package scraper

import (
	"context"
	"fmt"
)

// ScraperConstructor defines a function that creates a scraper
type ScraperConstructor func(*Config) Scraper

// ScraperRegistry manages scraper constructors without importing them
type ScraperRegistry struct {
	constructors map[SourceType]ScraperConstructor
}

// NewScraperRegistry creates a new registry
func NewScraperRegistry() *ScraperRegistry {
	return &ScraperRegistry{
		constructors: make(map[SourceType]ScraperConstructor),
	}
}

// Register registers a scraper constructor
func (r *ScraperRegistry) Register(sourceType SourceType, constructor ScraperConstructor) {
	r.constructors[sourceType] = constructor
}

// Create creates a scraper instance
func (r *ScraperRegistry) Create(sourceType SourceType, config *Config) Scraper {
	if constructor, exists := r.constructors[sourceType]; exists {
		return constructor(config)
	}
	return nil
}

// Global registry
var globalRegistry = NewScraperRegistry()

// RegisterScraper registers a scraper globally
func RegisterScraper(sourceType SourceType, constructor ScraperConstructor) {
	globalRegistry.Register(sourceType, constructor)
}

// CreateScraper creates a scraper using the global registry
func CreateScraper(sourceType SourceType, config *Config) Scraper {
	return globalRegistry.Create(sourceType, config)
}

// FallbackScraper provides basic functionality when specific scrapers aren't available
type FallbackScraper struct {
	config *Config
}

// NewFallbackScraper creates a fallback scraper
func NewFallbackScraper(config *Config) *FallbackScraper {
	return &FallbackScraper{config: config}
}

// Scrape implements basic scraping functionality
func (f *FallbackScraper) Scrape(ctx context.Context, source *Source) ([]*Document, error) {
	return nil, fmt.Errorf("fallback scraper not implemented for source type: %s", source.Type)
}

// DetectChanges implements basic change detection
func (f *FallbackScraper) DetectChanges(ctx context.Context, source *Source, lastHash string) (bool, string, error) {
	return false, "", fmt.Errorf("fallback scraper not implemented for source type: %s", source.Type)
}