// Package multichan implements the MultiChan manga base.
// Russian manga site; pages extracted from fullimg JSON array in HTML source.
package multichan

import (
	"context"
	"fmt"
	"io"
	"net/http"
	"strings"
	"time"

	"github.com/PuerkitoBio/goquery"

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

type Config struct {
	Name    string
	BaseURL string
	Lang    string
}

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

func New(cfg Config) *Source {
	c := flare.NewClient(flare.WithRateLimit(2, 3))
	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("multichan: HTTP %d", resp.StatusCode)
	}
	return goquery.NewDocumentFromReader(resp.Body)
}

func (s *Source) getRaw(ctx context.Context, rawURL string) (string, error) {
	req, err := http.NewRequestWithContext(ctx, http.MethodGet, rawURL, nil)
	if err != nil {
		return "", err
	}
	req.Header.Set("Referer", s.cfg.BaseURL)
	resp, err := s.client.Do(req)
	if err != nil {
		return "", err
	}
	defer resp.Body.Close()
	body, _ := io.ReadAll(resp.Body)
	return string(body), nil
}

func mangaFromElement(el *goquery.Selection, baseURL string) source.SManga {
	m := source.SManga{}
	m.Title = strings.TrimSpace(el.AttrOr("title", ""))
	el.Find("a").First().Each(func(_ int, a *goquery.Selection) {
		m.URL = a.AttrOr("href", "")
		if m.Title == "" {
			m.Title = strings.TrimSpace(a.Text())
		}
	})
	if img := el.Find("img").First(); img.Length() > 0 {
		m.ThumbnailURL = util.AbsURL(baseURL, img.AttrOr("src", ""))
	}
	return m
}

func (s *Source) parseMangaList(doc *goquery.Document, nextSel string) source.MangasPage {
	var mangas []source.SManga
	doc.Find("div.content_row").Each(func(_ int, el *goquery.Selection) {
		m := mangaFromElement(el, s.cfg.BaseURL)
		if m.URL != "" && m.Title != "" {
			mangas = append(mangas, m)
		}
	})
	hasNext := doc.Find(nextSel).Length() > 0
	return source.MangasPage{Mangas: mangas, HasNextPage: hasNext}
}

func (s *Source) GetPopularManga(page int) (source.MangasPage, error) {
	doc, err := s.get(context.Background(), fmt.Sprintf("%s/mostfavorites?offset=%d", s.base(), 20*(page-1)))
	if err != nil {
		return source.MangasPage{}, err
	}
	return s.parseMangaList(doc, "a:contains(Вперед)"), nil
}

func (s *Source) GetLatestUpdates(page int) (source.MangasPage, error) {
	doc, err := s.get(context.Background(), fmt.Sprintf("%s/manga/new?offset=%d", s.base(), 20*(page-1)))
	if err != nil {
		return source.MangasPage{}, err
	}
	return s.parseMangaList(doc, "a:contains(Вперед)"), nil
}

func (s *Source) GetSearchManga(page int, query string, filters []source.Filter) (source.MangasPage, error) {
	u := fmt.Sprintf("%s/?do=search&subaction=search&story=%s&search_start=%d", s.base(), query, page)
	doc, err := s.get(context.Background(), u)
	if err != nil {
		return source.MangasPage{}, err
	}
	return s.parseMangaList(doc, "a:contains(Далее)"), 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 from page title (strip " » ..." suffix)
	pageTitle := doc.Find("title").Text()
	if idx := strings.Index(pageTitle, " »"); idx > 0 {
		result.Title = strings.TrimSpace(pageTitle[:idx])
	} else {
		result.Title = strings.TrimSpace(pageTitle)
	}
	if result.Title == "" {
		result.Title = manga.Title
	}

	infoEl := doc.Find("#info_wrap tr, #info_wrap > div")
	result.Author = strings.TrimSpace(infoEl.Find(":contains(Автор) .item2").Text())

	rawCat := strings.ToLower(strings.TrimSpace(infoEl.Find(":contains(Тип) a").Text()))
	var tags []string
	if rawCat != "" {
		tags = append(tags, rawCat)
	}
	doc.Find(".sidetags ul a:last-child").Each(func(_ int, a *goquery.Selection) {
		if t := strings.TrimSpace(a.Text()); t != "" {
			tags = append(tags, t)
		}
	})
	result.Genre = strings.Join(tags, ", ")

	statusText := infoEl.Find(":contains(Загружено)").Text()
	switch {
	case strings.Contains(statusText, "перевод завершен"):
		result.Status = source.StatusCompleted
	case strings.Contains(statusText, "перевод продолжается"):
		result.Status = source.StatusOngoing
	default:
		result.Status = source.StatusUnknown
	}

	if desc := doc.Find("div#description").First(); desc.Length() > 0 {
		nodes := desc.Contents()
		nodes.Each(func(_ int, n *goquery.Selection) {
			if goquery.NodeName(n) == "#text" {
				if t := strings.TrimSpace(n.Text()); t != "" {
					result.Description = t
				}
			}
		})
	}

	if img := doc.Find("img#cover").First(); img.Length() > 0 {
		result.ThumbnailURL = util.AbsURL(s.cfg.BaseURL, img.AttrOr("src", ""))
	}
	return result, nil
}

func (s *Source) GetChapterList(manga source.SManga) ([]source.SChapter, error) {
	doc, err := s.get(context.Background(), util.AbsURL(s.cfg.BaseURL, manga.URL))
	if err != nil {
		return nil, err
	}
	var chapters []source.SChapter
	// Selector: table.table_cha tr (skip first 2 header rows)
	doc.Find("table.table_cha tr").Each(func(i int, el *goquery.Selection) {
		if i <= 1 {
			return // skip headers
		}
		a := el.Find("a").First()
		if a.Length() == 0 {
			return
		}
		href := a.AttrOr("href", "")
		if href == "" {
			return
		}
		// Make URL relative
		u := strings.TrimPrefix(href, s.base())
		if !strings.HasPrefix(u, "/") {
			u = "/" + u
		}

		dateStr := strings.TrimSpace(el.Find("div.date").First().Text())
		chapters = append(chapters, source.SChapter{
			URL:        u,
			Name:       strings.TrimSpace(a.Text()),
			DateUpload: parseDate(dateStr),
		})
	})
	return chapters, nil
}

func parseDate(s string) int64 {
	t, err := time.Parse("2006-01-02", s)
	if err != nil {
		return 0
	}
	return t.UnixMilli()
}

func (s *Source) GetPageList(chapter source.SChapter) ([]source.Page, error) {
	html, err := s.getRaw(context.Background(), util.AbsURL(s.cfg.BaseURL, chapter.URL))
	if err != nil {
		return nil, err
	}

	// Extract fullimg":[...] from raw HTML
	const marker = `fullimg":[`
	start := strings.Index(html, marker)
	if start < 0 {
		return nil, fmt.Errorf("multichan: fullimg array not found")
	}
	start += len(marker)
	end := strings.Index(html[start:], ",]")
	if end < 0 {
		return nil, fmt.Errorf("multichan: fullimg array end not found")
	}
	rawURLs := html[start : start+end]
	rawURLs = strings.ReplaceAll(rawURLs, `"`, "")

	var pages []source.Page
	for i, u := range strings.Split(rawURLs, ",") {
		u = strings.TrimSpace(u)
		if u != "" {
			pages = append(pages, source.Page{Index: i, ImageURL: 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 }