// Package initmanga implements the InitManga manga base.
// HTML scraping (UIkit-based); pages use AES-256-CBC with PBKDF2-SHA512 key derivation.
package initmanga

import (
	"context"
	"crypto/aes"
	"crypto/cipher"
	"crypto/sha512"
	"encoding/base64"
	"encoding/hex"
	"encoding/json"
	"fmt"
	"net/http"
	"regexp"
	"strings"

	"github.com/PuerkitoBio/goquery"
	"golang.org/x/crypto/pbkdf2"

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

type Config struct {
	Name           string
	BaseURL        string
	Lang           string
	PopularUrlSlug string // e.g. "manga" or "seri"
	LatestUrlSlug  string // e.g. "manga"
}

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

func New(cfg Config) *Source {
	if cfg.PopularUrlSlug == "" {
		cfg.PopularUrlSlug = "seri"
	}
	if cfg.LatestUrlSlug == "" {
		cfg.LatestUrlSlug = cfg.PopularUrlSlug
	}
	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("initmanga: HTTP %d", resp.StatusCode)
	}
	return goquery.NewDocumentFromReader(resp.Body)
}

const popularMangaSelector = "div.manga-item-grid > div.uk-panel.uk-position-relative, " +
	"div.manga-item-grid > div.uk-panel:not(.manga-item-ranking):not(.user-item-info), " +
	"div.uk-panel.uk-position-relative, " +
	"div.uk-panel:not(.manga-item-ranking):not(.user-item-info)"

const nextPageSelector = "head link[rel=next], link[rel=next], " +
	"ul.uk-pagination li:not(.uk-disabled) a[aria-label=\"Sonraki sayfa\"], " +
	"a:contains(Sonraki sayfa), a:contains(Next page), a.next"

func mangaFromElement(el *goquery.Selection, baseURL string) source.SManga {
	m := source.SManga{}
	link := el.Find("h3 a, div.uk-overflow-hidden a").First()
	if link.Length() == 0 {
		link = el.Find("a").First()
	}
	m.URL, _ = link.Attr("href")
	m.Title = strings.TrimSpace(el.Find("h3").Text())
	if m.Title == "" {
		clone := el.Find("a").Clone()
		clone.Find("span, small").Remove()
		m.Title = strings.TrimSpace(clone.Text())
	}
	imgEl := el.Find("img")
	if src := imgEl.AttrOr("data-src", ""); src != "" {
		m.ThumbnailURL = util.AbsURL(baseURL, src)
	} else if src := imgEl.AttrOr("src", ""); src != "" {
		m.ThumbnailURL = util.AbsURL(baseURL, src)
	}
	return m
}

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

func (s *Source) fetchListing(slug string, page int) (source.MangasPage, error) {
	var u string
	if page == 1 {
		u = fmt.Sprintf("%s/%s/", s.base(), slug)
	} else {
		u = fmt.Sprintf("%s/%s/page/%d/", s.base(), slug, page)
	}
	doc, err := s.get(context.Background(), u)
	if err != nil {
		return source.MangasPage{}, err
	}
	return s.parsePage(doc), nil
}

func (s *Source) GetPopularManga(page int) (source.MangasPage, error) {
	return s.fetchListing(s.cfg.PopularUrlSlug, page)
}

func (s *Source) GetLatestUpdates(page int) (source.MangasPage, error) {
	return s.fetchListing(s.cfg.LatestUrlSlug, page)
}

type searchDTO struct {
	Title *string `json:"title"`
	URL   *string `json:"url"`
	Thumb *string `json:"thumb"`
}

func (s *Source) GetSearchManga(page int, query string, filters []source.Filter) (source.MangasPage, error) {
	u := fmt.Sprintf("%s/wp-json/initlise/v1/search?term=%s&page=%d", s.base(), query, page)
	req, err := http.NewRequestWithContext(context.Background(), http.MethodGet, u, nil)
	if err != nil {
		return source.MangasPage{}, err
	}
	req.Header.Set("Referer", s.cfg.BaseURL+"/")
	resp, err := s.client.Do(req)
	if err != nil {
		return source.MangasPage{}, err
	}
	defer resp.Body.Close()

	body := make([]byte, 0, 4096)
	buf := make([]byte, 4096)
	for {
		n, readErr := resp.Body.Read(buf)
		body = append(body, buf[:n]...)
		if readErr != nil {
			break
		}
	}

	bodyStr := strings.TrimSpace(string(body))
	if strings.HasPrefix(bodyStr, "<") {
		// HTML response — parse as list page
		doc, err := goquery.NewDocumentFromReader(strings.NewReader(bodyStr))
		if err != nil {
			return source.MangasPage{}, err
		}
		return s.parsePage(doc), nil
	}

	var dtos []searchDTO
	if err := json.Unmarshal(body, &dtos); err != nil {
		return source.MangasPage{}, err
	}
	var mangas []source.SManga
	for _, dto := range dtos {
		m := source.SManga{}
		if dto.Title != nil {
			m.Title = strings.TrimSpace(*dto.Title)
		}
		if dto.URL != nil {
			m.URL = *dto.URL
		}
		if dto.Thumb != nil {
			m.ThumbnailURL = *dto.Thumb
		}
		if m.URL != "" && m.Title != "" {
			mangas = append(mangas, m)
		}
	}
	return source.MangasPage{Mangas: mangas, HasNextPage: false}, 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}

	descClone := doc.Find("div#manga-description").Clone()
	descClone.Find("a, span").Remove()
	result.Description = strings.TrimSpace(descClone.Text())
	if altName := strings.TrimSpace(doc.Find("span#comic-othername").Text()); altName != "" {
		result.Description += "\n\nAlternatif Başlık: " + altName
	}

	var genres []string
	doc.Find("span.uk-label-contest").Each(func(_ int, el *goquery.Selection) {
		t := strings.TrimPrefix(strings.TrimSpace(el.Text()), "#")
		if t != "" {
			genres = append(genres, t)
		}
	})
	if len(genres) == 0 {
		doc.Find("div#genre-tags a").Each(func(_ int, el *goquery.Selection) {
			if t := strings.TrimSpace(el.Text()); t != "" {
				genres = append(genres, t)
			}
		})
	}
	result.Genre = strings.Join(genres, ", ")

	result.Author = strings.TrimSpace(doc.Find("div.manga-info-details a").FilterFunction(func(_ int, s *goquery.Selection) bool {
		parent, _ := s.Parent().Html()
		return strings.Contains(parent, "Yazar")
	}).Text())
	if result.Author == "" {
		t := doc.Find("div.manga-info-details").FilterFunction(func(_ int, el *goquery.Selection) bool {
			return strings.Contains(el.Text(), "Yazar")
		}).Text()
		result.Author = strings.TrimSpace(strings.SplitN(strings.SplitN(t, "Yazar:", 2)[len(strings.SplitN(t, "Yazar:", 2))-1], "Çizer:", 2)[0])
	}

	statusText := strings.ToLower(strings.TrimSpace(
		doc.Find("span#manga-status, div.manga-status-ribbons span.manga-status-ribbon__text").First().Text()))
	if statusText == "" {
		t := doc.Find("div.manga-info-details").FilterFunction(func(_ int, el *goquery.Selection) bool {
			return strings.Contains(el.Text(), "Durum")
		}).Text()
		statusText = strings.ToLower(strings.TrimSpace(strings.SplitN(t, "Durum:", 2)[len(strings.SplitN(t, "Durum:", 2))-1]))
	}
	switch {
	case strings.Contains(statusText, "güncel") || strings.Contains(statusText, "devam") || strings.Contains(statusText, "ongoing"):
		result.Status = source.StatusOngoing
	case strings.Contains(statusText, "tamamland") || strings.Contains(statusText, "bitti") || strings.Contains(statusText, "completed"):
		result.Status = source.StatusCompleted
	case strings.Contains(statusText, "ara ver") || strings.Contains(statusText, "sezon") || strings.Contains(statusText, "hiatus"):
		result.Status = source.StatusHiatus
	case strings.Contains(statusText, "bırakıldı") || strings.Contains(statusText, "iptal") || strings.Contains(statusText, "dropped"):
		result.Status = source.StatusCancelled
	default:
		result.Status = source.StatusUnknown
	}

	for _, sel := range []string{"div.story-cover-wrap img", "div.single-thumb img", "a.story-cover img"} {
		if img := doc.Find(sel).First(); img.Length() > 0 {
			if src := img.AttrOr("abs:src", img.AttrOr("src", "")); src != "" {
				result.ThumbnailURL = util.AbsURL(s.cfg.BaseURL, src)
				break
			}
		}
	}

	title := strings.TrimSpace(doc.Find("h1").First().Text())
	if title == "" {
		title = strings.TrimSpace(doc.Find("h2.uk-h3").First().Text())
	}
	result.Title = title
	if result.Title == "" {
		result.Title = manga.Title
	}
	return result, nil
}

func (s *Source) GetChapterList(manga source.SManga) ([]source.SChapter, error) {
	mangaURL := util.AbsURL(s.cfg.BaseURL, manga.URL)
	doc, err := s.get(context.Background(), mangaURL)
	if err != nil {
		return nil, err
	}
	var chapters []source.SChapter
	chapterFromEl := func(el *goquery.Selection) source.SChapter {
		ch := source.SChapter{}
		el.Find("a").First().Each(func(_ int, a *goquery.Selection) {
			ch.URL, _ = a.Attr("href")
		})
		rawName := strings.TrimSpace(el.Find("h3").Text())
		ch.Name = strings.TrimSpace(lastPart(rawName, "–", "-"))
		if ch.Name == "" {
			ch.Name = rawName
		}
		dateStr := el.Find("time").AttrOr("datetime", "")
		ch.DateUpload = util.ParseAbsoluteDate(dateStr, "2006-01-02T15:04:05")
		return ch
	}

	doc.Find("div.chapter-item").Each(func(_ int, el *goquery.Selection) {
		if ch := chapterFromEl(el); ch.URL != "" {
			chapters = append(chapters, ch)
		}
	})

	// paginate
	page := 2
	for {
		paginURL := strings.TrimRight(mangaURL, "/") + "/bolum/page/" + fmt.Sprintf("%d", page) + "/"
		nextDoc, err := s.get(context.Background(), paginURL)
		if err != nil {
			break
		}
		items := nextDoc.Find("div.chapter-item")
		if items.Length() == 0 {
			break
		}
		items.Each(func(_ int, el *goquery.Selection) {
			if ch := chapterFromEl(el); ch.URL != "" {
				chapters = append(chapters, ch)
			}
		})
		if nextDoc.Find("ul.uk-pagination a[href^=http]").Length() == 0 {
			break
		}
		page++
	}
	return chapters, nil
}

func lastPart(s string, seps ...string) string {
	for _, sep := range seps {
		if idx := strings.LastIndex(s, sep); idx >= 0 {
			return s[idx+len(sep):]
		}
	}
	return s
}

// Regexes for page decryption
var (
	reEncryptedData  = regexp.MustCompile(`(?s)var\s+InitMangaEncryptedChapter\s*=\s*(\{.*?\});`)
	reInitMangaChunk = regexp.MustCompile(`(?s)InitMangaEncryptedChapter\s*=\s*(\{.*?\})`)
	reDecryptKey     = regexp.MustCompile(`["']?decryption_key["']?\s*[:=]\s*["']([^"']+)["']`)
	reSmartKey       = regexp.MustCompile(`(?s)InitMangaData[\s\S]*?decryption_key["']?\s*[:=]\s*["']([^"']+)["']`)
)

type encryptedChapter struct {
	Ciphertext string `json:"ciphertext"`
	IV         string `json:"iv"`
	Salt       string `json:"salt"`
}

func decryptWithPassphrase(ciphertextB64, passphrase, saltHex, ivHex string) (string, error) {
	salt, err := hex.DecodeString(saltHex)
	if err != nil {
		return "", err
	}
	iv, err := hex.DecodeString(ivHex)
	if err != nil {
		return "", err
	}
	ct, err := base64.StdEncoding.DecodeString(ciphertextB64)
	if err != nil {
		return "", err
	}
	key := pbkdf2.Key([]byte(passphrase), salt, 999, 32, sha512.New)
	block, err := aes.NewCipher(key)
	if err != nil {
		return "", err
	}
	if len(ct)%aes.BlockSize != 0 {
		return "", fmt.Errorf("initmanga: ciphertext not block-aligned")
	}
	mode := cipher.NewCBCDecrypter(block, iv)
	mode.CryptBlocks(ct, ct)
	// PKCS5 unpad
	if len(ct) == 0 {
		return "", fmt.Errorf("initmanga: empty decrypted block")
	}
	padLen := int(ct[len(ct)-1])
	if padLen == 0 || padLen > aes.BlockSize || padLen > len(ct) {
		return "", fmt.Errorf("initmanga: invalid padding %d", padLen)
	}
	return string(ct[:len(ct)-padLen]), 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
	}
	html, _ := doc.Html()

	// --- Path 1: script[src*=dmFyIElua] base64-encoded data ---
	var encObj encryptedChapter
	doc.Find("script[src]").Each(func(_ int, el *goquery.Selection) {
		if encObj.Ciphertext != "" {
			return
		}
		src := el.AttrOr("src", "")
		if !strings.Contains(src, "dmFyIElua") {
			return
		}
		b64 := strings.TrimSuffix(
			strings.SplitN(src, "base64,", 2)[len(strings.SplitN(src, "base64,", 2))-1], "\"")
		raw, err := base64.StdEncoding.DecodeString(b64)
		if err != nil {
			return
		}
		decoded := string(raw)
		// extract InitMangaEncryptedChapter JSON
		jsonStr := ""
		if m := reInitMangaChunk.FindStringSubmatch(decoded); len(m) > 1 {
			jsonStr = m[1]
		} else if idx := strings.Index(decoded, "InitMangaEncryptedChapter="); idx >= 0 {
			jsonStr = strings.SplitN(decoded[idx+len("InitMangaEncryptedChapter="):], ";", 2)[0]
		}
		if jsonStr == "" {
			return
		}
		json.Unmarshal([]byte(jsonStr), &encObj) //nolint:errcheck
	})

	// --- Path 2: inline JS var InitMangaEncryptedChapter ---
	if encObj.Ciphertext == "" {
		if m := reEncryptedData.FindStringSubmatch(html); len(m) > 1 {
			json.Unmarshal([]byte(m[1]), &encObj) //nolint:errcheck
		}
	}

	if encObj.Ciphertext != "" {
		// Find decryption key
		rawKey := ""
		// Try script#init-main-js-extra src (base64-encoded)
		doc.Find("script#init-main-js-extra[src]").First().Each(func(_ int, el *goquery.Selection) {
			src := el.AttrOr("src", "")
			if !strings.Contains(src, "base64,") {
				return
			}
			b64 := strings.SplitN(src, "base64,", 2)[1]
			b64 = strings.TrimSuffix(b64, "\"")
			if raw, err := base64.StdEncoding.DecodeString(b64); err == nil {
				if m := reDecryptKey.FindStringSubmatch(string(raw)); len(m) > 1 {
					rawKey = m[1]
				}
			}
		})
		if rawKey == "" {
			if m := reSmartKey.FindStringSubmatch(html); len(m) > 1 {
				rawKey = m[1]
			}
		}
		if rawKey != "" {
			passBytes, err := base64.StdEncoding.DecodeString(rawKey)
			if err == nil {
				passphrase := string(passBytes)
				if content, err := decryptWithPassphrase(encObj.Ciphertext, passphrase, encObj.Salt, encObj.IV); err == nil {
					return parseDecryptedPages(content, s.cfg.BaseURL), nil
				}
			}
		}
	}

	// Fallback: plain img tags
	return fallbackPages(doc, s.cfg.BaseURL), nil
}

func parseDecryptedPages(content, baseURL string) []source.Page {
	trimmed := strings.TrimSpace(content)
	if strings.HasPrefix(trimmed, "<") {
		doc, err := goquery.NewDocumentFromReader(strings.NewReader(trimmed))
		if err != nil {
			return nil
		}
		var pages []source.Page
		doc.Find("img").Each(func(i int, img *goquery.Selection) {
			src := img.AttrOr("data-src", img.AttrOr("src", ""))
			if src == "" || strings.HasPrefix(src, "data:") {
				return
			}
			pages = append(pages, source.Page{Index: i, ImageURL: util.AbsURL(baseURL, src)})
		})
		return pages
	}
	// Try JSON array of URLs
	var srcs []string
	if err := json.Unmarshal([]byte(trimmed), &srcs); err == nil {
		pages := make([]source.Page, 0, len(srcs))
		for i, src := range srcs {
			switch {
			case strings.HasPrefix(src, "//"):
				src = "https:" + src
			case strings.HasPrefix(src, "/"):
				src = strings.TrimRight(baseURL, "/") + src
			}
			pages = append(pages, source.Page{Index: i, ImageURL: src})
		}
		return pages
	}
	return nil
}

func fallbackPages(doc *goquery.Document, baseURL string) []source.Page {
	var pages []source.Page
	doc.Find("div#chapter-content img[src]").Each(func(i int, img *goquery.Selection) {
		src := img.AttrOr("src", img.AttrOr("data-src", ""))
		if src != "" {
			pages = append(pages, source.Page{Index: i, ImageURL: util.AbsURL(baseURL, src)})
		}
	})
	return pages
}

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