// Package comiciviewer implements the ComiciViewer Japanese manga base.
// GET {base}/ranking/manga for popular; API viewer for pages (requires login).
package comiciviewer

import (
	"context"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"strings"

	"github.com/PuerkitoBio/goquery"

	"goyomi/internal/httpclient"
	"goyomi/internal/source"
	"goyomi/sources/base/util"
)

type Config struct {
	Name    string
	BaseURL string
	Lang    string
}

type Source struct {
	cfg    Config
	client *httpclient.Client
	id     int64
}

func New(cfg Config) *Source {
	c := httpclient.NewClient(httpclient.WithRateLimit(1, 2))
	return &Source{cfg: cfg, client: c, id: source.GenerateSourceID(cfg.Name, cfg.Lang)}
}

func (s *Source) ID() int64            { return s.id }
func (s *Source) Name() string         { return s.cfg.Name }
func (s *Source) Lang() string         { return s.cfg.Lang }
func (s *Source) SupportsLatest() bool { return true }

func (s *Source) base() string { return strings.TrimRight(s.cfg.BaseURL, "/") }

func (s *Source) get(ctx context.Context, rawURL string) (*goquery.Document, error) {
	req, err := http.NewRequestWithContext(ctx, http.MethodGet, rawURL, nil)
	if err != nil {
		return nil, err
	}
	req.Header.Set("Referer", s.cfg.BaseURL+"/")
	resp, err := s.client.Do(req)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusOK {
		return nil, fmt.Errorf("comiciviewer: HTTP %d", resp.StatusCode)
	}
	return goquery.NewDocumentFromReader(resp.Body)
}

func srcsetToURL(s string) string {
	// "//cdn.example.com/img.jpg 1x" → "https://cdn.example.com/img.jpg"
	if idx := strings.Index(s, " "); idx >= 0 {
		s = s[:idx]
	}
	if strings.HasPrefix(s, "//") {
		return "https:" + s
	}
	return s
}

func mangaFromElement(el *goquery.Selection) source.SManga {
	m := source.SManga{}
	el.Find("a").First().Each(func(_ int, a *goquery.Selection) {
		m.URL, _ = a.Attr("href")
	})
	m.Title = strings.TrimSpace(el.Find(".title-text").Text())
	el.Find("source").First().Each(func(_ int, e *goquery.Selection) {
		if v, ok := e.Attr("data-srcset"); ok {
			m.ThumbnailURL = srcsetToURL(v)
		}
	})
	return m
}

func (s *Source) GetPopularManga(page int) (source.MangasPage, error) {
	doc, err := s.get(context.Background(), s.base()+"/ranking/manga")
	if err != nil {
		return source.MangasPage{}, err
	}
	var mangas []source.SManga
	doc.Find("div.ranking-box-vertical, div.ranking-box-vertical-top3").Each(func(_ int, el *goquery.Selection) {
		m := mangaFromElement(el)
		if m.URL != "" {
			mangas = append(mangas, m)
		}
	})
	return source.MangasPage{Mangas: mangas, HasNextPage: false}, nil
}

func (s *Source) GetLatestUpdates(page int) (source.MangasPage, error) {
	doc, err := s.get(context.Background(), s.base()+"/category/manga")
	if err != nil {
		return source.MangasPage{}, err
	}
	var mangas []source.SManga
	doc.Find("div.category-box-vertical").Each(func(_ int, el *goquery.Selection) {
		m := mangaFromElement(el)
		if m.URL != "" {
			mangas = append(mangas, m)
		}
	})
	hasNext := doc.Find("li.mode-paging-active + li > a").Length() > 0
	return source.MangasPage{Mangas: mangas, HasNextPage: hasNext}, nil
}

func (s *Source) GetSearchManga(page int, query string, filters []source.Filter) (source.MangasPage, error) {
	doc, err := s.get(context.Background(), fmt.Sprintf("%s/search?keyword=%s", s.base(), query))
	if err != nil {
		return source.MangasPage{}, err
	}
	var mangas []source.SManga
	doc.Find("div.manga-store-item").Each(func(_ int, el *goquery.Selection) {
		m := source.SManga{}
		el.Find("a.c-ms-clk-article").First().Each(func(_ int, a *goquery.Selection) {
			m.URL, _ = a.Attr("href")
		})
		m.Title = strings.TrimSpace(el.Find("h2.manga-title").Text())
		el.Find("source").First().Each(func(_ int, e *goquery.Selection) {
			if v, ok := e.Attr("data-srcset"); ok {
				m.ThumbnailURL = srcsetToURL(v)
			}
		})
		if m.URL != "" {
			mangas = append(mangas, m)
		}
	})
	hasNext := doc.Find("li.mode-paging-active + li > a").Length() > 0
	return source.MangasPage{Mangas: mangas, HasNextPage: hasNext}, nil
}

func (s *Source) GetMangaDetails(manga source.SManga) (source.SManga, error) {
	doc, err := s.get(context.Background(), util.AbsURL(s.cfg.BaseURL, manga.URL))
	if err != nil {
		return manga, err
	}
	result := source.SManga{URL: manga.URL}
	// title: last span in h1.series-h-title
	doc.Find("h1.series-h-title span").Last().Each(func(_ int, el *goquery.Selection) {
		result.Title = strings.TrimSpace(el.Text())
	})
	if result.Title == "" {
		result.Title = manga.Title
	}
	result.Author = strings.TrimSpace(doc.Find("div.series-h-author").Text())
	result.Description = strings.TrimSpace(doc.Find("div.series-h-description, p.series-description").Text())
	var genres []string
	doc.Find("a.series-h-tag-link").Each(func(_ int, el *goquery.Selection) {
		t := strings.TrimPrefix(strings.TrimSpace(el.Text()), "#")
		if t != "" {
			genres = append(genres, t)
		}
	})
	result.Genre = strings.Join(genres, ", ")
	doc.Find("div.series-h-img source").First().Each(func(_ int, e *goquery.Selection) {
		if v, ok := e.Attr("data-srcset"); ok {
			result.ThumbnailURL = srcsetToURL(v)
		}
	})
	return result, nil
}

func (s *Source) GetChapterList(manga source.SManga) ([]source.SChapter, error) {
	chURL := fmt.Sprintf("%s%s/list?s=1", s.base(), manga.URL)
	doc, err := s.get(context.Background(), chURL)
	if err != nil {
		return nil, err
	}
	var chapters []source.SChapter
	doc.Find("li.episode-item, .chapter-list li").Each(func(_ int, el *goquery.Selection) {
		ch := source.SChapter{}
		el.Find("a").First().Each(func(_ int, a *goquery.Selection) {
			ch.URL, _ = a.Attr("href")
			ch.Name = strings.TrimSpace(a.Find(".episode-title, .title-text").Text())
			if ch.Name == "" {
				ch.Name = strings.TrimSpace(a.Text())
			}
		})
		el.Find("time").First().Each(func(_ int, e *goquery.Selection) {
			dt := e.AttrOr("datetime", e.Text())
			ch.DateUpload = util.ParseAbsoluteDate(dt, "2006-01-02 15:04:05")
		})
		if ch.URL != "" {
			chapters = append(chapters, ch)
		}
	})
	return chapters, nil
}

func (s *Source) GetPageList(chapter source.SChapter) ([]source.Page, error) {
	doc, err := s.get(context.Background(), util.AbsURL(s.cfg.BaseURL, chapter.URL))
	if err != nil {
		return nil, err
	}
	viewer := doc.Find("#comici-viewer")
	if viewer.Length() == 0 {
		return nil, fmt.Errorf("comiciviewer: WebView login required to read this chapter")
	}
	viewerID := viewer.AttrOr("comici-viewer-id", "")
	memberJWT := viewer.AttrOr("data-member-jwt", "")
	if viewerID == "" {
		return nil, fmt.Errorf("comiciviewer: could not find viewer ID")
	}
	// Step 1: get total pages
	apiURL := fmt.Sprintf("%s/book/contentsInfo?comici-viewer-id=%s&user-id=%s&page-from=0&page-to=1",
		s.base(), viewerID, memberJWT)
	pages, err := s.fetchViewerPages(apiURL, viewerID, memberJWT)
	if err != nil {
		return nil, err
	}
	return pages, nil
}

type viewerResponse struct {
	TotalPages int `json:"totalPages"`
	Result     []struct {
		ImageURL string `json:"imageUrl"`
		Sort     int    `json:"sort"`
		Scramble string `json:"scramble"`
	} `json:"result"`
}

func (s *Source) fetchViewerPages(initialURL, viewerID, jwt string) ([]source.Page, error) {
	req, err := http.NewRequestWithContext(context.Background(), http.MethodGet, initialURL, nil)
	if err != nil {
		return nil, err
	}
	req.Header.Set("Referer", s.cfg.BaseURL+"/")
	resp, err := s.client.Do(req)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()
	body, _ := io.ReadAll(resp.Body)
	var vr viewerResponse
	if err := json.Unmarshal(body, &vr); err != nil {
		return nil, err
	}
	if vr.TotalPages == 0 {
		return nil, fmt.Errorf("comiciviewer: no pages found")
	}
	// fetch all pages
	allURL := fmt.Sprintf("%s/book/contentsInfo?comici-viewer-id=%s&user-id=%s&page-from=0&page-to=%d",
		s.base(), viewerID, jwt, vr.TotalPages)
	req2, _ := http.NewRequestWithContext(context.Background(), http.MethodGet, allURL, nil)
	req2.Header.Set("Referer", s.cfg.BaseURL+"/")
	resp2, err := s.client.Do(req2)
	if err != nil {
		return nil, err
	}
	defer resp2.Body.Close()
	body2, _ := io.ReadAll(resp2.Body)
	var vr2 viewerResponse
	if err := json.Unmarshal(body2, &vr2); err != nil {
		return nil, err
	}
	pages := make([]source.Page, len(vr2.Result))
	for i, p := range vr2.Result {
		imgURL := p.ImageURL
		if p.Scramble != "" {
			imgURL += "#" + p.Scramble
		}
		pages[i] = source.Page{Index: p.Sort, ImageURL: imgURL}
	}
	return pages, nil
}

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