package app

import (
	"fmt"
	"io"
	"net/http"
	"net/url"
	"strings"

	"github.com/PuerkitoBio/goquery"
)

func downloadAssetFile(url string) ([]byte, error) {
	resp, err := http.Get(url)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()

	return io.ReadAll(resp.Body)
}

type page struct {
	Title       string
	Description string
	Body        string
	ImageURL    string
}

// FetchArticleHTML returns page struct and error
func FetchArticleHTML(urlToFetch string) (page, error) {
	page := page{}

	url, err := url.Parse(urlToFetch)
	if err != nil {
		return page, err
	}

	resp, err := http.Get(url.String())
	if err != nil {
		return page, err
	}
	defer resp.Body.Close()

	doc, err := goquery.NewDocumentFromReader(resp.Body)
	if err != nil {
		return page, err
	}

	doc.Find(`head link[rel="stylesheet"]`).Each(func(i int, s *goquery.Selection) {
		v, ok := s.Attr("href")
		if !ok || v == "" {
			return
		}

		if strings.HasPrefix(v, "/") {
			styles, err := downloadAssetFile(fmt.Sprintf("https://%s%s", url.Hostname(), v))
			if err != nil {
				return
			}
			doc.Find("head").AppendHtml("<style>" + string(styles) + "</style>")
			s.Remove()
		}
	})

	doc.Find("a").Each(func(i int, s *goquery.Selection) {
		href, ok := s.Attr("href")
		if !ok || href == "" {
			return
		}

		if strings.HasPrefix(href, "/") {
			s.SetAttr("href", "https://"+url.Hostname()+href)
		}
	})

	doc.Find("img").Each(func(i int, s *goquery.Selection) {
		src, ok := s.Attr("src")
		if !ok || src == "" {
			return
		}

		if strings.HasPrefix(src, "/") {
			s.SetAttr("src", "https://"+url.Hostname()+src)
		}
	})

	doc.Find("script").Each(func(i int, s *goquery.Selection) {
		s.Remove()
	})

	page.Title = doc.Find("head title").Text()
	page.Body, _ = doc.Html()

	page.Description = doc.Find(`head meta[name="description"]`).AttrOr("content", "")
	if page.Description == "" {
		page.Description = doc.Find(`head meta[property="og:description"]`).AttrOr("content", "")
	}

	page.ImageURL = doc.Find(`head meta[property="og:image"]`).AttrOr("content", "")
	if page.ImageURL == "" {
		doc.Find("img").Each(func(i int, s *goquery.Selection) {
			if page.ImageURL != "" {
				return
			}

			src, exists := s.Attr("src")
			if !exists {
				return
			}

			u, err := url.Parse(src)
			if err != nil {
				return
			}

			allowedTypes := []string{"png", "jpg", "jpeg", "webp"}
			isAllowed := false
			for _, tp := range allowedTypes {
				if strings.HasSuffix(u.Path, tp) {
					isAllowed = true
				}
			}

			if isAllowed {
				page.ImageURL = src
			}
		})
	}

	return page, err
}