package astrodocs

import (
	"net/url"
	"strings"
	"time"

	"github.com/PuerkitoBio/goquery"
)

type Parser struct {
	baseURL string
}

func NewParser() *Parser {
	return &Parser{
		baseURL: "https://docs.astro.build",
	}
}

func (p *Parser) ParsePage(html string, docURL string) (*Page, error) {
	doc, err := goquery.NewDocumentFromReader(strings.NewReader(html))
	if err != nil {
		return nil, err
	}

	page := &Page{
		URL:       docURL,
		FetchedAt: time.Now(),
	}

	page.Title = p.extractTitle(doc)
	page.Description = p.extractDescription(doc)
	page.Content = p.extractContent(doc)
	page.Sections = p.extractSections(doc, docURL)
	page.CodeBlocks = p.extractCodeBlocks(doc)

	return page, nil
}

func (p *Parser) ParseSidebar(html string) ([]*Section, error) {
	doc, err := goquery.NewDocumentFromReader(strings.NewReader(html))
	if err != nil {
		return nil, err
	}

	var sections []*Section

	doc.Find(".sidebar a, nav a, [data-sidebar] a").Each(func(_ int, s *goquery.Selection) {
		section := &Section{}

		section.Title = strings.TrimSpace(s.Text())

		if href, exists := s.Attr("href"); exists {
			section.DocURL = resolveURL(p.baseURL, href)
		}

		if section.Title != "" && section.DocURL != "" {
			sections = append(sections, section)
		}
	})

	return sections, nil
}

func (p *Parser) extractTitle(doc *goquery.Document) string {
	title := doc.Find("h1").First().Text()
	title = strings.TrimSpace(title)

	if title == "" {
		title = doc.Find("title").First().Text()
		title = strings.TrimSpace(title)
		if idx := strings.Index(title, " | "); idx > 0 {
			title = title[:idx]
		}
	}

	return title
}

func (p *Parser) extractDescription(doc *goquery.Document) string {
	desc := doc.Find("meta[name='description']").AttrOr("content", "")
	if desc != "" {
		return desc
	}

	return doc.Find("meta[property='og:description']").AttrOr("content", "")
}

func (p *Parser) extractContent(doc *goquery.Document) string {
	content := doc.Find("article, main, .content, .sl-markdown-content").First()
	if content.Length() == 0 {
		content = doc.Find("body")
	}

	return strings.TrimSpace(content.Text())
}

func (p *Parser) extractSections(doc *goquery.Document, docURL string) []*Section {
	var sections []*Section

	doc.Find("h1, h2, h3").Each(func(_ int, s *goquery.Selection) {
		section := &Section{}

		section.Title = strings.TrimSpace(s.Text())

		if id, exists := s.Attr("id"); exists {
			section.ID = id
			section.DocURL = docURL + "#" + id
		} else {
			section.DocURL = docURL
		}

		if section.Title != "" {
			sections = append(sections, section)
		}
	})

	return sections
}

func (p *Parser) extractCodeBlocks(doc *goquery.Document) []*CodeBlock {
	var blocks []*CodeBlock

	doc.Find("pre code, pre").Each(func(_ int, s *goquery.Selection) {
		block := &CodeBlock{}

		if classes, exists := s.Attr("class"); exists {
			parts := strings.Split(classes, " ")
			for _, part := range parts {
				if strings.HasPrefix(part, "language-") {
					block.Language = strings.TrimPrefix(part, "language-")
					break
				}
			}
		}

		if block.Language == "" {
			parent := s.Parent()
			if classes, exists := parent.Attr("class"); exists {
				parts := strings.Split(classes, " ")
				for _, part := range parts {
					if strings.HasPrefix(part, "language-") {
						block.Language = strings.TrimPrefix(part, "language-")
						break
					}
				}
			}
		}

		block.Code = strings.TrimSpace(s.Text())

		if block.Code != "" {
			blocks = append(blocks, block)
		}
	})

	return blocks
}

func resolveURL(base string, href string) string {
	if strings.HasPrefix(href, "http") {
		return href
	}

	baseURL, err := url.Parse(base)
	if err != nil {
		return href
	}

	hrefURL, err := url.Parse(href)
	if err != nil {
		return href
	}

	return baseURL.ResolveReference(hrefURL).String()
}