// Package asmhentai implements the AsmHentai source (GalleryAdults-style).
// Multi-language: en/english, ja/japanese, zh/chinese, all (multi).
// Page list may require a POST to /inc/api.php for galleries with many pages.
package asmhentai

import (
	"context"
	"fmt"
	"net/http"
	"net/url"
	"strconv"
	"strings"

	"github.com/PuerkitoBio/goquery"

	"goyomi/internal/httpclient/flare"
	"goyomi/internal/registry"
	"goyomi/internal/source"
)

const siteURL = "https://asmhentai.com"

type Source struct {
	name      string
	lang      string
	mangaLang string // e.g. "english", "japanese", "" for all
	client    *flare.Client
	id        int64
}

func newSource(name, lang, mangaLang string) *Source {
	return &Source{
		name:      name,
		lang:      lang,
		mangaLang: mangaLang,
		client:    flare.NewClient(flare.WithRateLimit(1, 2)),
		id:        source.GenerateSourceID(name, lang),
	}
}

func (s *Source) ID() int64            { return s.id }
func (s *Source) Name() string         { return s.name }
func (s *Source) Lang() string         { return s.lang }
func (s *Source) SupportsLatest() bool { return s.mangaLang != "" }

func (s *Source) langPath() string {
	if s.mangaLang != "" {
		return "language/" + s.mangaLang + "/"
	}
	return ""
}

func (s *Source) get(ctx context.Context, rawURL string) (*goquery.Document, error) {
	resp, err := s.client.Get(ctx, rawURL)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusOK {
		return nil, fmt.Errorf("asmhentai: HTTP %d", resp.StatusCode)
	}
	return goquery.NewDocumentFromReader(resp.Body)
}

func imgAttr(img *goquery.Selection) string {
	for _, attr := range []string{"data-lazy-src", "data-src", "src"} {
		if v := img.AttrOr(attr, ""); v != "" && !strings.HasPrefix(v, "data:") {
			return v
		}
	}
	return ""
}

func thumbnailToFull(u string) string {
	ext := u[strings.LastIndex(u, "."):]
	return strings.Replace(u, "t"+ext, ext, 1)
}

func (s *Source) parsePage(doc *goquery.Document) source.MangasPage {
	var mangas []source.SManga
	doc.Find(".preview_item").Each(func(_ int, el *goquery.Selection) {
		href := el.Find(".image a").First().AttrOr("href", "")
		if href == "" {
			return
		}
		m := source.SManga{URL: href}
		m.ThumbnailURL = imgAttr(el.Find(".image img").First())
		m.Title = strings.TrimSpace(el.Find(".caption").Text())
		if m.Title == "" {
			m.Title = strings.TrimSpace(el.Find("h2, h3").First().Text())
		}
		if m.URL != "" && m.Title != "" {
			mangas = append(mangas, m)
		}
	})
	hasNext := doc.Find(".next.page-numbers, a[aria-label=Next]").Length() > 0
	return source.MangasPage{Mangas: mangas, HasNextPage: hasNext}
}

func (s *Source) GetPopularManga(page int) (source.MangasPage, error) {
	u := fmt.Sprintf("%s/%spopular/?page=%d", siteURL, s.langPath(), page)
	doc, err := s.get(context.Background(), u)
	if err != nil {
		return source.MangasPage{}, err
	}
	return s.parsePage(doc), nil
}

func (s *Source) GetLatestUpdates(page int) (source.MangasPage, error) {
	u := fmt.Sprintf("%s/%s?page=%d", siteURL, s.langPath(), page)
	doc, err := s.get(context.Background(), u)
	if err != nil {
		return source.MangasPage{}, err
	}
	return s.parsePage(doc), nil
}

func (s *Source) GetSearchManga(page int, query string, filters []source.Filter) (source.MangasPage, error) {
	u := fmt.Sprintf("%s/search/?q=%s&page=%d", siteURL, url.QueryEscape(query), page)
	doc, err := s.get(context.Background(), u)
	if err != nil {
		return source.MangasPage{}, err
	}
	return s.parsePage(doc), nil
}

func extractTags(info *goquery.Selection, tag string) string {
	var items []string
	info.Find(".tags").Each(func(_ int, tags *goquery.Selection) {
		if !strings.Contains(tags.Text(), tag+":") {
			return
		}
		tags.Find(".tag_list a").Each(func(_ int, a *goquery.Selection) {
			t := strings.TrimSpace(a.Find(".tag").Text())
			if t == "" {
				t = strings.TrimSpace(a.Text())
			}
			if t != "" {
				items = append(items, t)
			}
		})
	})
	return strings.Join(items, ", ")
}

func (s *Source) GetMangaDetails(manga source.SManga) (source.SManga, error) {
	rawURL := manga.URL
	if !strings.HasPrefix(rawURL, "http") {
		rawURL = siteURL + rawURL
	}
	doc, err := s.get(context.Background(), rawURL)
	if err != nil {
		return manga, err
	}
	result := source.SManga{URL: manga.URL, Status: source.StatusCompleted}
	info := doc.Find(".book_page")
	result.Title = strings.TrimSpace(info.Find("h1").Text())
	if result.Title == "" {
		result.Title = manga.Title
	}
	result.ThumbnailURL = imgAttr(info.Find(".cover img").First())
	result.Genre = extractTags(info, "Tags")
	result.Author = extractTags(info, "Artists")
	return result, nil
}

func (s *Source) GetChapterList(manga source.SManga) ([]source.SChapter, error) {
	return []source.SChapter{{URL: manga.URL, Name: "Chapter"}}, nil
}

func (s *Source) GetPageList(chapter source.SChapter) ([]source.Page, error) {
	rawURL := chapter.URL
	if !strings.HasPrefix(rawURL, "http") {
		rawURL = siteURL + rawURL
	}
	doc, err := s.get(context.Background(), rawURL)
	if err != nil {
		return nil, err
	}

	var pages []source.Page
	doc.Find(".preview_thumb img").Each(func(_ int, img *goquery.Selection) {
		if u := imgAttr(img); u != "" {
			pages = append(pages, source.Page{Index: len(pages), ImageURL: thumbnailToFull(u)})
		}
	})

	// POST for remaining pages when gallery has more than the initially loaded count.
	tPagesStr := doc.Find("input#t_pages").AttrOr("value", "")
	tPages, _ := strconv.Atoi(tPagesStr)
	if tPages > len(pages) && tPages > 0 {
		loadID := doc.Find("input#load_id").AttrOr("value", "")
		loadDir := doc.Find("input#load_dir").AttrOr("value", "")
		csrfToken := doc.Find("meta[name=csrf-token]").AttrOr("content", "")
		form := url.Values{
			"id":            {loadID},
			"dir":           {loadDir},
			"visible_pages": {strconv.Itoa(len(pages))},
			"t_pages":       {tPagesStr},
			"type":          {"2"},
		}
		if csrfToken != "" {
			form.Set("_token", csrfToken)
		}
		req, err := http.NewRequestWithContext(context.Background(), http.MethodPost,
			siteURL+"/inc/api.php", strings.NewReader(form.Encode()))
		if err == nil {
			req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
			req.Header.Set("X-Requested-With", "XMLHttpRequest")
			req.Header.Set("Referer", rawURL)
			resp, err := s.client.Do(req)
			if err == nil {
				defer resp.Body.Close()
				if resp.StatusCode == http.StatusOK {
					if extraDoc, err := goquery.NewDocumentFromReader(resp.Body); err == nil {
						extraDoc.Find(".preview_thumb img").Each(func(_ int, img *goquery.Selection) {
							if u := imgAttr(img); u != "" {
								pages = append(pages, source.Page{Index: len(pages), ImageURL: thumbnailToFull(u)})
							}
						})
					}
				}
			}
		}
	}

	return pages, nil
}

func (s *Source) GetImageURL(page source.Page) (string, error) { return page.ImageURL, nil }
func (s *Source) GetFilterList() []source.Filter               { return nil }

func init() {
	registry.Register(newSource("AsmHentai", "all", ""))
	registry.Register(newSource("AsmHentai (English)", "en", "english"))
	registry.Register(newSource("AsmHentai (Japanese)", "ja", "japanese"))
	registry.Register(newSource("AsmHentai (Chinese)", "zh", "chinese"))
}