package fa

import (
	"fmt"
	"strconv"
	"strings"

	"github.com/PuerkitoBio/goquery"

	"git.anthrove.art/public/go-fa-api/internal/urls"
)

// parseSubmission lifts a [Submission] out of a /view/{id}/ document. The
// selectors target FA's beta theme as captured in testdata/html/submission.html.
//
// FA's beta page renders submission metadata as two parallel <span> columns
// inside .submission-content-stats labels in the first, values in the
// second so this parser pairs them up positionally rather than scanning
// label-then-value rows.
func parseSubmission(id SubmissionID, doc *goquery.Document) (*Submission, error) {
	s := &Submission{ID: id}

	// Resolve the canonical ID from the og:url meta tag when caller passed 0
	// (e.g. the real-fixture test). Lets the parser stand on its own.
	if s.ID == 0 {
		if og := trimAttr(doc.Find(`meta[property="og:url"]`).First(), "content"); og != "" {
			if n := extractIntFromHref(og); n > 0 {
				s.ID = SubmissionID(n)
			}
		}
	}

	// Author scoping: there can be multiple .iconusername references on the
	// page (e.g. inside the description). The submission's true author lives
	// inside .submission-description-artist.
	authorBox := doc.Find("div.submission-description-artist").First()

	// Title.
	s.Title = strings.TrimSpace(authorBox.Find("div.submission-title h2").First().Text())
	if s.Title == "" {
		s.Title = strings.TrimSpace(doc.Find("div.submission-title h2").First().Text())
	}
	if s.Title == "" {
		// Surface what FA actually served so the caller can tell the
		// difference between a CF challenge, an SFW guard, a deleted
		// submission, and a real markup-drift bug.
		pageTitle := strings.TrimSpace(doc.Find("title").First().Text())
		return nil, fmt.Errorf("%w: submission %d: missing title (page <title>=%q)",
			ErrParse, id, pageTitle)
	}

	// Author.
	if authorBox.Length() > 0 {
		avatarLink := authorBox.Find("a[href^='/user/'] img").First()
		nameSpan := authorBox.Find(".c-usernameBlockSimple__displayName").First()
		s.Author = UserRef{
			DisplayName: trimText(nameSpan),
			AvatarURL:   urls.AbsoluteCDN(trimAttr(avatarLink, "src")),
		}
		// Prefer the title attr (URL-safe login) when present; fall back to href.
		if t := strings.TrimSpace(trimAttr(nameSpan, "title")); t != "" {
			s.Author.Name = strings.ToLower(t)
		}
		if s.Author.Name == "" {
			href, _ := authorBox.Find("a[href^='/user/']").First().Attr("href")
			if parts := strings.Split(strings.Trim(href, "/"), "/"); len(parts) >= 2 {
				s.Author.Name = strings.ToLower(parts[1])
			}
		}
	}

	// Posted date popup_date carries authoritative data-time.
	s.PostedAt = parsePopupDate(authorBox.Find("span.popup_date").First())
	if s.PostedAt.IsZero() {
		s.PostedAt = parsePopupDate(doc.Find("span.popup_date").First())
	}

	// Rating div with class c-contentRating--{general,mature,adult} in the
	// page stats panel; fall back to legacy .rating-box for older markup.
	doc.Find("div.submission-page-stats div[class*='c-contentRating--']").EachWithBreak(func(_ int, sel *goquery.Selection) bool {
		s.Rating = ParseRating(trimText(sel))
		return false
	})
	if s.Rating == "" {
		doc.Find(".rating-box").EachWithBreak(func(_ int, sel *goquery.Selection) bool {
			s.Rating = ParseRating(trimText(sel))
			return false
		})
	}

	// Stats .submission-page-stats > div[title=...] each holds <div>N</div>
	// <div class="highlight">Label</div>.
	doc.Find("div.submission-page-stats > div[title]").Each(func(_ int, sel *goquery.Selection) {
		title := strings.ToLower(trimAttr(sel, "title"))
		val := parseStatNumber(trimText(sel.Find("div").First()))
		switch title {
		case "views":
			s.Stats.Views = val
		case "favorites":
			s.Stats.Favorites = val
		case "comments":
			s.Stats.Comments = val
		}
	})

	// Category / Theme / Species / Resolution / File Size are two parallel
	// span columns inside .submission-content-stats. Pair them up by index.
	statsBlock := doc.Find("div.submission-content-stats").First()
	if statsBlock.Length() > 0 {
		var labels []string
		statsBlock.Find("span.highlight > span").Each(func(_ int, sel *goquery.Selection) {
			labels = append(labels, strings.ToLower(strings.TrimSpace(sel.Text())))
		})
		var values []string
		statsBlock.ChildrenFiltered("span").Each(func(_ int, sel *goquery.Selection) {
			if class, _ := sel.Attr("class"); strings.Contains(class, "highlight") {
				return // skip the labels column
			}
			sel.ChildrenFiltered("span").Each(func(_ int, inner *goquery.Selection) {
				values = append(values, strings.TrimSpace(inner.Text()))
			})
		})
		for i := 0; i < len(labels) && i < len(values); i++ {
			switch labels[i] {
			case "category":
				s.Category = Category(values[i])
			case "type", "theme":
				s.Type = Type(values[i])
			case "species":
				s.Species = Species(values[i])
			case "gender":
				s.Gender = Gender(values[i])
			case "resolution":
				if w, h, ok := parseResolution(values[i]); ok {
					s.Width, s.Height = w, h
				}
			}
		}
	}

	// Description section.submission-description holds the body inside
	// .section-body > .submission-description-text.
	descBody := doc.Find("section.submission-description div.submission-description-text").First()
	if descBody.Length() == 0 {
		descBody = doc.Find("div.submission-description").First()
	}
	s.Description = htmlOf(descBody)
	s.DescriptionText = strings.TrimSpace(descBody.Text())

	// Tags anchors inside .submission-tags whose href targets the search.
	// Tag-block helper anchors and invalid system tags are filtered out.
	doc.Find("div.submission-tags span.tags a[href*='/search/']").Each(func(_ int, a *goquery.Selection) {
		t := strings.TrimSpace(a.Text())
		if t != "" {
			s.Tags = append(s.Tags, t)
		}
	})

	// File URL FA renders a "Download" button in #submission-options that
	// links to the canonical file for *every* submission type. For visual
	// art it equals the #submissionImg source; for stories and music it's
	// the only correct source, because FA injects a generated thumbnail
	// (e.g. ".thumbnail.<name>.docx.gif") into #submissionImg there. So the
	// Download button is authoritative; #submissionImg is only a fallback.
	doc.Find("div#submission-options a").EachWithBreak(func(_ int, a *goquery.Selection) bool {
		if strings.EqualFold(trimText(a), "download") {
			s.FileURL = urls.AbsoluteCDN(trimAttr(a, "href"))
			return false
		}
		return true
	})

	// #submissionImg holds the inline image for visual art, or a generated
	// thumbnail for non-image submissions. It always supplies ThumbURL, but
	// only supplies FileURL when no Download button was found.
	img := doc.Find("#submissionImg").First()
	if img.Length() > 0 {
		s.ThumbURL = urls.AbsoluteCDN(firstNonEmpty(
			trimAttr(img, "data-preview-src"),
			trimAttr(img, "src"),
		))
		if s.FileURL == "" {
			s.FileURL = urls.AbsoluteCDN(firstNonEmpty(
				trimAttr(img, "data-fullview-src"),
				trimAttr(img, "src"),
			))
		}
		// Dimensions also live in width/height attrs on some pages.
		if w, err := strconv.Atoi(trimAttr(img, "data-fullview-width")); err == nil {
			s.Width = w
		}
		if h, err := strconv.Atoi(trimAttr(img, "data-fullview-height")); err == nil {
			s.Height = h
		}
	}
	// Legacy fallback for older themes that predate #submission-options.
	if s.FileURL == "" {
		dl := doc.Find("div.submission-controls-upper a[href*='/d.furaffinity.net/'], div.download a, a.download-logged-in").First()
		s.FileURL = urls.AbsoluteCDN(trimAttr(dl, "href"))
	}

	// Prev / Next (FA's minigallery-navigation: "Newer" / "Older").
	doc.Find("div.minigallery-navigation a").Each(func(_ int, a *goquery.Selection) {
		href, _ := a.Attr("href")
		text := strings.ToLower(trimText(a))
		id := SubmissionID(extractIntFromHref(href))
		if id == 0 {
			return
		}
		switch {
		case strings.Contains(text, "newer"):
			// "Newer" goes to a more recent submission surface as Prev so
			// callers walking a gallery can call client.GetSubmission(s.Prev)
			// to step toward the newest.
			s.Prev = id
		case strings.Contains(text, "older"):
			s.Next = id
		}
	})
	// Legacy fallback for older themes that still use favorite-nav.
	if s.Prev == 0 && s.Next == 0 {
		doc.Find("div.favorite-nav a, .submission-nav a").Each(func(_ int, a *goquery.Selection) {
			href, _ := a.Attr("href")
			text := strings.ToLower(trimText(a))
			id := SubmissionID(extractIntFromHref(href))
			if id == 0 {
				return
			}
			switch {
			case strings.Contains(text, "prev"):
				s.Prev = id
			case strings.Contains(text, "next"):
				s.Next = id
			}
		})
	}

	// Favorite state FA renders exactly one of the "+Fav" / "−Fav" anchors
	// for an authenticated viewer; the "−Fav" (/unfav/) link means this
	// submission is currently favorited. findFavLinks (actions.go) already
	// scrapes both. An anonymous fetch shows neither, leaving Favorited false.
	if _, unfav := findFavLinks(doc, int64(s.ID)); unfav != "" {
		s.Favorited = true
	}

	return s, nil
}

// parseResolution splits a "2071 x 1779" string into width and height ints.
// Returns ok=false on any malformed input so callers can leave Width/Height
// at zero.
func parseResolution(s string) (w, h int, ok bool) {
	parts := strings.Split(s, "x")
	if len(parts) != 2 {
		return 0, 0, false
	}
	wn, err := strconv.Atoi(strings.TrimSpace(parts[0]))
	if err != nil {
		return 0, 0, false
	}
	hn, err := strconv.Atoi(strings.TrimSpace(parts[1]))
	if err != nil {
		return 0, 0, false
	}
	return wn, hn, true
}