package scraper

import (
	"context"
	"crypto/sha256"
	"encoding/hex"
	"fmt"
	"net/http"
	"strings"
	"time"

	"github.com/yourorg/devour/pkg/tsdocs"
)

type TSDocsScraper struct {
	config *Config
	parser *tsdocs.Parser
	client *http.Client
}

func NewTSDocsScraper(config *Config) *TSDocsScraper {
	return &TSDocsScraper{
		config: config,
		parser: tsdocs.NewParser(),
		client: &http.Client{
			Timeout: config.Timeout,
		},
	}
}

func (s *TSDocsScraper) Scrape(ctx context.Context, source *Source) ([]*Document, error) {
	var documents []*Document

	if source.URL == "" {
		return nil, fmt.Errorf("URL is required for TypeScript docs scraper")
	}

	html, err := s.fetchPage(ctx, source.URL)
	if err != nil {
		return nil, fmt.Errorf("failed to fetch page: %w", err)
	}

	module, err := s.parser.ParseModulePage(html, source.URL)
	if err != nil {
		return nil, fmt.Errorf("failed to parse module: %w", err)
	}

	mainDoc := s.moduleToDocument(module, source.Name)
	documents = append(documents, mainDoc)

	for _, iface := range module.Interfaces {
		doc := s.interfaceToDocument(iface, module, source.Name)
		documents = append(documents, doc)
	}

	for _, fn := range module.Functions {
		doc := s.functionToDocument(fn, module, source.Name)
		documents = append(documents, doc)
	}

	for _, class := range module.Classes {
		doc := s.classToDocument(class, module, source.Name)
		documents = append(documents, doc)
	}

	for _, ta := range module.Types {
		doc := s.typeAliasToDocument(ta, module, source.Name)
		documents = append(documents, doc)
	}

	return documents, nil
}

func (s *TSDocsScraper) DetectChanges(ctx context.Context, source *Source, lastHash string) (bool, string, error) {
	html, err := s.fetchPage(ctx, source.URL)
	if err != nil {
		return false, "", err
	}

	hash := s.generateHash(html)
	changed := hash != lastHash

	return changed, hash, nil
}

func (s *TSDocsScraper) fetchPage(ctx context.Context, url string) (string, error) {
	return fetchExternalPage(ctx, s.client, s.config.UserAgent, url)
}

func (s *TSDocsScraper) generateHash(content string) string {
	hash := sha256.Sum256([]byte(content))
	return hex.EncodeToString(hash[:])
}

func (s *TSDocsScraper) moduleToDocument(module *tsdocs.Module, sourceName string) *Document {
	var content strings.Builder
	fmt.Fprintf(&content, "# %s\n\n", module.Name)
	fmt.Fprintf(&content, "%s\n", module.Doc)

	metadata := map[string]interface{}{
		"module":   module.Name,
		"version":  module.Version,
		"doc_url":  module.DocURL,
		"doc_type": "ts-module",
	}

	return &Document{
		ID:        generateDocID(module.DocURL),
		Source:    sourceName,
		Type:      "ts-module",
		Title:     module.Name,
		Content:   content.String(),
		URL:       module.DocURL,
		Metadata:  metadata,
		Hash:      s.generateHash(content.String()),
		Timestamp: time.Now(),
	}
}

func (s *TSDocsScraper) interfaceToDocument(iface *tsdocs.Interface, module *tsdocs.Module, sourceName string) *Document {
	var content strings.Builder
	fmt.Fprintf(&content, "# %s (interface)\n\n", iface.Name)
	if iface.Doc != "" {
		fmt.Fprintf(&content, "%s\n\n", iface.Doc)
	}
	if len(iface.Properties) > 0 {
		fmt.Fprintf(&content, "## Properties\n")
		for _, p := range iface.Properties {
			fmt.Fprintf(&content, "- `%s: %s`\n", p.Name, p.Type)
		}
	}

	metadata := map[string]interface{}{
		"module":  module.Name,
		"name":    iface.Name,
		"doc_url": coalesceDocURL(iface.DocURL, module.DocURL),
	}

	docURL := coalesceDocURL(iface.DocURL, module.DocURL)

	return &Document{
		ID:        generateDocID(docURL),
		Source:    sourceName,
		Type:      "ts-interface",
		Title:     iface.Name,
		Content:   content.String(),
		URL:       docURL,
		Metadata:  metadata,
		Hash:      s.generateHash(content.String()),
		Timestamp: time.Now(),
	}
}

func (s *TSDocsScraper) functionToDocument(fn *tsdocs.Function, module *tsdocs.Module, sourceName string) *Document {
	var content strings.Builder
	fmt.Fprintf(&content, "# %s()\n\n", fn.Name)
	if fn.Signature != "" {
		fmt.Fprintf(&content, "```typescript\n%s\n```\n\n", fn.Signature)
	}
	if fn.Doc != "" {
		fmt.Fprintf(&content, "%s\n", fn.Doc)
	}

	metadata := map[string]interface{}{
		"module":      module.Name,
		"name":        fn.Name,
		"return_type": fn.ReturnType,
		"doc_url":     coalesceDocURL(fn.DocURL, module.DocURL),
	}

	docURL := coalesceDocURL(fn.DocURL, module.DocURL)

	return &Document{
		ID:        generateDocID(docURL),
		Source:    sourceName,
		Type:      "ts-function",
		Title:     fn.Name,
		Content:   content.String(),
		URL:       docURL,
		Metadata:  metadata,
		Hash:      s.generateHash(content.String()),
		Timestamp: time.Now(),
	}
}

func (s *TSDocsScraper) classToDocument(class *tsdocs.Class, module *tsdocs.Module, sourceName string) *Document {
	var content strings.Builder
	fmt.Fprintf(&content, "# %s (class)\n\n", class.Name)
	if class.Doc != "" {
		fmt.Fprintf(&content, "%s\n\n", class.Doc)
	}
	if len(class.Methods) > 0 {
		fmt.Fprintf(&content, "## Methods\n")
		for _, m := range class.Methods {
			fmt.Fprintf(&content, "- `%s()`\n", m.Name)
		}
	}

	metadata := map[string]interface{}{
		"module":  module.Name,
		"name":    class.Name,
		"doc_url": coalesceDocURL(class.DocURL, module.DocURL),
	}

	docURL := coalesceDocURL(class.DocURL, module.DocURL)

	return &Document{
		ID:        generateDocID(docURL),
		Source:    sourceName,
		Type:      "ts-class",
		Title:     class.Name,
		Content:   content.String(),
		URL:       docURL,
		Metadata:  metadata,
		Hash:      s.generateHash(content.String()),
		Timestamp: time.Now(),
	}
}

func (s *TSDocsScraper) typeAliasToDocument(ta *tsdocs.TypeAlias, module *tsdocs.Module, sourceName string) *Document {
	var content strings.Builder
	fmt.Fprintf(&content, "# %s (type)\n\n", ta.Name)
	fmt.Fprintf(&content, "```typescript\ntype %s = %s\n```\n\n", ta.Name, ta.Type)
	if ta.Doc != "" {
		fmt.Fprintf(&content, "%s\n", ta.Doc)
	}

	metadata := map[string]interface{}{
		"module":  module.Name,
		"name":    ta.Name,
		"doc_url": coalesceDocURL(ta.DocURL, module.DocURL),
	}

	docURL := coalesceDocURL(ta.DocURL, module.DocURL)

	return &Document{
		ID:        generateDocID(docURL),
		Source:    sourceName,
		Type:      "ts-type",
		Title:     ta.Name,
		Content:   content.String(),
		URL:       docURL,
		Metadata:  metadata,
		Hash:      s.generateHash(content.String()),
		Timestamp: time.Now(),
	}
}

func coalesceDocURL(primary, fallback string) string {
	if strings.TrimSpace(primary) != "" {
		return primary
	}
	return fallback
}