import React, { useState } from 'react';
import { AppScreen, Book } from './types';
import { INITIAL_BOOKS } from './constants';
import { Layout } from './components/Layout';
import { Library } from './screens/Library';
import { Categories } from './screens/Categories';
import { BookDetails } from './screens/BookDetails';
import { AddBook } from './screens/AddBook';
import { Scanner } from './screens/Scanner';

const App: React.FC = () => {
  const [currentScreen, setCurrentScreen] = useState<AppScreen>(AppScreen.LIBRARY);
  const [books, setBooks] = useState<Book[]>(INITIAL_BOOKS);
  const [selectedBook, setSelectedBook] = useState<Book | null>(null);
  const [prefilledData, setPrefilledData] = useState<Partial<Book> | null>(null);

  const handleBookClick = (book: Book) => {
    setSelectedBook(book);
    setCurrentScreen(AppScreen.DETAILS);
  };

  const handleAddClick = () => {
    setPrefilledData(null);
    setCurrentScreen(AppScreen.ADD_BOOK);
  };

  const handleSaveBook = (bookData: Partial<Book>) => {
    if (selectedBook) {
      // Edit existing
      setBooks(prev => prev.map(b => b.id === selectedBook.id ? { ...b, ...bookData } as Book : b));
    } else {
      // Add new
      const newBook: Book = {
        id: Math.random().toString(36).substr(2, 9),
        title: bookData.title || 'Unknown',
        author: bookData.author || 'Unknown',
        genre: bookData.genre || 'Unknown',
        annotation: bookData.annotation || '',
        coverUrl: bookData.coverUrl || 'https://picsum.photos/seed/new/400/600',
        status: 'want_to_read',
        ...bookData
      } as Book;
      setBooks(prev => [...prev, newBook]);
    }
    setCurrentScreen(AppScreen.LIBRARY);
    setSelectedBook(null);
    setPrefilledData(null);
  };

  const handleDeleteBook = (id: string) => {
    setBooks(prev => prev.filter(b => b.id !== id));
    setCurrentScreen(AppScreen.LIBRARY);
  };

  const handleDetected = (data: Partial<Book>) => {
    setPrefilledData(data);
    setCurrentScreen(AppScreen.ADD_BOOK);
  };

  const renderScreen = () => {
    switch (currentScreen) {
      case AppScreen.LIBRARY:
        return (
          <Library
            books={books}
            onBookClick={handleBookClick}
            onAddClick={handleAddClick}
          />
        );
      case AppScreen.CATEGORIES:
        return <Categories />;
      case AppScreen.DETAILS:
        return selectedBook ? (
          <BookDetails
            book={selectedBook}
            onBack={() => setCurrentScreen(AppScreen.LIBRARY)}
            onDelete={handleDeleteBook}
            onEdit={(b) => {
              setSelectedBook(b);
              setCurrentScreen(AppScreen.ADD_BOOK);
            }}
          />
        ) : null;
      case AppScreen.ADD_BOOK:
        return (
          <AddBook
            initialData={selectedBook || prefilledData || {}}
            onSave={handleSaveBook}
            onCancel={() => {
              setCurrentScreen(selectedBook ? AppScreen.DETAILS : AppScreen.LIBRARY);
              setPrefilledData(null);
            }}
            onScanClick={() => setCurrentScreen(AppScreen.SCANNER)}
          />
        );
      case AppScreen.SCANNER:
        return (
          <Scanner
            onCancel={() => setCurrentScreen(AppScreen.ADD_BOOK)}
            onDetected={handleDetected}
          />
        );
      case AppScreen.WISHLIST:
        return (
           <div className="p-10 text-center">
            <h2 className="text-xl font-bold">Вишлист</h2>
            <p className="text-text-muted mt-2">Здесь будут книги, которые вы хотите прочитать.</p>
          </div>
        );
      case AppScreen.SETTINGS:
        return (
          <div className="p-10 text-center">
            <h2 className="text-xl font-bold">Настройки</h2>
            <p className="text-text-muted mt-2">Персонализируйте ваше приложение.</p>
          </div>
        );
      default:
        return <Library books={books} onBookClick={handleBookClick} onAddClick={handleAddClick} />;
    }
  };

  const hideNav = [AppScreen.SCANNER, AppScreen.DETAILS, AppScreen.ADD_BOOK].includes(currentScreen);

  return (
    <Layout currentScreen={currentScreen} setScreen={setCurrentScreen} hideNav={hideNav}>
      {renderScreen()}
    </Layout>
  );
};

export default App;