), "user-token")
	client := pb.NewRegistryServiceClient(cc)
	_, err := client.DeleteRepository(ctx, &pb.DeleteRepositoryRequest{Name: "test"})
	if err == nil {
		t.Fatal("expected error for non-admin user trying to delete repo")
	}

	st, ok := status.FromError(err)
	if !ok {
		t.Fatalf("expected gRPC status error, got %v", err)
	}
	if st.Code() != codes.PermissionDenied {
		t.Fatalf("code: got %v, want PermissionDenied", st.Code())
	}
}

func TestGCRequiresAdmin(t *testing.T) {
	mcias := mockMCIAS(t)
	auth := testAuthenticator(t, mcias.URL)
	database := openTestDB(t)

	cc := startTestServer(t, Deps{
		DB:            database,
		Authenticator: auth,
	})

	ctx := withAuth(context.Background(), "user-token")
	client := pb.NewRegistryServiceClient(cc)
	_, err := client.GarbageCollect(ctx, &pb.GarbageCollectRequest{})
	if err == nil {
		t.Fatal("expected error for non-admin user trying to trigger GC")
	}

	st, ok := status.FromError(err)
	if !ok {
		t.Fatalf("expected gRPC status error, got %v", err)
	}
	if st.Code() != codes.PermissionDenied {
		t.Fatalf("code: got %v, want PermissionDenied", st.Code())
	}
}

func TestAuditRequiresAdmin(t *testing.T) {
	mcias := mockMCIAS(t)
	auth := testAuthenticator(t, mcias.URL)
	database := openTestDB(t)

	cc := startTestServer(t, Deps{
		DB:            database,
		Authenticator: auth,
	})

	ctx := withAuth(context.Background(), "user-token")
	client := pb.NewAuditServiceClient(cc)
	_, err := client.ListAuditEvents(ctx, &pb.ListAuditEventsRequest{})
	if err == nil {
		t.Fatal("expected error for non-admin user trying to list audit events")
	}

	st, ok := status.FromError(err)
	if !ok {
		t.Fatalf("expected gRPC status error, got %v", err)
	}
	if st.Code() != codes.PermissionDenied {
		t.Fatalf("code: got %v, want PermissionDenied", st.Code())
	}
}