package providers

import (
	"fmt"
	"strings"

	"chorus/pkg/repository"
)

// ProviderFactory creates task providers for different repository types
type ProviderFactory struct {
	supportedProviders map[string]ProviderCreator
}

// ProviderCreator is a function that creates a provider from config
type ProviderCreator func(config *repository.Config) (repository.TaskProvider, error)

// NewProviderFactory creates a new provider factory with all supported providers
func NewProviderFactory() *ProviderFactory {
	factory := &ProviderFactory{
		supportedProviders: make(map[string]ProviderCreator),
	}

	// Register all supported providers
	factory.RegisterProvider("gitea", func(config *repository.Config) (repository.TaskProvider, error) {
		return NewGiteaProvider(config)
	})

	factory.RegisterProvider("github", func(config *repository.Config) (repository.TaskProvider, error) {
		return NewGitHubProvider(config)
	})

	factory.RegisterProvider("gitlab", func(config *repository.Config) (repository.TaskProvider, error) {
		return NewGitLabProvider(config)
	})

	factory.RegisterProvider("mock", func(config *repository.Config) (repository.TaskProvider, error) {
		return &repository.MockTaskProvider{}, nil
	})

	return factory
}

// RegisterProvider registers a new provider creator
func (f *ProviderFactory) RegisterProvider(providerType string, creator ProviderCreator) {
	f.supportedProviders[strings.ToLower(providerType)] = creator
}

// CreateProvider creates a task provider based on the configuration
func (f *ProviderFactory) CreateProvider(ctx interface{}, config *repository.Config) (repository.TaskProvider, error) {
	if config == nil {
		return nil, fmt.Errorf("configuration cannot be nil")
	}

	providerType := strings.ToLower(config.Provider)
	if providerType == "" {
		// Fall back to Type field if Provider is not set
		providerType = strings.ToLower(config.Type)
	}

	if providerType == "" {
		return nil, fmt.Errorf("provider type must be specified in config.Provider or config.Type")
	}

	creator, exists := f.supportedProviders[providerType]
	if !exists {
		return nil, fmt.Errorf("unsupported provider type: %s. Supported types: %v",
			providerType, f.GetSupportedTypes())
	}

	provider, err := creator(config)
	if err != nil {
		return nil, fmt.Errorf("failed to create %s provider: %w", providerType, err)
	}

	return provider, nil
}

// GetSupportedTypes returns a list of all supported provider types
func (f *ProviderFactory) GetSupportedTypes() []string {
	types := make([]string, 0, len(f.supportedProviders))
	for providerType := range f.supportedProviders {
		types = append(types, providerType)
	}
	return types
}

// SupportedProviders returns list of supported providers (alias for GetSupportedTypes)
func (f *ProviderFactory) SupportedProviders() []string {
	return f.GetSupportedTypes()
}

// ValidateConfig validates a provider configuration
func (f *ProviderFactory) ValidateConfig(config *repository.Config) error {
	if config == nil {
		return fmt.Errorf("configuration cannot be nil")
	}

	providerType := strings.ToLower(config.Provider)
	if providerType == "" {
		providerType = strings.ToLower(config.Type)
	}

	if providerType == "" {
		return fmt.Errorf("provider type must be specified")
	}

	// Check if provider type is supported
	if _, exists := f.supportedProviders[providerType]; !exists {
		return fmt.Errorf("unsupported provider type: %s", providerType)
	}

	// Provider-specific validation
	switch providerType {
	case "gitea":
		return f.validateGiteaConfig(config)
	case "github":
		return f.validateGitHubConfig(config)
	case "gitlab":
		return f.validateGitLabConfig(config)
	case "mock":
		return nil // Mock provider doesn't need validation
	default:
		return fmt.Errorf("validation not implemented for provider type: %s", providerType)
	}
}

// validateGiteaConfig validates Gitea-specific configuration
func (f *ProviderFactory) validateGiteaConfig(config *repository.Config) error {
	if config.BaseURL == "" {
		return fmt.Errorf("baseURL is required for Gitea provider")
	}
	if config.AccessToken == "" {
		return fmt.Errorf("accessToken is required for Gitea provider")
	}
	if config.Owner == "" {
		return fmt.Errorf("owner is required for Gitea provider")
	}
	if config.Repository == "" {
		return fmt.Errorf("repository is required for Gitea provider")
	}
	return nil
}

// validateGitHubConfig validates GitHub-specific configuration
func (f *ProviderFactory) validateGitHubConfig(config *repository.Config) error {
	if config.AccessToken == "" {
		return fmt.Errorf("accessToken is required for GitHub provider")
	}
	if config.Owner == "" {
		return fmt.Errorf("owner is required for GitHub provider")
	}
	if config.Repository == "" {
		return fmt.Errorf("repository is required for GitHub provider")
	}
	return nil
}

// validateGitLabConfig validates GitLab-specific configuration
func (f *ProviderFactory) validateGitLabConfig(config *repository.Config) error {
	if config.AccessToken == "" {
		return fmt.Errorf("accessToken is required for GitLab provider")
	}

	// GitLab requires either owner/repository or project_id in settings
	if config.Owner != "" && config.Repository != "" {
		return nil // owner/repo provided
	}

	if config.Settings != nil {
		if projectID, ok := config.Settings["project_id"].(string); ok && projectID != "" {
			return nil // project_id provided
		}
	}

	return fmt.Errorf("either owner/repository or project_id in settings is required for GitLab provider")
}

// GetProviderInfo returns information about a specific provider
func (f *ProviderFactory) GetProviderInfo(providerType string) (*ProviderInfo, error) {
	providerType = strings.ToLower(providerType)

	if _, exists := f.supportedProviders[providerType]; !exists {
		return nil, fmt.Errorf("unsupported provider type: %s", providerType)
	}

	switch providerType {
	case "gitea":
		return &ProviderInfo{
			Name:               "Gitea",
			Type:               "gitea",
			Description:        "Gitea self-hosted Git service provider",
			RequiredFields:     []string{"baseURL", "accessToken", "owner", "repository"},
			OptionalFields:     []string{"taskLabel", "inProgressLabel", "completedLabel", "baseBranch", "branchPrefix"},
			SupportedFeatures:  []string{"issues", "labels", "comments", "assignments"},
			APIDocumentation:   "https://docs.gitea.io/en-us/api-usage/",
		}, nil

	case "github":
		return &ProviderInfo{
			Name:               "GitHub",
			Type:               "github",
			Description:        "GitHub cloud and enterprise Git service provider",
			RequiredFields:     []string{"accessToken", "owner", "repository"},
			OptionalFields:     []string{"taskLabel", "inProgressLabel", "completedLabel", "baseBranch", "branchPrefix"},
			SupportedFeatures:  []string{"issues", "labels", "comments", "assignments", "projects"},
			APIDocumentation:   "https://docs.github.com/en/rest",
		}, nil

	case "gitlab":
		return &ProviderInfo{
			Name:               "GitLab",
			Type:               "gitlab",
			Description:        "GitLab cloud and self-hosted Git service provider",
			RequiredFields:     []string{"accessToken", "owner/repository OR project_id"},
			OptionalFields:     []string{"baseURL", "taskLabel", "inProgressLabel", "completedLabel", "baseBranch", "branchPrefix"},
			SupportedFeatures:  []string{"issues", "labels", "notes", "assignments", "time_tracking", "milestones"},
			APIDocumentation:   "https://docs.gitlab.com/ee/api/",
		}, nil

	case "mock":
		return &ProviderInfo{
			Name:               "Mock Provider",
			Type:               "mock",
			Description:        "Mock provider for testing and development",
			RequiredFields:     []string{},
			OptionalFields:     []string{},
			SupportedFeatures:  []string{"basic_operations"},
			APIDocumentation:   "Built-in mock for testing purposes",
		}, nil

	default:
		return nil, fmt.Errorf("provider info not available for: %s", providerType)
	}
}

// ProviderInfo contains metadata about a provider
type ProviderInfo struct {
	Name               string   `json:"name"`
	Type               string   `json:"type"`
	Description        string   `json:"description"`
	RequiredFields     []string `json:"required_fields"`
	OptionalFields     []string `json:"optional_fields"`
	SupportedFeatures  []string `json:"supported_features"`
	APIDocumentation   string   `json:"api_documentation"`
}

// ListProviders returns detailed information about all supported providers
func (f *ProviderFactory) ListProviders() ([]*ProviderInfo, error) {
	providers := make([]*ProviderInfo, 0, len(f.supportedProviders))

	for providerType := range f.supportedProviders {
		info, err := f.GetProviderInfo(providerType)
		if err != nil {
			continue // Skip providers without info
		}
		providers = append(providers, info)
	}

	return providers, nil
}