# Configuration Management Refactoring Plan

## Current State Analysis

**File**: `internal/config/config.go` (1,767 lines)

**Issues**:
- Single file with all config structures
- Mix of loading, validation, and migration logic
- Complex nested structs with 326+ lines of YAML example
- No clear separation between config sources (file, env, DB)
- Migration logic scattered throughout
- No structured validation (manual checks)

## Target Architecture

```
internal/config/
├── domain/
│   ├── models.go          # Core config structs (no logic)
│   └── validation.go      # Validation rules
├── loader/
│   ├── file.go           # YAML/JSON file loading
│   ├── env.go            # Environment variable loading
│   └── merge.go          # Config merging logic
├── provider/
│   ├── interface.go      # ConfigProvider interface
│   ├── file.go           # File-based provider
│   ├── postgres.go       # PostgreSQL provider
│   ├── git.go            # Git-based provider
│   └── objectstore.go    # S3/MinIO provider
├── migrations/
│   ├── registry.go       # Migration registry
│   ├── v1_to_v2.go       # Specific migrations
│   └── runner.go         # Migration runner
├── watcher/
│   └── file.go           # File watching for hot reload
└── config.go             # Public API (facade)
```

## Phase 1: Domain Models Extraction (Week 1)

### 1.1 Core Models
**File**: `internal/config/domain/models.go`

```go
package domain

import (
    "time"
    "github.com/echyai/cliproxyapi/internal/domain/auth"
)

// Config is the root configuration
type Config struct {
    Version   string    `yaml:"version" json:"version" validate:"required,semver"`
    Server    Server    `yaml:"server" json:"server" validate:"required"`
    Providers Providers `yaml:"providers" json:"providers"`
    Storage   Storage   `yaml:"storage" json:"storage" validate:"required"`
    Logging   Logging   `yaml:"logging" json:"logging"`
    Metrics   Metrics   `yaml:"metrics" json:"metrics"`
}

func (c *Config) Validate() error {
    validate := validator.New()
    validate.RegisterValidation("semver", validateSemver)
    return validate.Struct(c)
}

// Server configuration
type Server struct {
    Host           string        `yaml:"host" json:"host" validate:"hostname|ip"`
    Port           int           `yaml:"port" json:"port" validate:"required,min=1,max=65535"`
    ReadTimeout    time.Duration `yaml:"read_timeout" json:"read_timeout" validate:"min=1s"`
    WriteTimeout   time.Duration `yaml:"write_timeout" json:"write_timeout" validate:"min=1s"`
    MaxHeaderBytes int           `yaml:"max_header_bytes" json:"max_header_bytes" validate:"min=1024"`
    TLS            *TLSConfig    `yaml:"tls,omitempty" json:"tls,omitempty"`
}

// TLS configuration
type TLSConfig struct {
    CertFile string `yaml:"cert_file" json:"cert_file" validate:"required,file"`
    KeyFile  string `yaml:"key_file" json:"key_file" validate:"required,file"`
}

// Providers configuration
type Providers struct {
    Gemini      *GeminiConfig      `yaml:"gemini,omitempty" json:"gemini,omitempty"`
    Claude      *ClaudeConfig      `yaml:"claude,omitempty" json:"claude,omitempty"`
    Codex       *CodexConfig       `yaml:"codex,omitempty" json:"codex,omitempty"`
    Antigravity *AntigravityConfig `yaml:"antigravity,omitempty" json:"antigravity,omitempty"`
    Qwen        *QwenConfig        `yaml:"qwen,omitempty" json:"qwen,omitempty"`
    Vertex      *VertexConfig      `yaml:"vertex,omitempty" json:"vertex,omitempty"`
}

// Gemini configuration
type GeminiConfig struct {
    Enabled      bool              `yaml:"enabled" json:"enabled"`
    APIKey       string            `yaml:"api_key,omitempty" json:"api_key,omitempty" validate:"omitempty,min=10"`
    OAuth        *OAuthConfig      `yaml:"oauth,omitempty" json:"oauth,omitempty"`
    RateLimit    RateLimitConfig   `yaml:"rate_limit" json:"rate_limit"`
    Models       []ModelConfig     `yaml:"models" json:"models" validate:"dive"`
}

// OAuth configuration (shared)
type OAuthConfig struct {
    ClientID     string   `yaml:"client_id" validate:"required"`
    ClientSecret string   `yaml:"client_secret" validate:"required"`
    RedirectURL  string   `yaml:"redirect_url" validate:"required,url"`
    Scopes       []string `yaml:"scopes" validate:"min=1"`
}

// Rate limit configuration
type RateLimitConfig struct {
    RequestsPerSecond float64       `yaml:"requests_per_second" validate:"min=0.1"`
    Burst             int           `yaml:"burst" validate:"min=1"`
    Cooldown          time.Duration `yaml:"cooldown" validate:"min=0"`
}

// Model configuration
type ModelConfig struct {
    Name        string  `yaml:"name" validate:"required"`
    DisplayName string  `yaml:"display_name"`
    MaxTokens   int     `yaml:"max_tokens" validate:"min=1"`
    Enabled     bool    `yaml:"enabled"`
}

// Storage configuration
type Storage struct {
    Type   StorageType    `yaml:"type" validate:"required,oneof=file postgres git objectstore"`
    File   *FileStorage   `yaml:"file,omitempty"`
    Postgres *PostgresStorage `yaml:"postgres,omitempty"`
    Git    *GitStorage    `yaml:"git,omitempty"`
    Object *ObjectStorage `yaml:"object,omitempty"`
}

type StorageType string

const (
    StorageTypeFile       StorageType = "file"
    StorageTypePostgres   StorageType = "postgres"
    StorageTypeGit        StorageType = "git"
    StorageTypeObject     StorageType = "objectstore"
)

// FileStorage configuration
type FileStorage struct {
    Path string `yaml:"path" validate:"required,dirpath"`
}

// PostgresStorage configuration
type PostgresStorage struct {
    Host     string `yaml:"host" validate:"required"`
    Port     int    `yaml:"port" validate:"min=1,max=65535"`
    Database string `yaml:"database" validate:"required"`
    Username string `yaml:"username" validate:"required"`
    Password string `yaml:"password" validate:"required"`
    SSLMode  string `yaml:"ssl_mode" validate:"oneof=disable require verify-ca verify-full"`
}

// Logging configuration
type Logging struct {
    Level  string `yaml:"level" validate:"oneof=debug info warn error fatal panic"`
    Format string `yaml:"format" validate:"oneof=json text"`
    Output string `yaml:"output" validate:"oneof=stdout stderr file"`
    File   string `yaml:"file,omitempty"`
}

// Metrics configuration
type Metrics struct {
    Enabled bool   `yaml:"enabled"`
    Path    string `yaml:"path" validate:"startswith=/"`
    Port    int    `yaml:"port" validate:"min=1,max=65535"`
}

// Provider-specific configs (Claude, Codex, etc. follow similar pattern)
type ClaudeConfig struct {
    Enabled   bool            `yaml:"enabled"`
    APIKey    string          `yaml:"api_key,omitempty"`
    OAuth     *OAuthConfig    `yaml:"oauth,omitempty"`
    RateLimit RateLimitConfig `yaml:"rate_limit"`
}

// ... other provider configs
```

### 1.2 Validation Rules
**File**: `internal/config/domain/validation.go`

```go
package domain

import (
    "github.com/go-playground/validator/v10"
    "regexp"
)

var semverRegex = regexp.MustCompile(`^v?(\d+)\.(\d+)\.(\d+)(?:-([\da-zA-Z-]+(?:\.[\da-zA-Z-]+)*))?(?:\+([\da-zA-Z-]+(?:\.[\da-zA-Z-]+)*))?$`)

func validateSemver(fl validator.FieldLevel) bool {
    return semverRegex.MatchString(fl.Field().String())
}

// ConfigValidator handles validation with custom rules
type ConfigValidator struct {
    validate *validator.Validate
}

func NewValidator() *ConfigValidator {
    v := validator.New()
    v.RegisterValidation("semver", validateSemver)
    return &ConfigValidator{validate: v}
}

func (cv *ConfigValidator) Validate(cfg *Config) error {
    if err := cv.validate.Struct(cfg); err != nil {
        return NewValidationError(err)
    }

    // Cross-field validations
    if err := cv.validateStorage(cfg.Storage); err != nil {
        return err
    }

    if err := cv.validateProviders(cfg.Providers); err != nil {
        return err
    }

    return nil
}

func (cv *ConfigValidator) validateStorage(s Storage) error {
    switch s.Type {
    case StorageTypeFile:
        if s.File == nil {
            return ValidationError{Field: "storage.file", Message: "required when type is file"}
        }
    case StorageTypePostgres:
        if s.Postgres == nil {
            return ValidationError{Field: "storage.postgres", Message: "required when type is postgres"}
        }
    // ... other cases
    }
    return nil
}

func (cv *ConfigValidator) validateProviders(p Providers) error {
    // At least one provider should be enabled
    hasEnabled := false
    // Check each provider...
    if !hasEnabled {
        return ValidationError{Message: "at least one provider must be enabled"}
    }
    return nil
}
```

## Phase 2: Provider Interface (Week 2)

### 2.1 Provider Interface
**File**: `internal/config/provider/interface.go`

```go
package provider

import (
    "context"
    "github.com/echyai/cliproxyapi/internal/config/domain"
)

// Provider loads and saves configuration
type Provider interface {
    // Load retrieves the current configuration
    Load(ctx context.Context) (*domain.Config, error)

    // Save persists the configuration
    Save(ctx context.Context, cfg *domain.Config) error

    // Watch returns a channel that receives config updates
    Watch(ctx context.Context) (<-chan domain.Config, error)

    // Close cleans up resources
    Close() error
}

// ProviderFactory creates providers based on type
type ProviderFactory struct {
    // dependencies
}

func (f *ProviderFactory) Create(storage domain.Storage) (Provider, error) {
    switch storage.Type {
    case domain.StorageTypeFile:
        return NewFileProvider(storage.File)
    case domain.StorageTypePostgres:
        return NewPostgresProvider(storage.Postgres)
    case domain.StorageTypeGit:
        return NewGitProvider(storage.Git)
    case domain.StorageTypeObject:
        return NewObjectProvider(storage.Object)
    default:
        return nil, fmt.Errorf("unknown storage type: %s", storage.Type)
    }
}
```

### 2.2 File Provider
**File**: `internal/config/provider/file.go`

```go
package provider

import (
    "context"
    "fmt"
    "os"
    "path/filepath"

    "github.com/fsnotify/fsnotify"
    "gopkg.in/yaml.v3"

    "github.com/echyai/cliproxyapi/internal/config/domain"
)

type FileProvider struct {
    path     string
    watcher  *fsnotify.Watcher
    validate *domain.ConfigValidator
}

func NewFileProvider(cfg *domain.FileStorage) (*FileProvider, error) {
    absPath, err := filepath.Abs(cfg.Path)
    if err != nil {
        return nil, fmt.Errorf("invalid path: %w", err)
    }

    return &FileProvider{
        path:     absPath,
        validate: domain.NewValidator(),
    }, nil
}

func (p *FileProvider) Load(ctx context.Context) (*domain.Config, error) {
    data, err := os.ReadFile(p.path)
    if err != nil {
        if os.IsNotExist(err) {
            return nil, domain.ErrConfigNotFound
        }
        return nil, fmt.Errorf("read config: %w", err)
    }

    var cfg domain.Config
    if err := yaml.Unmarshal(data, &cfg); err != nil {
        return nil, fmt.Errorf("parse config: %w", err)
    }

    if err := p.validate.Validate(&cfg); err != nil {
        return nil, fmt.Errorf("validate config: %w", err)
    }

    return &cfg, nil
}

func (p *FileProvider) Save(ctx context.Context, cfg *domain.Config) error {
    if err := p.validate.Validate(cfg); err != nil {
        return err
    }

    data, err := yaml.Marshal(cfg)
    if err != nil {
        return fmt.Errorf("marshal config: %w", err)
    }

    // Write atomically
    tmpPath := p.path + ".tmp"
    if err := os.WriteFile(tmpPath, data, 0644); err != nil {
        return fmt.Errorf("write temp file: %w", err)
    }

    return os.Rename(tmpPath, p.path)
}

func (p *FileProvider) Watch(ctx context.Context) (<-chan domain.Config, error) {
    watcher, err := fsnotify.NewWatcher()
    if err != nil {
        return nil, err
    }

    if err := watcher.Add(p.path); err != nil {
        return nil, err
    }

    p.watcher = watcher
    updates := make(chan domain.Config)

    go func() {
        defer close(updates)
        defer watcher.Close()

        for {
            select {
            case event, ok := <-watcher.Events:
                if !ok {
                    return
                }
                if event.Op&fsnotify.Write == fsnotify.Write {
                    cfg, err := p.Load(ctx)
                    if err == nil {
                        updates <- *cfg
                    }
                }
            case err, ok := <-watcher.Errors:
                if !ok {
                    return
                }
                // Log error
                _ = err
            case <-ctx.Done():
                return
            }
        }
    }()

    return updates, nil
}

func (p *FileProvider) Close() error {
    if p.watcher != nil {
        return p.watcher.Close()
    }
    return nil
}
```

## Phase 3: Migration System (Week 2)

### 3.1 Migration Framework
**File**: `internal/config/migrations/registry.go`

```go
package migrations

import (
    "fmt"

    "github.com/echyai/cliproxyapi/internal/config/domain"
)

// Migration transforms config from one version to another
type Migration interface {
    FromVersion() string
    ToVersion() string
    Migrate(cfg map[string]interface{}) (map[string]interface{}, error)
}

// Registry holds all migrations
type Registry struct {
    migrations map[string]Migration
}

func NewRegistry() *Registry {
    r := &Registry{migrations: make(map[string]Migration)}
    r.registerDefaults()
    return r
}

func (r *Registry) register(m Migration) {
    key := fmt.Sprintf("%s->%s", m.FromVersion(), m.ToVersion())
    r.migrations[key] = m
}

func (r *Registry) registerDefaults() {
    r.register(&V1ToV2Migration{})
    r.register(&V2ToV3Migration{})
    // ... more migrations
}

// Runner executes migrations
type Runner struct {
    registry *Registry
}

func (r *Runner) Migrate(cfg map[string]interface{}, targetVersion string) (map[string]interface{}, error) {
    currentVersion, _ := cfg["version"].(string)
    if currentVersion == "" {
        currentVersion = "1.0.0"
    }

    for currentVersion != targetVersion {
        key := fmt.Sprintf("%s->%s", currentVersion, targetVersion)
        migration, ok := r.registry.migrations[key]
        if !ok {
            // Try to find intermediate step
            nextVersion := findNextVersion(currentVersion)
            if nextVersion == "" {
                return nil, fmt.Errorf("no migration path from %s to %s", currentVersion, targetVersion)
            }
            key = fmt.Sprintf("%s->%s", currentVersion, nextVersion)
            migration = r.registry.migrations[key]
        }

        var err error
        cfg, err = migration.Migrate(cfg)
        if err != nil {
            return nil, fmt.Errorf("migrate %s: %w", key, err)
        }
        currentVersion = migration.ToVersion()
    }

    return cfg, nil
}
```

## Phase 4: Public API Facade (Week 3)

**File**: `internal/config/config.go` (simplified facade)

```go
package config

import (
    "context"
    "sync"

    "github.com/echyai/cliproxyapi/internal/config/domain"
    "github.com/echyai/cliproxyapi/internal/config/migrations"
    "github.com/echyai/cliproxyapi/internal/config/provider"
)

// Manager is the public API for configuration
type Manager struct {
    provider provider.Provider
    current  *domain.Config
    mu       sync.RWMutex
    validate *domain.ConfigValidator
}

func NewManager(storage domain.Storage) (*Manager, error) {
    p, err := provider.NewFactory().Create(storage)
    if err != nil {
        return nil, err
    }

    return &Manager{
        provider: p,
        validate: domain.NewValidator(),
    }, nil
}

func (m *Manager) Load(ctx context.Context) error {
    cfg, err := m.provider.Load(ctx)
    if err != nil {
        return err
    }

    m.mu.Lock()
    m.current = cfg
    m.mu.Unlock()

    return nil
}

func (m *Manager) Get() *domain.Config {
    m.mu.RLock()
    defer m.mu.RUnlock()
    return m.current
}

func (m *Manager) Update(ctx context.Context, updater func(*domain.Config) error) error {
    m.mu.Lock()
    defer m.mu.Unlock()

    cfg := *m.current // Copy
    if err := updater(&cfg); err != nil {
        return err
    }

    if err := m.validate.Validate(&cfg); err != nil {
        return err
    }

    if err := m.provider.Save(ctx, &cfg); err != nil {
        return err
    }

    m.current = &cfg
    return nil
}

func (m *Manager) Watch(ctx context.Context) (<-chan domain.Config, error) {
    return m.provider.Watch(ctx)
}

func (m *Manager) Close() error {
    return m.provider.Close()
}
```

## Migration Steps

1. **Week 1**: Create new structure alongside existing code
2. **Week 2**: Implement providers and migrations
3. **Week 3**: Switch to new config system, keep old as backup
4. **Week 4**: Remove old config code after testing

## Success Metrics

- [ ] Config file split into logical packages
- [ ] Validation using struct tags
- [ ] All providers implement same interface
- [ ] Hot reload works for all storage types
- [ ] Migrations tested and documented