package cliproxy

import (
	"fmt"

	"github.com/router-for-me/CLIProxyAPI/v6/internal/api"
	"github.com/router-for-me/CLIProxyAPI/v6/internal/config"
	sdkAuth "github.com/router-for-me/CLIProxyAPI/v6/sdk/auth"
	coreauth "github.com/router-for-me/CLIProxyAPI/v6/sdk/cliproxy/auth"
)

// Builder constructs a Service instance with customizable providers.
type Builder struct {
	cfg            *config.Config
	configPath     string
	tokenProvider  TokenClientProvider
	apiKeyProvider APIKeyClientProvider
	watcherFactory WatcherFactory
	hooks          Hooks
	authManager    *sdkAuth.Manager
	coreManager    *coreauth.Manager
	serverOptions  []api.ServerOption
}

// Hooks allows callers to plug into service lifecycle stages.
type Hooks struct {
	OnBeforeStart func(*config.Config)
	OnAfterStart  func(*Service)
}

// NewBuilder creates a Builder with default dependencies left unset.
func NewBuilder() *Builder {
	return &Builder{}
}

// WithConfig sets the configuration instance used by the service.
func (b *Builder) WithConfig(cfg *config.Config) *Builder {
	b.cfg = cfg
	return b
}

// WithConfigPath sets the absolute configuration file path used for reload watching.
func (b *Builder) WithConfigPath(path string) *Builder {
	b.configPath = path
	return b
}

// WithTokenClientProvider overrides the provider responsible for token-backed clients.
func (b *Builder) WithTokenClientProvider(provider TokenClientProvider) *Builder {
	b.tokenProvider = provider
	return b
}

// WithAPIKeyClientProvider overrides the provider responsible for API key-backed clients.
func (b *Builder) WithAPIKeyClientProvider(provider APIKeyClientProvider) *Builder {
	b.apiKeyProvider = provider
	return b
}

// WithWatcherFactory allows customizing the watcher factory that handles reloads.
func (b *Builder) WithWatcherFactory(factory WatcherFactory) *Builder {
	b.watcherFactory = factory
	return b
}

// WithHooks registers lifecycle hooks executed around service startup.
func (b *Builder) WithHooks(h Hooks) *Builder {
	b.hooks = h
	return b
}

// WithAuthManager overrides the authentication manager used for token lifecycle operations.
func (b *Builder) WithAuthManager(mgr *sdkAuth.Manager) *Builder {
	b.authManager = mgr
	return b
}

// WithCoreAuthManager overrides the runtime auth manager responsible for request execution.
func (b *Builder) WithCoreAuthManager(mgr *coreauth.Manager) *Builder {
	b.coreManager = mgr
	return b
}

// WithServerOptions appends server configuration options used during construction.
func (b *Builder) WithServerOptions(opts ...api.ServerOption) *Builder {
	b.serverOptions = append(b.serverOptions, opts...)
	return b
}

// Build validates inputs, applies defaults, and returns a ready-to-run service.
func (b *Builder) Build() (*Service, error) {
	if b.cfg == nil {
		return nil, fmt.Errorf("cliproxy: configuration is required")
	}
	if b.configPath == "" {
		return nil, fmt.Errorf("cliproxy: configuration path is required")
	}

	tokenProvider := b.tokenProvider
	if tokenProvider == nil {
		tokenProvider = NewFileTokenClientProvider()
	}

	apiKeyProvider := b.apiKeyProvider
	if apiKeyProvider == nil {
		apiKeyProvider = NewAPIKeyClientProvider()
	}

	watcherFactory := b.watcherFactory
	if watcherFactory == nil {
		watcherFactory = defaultWatcherFactory
	}

	authManager := b.authManager
	if authManager == nil {
		authManager = newDefaultAuthManager()
	}

	coreManager := b.coreManager
	if coreManager == nil {
		coreManager = coreauth.NewManager(coreauth.NewFileStore(b.cfg.AuthDir), nil, nil)
	}
	// Attach a default RoundTripper provider so providers can opt-in per-auth transports.
	coreManager.SetRoundTripperProvider(newDefaultRoundTripperProvider())

	service := &Service{
		cfg:            b.cfg,
		configPath:     b.configPath,
		tokenProvider:  tokenProvider,
		apiKeyProvider: apiKeyProvider,
		watcherFactory: watcherFactory,
		hooks:          b.hooks,
		authManager:    authManager,
		coreManager:    coreManager,
		serverOptions:  append([]api.ServerOption(nil), b.serverOptions...),
	}
	return service, nil
}