package repl_util

import (
	"bytes"
	"context"
	"crypto/aes"
	"crypto/cipher"
	"crypto/rand"
	"encoding/base64"
	"encoding/hex"
	"encoding/json"
	"fmt"
	"io"
	"os"
	"testing"

	"github.com/seaweedfs/seaweedfs/weed/kms"
	"github.com/seaweedfs/seaweedfs/weed/pb/filer_pb"
	"github.com/seaweedfs/seaweedfs/weed/s3api"
	"github.com/seaweedfs/seaweedfs/weed/s3api/s3_constants"
	"github.com/seaweedfs/seaweedfs/weed/util"
)

func TestDetectSSEType(t *testing.T) {
	tests := []struct {
		name      string
		entry     *filer_pb.Entry
		wantType  filer_pb.SSEType
		wantError bool
	}{
		{
			name:     "no chunks no extended",
			entry:    &filer_pb.Entry{},
			wantType: filer_pb.SSEType_NONE,
		},
		{
			name: "plaintext chunks",
			entry: &filer_pb.Entry{
				Chunks: []*filer_pb.FileChunk{
					{SseType: filer_pb.SSEType_NONE},
					{SseType: filer_pb.SSEType_NONE},
				},
			},
			wantType: filer_pb.SSEType_NONE,
		},
		{
			name: "uniform SSE-S3 chunks",
			entry: &filer_pb.Entry{
				Chunks: []*filer_pb.FileChunk{
					{SseType: filer_pb.SSEType_SSE_S3},
					{SseType: filer_pb.SSEType_SSE_S3},
				},
			},
			wantType: filer_pb.SSEType_SSE_S3,
		},
		{
			name: "uniform SSE-KMS chunks",
			entry: &filer_pb.Entry{
				Chunks: []*filer_pb.FileChunk{
					{SseType: filer_pb.SSEType_SSE_KMS},
				},
			},
			wantType: filer_pb.SSEType_SSE_KMS,
		},
		{
			name: "mixed chunk SSE types",
			entry: &filer_pb.Entry{
				Chunks: []*filer_pb.FileChunk{
					{SseType: filer_pb.SSEType_SSE_S3},
					{SseType: filer_pb.SSEType_SSE_KMS},
				},
			},
			wantError: true,
		},
		{
			name: "inline SSE-S3 via extended",
			entry: &filer_pb.Entry{
				Extended: map[string][]byte{
					s3_constants.SeaweedFSSSES3Key: {0x01},
				},
			},
			wantType: filer_pb.SSEType_SSE_S3,
		},
		{
			name: "inline SSE-KMS via extended",
			entry: &filer_pb.Entry{
				Extended: map[string][]byte{
					s3_constants.SeaweedFSSSEKMSKey: {0x01},
				},
			},
			wantType: filer_pb.SSEType_SSE_KMS,
		},
		{
			name: "inline SSE-C via extended",
			entry: &filer_pb.Entry{
				Extended: map[string][]byte{
					s3_constants.SeaweedFSSSEIV: {0x01},
				},
			},
			wantType: filer_pb.SSEType_SSE_C,
		},
		{
			name: "conflicting extended metadata",
			entry: &filer_pb.Entry{
				Extended: map[string][]byte{
					s3_constants.SeaweedFSSSES3Key:  {0x01},
					s3_constants.SeaweedFSSSEKMSKey: {0x02},
				},
			},
			wantError: true,
		},
		{
			name: "chunks take precedence over extended",
			entry: &filer_pb.Entry{
				Chunks: []*filer_pb.FileChunk{
					{SseType: filer_pb.SSEType_SSE_S3},
				},
				Extended: map[string][]byte{
					s3_constants.SeaweedFSSSEKMSKey: {0x01},
				},
			},
			wantType: filer_pb.SSEType_SSE_S3,
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			got, err := detectSSEType(tt.entry)
			if tt.wantError {
				if err == nil {
					t.Fatalf("expected error, got type %v", got)
				}
				return
			}
			if err != nil {
				t.Fatalf("unexpected error: %v", err)
			}
			if got != tt.wantType {
				t.Errorf("got %v, want %v", got, tt.wantType)
			}
		})
	}
}

func TestMaybeDecryptReader_Plaintext(t *testing.T) {
	content := []byte("hello world")
	entry := &filer_pb.Entry{}
	reader := bytes.NewReader(content)

	got, err := MaybeDecryptReader(reader, entry)
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	result, err := io.ReadAll(got)
	if err != nil {
		t.Fatalf("ReadAll error: %v", err)
	}
	if !bytes.Equal(result, content) {
		t.Errorf("got %q, want %q", result, content)
	}
}

func TestMaybeDecryptReader_NilEntry(t *testing.T) {
	content := []byte("hello")
	reader := bytes.NewReader(content)

	got, err := MaybeDecryptReader(reader, nil)
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	result, err := io.ReadAll(got)
	if err != nil {
		t.Fatalf("ReadAll error: %v", err)
	}
	if !bytes.Equal(result, content) {
		t.Errorf("got %q, want %q", result, content)
	}
}

func TestMaybeDecryptReader_SSEC_Error(t *testing.T) {
	entry := &filer_pb.Entry{
		Extended: map[string][]byte{
			s3_constants.SeaweedFSSSEIV: {0x01},
		},
	}
	reader := bytes.NewReader([]byte("data"))

	_, err := MaybeDecryptReader(reader, entry)
	if err == nil {
		t.Fatal("expected error for SSE-C")
	}
}

func TestMaybeDecryptContent_Plaintext(t *testing.T) {
	content := []byte("hello world")
	entry := &filer_pb.Entry{}

	got, err := MaybeDecryptContent(content, entry)
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if !bytes.Equal(got, content) {
		t.Errorf("got %q, want %q", got, content)
	}
}

func TestMaybeDecryptContent_NilEntry(t *testing.T) {
	content := []byte("data")
	got, err := MaybeDecryptContent(content, nil)
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if !bytes.Equal(got, content) {
		t.Errorf("got %q, want %q", got, content)
	}
}

func TestMaybeDecryptContent_Empty(t *testing.T) {
	got, err := MaybeDecryptContent(nil, &filer_pb.Entry{})
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if got != nil {
		t.Errorf("expected nil, got %v", got)
	}
}

func TestMaybeDecryptContent_SSEC_Error(t *testing.T) {
	entry := &filer_pb.Entry{
		Extended: map[string][]byte{
			s3_constants.SeaweedFSSSEIV: {0x01},
		},
	}

	_, err := MaybeDecryptContent([]byte("data"), entry)
	if err == nil {
		t.Fatal("expected error for SSE-C")
	}
}

func TestMaybeDecryptContent_MixedExtended_Error(t *testing.T) {
	entry := &filer_pb.Entry{
		Extended: map[string][]byte{
			s3_constants.SeaweedFSSSES3Key:  {0x01},
			s3_constants.SeaweedFSSSEKMSKey: {0x02},
		},
	}

	_, err := MaybeDecryptContent([]byte("data"), entry)
	if err == nil {
		t.Fatal("expected error for conflicting SSE metadata")
	}
}

// --- SSE-S3 integration tests ---
// These tests exercise the full MaybeDecryptReader/MaybeDecryptContent path
// for SSE-S3: detectSSEType → decryptSSES3 → DeserializeSSES3Metadata →
// GetSSES3IV → CreateSSES3DecryptedReader. A test KEK is injected via
// WEED_S3_SSE_KEK env var and a mock filer client.

// testFilerClient is a minimal filer_pb.FilerClient mock that returns
// ErrNotFound for all lookups (no KEK on filer — we use env var instead).
type testFilerClient struct{}

func (c *testFilerClient) WithFilerClient(_ bool, fn func(filer_pb.SeaweedFilerClient) error) error {
	return fmt.Errorf("%w", filer_pb.ErrNotFound)
}
func (c *testFilerClient) AdjustedUrl(loc *filer_pb.Location) string { return loc.Url }
func (c *testFilerClient) GetDataCenter() string                     { return "" }

// setupTestSSES3 initializes the global SSE-S3 key manager with a test KEK
// via the WEED_S3_SSE_KEK env var and returns the KEK bytes + cleanup func.
func setupTestSSES3(t *testing.T) (kek []byte, cleanup func()) {
	t.Helper()

	kek = make([]byte, 32)
	if _, err := io.ReadFull(rand.Reader, kek); err != nil {
		t.Fatal(err)
	}

	// Force Viper to pick up the new env var
	os.Setenv("WEED_S3_SSE_KEK", hex.EncodeToString(kek))

	// Reset Viper cache so it reads the new env var
	v := util.GetViper()
	v.AutomaticEnv()

	// Re-initialize the global key manager with the KEK from env
	km := s3api.GetSSES3KeyManager()
	if err := km.InitializeWithFiler(&testFilerClient{}); err != nil {
		os.Unsetenv("WEED_S3_SSE_KEK")
		t.Fatalf("InitializeWithFiler: %v", err)
	}

	return kek, func() {
		os.Unsetenv("WEED_S3_SSE_KEK")
		// Re-initialize with no KEK to clear the super key
		km.InitializeWithFiler(&testFilerClient{})
	}
}

func TestMaybeDecryptReader_SSES3(t *testing.T) {
	_, cleanup := setupTestSSES3(t)
	defer cleanup()

	plaintext := []byte("SSE-S3 encrypted content for testing round-trip decryption")

	// Generate a DEK and encrypt
	sseKey, err := s3api.GenerateSSES3Key()
	if err != nil {
		t.Fatal(err)
	}
	encReader, encIV, err := s3api.CreateSSES3EncryptedReader(bytes.NewReader(plaintext), sseKey)
	if err != nil {
		t.Fatalf("encrypt: %v", err)
	}
	ciphertext, err := io.ReadAll(encReader)
	if err != nil {
		t.Fatalf("read ciphertext: %v", err)
	}

	// Build serialized SSE-S3 metadata (uses the global key manager to
	// envelope-encrypt the DEK with the test KEK)
	sseKey.IV = encIV
	metadataBytes, err := s3api.SerializeSSES3Metadata(sseKey)
	if err != nil {
		t.Fatalf("serialize metadata: %v", err)
	}

	entry := &filer_pb.Entry{
		Extended: map[string][]byte{
			s3_constants.SeaweedFSSSES3Key: metadataBytes,
		},
	}

	// Test full path: MaybeDecryptReader → decryptSSES3 → DeserializeSSES3Metadata → CreateSSES3DecryptedReader
	decrypted, err := MaybeDecryptReader(bytes.NewReader(ciphertext), entry)
	if err != nil {
		t.Fatalf("MaybeDecryptReader: %v", err)
	}
	result, err := io.ReadAll(decrypted)
	if err != nil {
		t.Fatalf("ReadAll: %v", err)
	}
	if !bytes.Equal(result, plaintext) {
		t.Errorf("SSE-S3 round-trip failed: got %q, want %q", result, plaintext)
	}
}

func TestMaybeDecryptContent_SSES3(t *testing.T) {
	_, cleanup := setupTestSSES3(t)
	defer cleanup()

	plaintext := []byte("inline SSE-S3 content")

	// Generate a DEK and encrypt inline content
	sseKey, err := s3api.GenerateSSES3Key()
	if err != nil {
		t.Fatal(err)
	}
	encReader, encIV, err := s3api.CreateSSES3EncryptedReader(bytes.NewReader(plaintext), sseKey)
	if err != nil {
		t.Fatalf("encrypt: %v", err)
	}
	ciphertext, err := io.ReadAll(encReader)
	if err != nil {
		t.Fatalf("read ciphertext: %v", err)
	}

	sseKey.IV = encIV
	metadataBytes, err := s3api.SerializeSSES3Metadata(sseKey)
	if err != nil {
		t.Fatalf("serialize metadata: %v", err)
	}

	entry := &filer_pb.Entry{
		Extended: map[string][]byte{
			s3_constants.SeaweedFSSSES3Key: metadataBytes,
		},
	}

	// Test full path: MaybeDecryptContent → MaybeDecryptReader → decryptSSES3
	result, err := MaybeDecryptContent(ciphertext, entry)
	if err != nil {
		t.Fatalf("MaybeDecryptContent: %v", err)
	}
	if !bytes.Equal(result, plaintext) {
		t.Errorf("SSE-S3 round-trip failed: got %q, want %q", result, plaintext)
	}
}

// --- SSE-KMS integration tests ---

// testKMSProvider is a minimal KMSProvider mock for testing.
type testKMSProvider struct {
	keyID     string
	plaintext []byte // the DEK plaintext returned by Decrypt
}

func (p *testKMSProvider) GenerateDataKey(_ context.Context, _ *kms.GenerateDataKeyRequest) (*kms.GenerateDataKeyResponse, error) {
	return nil, nil
}

func (p *testKMSProvider) Decrypt(_ context.Context, _ *kms.DecryptRequest) (*kms.DecryptResponse, error) {
	return &kms.DecryptResponse{
		KeyID:     p.keyID,
		Plaintext: append([]byte(nil), p.plaintext...), // return a copy
	}, nil
}

func (p *testKMSProvider) DescribeKey(_ context.Context, _ *kms.DescribeKeyRequest) (*kms.DescribeKeyResponse, error) {
	return nil, nil
}

func (p *testKMSProvider) GetKeyID(_ context.Context, keyIdentifier string) (string, error) {
	return p.keyID, nil
}

func (p *testKMSProvider) Close() error { return nil }

func TestMaybeDecryptReader_SSEKMS(t *testing.T) {
	plaintext := []byte("SSE-KMS encrypted content for testing")

	// Generate a random DEK and IV
	dek := make([]byte, 32)
	iv := make([]byte, aes.BlockSize)
	if _, err := io.ReadFull(rand.Reader, dek); err != nil {
		t.Fatal(err)
	}
	if _, err := io.ReadFull(rand.Reader, iv); err != nil {
		t.Fatal(err)
	}

	// Encrypt with AES-CTR (same cipher mode as SSE-KMS)
	block, err := aes.NewCipher(dek)
	if err != nil {
		t.Fatal(err)
	}
	ciphertext := make([]byte, len(plaintext))
	cipher.NewCTR(block, iv).XORKeyStream(ciphertext, plaintext)

	// Set up a mock KMS provider that returns our DEK
	keyID := "test-kms-key-1"
	encryptedDEK := []byte("fake-encrypted-dek") // mock doesn't validate
	kms.SetGlobalKMSProvider(&testKMSProvider{
		keyID:     keyID,
		plaintext: dek,
	})
	defer kms.SetGlobalKMSProvider(nil)

	// Build serialized KMS metadata
	kmsMetadata := s3api.SSEKMSMetadata{
		Algorithm:        s3_constants.SSEAlgorithmKMS,
		KeyID:            keyID,
		EncryptedDataKey: base64.StdEncoding.EncodeToString(encryptedDEK),
		IV:               base64.StdEncoding.EncodeToString(iv),
	}
	metadataBytes, err := json.Marshal(kmsMetadata)
	if err != nil {
		t.Fatal(err)
	}

	entry := &filer_pb.Entry{
		Extended: map[string][]byte{
			s3_constants.SeaweedFSSSEKMSKey: metadataBytes,
		},
	}

	// Test MaybeDecryptReader
	reader := bytes.NewReader(ciphertext)
	decrypted, err := MaybeDecryptReader(reader, entry)
	if err != nil {
		t.Fatalf("MaybeDecryptReader: %v", err)
	}
	result, err := io.ReadAll(decrypted)
	if err != nil {
		t.Fatalf("ReadAll: %v", err)
	}
	if !bytes.Equal(result, plaintext) {
		t.Errorf("SSE-KMS round-trip failed: got %q, want %q", result, plaintext)
	}
}

func TestMaybeDecryptContent_SSEKMS(t *testing.T) {
	plaintext := []byte("inline SSE-KMS content")

	dek := make([]byte, 32)
	iv := make([]byte, aes.BlockSize)
	if _, err := io.ReadFull(rand.Reader, dek); err != nil {
		t.Fatal(err)
	}
	if _, err := io.ReadFull(rand.Reader, iv); err != nil {
		t.Fatal(err)
	}

	block, err := aes.NewCipher(dek)
	if err != nil {
		t.Fatal(err)
	}
	ciphertext := make([]byte, len(plaintext))
	cipher.NewCTR(block, iv).XORKeyStream(ciphertext, plaintext)

	keyID := "test-kms-key-2"
	kms.SetGlobalKMSProvider(&testKMSProvider{
		keyID:     keyID,
		plaintext: dek,
	})
	defer kms.SetGlobalKMSProvider(nil)

	kmsMetadata := s3api.SSEKMSMetadata{
		Algorithm:        s3_constants.SSEAlgorithmKMS,
		KeyID:            keyID,
		EncryptedDataKey: base64.StdEncoding.EncodeToString([]byte("fake-encrypted-dek")),
		IV:               base64.StdEncoding.EncodeToString(iv),
	}
	metadataBytes, err := json.Marshal(kmsMetadata)
	if err != nil {
		t.Fatal(err)
	}

	entry := &filer_pb.Entry{
		Extended: map[string][]byte{
			s3_constants.SeaweedFSSSEKMSKey: metadataBytes,
		},
	}

	result, err := MaybeDecryptContent(ciphertext, entry)
	if err != nil {
		t.Fatalf("MaybeDecryptContent: %v", err)
	}
	if !bytes.Equal(result, plaintext) {
		t.Errorf("SSE-KMS round-trip failed: got %q, want %q", result, plaintext)
	}
}