package scraper

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

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

type SpringDocsScraper struct {
	config *Config
	parser *springdocs.Parser
	client *http.Client
}

func NewSpringDocsScraper(config *Config) *SpringDocsScraper {
	return &SpringDocsScraper{
		config: config,
		parser: springdocs.NewParser(),
		client: &http.Client{
			Timeout: config.Timeout,
		},
	}
}

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

	if source.URL == "" {
		return nil, fmt.Errorf("URL is required for Spring 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 _, class := range module.Classes {
		doc := s.classToDocument(class, module, source.Name)
		documents = append(documents, doc)
	}

	for _, prop := range module.Properties {
		doc := s.propertyToDocument(prop, source.Name)
		documents = append(documents, doc)
	}

	for _, guide := range module.Guides {
		doc := s.guideToDocument(guide, source.Name)
		documents = append(documents, doc)
	}

	return documents, nil
}

func (s *SpringDocsScraper) 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 *SpringDocsScraper) fetchPage(ctx context.Context, url string) (string, error) {
	req, err := http.NewRequestWithContext(ctx, "GET", url, nil)
	if err != nil {
		return "", err
	}

	req.Header.Set("User-Agent", s.config.UserAgent)

	resp, err := s.client.Do(req)
	if err != nil {
		return "", err
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		return "", fmt.Errorf("HTTP %d", resp.StatusCode)
	}

	body, err := io.ReadAll(resp.Body)
	if err != nil {
		return "", err
	}
	return string(body), nil
}

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

func (s *SpringDocsScraper) moduleToDocument(module *springdocs.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": "spring-module",
	}

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

func (s *SpringDocsScraper) classToDocument(class *springdocs.Class, module *springdocs.Module, sourceName string) *Document {
	var content strings.Builder
	fmt.Fprintf(&content, "# %s\n\n", class.QualifiedName)
	fmt.Fprintf(&content, "%s\n", class.Doc)

	if len(class.Methods) > 0 {
		fmt.Fprintf(&content, "\n## Methods\n")
		for _, m := range class.Methods {
			fmt.Fprintf(&content, "- `%s`\n", m.Signature)
		}
	}

	metadata := map[string]interface{}{
		"module":         module.Name,
		"qualified_name": class.QualifiedName,
		"kind":           class.Kind,
		"doc_url":        class.DocURL,
	}

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

func (s *SpringDocsScraper) propertyToDocument(prop *springdocs.Property, sourceName string) *Document {
	var content strings.Builder
	fmt.Fprintf(&content, "# %s\n\n", prop.Name)
	fmt.Fprintf(&content, "Type: %s\n", prop.Type)
	if prop.Default != "" {
		fmt.Fprintf(&content, "Default: `%s`\n", prop.Default)
	}
	fmt.Fprintf(&content, "\n%s\n", prop.Doc)

	metadata := map[string]interface{}{
		"property": prop.Name,
		"type":     prop.Type,
		"default":  prop.Default,
		"doc_url":  prop.DocURL,
	}

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

func (s *SpringDocsScraper) guideToDocument(guide *springdocs.Guide, sourceName string) *Document {
	var content strings.Builder
	fmt.Fprintf(&content, "# %s\n\n", guide.Title)
	fmt.Fprintf(&content, "%s\n", guide.Description)

	metadata := map[string]interface{}{
		"title":    guide.Title,
		"doc_url":  guide.DocURL,
		"level":    guide.Level,
		"doc_type": "spring-guide",
	}

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