# Bedrock-API Codebase Analysis

## Project Structure

```
bedrock-api/
├── bedrock_server/          # Main application
│   ├── main.go              # Service implementation (1329 lines)
│   ├── resolver.go          # Stream resolution logic
│   ├── proxy.go             # HTTP streaming proxy
│   ├── auth.go              # JWT authentication
│   ├── lrclib.go            # Synced lyrics (LrcLib)
│   └── genius.go            # Plain lyrics (Genius)
├── providers/               # Platform adapters
│   ├── spotify.go           # Spotify integration
│   ├── soundcloud.go        # SoundCloud integration
│   ├── deezer.go            # Deezer integration
│   ├── youtube.go           # YouTube Music integration
│   ├── yandex.go            # Yandex stub
│   └── vk.go                # VK stub
├── store/                   # Data access layer
│   └── user.go              # User CRUD operations
├── db/                      # Database
│   └── migrations/          # SQL migration files
├── proto/                   # Protocol buffers
│   └── bedrock_service.proto # gRPC service definition (622 lines)
├── tests/                   # Integration tests
│   ├── auth_test.go
│   ├── spotify_test.go
│   ├── soundcloud_test.go
│   ├── youtube_test.go
│   ├── deezer_test.go
│   └── lyrics_test.go
├── spotapi-go/              # Git submodule (Spotify wrapper)
├── .github/
│   └── workflows/
│       ├── test.yml         # Integration tests
│       └── lint.yml         # Code linting
├── Dockerfile               # Multi-stage build
├── docker-compose.yml       # PostgreSQL only
├── go.mod                   # Go 1.25
├── go.sum
├── .env.example             # Environment template
└── README.md
```

**Total Lines of Code**: ~5000+ (excluding tests, proto, submodules)

## Configuration Management

### Environment Variables

**Loading Strategy**: Three-location search

**File**: `bedrock_server/main.go`

```go
func loadEnv() {
    locations := []string{
        ".env",                    // Current directory
        "bedrock_server/.env",     // Server directory
        "../.env",                 // Parent directory
    }
    
    for _, loc := range locations {
        if err := godotenv.Load(loc); err == nil {
            log.Printf("Loaded environment from %s", loc)
            return
        }
    }
    
    log.Println("No .env file found, using system environment variables")
}
```

**Precedence**: First found file wins (no merging)

### Required Variables

```
DATABASE_URL=postgresql://user:pass@host:port/database
JWT_SECRET=your-secret-key
```

### Optional Variables (Provider Credentials)

```
SPOTIFY_CLIENT_ID=your_id
SPOTIFY_CLIENT_SECRET=your_secret
SOUNDCLOUD_CLIENT_IDS=id1,id2,id3
DEEZER_APP_ID=your_id
YOUTUBE_COOKIES=cookie-string
GENIUS_ACCESS_TOKEN=your_token
```

### CLI Flags

**File**: `bedrock_server/main.go`

```go
var (
    grpcPort   = flag.Int("port", 50052, "gRPC server port")
    proxyAddr  = flag.String("proxy-addr", ":8080", "HTTP proxy address")
    proxyHost  = flag.String("proxy-host", "", "HTTP proxy host for URL generation")
)

func main() {
    flag.Parse()
    loadEnv()
    
    // Flags override environment variables
    if *grpcPort != 50052 {
        log.Printf("Using custom gRPC port: %d", *grpcPort)
    }
}
```

**Usage**:
```bash
./bedrock-server -port 9090 -proxy-addr :8888 -proxy-host https://api.example.com
```

### Configuration Validation

**No Validation**: Application crashes if required variables are missing

**Example Crash**:
```go
dbURL := os.Getenv("DATABASE_URL")
pool, err := pgxpool.New(context.Background(), dbURL) // Panics if dbURL is empty
```

**Recommendation**: Add startup validation

```go
func validateConfig() error {
    required := []string{"DATABASE_URL", "JWT_SECRET"}
    
    for _, key := range required {
        if os.Getenv(key) == "" {
            return fmt.Errorf("required environment variable %s not set", key)
        }
    }
    
    return nil
}
```

## Logging

### Implementation

**Library**: Go stdlib `log` package  
**Format**: Plain text with provider prefixes

**Examples**:
```go
log.Printf("[spotify] Searching for: %s", query)
log.Printf("[soundcloud] Client ID rotation: %d -> %d", old, new)
log.Printf("[youtube] Client %s failed: %v", clientName, err)
log.Printf("[auth] User registered: %s", email)
```

### Log Levels

**No Levels**: All logs are info-level (no debug/warn/error distinction)

**Example** (no level):
```go
log.Printf("[spotify] Search failed: %v", err) // Is this error or warning?
```

**Recommendation**: Use structured logging with levels

```go
import "go.uber.org/zap"

logger.Info("search request", zap.String("provider", "spotify"), zap.String("query", query))
logger.Error("search failed", zap.String("provider", "spotify"), zap.Error(err))
```

### Log Output

**Destination**: stdout (default)  
**Rotation**: No (relies on systemd or Docker log rotation)  
**Aggregation**: No (manual collection required)

**Systemd Logging**:
```bash
journalctl -u bedrock-api -f
```

**Docker Logging**:
```bash
docker logs -f bedrock-api
```

### Correlation IDs

**Not Implemented**: No request tracing across logs

**Recommendation**: Add correlation IDs

```go
func (s *server) SearchTracks(ctx context.Context, req *pb.SearchRequest) (*pb.SearchTracksResponse, error) {
    correlationID := uuid.New().String()
    ctx = context.WithValue(ctx, "correlation_id", correlationID)
    
    log.Printf("[%s] Search request: %s", correlationID, req.Query)
    // Pass ctx to providers
}
```

## Authentication Implementation

### JWT Token Generation

**File**: `bedrock_server/auth.go`

```go
func (s *server) generateTokens(userID, email string) (accessToken, refreshToken string, err error) {
    // Access token (15 minutes)
    accessClaims := jwt.MapClaims{
        "user_id": userID,
        "email":   email,
        "exp":     time.Now().Add(15 * time.Minute).Unix(),
        "iat":     time.Now().Unix(),
    }
    
    accessTokenObj := jwt.NewWithClaims(jwt.SigningMethodHS256, accessClaims)
    accessToken, err = accessTokenObj.SignedString(s.jwtSecret)
    if err != nil {
        return "", "", fmt.Errorf("sign access token: %w", err)
    }
    
    // Refresh token (7 days)
    refreshClaims := jwt.MapClaims{
        "user_id": userID,
        "email":   email,
        "exp":     time.Now().Add(7 * 24 * time.Hour).Unix(),
        "iat":     time.Now().Unix(),
    }
    
    refreshTokenObj := jwt.NewWithClaims(jwt.SigningMethodHS256, refreshClaims)
    refreshToken, err = refreshTokenObj.SignedString(s.jwtSecret)
    if err != nil {
        return "", "", fmt.Errorf("sign refresh token: %w", err)
    }
    
    return accessToken, refreshToken, nil
}
```

**Algorithm**: HS256 (HMAC with SHA-256)  
**Secret**: Single shared secret from `JWT_SECRET` environment variable

**Security Considerations**:
- HS256 is symmetric (same key for signing and verification)
- No key rotation (single secret for all tokens)
- No token revocation (valid until expiration)

**Recommendation**: Use RS256 (asymmetric) for better security

```go
// Generate RSA key pair
privateKey, _ := rsa.GenerateKey(rand.Reader, 2048)
publicKey := &privateKey.PublicKey

// Sign with private key
token := jwt.NewWithClaims(jwt.SigningMethodRS256, claims)
tokenString, _ := token.SignedString(privateKey)

// Verify with public key (can be distributed to other services)
token, _ := jwt.Parse(tokenString, func(token *jwt.Token) (interface{}, error) {
    return publicKey, nil
})
```

### Password Hashing

**File**: `bedrock_server/auth.go`

```go
func hashPassword(password string) (string, error) {
    bytes, err := bcrypt.GenerateFromPassword([]byte(password), 10)
    return string(bytes), err
}

func checkPasswordHash(password, hash string) bool {
    err := bcrypt.CompareHashAndPassword([]byte(hash), []byte(password))
    return err == nil
}
```

**Algorithm**: bcrypt  
**Cost Factor**: 10 (2^10 = 1024 iterations)  
**Time**: ~100ms per hash (intentionally slow)

**Security**: Strong (salted, slow, resistant to brute force)

### gRPC Interceptors

**Unary Interceptor** (single request/response):

```go
func (s *server) authInterceptor(
    ctx context.Context,
    req interface{},
    info *grpc.UnaryServerInfo,
    handler grpc.UnaryHandler,
) (interface{}, error) {
    // Public methods bypass auth
    publicMethods := map[string]bool{
        "/bedrock.BedrockService/Register":        true,
        "/bedrock.BedrockService/Login":           true,
        "/bedrock.BedrockService/RefreshToken":    true,
        "/bedrock.BedrockService/GetServiceStatus": true,
    }
    
    if publicMethods[info.FullMethod] {
        return handler(ctx, req)
    }
    
    // Extract token from metadata
    md, ok := metadata.FromIncomingContext(ctx)
    if !ok {
        return nil, status.Error(codes.Unauthenticated, "missing metadata")
    }
    
    tokens := md.Get("authorization")
    if len(tokens) == 0 {
        return nil, status.Error(codes.Unauthenticated, "missing authorization header")
    }
    
    // Remove "Bearer " prefix
    tokenString := strings.TrimPrefix(tokens[0], "Bearer ")
    
    // Validate token
    claims := jwt.MapClaims{}
    token, err := jwt.ParseWithClaims(tokenString, claims, func(t *jwt.Token) (interface{}, error) {
        // Verify signing method
        if _, ok := t.Method.(*jwt.SigningMethodHMAC); !ok {
            return nil, fmt.Errorf("unexpected signing method: %v", t.Header["alg"])
        }
        return s.jwtSecret, nil
    })
    
    if err != nil || !token.Valid {
        return nil, status.Error(codes.Unauthenticated, "invalid token")
    }
    
    // Add user info to context
    ctx = context.WithValue(ctx, "user_id", claims["user_id"])
    ctx = context.WithValue(ctx, "email", claims["email"])
    
    return handler(ctx, req)
}
```

**Stream Interceptor** (streaming requests):

```go
func (s *server) streamAuthInterceptor(
    srv interface{},
    ss grpc.ServerStream,
    info *grpc.StreamServerInfo,
    handler grpc.StreamHandler,
) error {
    // Similar logic to unary interceptor
    // Validates token once at stream start
    // No per-message validation
}
```

**Registration**:
```go
grpcServer := grpc.NewServer(
    grpc.UnaryInterceptor(s.authInterceptor),
    grpc.StreamInterceptor(s.streamAuthInterceptor),
)
```

### Registration Flow

**File**: `bedrock_server/main.go`

```go
func (s *server) Register(ctx context.Context, req *pb.AuthRequest) (*pb.AuthResponse, error) {
    // Validate email format
    if !isValidEmail(req.Email) {
        return nil, status.Error(codes.InvalidArgument, "invalid email format")
    }
    
    // Hash password
    passwordHash, err := hashPassword(req.Password)
    if err != nil {
        return nil, status.Error(codes.Internal, "failed to hash password")
    }
    
    // Save user
    userStore := store.NewUserStore(s.db)
    userID, err := userStore.Save(ctx, req.Email, passwordHash)
    if err != nil {
        if strings.Contains(err.Error(), "duplicate key") {
            return nil, status.Error(codes.AlreadyExists, "email already registered")
        }
        return nil, status.Error(codes.Internal, "failed to create user")
    }
    
    // Generate tokens
    accessToken, refreshToken, err := s.generateTokens(userID, req.Email)
    if err != nil {
        return nil, status.Error(codes.Internal, "failed to generate tokens")
    }
    
    return &pb.AuthResponse{
        AccessToken:  accessToken,
        RefreshToken: refreshToken,
        User: &pb.User{
            Id:         userID,
            Email:      req.Email,
            Role:       "user",
            IsVerified: false,
        },
    }, nil
}
```

**No Password Requirements**: Any password is accepted (no minimum length, complexity rules)

**Recommendation**: Add password validation

```go
func validatePassword(password string) error {
    if len(password) < 8 {
        return errors.New("password must be at least 8 characters")
    }
    
    hasUpper := regexp.MustCompile(`[A-Z]`).MatchString(password)
    hasLower := regexp.MustCompile(`[a-z]`).MatchString(password)
    hasDigit := regexp.MustCompile(`[0-9]`).MatchString(password)
    
    if !hasUpper || !hasLower || !hasDigit {
        return errors.New("password must contain uppercase, lowercase, and digit")
    }
    
    return nil
}
```

### Login Flow

```go
func (s *server) Login(ctx context.Context, req *pb.AuthRequest) (*pb.AuthResponse, error) {
    // Find user by email
    userStore := store.NewUserStore(s.db)
    user, err := userStore.Find(ctx, req.Email)
    if err != nil {
        return nil, status.Error(codes.NotFound, "user not found")
    }
    
    // Verify password
    if !checkPasswordHash(req.Password, user.PasswordHash) {
        return nil, status.Error(codes.Unauthenticated, "invalid credentials")
    }
    
    // Generate tokens
    accessToken, refreshToken, err := s.generateTokens(user.ID, user.Email)
    if err != nil {
        return nil, status.Error(codes.Internal, "failed to generate tokens")
    }
    
    return &pb.AuthResponse{
        AccessToken:  accessToken,
        RefreshToken: refreshToken,
        User: &pb.User{
            Id:         user.ID,
            Email:      user.Email,
            Role:       user.Role,
            IsVerified: user.IsVerified,
        },
    }, nil
}
```

**No Rate Limiting**: Unlimited login attempts (brute force possible)

**Recommendation**: Add rate limiting

```go
import "golang.org/x/time/rate"

var loginLimiters = make(map[string]*rate.Limiter)
var mu sync.Mutex

func getLoginLimiter(email string) *rate.Limiter {
    mu.Lock()
    defer mu.Unlock()
    
    limiter, exists := loginLimiters[email]
    if !exists {
        limiter = rate.NewLimiter(rate.Every(time.Minute), 5) // 5 attempts per minute
        loginLimiters[email] = limiter
    }
    
    return limiter
}

func (s *server) Login(ctx context.Context, req *pb.AuthRequest) (*pb.AuthResponse, error) {
    limiter := getLoginLimiter(req.Email)
    if !limiter.Allow() {
        return nil, status.Error(codes.ResourceExhausted, "too many login attempts")
    }
    
    // Continue with login logic
}
```

## Testing

### Test Structure

**Directory**: `tests/`

**Files**:
- `auth_test.go` - Authentication tests (register, login, refresh)
- `spotify_test.go` - Spotify provider tests
- `soundcloud_test.go` - SoundCloud provider tests
- `youtube_test.go` - YouTube Music provider tests
- `deezer_test.go` - Deezer provider tests
- `lyrics_test.go` - Lyrics integration tests (LrcLib, Genius)

### Integration Tests

**Example**: `tests/spotify_test.go`

```go
func TestSpotifySearch(t *testing.T) {
    // Connect to test server
    addr := os.Getenv("BEDROCK_TEST_ADDR")
    if addr == "" {
        addr = "localhost:50052"
    }
    
    conn, err := grpc.Dial(addr, grpc.WithInsecure())
    if err != nil {
        t.Fatalf("dial: %v", err)
    }
    defer conn.Close()
    
    client := pb.NewBedrockServiceClient(conn)
    
    // Register test user
    authResp, err := client.Register(context.Background(), &pb.AuthRequest{
        Email:    "test@example.com",
        Password: "password123",
    })
    if err != nil {
        t.Fatalf("register: %v", err)
    }
    
    // Authenticated context
    ctx := metadata.AppendToOutgoingContext(
        context.Background(),
        "authorization", "Bearer "+authResp.AccessToken,
    )
    
    // Search tracks
    resp, err := client.SearchTracks(ctx, &pb.SearchRequest{
        Query: "Bohemian Rhapsody",
        Limit: 10,
    })
    if err != nil {
        t.Fatalf("search: %v", err)
    }
    
    // Verify results
    if len(resp.Tracks) == 0 {
        t.Fatal("no tracks returned")
    }
    
    // Verify Spotify results present
    hasSpotify := false
    for _, track := range resp.Tracks {
        if track.Platform == pb.Platform_SPOTIFY {
            hasSpotify = true
            break
        }
    }
    
    if !hasSpotify {
        t.Error("no Spotify results found")
    }
}
```

**Test Requirements**:
- Running server (BEDROCK_TEST_ADDR)
- PostgreSQL database
- Provider credentials (environment variables)

**Test Timeout**: 120 seconds (configured in GitHub Actions)

### No Unit Tests

**Missing**:
- Provider adapter unit tests (mocked HTTP responses)
- Database store unit tests (mocked database)
- Authentication unit tests (mocked JWT)
- Stream resolution unit tests

**Recommendation**: Add unit tests with mocks

```go
func TestSpotifyProvider_SearchTracks(t *testing.T) {
    // Mock HTTP server
    server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        w.Header().Set("Content-Type", "application/json")
        w.Write([]byte(`{
            "tracks": {
                "items": [
                    {
                        "id": "abc123",
                        "name": "Test Track",
                        "artists": [{"id": "artist1", "name": "Test Artist"}],
                        "album": {"id": "album1", "name": "Test Album"}
                    }
                ]
            }
        }`))
    }))
    defer server.Close()
    
    // Create provider with mock server URL
    provider := &SpotifyProvider{
        client: spotify.New(/* mock client */),
    }
    
    // Test search
    tracks, err := provider.SearchTracks(context.Background(), "test", 10)
    if err != nil {
        t.Fatalf("search failed: %v", err)
    }
    
    if len(tracks) != 1 {
        t.Errorf("expected 1 track, got %d", len(tracks))
    }
}
```

### Test Coverage

**No Coverage Reports**: Coverage not measured

**Recommendation**: Add coverage reporting

```bash
go test -cover ./...
go test -coverprofile=coverage.out ./...
go tool cover -html=coverage.out -o coverage.html
```

**GitHub Actions Integration**:
```yaml
- name: Run tests with coverage
  run: go test -v -coverprofile=coverage.out ./...

- name: Upload coverage to Codecov
  uses: codecov/codecov-action@v3
  with:
    files: ./coverage.out
```

## Health Checks

### Service Status

**File**: `bedrock_server/main.go`

```go
func (s *server) GetServiceStatus(ctx context.Context, req *pb.Empty) (*pb.ServiceStatusResponse, error) {
    // Stub implementation (always returns healthy)
    return &pb.ServiceStatusResponse{
        Status: pb.ServiceStatus_HEALTHY,
        Dependencies: []*pb.DependencyStatus{
            {Name: "spotify", Health: pb.HealthStatus_HEALTHY, Latency: 0},
            {Name: "soundcloud", Health: pb.HealthStatus_HEALTHY, Latency: 0},
            {Name: "deezer", Health: pb.HealthStatus_HEALTHY, Latency: 0},
            {Name: "youtube", Health: pb.HealthStatus_HEALTHY, Latency: 0},
            {Name: "postgres", Health: pb.HealthStatus_HEALTHY, Latency: 0},
        },
    }, nil
}
```

**Issues**:
- No actual health checks (stub only)
- No latency measurement
- No database connection check
- No provider API checks

**Recommendation**: Implement real health checks

```go
func (s *server) GetServiceStatus(ctx context.Context, req *pb.Empty) (*pb.ServiceStatusResponse, error) {
    var dependencies []*pb.DependencyStatus
    
    // Check database
    dbStart := time.Now()
    if err := s.db.Ping(ctx); err != nil {
        dependencies = append(dependencies, &pb.DependencyStatus{
            Name:    "postgres",
            Health:  pb.HealthStatus_UNHEALTHY,
            Latency: 0,
        })
    } else {
        dependencies = append(dependencies, &pb.DependencyStatus{
            Name:    "postgres",
            Health:  pb.HealthStatus_HEALTHY,
            Latency: int32(time.Since(dbStart).Milliseconds()),
        })
    }
    
    // Check each provider
    for _, provider := range s.providers {
        providerStart := time.Now()
        _, err := provider.SearchTracks(ctx, "test", 1)
        
        health := pb.HealthStatus_HEALTHY
        if err != nil {
            health = pb.HealthStatus_UNHEALTHY
        }
        
        dependencies = append(dependencies, &pb.DependencyStatus{
            Name:    provider.Name(),
            Health:  health,
            Latency: int32(time.Since(providerStart).Milliseconds()),
        })
    }
    
    // Determine overall status
    status := pb.ServiceStatus_HEALTHY
    for _, dep := range dependencies {
        if dep.Health == pb.HealthStatus_UNHEALTHY {
            status = pb.ServiceStatus_DEGRADED
            break
        }
    }
    
    return &pb.ServiceStatusResponse{
        Status:       status,
        Dependencies: dependencies,
    }, nil
}
```

### Readiness vs Liveness

**Not Implemented**: No distinction between readiness and liveness

**Kubernetes Probes** (recommended):

```yaml
livenessProbe:
  exec:
    command:
    - grpc_health_probe
    - -addr=:50052
  initialDelaySeconds: 10
  periodSeconds: 10

readinessProbe:
  exec:
    command:
    - grpc_health_probe
    - -addr=:50052
    - -service=bedrock.BedrockService
  initialDelaySeconds: 5
  periodSeconds: 5
```

**gRPC Health Checking Protocol**:
```go
import "google.golang.org/grpc/health/grpc_health_v1"

type healthServer struct {
    grpc_health_v1.UnimplementedHealthServer
}

func (h *healthServer) Check(ctx context.Context, req *grpc_health_v1.HealthCheckRequest) (*grpc_health_v1.HealthCheckResponse, error) {
    // Check if service is ready
    return &grpc_health_v1.HealthCheckResponse{
        Status: grpc_health_v1.HealthCheckResponse_SERVING,
    }, nil
}

// Register health server
grpc_health_v1.RegisterHealthServer(grpcServer, &healthServer{})
```

## Error Handling

### Error Patterns

**Provider Errors**: Log and continue

```go
tracks, err := provider.SearchTracks(ctx, query, limit)
if err != nil {
    log.Printf("[%s] Search failed: %v", provider.Name(), err)
    errors = append(errors, &pb.ProviderError{
        Provider: provider.Name(),
        Message:  err.Error(),
    })
    // Don't return, continue to next provider
}
```

**Database Errors**: Return immediately

```go
user, err := userStore.Find(ctx, email)
if err != nil {
    return nil, status.Error(codes.NotFound, "user not found")
}
```

**gRPC Status Codes**:

| Code | Usage |
|------|-------|
| `OK` | Successful operation |
| `InvalidArgument` | Invalid request parameters |
| `NotFound` | Entity not found |
| `AlreadyExists` | Duplicate entity (email) |
| `Unauthenticated` | Missing or invalid JWT |
| `Internal` | Server error |
| `ResourceExhausted` | Rate limit (not implemented) |

### Error Wrapping

**No Error Wrapping**: Errors are not wrapped with context

**Example** (no wrapping):
```go
if err != nil {
    return nil, err
}
```

**Recommendation**: Wrap errors with context

```go
if err != nil {
    return nil, fmt.Errorf("search spotify: %w", err)
}
```

**Benefits**:
- Error chain for debugging
- Context preservation
- Stack trace (with errors package)

## Code Style

### Comment Linting

**Custom Linter**: `.github/workflows/lint.yml`

**Rules**:
1. No decorative comments (`// ========`, `// --------`, etc.)
2. No uppercase-leading comments (except `TODO`, `FIXME`, `NOTE`)

**Examples**:

**Forbidden**:
```go
// ========================================
// Spotify Provider
// ========================================

// This function searches for tracks
func SearchTracks() {}
```

**Allowed**:
```go
// searchTracks queries Spotify API for tracks matching the query
func searchTracks() {}

// TODO: Add caching
func searchTracks() {}
```

**Enforcement**: GitHub Actions fails on violations

### Naming Conventions

**Exported Functions**: PascalCase
```go
func SearchTracks() {}
func GetStreamURL() {}
```

**Unexported Functions**: camelCase
```go
func parseNamespacedID() {}
func selectBestFormat() {}
```

**Constants**: PascalCase or SCREAMING_SNAKE_CASE
```go
const DefaultLimit = 20
const MAX_RETRIES = 3
```

**Interfaces**: Noun or adjective ending in "er"
```go
type trackProvider interface {}
type streamResolver interface {}
```

### Code Organization

**Single File Service**: `main.go` (1329 lines)

**Issues**:
- All RPC methods in one file
- Hard to navigate
- Merge conflicts likely

**Recommendation**: Split by domain

```
bedrock_server/
├── main.go              # Server setup, initialization
├── search.go            # Search methods
├── retrieval.go         # Get methods
├── streaming.go         # Stream methods
├── recommendations.go   # Similar tracks
├── statistics.go        # Top tracks/albums/artists
├── import.go            # Playlist import
├── auth.go              # Authentication
└── lyrics.go            # Lyrics methods
```

## Dependency Management

### Go Modules

**File**: `go.mod`

```go
module github.com/feralbureau/bedrock-api

go 1.25

require (
    github.com/golang-jwt/jwt/v5 v5.2.1
    github.com/jackc/pgx/v5 v5.7.2
    github.com/joho/godotenv v1.5.1
    github.com/kkdai/youtube/v2 v2.10.3
    github.com/rhnvrm/lyric-api-go v0.1.4
    golang.org/x/crypto v0.31.0
    google.golang.org/grpc v1.79.1
    google.golang.org/protobuf v1.36.4
)
```

**Direct Dependencies**: 8  
**Indirect Dependencies**: ~50 (transitive)

### Submodule Dependency

**Submodule**: `spotapi-go` (custom Spotify wrapper)

**Issues**:
- Custom fork (not official library)
- Maintenance burden
- Submodule initialization required

**Recommendation**: Use official library directly

```go
import "github.com/zmb3/spotify/v2"

// Remove spotapi-go submodule
// Use spotify/v2 directly
```

### Dependency Updates

**No Automated Updates**: Dependabot not configured

**Recommendation**: Add Dependabot

**File**: `.github/dependabot.yml`

```yaml
version: 2
updates:
  - package-ecosystem: "gomod"
    directory: "/"
    schedule:
      interval: "weekly"
    open-pull-requests-limit: 10
```

## Performance Considerations

### Goroutine Management

**Unbounded Goroutines**: No limit on concurrent goroutines

**Example**:
```go
for _, provider := range providers {
    wg.Add(1)
    go func(p trackProvider) {
        defer wg.Done()
        // Query provider
    }(provider)
}
```

**Risk**: High request volume spawns thousands of goroutines

**Recommendation**: Use worker pool

```go
type workerPool struct {
    workers int
    tasks   chan func()
}

func newWorkerPool(workers int) *workerPool {
    p := &workerPool{
        workers: workers,
        tasks:   make(chan func(), workers*2),
    }
    
    for i := 0; i < workers; i++ {
        go p.worker()
    }
    
    return p
}

func (p *workerPool) worker() {
    for task := range p.tasks {
        task()
    }
}

func (p *workerPool) submit(task func()) {
    p.tasks <- task
}
```

### Connection Pooling

**HTTP Clients**: Reused per provider (good)

```go
type SoundCloudProvider struct {
    httpClient *http.Client
}

func NewSoundCloudProvider() *SoundCloudProvider {
    return &SoundCloudProvider{
        httpClient: &http.Client{
            Timeout: 10 * time.Second,
            Transport: &http.Transport{
                MaxIdleConns:        100,
                MaxIdleConnsPerHost: 10,
                IdleConnTimeout:     90 * time.Second,
            },
        },
    }
}
```

**Database**: Connection pooling configured (good)

```go
config.MaxConns = 10
config.MinConns = 2
```

### Memory Allocation

**No Object Pooling**: Objects allocated per request

**Recommendation**: Use sync.Pool for frequently allocated objects

```go
var trackPool = sync.Pool{
    New: func() interface{} {
        return &pb.Track{}
    },
}

func getTrack() *pb.Track {
    return trackPool.Get().(*pb.Track)
}

func putTrack(t *pb.Track) {
    // Reset fields
    t.Id = ""
    t.Title = ""
    // ...
    trackPool.Put(t)
}
```

## Security Best Practices

### Input Validation

**Minimal Validation**: Only email format checked

**Missing**:
- Query length limits (SQL injection via search)
- ID format validation
- Limit parameter bounds

**Recommendation**: Add comprehensive validation

```go
func validateSearchRequest(req *pb.SearchRequest) error {
    if len(req.Query) == 0 {
        return errors.New("query cannot be empty")
    }
    
    if len(req.Query) > 500 {
        return errors.New("query too long (max 500 characters)")
    }
    
    if req.Limit < 1 || req.Limit > 50 {
        return errors.New("limit must be between 1 and 50")
    }
    
    return nil
}
```

### SQL Injection Prevention

**Parameterized Queries**: All queries use placeholders (good)

```go
err := s.db.QueryRow(ctx,
    "SELECT * FROM users WHERE email = $1",
    email,
).Scan(&user)
```

**No String Concatenation**: No SQL injection risk

### Secrets Management

**Environment Variables**: Secrets in plaintext `.env` files

**Recommendation**: Use secrets manager

```go
import "github.com/aws/aws-sdk-go/service/secretsmanager"

func getSecret(secretName string) (string, error) {
    svc := secretsmanager.New(session.New())
    
    result, err := svc.GetSecretValue(&secretsmanager.GetSecretValueInput{
        SecretId: aws.String(secretName),
    })
    
    if err != nil {
        return "", err
    }
    
    return *result.SecretString, nil
}
```

## Code Quality Metrics

### Cyclomatic Complexity

**High Complexity**: `main.go` (1329 lines, 23 methods)

**Recommendation**: Split into smaller files

### Code Duplication

**Provider Adapters**: Similar patterns across providers (acceptable)

**Search Methods**: Identical fan-out pattern (could be abstracted)

**Recommendation**: Extract common fan-out logic

```go
func (s *server) fanOutSearch(
    ctx context.Context,
    providers []trackProvider,
    searchFunc func(trackProvider) ([]*pb.Track, error),
) ([]*pb.Track, []*pb.ProviderError, pb.ResponseStatus) {
    var (
        mu      sync.Mutex
        wg      sync.WaitGroup
        tracks  []*pb.Track
        errors  []*pb.ProviderError
    )
    
    for _, provider := range providers {
        wg.Add(1)
        go func(p trackProvider) {
            defer wg.Done()
            
            results, err := searchFunc(p)
            
            mu.Lock()
            defer mu.Unlock()
            
            if err != nil {
                errors = append(errors, &pb.ProviderError{
                    Provider: p.Name(),
                    Message:  err.Error(),
                })
            } else {
                tracks = append(tracks, results...)
            }
        }(provider)
    }
    
    wg.Wait()
    
    status := pb.ResponseStatus_OK
    if len(errors) > 0 {
        if len(tracks) == 0 {
            status = pb.ResponseStatus_ERROR
        } else {
            status = pb.ResponseStatus_PARTIAL
        }
    }
    
    return tracks, errors, status
}
```

### Documentation

**No Package Documentation**: Missing package-level comments

**Recommendation**: Add package docs

```go
// Package bedrock provides a unified music metadata and streaming API
// that aggregates data from multiple music platforms (Spotify, SoundCloud,
// Deezer, YouTube Music).
//
// The service exposes a gRPC interface with 23 methods for searching,
// retrieving, and streaming music content. It also provides an HTTP proxy
// for streaming audio and album art.
//
// Authentication is handled via JWT tokens with bcrypt password hashing.
// All provider queries are executed in parallel for optimal performance.
package main
```

## Recommendations for Metadata Aggregator

### Adopt

- Provider interface pattern (clean abstraction)
- Fan-out concurrency (parallel queries)
- Partial response handling (resilient to failures)
- gRPC interceptors (authentication)
- bcrypt password hashing (secure)
- Parameterized queries (SQL injection safe)

### Avoid

- Single 1300+ line file (split by domain)
- No unit tests (add mocked tests)
- No error wrapping (add context)
- Unbounded goroutines (use worker pool)
- No input validation (validate all inputs)
- Stub health checks (implement real checks)

### Enhance

- Add structured logging (zap, zerolog)
- Add metrics (Prometheus)
- Add caching (Redis)
- Add rate limiting (per-user, per-provider)
- Add circuit breakers (failing providers)
- Add retry logic (exponential backoff)
- Add comprehensive validation
- Add unit tests with mocks
- Add code coverage reporting
- Add API documentation (OpenAPI/Swagger for HTTP, gRPC reflection)