import React, { useCallback, useEffect, useMemo, useRef, useState } from "react";
import { useNavigate } from "react-router-dom";
import { useTranslation } from "react-i18n-lite";
import { booksApi } from "../api/books";
import type { BookListItem, BookSearchParams } from "../types/book";
import { useAuth } from "../context/AuthContext";
import { deriveReadingStatus, normalizeProgressPercent } from "../utils/libraryStatus";
import { FinishedBooksShelf } from "../components/library/FinishedBooksShelf";
import { LibraryBookCard } from "../components/library/LibraryBookCard";
import { useDebounce } from "../hooks/useDebounce";
import { useVoiceSearch } from "../hooks/useVoiceSearch";
import { useMediaQuery, BREAKPOINTS } from "../hooks/useMediaQuery";
import { SearchSuggestions } from "../components/search/SearchSuggestions";
import { BookContextMenu } from "../components/BookContextMenu";

interface FilterState {
  genre: string;
  author: string;
  reading_status: string;
}

type LibraryBook = BookListItem & {
  format: string;
  progressPercent: number | null;
};

interface ContextMenuState {
  book: LibraryBook;
  x: number;
  y: number;
}

/** WCAG 2.1 minimum touch target */
const TOUCH_TARGET: React.CSSProperties = {
  minHeight: 44,
  minWidth: 44,
  display: "inline-flex",
  alignItems: "center",
  justifyContent: "center",
};

export function LibraryPage() {
  const navigate = useNavigate();
  const { logout } = useAuth();
  const { t } = useTranslation();

  const [books, setBooks] = useState<LibraryBook[]>([]);
  const [loading, setLoading] = useState(true);
  const [error, setError] = useState<string | null>(null);
  const [readerNotice, setReaderNotice] = useState<string | null>(null);
  const [searchQuery, setSearchQuery] = useState("");
  const [filters, setFilters] = useState<FilterState>({ genre: "", author: "", reading_status: "" });
  const [genres, setGenres] = useState<string[]>([]);
  const [authors, setAuthors] = useState<string[]>([]);
  const [totalCount, setTotalCount] = useState(0);
  const [showFilters, setShowFilters] = useState(false);
  const [showSuggestions, setShowSuggestions] = useState(false);
  const [contextMenu, setContextMenu] = useState<ContextMenuState | null>(null);

  const debouncedSearch = useDebounce(searchQuery, 300);
  const loadedRef = useRef(false);
  const searchInputRef = useRef<HTMLInputElement>(null);
  const isMobile = useMediaQuery(BREAKPOINTS.md);

  // Voice search
  const voiceSearch = useVoiceSearch();

  // Sync voice transcript into search input
  useEffect(() => {
    if (voiceSearch.transcript && !voiceSearch.isListening) {
      setSearchQuery(voiceSearch.transcript);
      setShowSuggestions(false);
    }
  }, [voiceSearch.transcript, voiceSearch.isListening]);

  // Load filter options once
  useEffect(() => {
    if (loadedRef.current) return;
    loadedRef.current = true;
    void Promise.all([booksApi.getGenres(), booksApi.getAuthors()]).then(
      ([genreList, authorList]) => {
        setGenres(genreList);
        setAuthors(authorList);
      },
      () => {
        // Filters degrade gracefully if discovery endpoints fail
      },
    );
  }, []);

  const loadBooks = useCallback(async (params: BookSearchParams) => {
    setLoading(true);
    setError(null);
    try {
      const ebooks = await booksApi.getEBooks();
      let items: LibraryBook[] = ebooks.map((e) => {
        const reading_status = deriveReadingStatus(e.progress, Boolean(e.started));
        const progressPercent = normalizeProgressPercent(e.progress, reading_status);
        return {
          id: e.id,
          title: e.title,
          author: e.author,
          genre: e.format ? e.format.toUpperCase() : "",
          format: e.format,
          reading_status,
          reading_status_display: reading_status,
          cover_image: e.cover_image,
          progressPercent,
        };
      });
      const query = params.q?.trim().toLowerCase();
      if (query) {
        items = items.filter(
          (b) =>
            b.title.toLowerCase().includes(query) ||
            b.author.toLowerCase().includes(query) ||
            b.genre.toLowerCase().includes(query),
        );
      }
      if (params.author) items = items.filter((b) => b.author === params.author);
      if (params.genre) items = items.filter((b) => b.genre === params.genre);
      if (params.reading_status) {
        items = items.filter((b) => b.reading_status === params.reading_status);
      }
      setBooks(items);
      setTotalCount(items.length);
    } catch (err) {
      setError(err instanceof Error ? err.message : t("library.loadFailed"));
      setBooks([]);
      setTotalCount(0);
    } finally {
      setLoading(false);
    }
  }, [t]);

  const statusFilterOptions = [
    { value: "", label: t("library.allStatuses") },
    { value: "want_to_read", label: t("library.readingStatus.wantToRead") },
    { value: "reading", label: t("library.readingStatus.reading") },
    { value: "finished", label: t("library.readingStatus.finished") },
    { value: "dnf", label: t("library.readingStatus.dnf") },
  ];

  // Reload when search or filters change
  useEffect(() => {
    const params: BookSearchParams = {};
    if (debouncedSearch) params.q = debouncedSearch;
    if (filters.genre) params.genre = filters.genre;
    if (filters.author) params.author = filters.author;
    if (filters.reading_status) params.reading_status = filters.reading_status;
    void loadBooks(params);
  }, [debouncedSearch, filters, loadBooks]);

  const handleFilterChange = (key: keyof FilterState, value: string) => {
    setFilters((prev: FilterState) => ({ ...prev, [key]: value }));
  };

  const clearAllFilters = () => {
    setSearchQuery("");
    setFilters({ genre: "", author: "", reading_status: "" });
    setShowFilters(false);
  };

  const hasActiveFilters = !!searchQuery || !!filters.genre || !!filters.author || !!filters.reading_status;

  const handleBookUpdated = useCallback((updated: LibraryBook) => {
    setBooks((prev) =>
      prev.map((b) =>
        b.id === updated.id
          ? {
              ...b,
              ...updated,
              progressPercent: updated.progressPercent ?? b.progressPercent,
              reading_status: updated.reading_status ?? b.reading_status,
            }
          : b,
      ),
    );
  }, []);

  const handleBookRemoved = useCallback((id: number) => {
    setBooks((prev) => prev.filter((b) => b.id !== id));
    setTotalCount((count) => Math.max(0, count - 1));
  }, []);

  const handleBookContextMenu = useCallback((e: React.MouseEvent, book: LibraryBook) => {
    e.preventDefault();
    e.stopPropagation();
    setContextMenu({ book, x: e.clientX, y: e.clientY });
  }, []);

  const activeBooks = useMemo(
    () => books.filter((b) => b.reading_status !== "finished"),
    [books],
  );
  const finishedBooks = useMemo(
    () => books.filter((b) => b.reading_status === "finished"),
    [books],
  );
  const shelfVisible = finishedBooks.length > 0;
  const finishedFilterActive = filters.reading_status === "finished";

  const openBook = useCallback(
    (book: LibraryBook) => {
      if (book.format === "pdf") {
        setReaderNotice(t("library.pdfNotice"));
        return;
      }
      navigate(`/read/${book.id}`);
    },
    [navigate, t],
  );

  const containerStyle: React.CSSProperties = {
    maxWidth: 960,
    margin: "0 auto",
    padding: isMobile ? 12 : 16,
    paddingBottom: shelfVisible ? (isMobile ? 72 : 68) : undefined,
    minHeight: "100vh",
    background: "#f8f9fa",
  };

  const headerStyle: React.CSSProperties = {
    display: "flex",
    justifyContent: "space-between",
    alignItems: "center",
    marginBottom: isMobile ? 12 : 20,
    padding: isMobile ? "12px 0" : "16px 0",
    borderBottom: "1px solid #e5e7eb",
    flexWrap: "wrap",
    gap: 8,
  };

  const searchContainerStyle: React.CSSProperties = {
    position: "relative",
    flex: 1,
  };

  return (
    <div style={containerStyle}>
      {/* Header */}
      <header style={headerStyle}>
        <div>
          <h1 style={{ fontSize: isMobile ? 20 : 24, fontWeight: 700, color: "#1f2937", margin: 0 }}>{t("library.title")}</h1>
          {!loading && (
            <p style={{ fontSize: 13, color: "#6b7280", marginTop: 2 }}>
              {activeBooks.length === 1
                ? t("library.bookCountOne", { count: String(activeBooks.length) })
                : t("library.bookCountMany", { count: String(activeBooks.length) })}
              {finishedBooks.length > 0 && (
                <span>
                  {" · "}
                  {t("library.finishedCountShort", { count: String(finishedBooks.length) })}
                </span>
              )}
            </p>
          )}
        </div>
        <div style={{ display: "flex", gap: isMobile ? 4 : 8, flexWrap: "wrap", alignItems: "center" }}>
          {isMobile ? (
            <>
              <button onClick={() => navigate("/add")} style={{ ...TOUCH_TARGET, fontSize: 20, background: "none", border: "none", cursor: "pointer", padding: 8 }} title={t("library.addBook")}>➕</button>
              <button onClick={() => navigate("/bookmarks-notes")} style={{ ...TOUCH_TARGET, fontSize: 20, background: "none", border: "none", cursor: "pointer", padding: 8 }} title={t("library.bookmarks")}>🔖</button>
              <button onClick={() => navigate("/settings")} style={{ ...TOUCH_TARGET, fontSize: 20, background: "none", border: "none", cursor: "pointer", padding: 8 }} title={t("library.settings")}>⚙️</button>
              <button onClick={logout} style={{ ...TOUCH_TARGET, fontSize: 20, background: "none", border: "none", cursor: "pointer", padding: 8 }} title={t("library.logout")}>🚪</button>
            </>
          ) : (
            <>
              <button onClick={() => navigate("/add")} className="btn">+ {t("library.addBook")}</button>
              <button onClick={() => navigate("/bookmarks-notes")} className="btn btn-secondary">{t("library.bookmarks")}</button>
              <button onClick={() => navigate("/settings")} className="btn btn-secondary">{t("library.settings")}</button>
              <button onClick={logout} className="btn btn-danger">{t("library.logout")}</button>
            </>
          )}
        </div>
      </header>

      {/* Search Bar */}
      <div style={{ marginBottom: 16 }}>
        <div style={{ display: "flex", gap: 8, alignItems: "center" }}>
          <div style={searchContainerStyle}>
            <input
              ref={searchInputRef}
              type="text"
              placeholder={t("library.searchPlaceholder")}
              value={searchQuery}
              onChange={(e) => {
                setSearchQuery(e.target.value);
                setShowSuggestions(true);
              }}
              onFocus={() => setShowSuggestions(true)}
              style={{
                width: "100%",
                padding: `12px 16px 12px ${voiceSearch.isSupported ? 44 : 44}px`,
                paddingRight: voiceSearch.isSupported ? 48 : 16,
                borderRadius: 10,
                border: "1px solid #e5e7eb",
                fontSize: isMobile ? 16 : 15,
                background: "#fff",
                outline: "none",
                boxSizing: "border-box",
                minHeight: 44,
              }}
            />
            <span style={{
              position: "absolute", left: 14, top: "50%", transform: "translateY(-50%)",
              fontSize: 18, color: "#9ca3af", pointerEvents: "none",
            }}>🔍</span>

            {/* Voice Search Button */}
            {voiceSearch.isSupported && (
              <button
                onClick={() => {
                  if (voiceSearch.isListening) {
                    voiceSearch.stopListening();
                  } else {
                    voiceSearch.startListening();
                  }
                }}
                style={{
                  position: "absolute",
                  right: 8,
                  top: "50%",
                  transform: "translateY(-50%)",
                  background: voiceSearch.isListening ? "#dc2626" : "transparent",
                  border: "none",
                  borderRadius: 8,
                  cursor: "pointer",
                  fontSize: 20,
                  padding: "8px 8px",
                  minWidth: 36,
                  minHeight: 36,
                  display: "flex",
                  alignItems: "center",
                  justifyContent: "center",
                  color: voiceSearch.isListening ? "#fff" : "#6b7280",
                  transition: "background 0.15s",
                }}
                title={voiceSearch.isListening ? t("library.voiceSearchStopTitle") : t("library.voiceSearchTitle")}
              >
                🎤
              </button>
            )}

            {/* Real-time Suggestions */}
            <SearchSuggestions
              query={searchQuery}
              visible={showSuggestions && !voiceSearch.isListening}
              onClose={() => setShowSuggestions(false)}
              onSelectSuggestion={() => setShowSuggestions(false)}
            />
          </div>
          <button
            onClick={() => setShowFilters(!showFilters)}
            style={{
              ...TOUCH_TARGET,
              padding: "0 12px",
              borderRadius: 8,
              border: "1px solid #e5e7eb",
              background: showFilters ? "#4f46e5" : "#fff",
              color: showFilters ? "#fff" : "#374151",
              fontSize: 13,
              fontWeight: 600,
              cursor: "pointer",
              whiteSpace: "nowrap",
              gap: 4,
            }}
          >
            {isMobile ? "⚙️" : `▼ ${t("library.filtersLabel")}`}
          </button>
        </div>
      </div>

      {/* Voice search listening indicator */}
      {voiceSearch.isListening && (
        <div style={{
          background: "#fef2f2",
          padding: "10px 16px",
          borderRadius: 8,
          marginBottom: 12,
          display: "flex",
          alignItems: "center",
          gap: 8,
          fontSize: 14,
          color: "#dc2626",
        }}>
          <span style={{ display: "inline-block", width: 8, height: 8, borderRadius: "50%", background: "#dc2626", animation: "pulse 1s infinite" }} />
          {t("library.listening")}
          <button
            onClick={voiceSearch.stopListening}
            style={{
              marginLeft: "auto",
              background: "#dc2626",
              color: "#fff",
              border: "none",
              borderRadius: 4,
              padding: "4px 12px",
              cursor: "pointer",
              fontSize: 12,
            }}
          >
            {t("library.stop")}
          </button>
        </div>
      )}

      {/* Voice search error */}
      {voiceSearch.hasError && !voiceSearch.isListening && (
        <div style={{
          background: "#fef3c7",
          padding: "8px 12px",
          borderRadius: 8,
          marginBottom: 12,
          fontSize: 13,
          color: "#92400e",
        }}>
          {voiceSearch.errorMessage === "no-speech" ? t("library.voiceNoSpeech") : t("library.voiceError", { message: voiceSearch.errorMessage ?? "" })}
        </div>
      )}

      {/* Filters Panel */}
      {showFilters && (
        <div style={{
          background: "#fff",
          borderRadius: 10,
          padding: isMobile ? 12 : 16,
          marginBottom: 16,
          border: "1px solid #e5e7eb",
          display: "flex",
          flexDirection: isMobile ? "column" : "row",
          gap: 12,
          alignItems: isMobile ? "stretch" : "end",
        }}>
          <div style={{ minWidth: isMobile ? 0 : 160, flex: 1 }}>
            <label style={{ display: "block", fontSize: 12, fontWeight: 600, color: "#6b7280", marginBottom: 4 }}>{t("library.genre")}</label>
            <select
              value={filters.genre}
              onChange={(e) => handleFilterChange("genre", e.target.value)}
              style={{
                width: "100%",
                padding: "8px 12px",
                borderRadius: 6,
                border: "1px solid #e5e7eb",
                fontSize: 14,
                background: "#fff",
                cursor: "pointer",
                minHeight: 36,
              }}
            >
              <option value="">{t("library.allGenres")}</option>
              {genres.map((g) => <option key={g} value={g}>{g}</option>)}
            </select>
          </div>
          <div style={{ minWidth: isMobile ? 0 : 160, flex: 1 }}>
            <label style={{ display: "block", fontSize: 12, fontWeight: 600, color: "#6b7280", marginBottom: 4 }}>{t("library.author")}</label>
            <select
              value={filters.author}
              onChange={(e) => handleFilterChange("author", e.target.value)}
              style={{
                width: "100%",
                padding: "8px 12px",
                borderRadius: 6,
                border: "1px solid #e5e7eb",
                fontSize: 14,
                background: "#fff",
                cursor: "pointer",
                minHeight: 36,
              }}
            >
              <option value="">{t("library.allAuthors")}</option>
              {authors.map((a) => <option key={a} value={a}>{a}</option>)}
            </select>
          </div>
          <div style={{ minWidth: isMobile ? 0 : 160, flex: 1 }}>
            <label style={{ display: "block", fontSize: 12, fontWeight: 600, color: "#6b7280", marginBottom: 4 }}>{t("library.status")}</label>
            <select
              value={filters.reading_status}
              onChange={(e) => handleFilterChange("reading_status", e.target.value)}
              style={{
                width: "100%",
                padding: "8px 12px",
                borderRadius: 6,
                border: "1px solid #e5e7eb",
                fontSize: 14,
                background: "#fff",
                cursor: "pointer",
                minHeight: 36,
              }}
            >
              {statusFilterOptions.map((opt) => <option key={opt.value} value={opt.value}>{opt.label}</option>)}
            </select>
          </div>
          {hasActiveFilters && (
            <button
              onClick={clearAllFilters}
              style={{
                ...TOUCH_TARGET,
                padding: "8px 16px",
                borderRadius: 6,
                border: "1px solid #e5e7eb",
                background: "#fff",
                color: "#6b7280",
                fontSize: 13,
                cursor: "pointer",
                whiteSpace: "nowrap",
                width: isMobile ? "100%" : "auto",
              }}
            >
              ✕ {t("library.clearFilters")}
            </button>
          )}
        </div>
      )}

      {/* Error State */}
      {error && (
        <div style={{ background: "#fef2f2", padding: 16, borderRadius: 8, marginBottom: 16, textAlign: "center" }}>
          <p style={{ color: "#dc2626", fontSize: 14 }}>{error}</p>
          <button onClick={() => void loadBooks({})} style={{ marginTop: 8, padding: "8px 16px", border: "none", borderRadius: 6, background: "#dc2626", color: "#fff", cursor: "pointer", fontSize: 13, minHeight: 36 }}>{t("common.retry")}</button>
        </div>
      )}

      {readerNotice && (
        <div style={{ background: "#fffbeb", border: "1px solid #fde68a", borderRadius: 8, padding: "12px 16px", marginBottom: 16, display: "flex", justifyContent: "space-between", alignItems: "center", gap: 12 }}>
          <p style={{ color: "#92400e", fontSize: 14, margin: 0 }}>{readerNotice}</p>
          <button type="button" onClick={() => setReaderNotice(null)} style={{ padding: "4px 10px", border: "none", borderRadius: 6, background: "#f59e0b", color: "#fff", cursor: "pointer", fontSize: 12, flexShrink: 0 }}>{t("common.dismiss")}</button>
        </div>
      )}

      {/* Loading State */}
      {loading && (
        <div style={{
          display: "grid",
          gridTemplateColumns: isMobile ? "1fr" : "repeat(auto-fill, minmax(200px, 1fr))",
          gap: isMobile ? 12 : 16,
          opacity: 0.6,
        }}>
          {Array.from({ length: isMobile ? 4 : 8 }).map((_, i) => (
            <div key={i} style={{ background: "#fff", borderRadius: 12, overflow: "hidden", boxShadow: "0 2px 8px rgba(0,0,0,0.06)", display: isMobile ? "flex" : "block" }}>
              <div style={{ width: isMobile ? 80 : "100%", height: isMobile ? 120 : 180, background: "#f0f0f0", flexShrink: 0 }} />
              <div style={{ padding: 12 }}>
                <div style={{ height: 14, background: "#f0f0f0", borderRadius: 4, marginBottom: 6, width: "70%" }} />
                <div style={{ height: 12, background: "#f0f0f0", borderRadius: 4, width: "40%" }} />
              </div>
            </div>
          ))}
        </div>
      )}

      {/* Empty State */}
      {!loading && !error && books.length === 0 && (
        <div style={{ textAlign: "center", padding: isMobile ? "60px 16px" : "80px 20px" }}>
          <div style={{ fontSize: isMobile ? 48 : 64, marginBottom: 16 }}>{hasActiveFilters ? "🔍" : "📚"}</div>
          <h2 style={{ fontSize: isMobile ? 18 : 20, color: "#1f2937", marginBottom: 8 }}>
            {hasActiveFilters ? t("library.emptyFilteredTitle") : t("library.emptyTitle")}
          </h2>
          <p style={{ color: "#6b7280", marginBottom: 20, fontSize: 15, lineHeight: 1.5 }}>
            {hasActiveFilters
              ? t("library.emptyFilteredDescription")
              : t("library.emptyDescription")}
          </p>
          {hasActiveFilters ? (
            <button onClick={clearAllFilters} className="btn" style={{ padding: "12px 24px", fontSize: 15, minHeight: 44 }}>
              {t("library.clearAllFilters")}
            </button>
          ) : (
            <button onClick={() => navigate("/add")} className="btn" style={{ padding: "12px 24px", fontSize: 15, minHeight: 44 }}>
              {t("library.addFirstBook")}
            </button>
          )}
        </div>
      )}

      {!loading && activeBooks.length === 0 && finishedBooks.length > 0 && !hasActiveFilters && (
        <p style={{ textAlign: "center", color: "#6b7280", fontSize: 14, marginBottom: 16 }}>
          {t("library.allInFinishedShelf")}
        </p>
      )}

      {/* Active library grid (want to read, reading) */}
      {!loading && activeBooks.length > 0 && (
        <div
          style={{
            display: "grid",
            gridTemplateColumns: isMobile ? "1fr" : "repeat(auto-fill, minmax(200px, 1fr))",
            gap: isMobile ? 12 : 16,
          }}
        >
          {activeBooks.map((book) => (
            <LibraryBookCard
              key={book.id}
              book={book}
              isMobile={isMobile}
              onOpen={() => openBook(book)}
              onContextMenu={(e) => handleBookContextMenu(e, book)}
            />
          ))}
        </div>
      )}

      {shelfVisible && (
        <FinishedBooksShelf
          books={finishedBooks}
          defaultExpanded={finishedFilterActive}
          onOpenBook={(book) => openBook(book as LibraryBook)}
          onContextMenu={(e, book) => handleBookContextMenu(e, book as LibraryBook)}
        />
      )}

      {contextMenu && (
        <BookContextMenu
          book={contextMenu.book}
          x={contextMenu.x}
          y={contextMenu.y}
          onClose={() => setContextMenu(null)}
          onBookUpdated={handleBookUpdated}
          onBookRemoved={handleBookRemoved}
        />
      )}
    </div>
  );
}