import Combine
import Foundation
import SwiftUI

struct BookmarksView: View {

    // MARK: States
    
    @State private var viewModel: BookmarksViewModel
    @State private var showingAddBookmark = false
    @State private var selectedBookmarkId: String?
    @State private var showingAddBookmarkFromShare = false
    @State private var shareURL = ""
    @State private var shareTitle = ""
    @State private var bookmarkToDelete: Bookmark? = nil
    
    let state: BookmarkState
    let type: [BookmarkType]
    @Binding var selectedBookmark: Bookmark?
    @EnvironmentObject var playerUIState: PlayerUIState
    let tag: String?
    
    // MARK: Environments
    
    @Environment(\.horizontalSizeClass) var horizontalSizeClass
    @Environment(\.verticalSizeClass) var verticalSizeClass
    
    // MARK: Initializer
    
    init(viewModel: BookmarksViewModel = .init(), state: BookmarkState, type: [BookmarkType], selectedBookmark: Binding<Bookmark?>, tag: String? = nil) {
        self.state = state
        self.type = type
        self._selectedBookmark = selectedBookmark
        self.tag = tag
        self.viewModel = viewModel
    }

    var body: some View {
        ZStack {
            if viewModel.isLoading && viewModel.bookmarks?.bookmarks.isEmpty == true {
                VStack(spacing: 20) {
                    Spacer()
                    
                    VStack(spacing: 16) {
                        ProgressView()
                            .scaleEffect(1.3)
                            .tint(.accentColor)
                        
                        VStack(spacing: 8) {
                            Text("Loading \(state.displayName)")
                                .font(.headline)
                                .foregroundColor(.primary)
                            
                            Text("Please wait while we fetch your bookmarks...")
                                .font(.subheadline)
                                .foregroundColor(.secondary)
                                .multilineTextAlignment(.center)
                        }
                    }
                    .padding(.horizontal, 40)
                    
                    Spacer()
                }
                .frame(maxWidth: .infinity, maxHeight: .infinity)
                .background(Color(R.color.bookmark_list_bg))
            } else {
                List {
                    ForEach(viewModel.bookmarks?.bookmarks ?? [], id: \.id) { bookmark in
                        Button(action: {
                            if UIDevice.isPhone {
                                selectedBookmarkId = bookmark.id
                            } else {
                                if selectedBookmark?.id == bookmark.id {
                                    selectedBookmark = nil
                                    DispatchQueue.main.async {
                                        selectedBookmark = bookmark
                                    }
                                } else {
                                    selectedBookmark = bookmark
                                }
                            }
                        }) {
                            BookmarkCardView(
                                bookmark: bookmark,
                                currentState: state,
                                onArchive: { bookmark in
                                    Task {
                                        await viewModel.toggleArchive(bookmark: bookmark)
                                    }
                                },
                                onDelete: { bookmark in
                                    bookmarkToDelete = bookmark
                                },
                                onToggleFavorite: { bookmark in
                                    Task {
                                        await viewModel.toggleFavorite(bookmark: bookmark)
                                    }
                                }
                            )
                            .onAppear {
                                if bookmark.id == viewModel.bookmarks?.bookmarks.last?.id {
                                    Task {
                                        await viewModel.loadMoreBookmarks()
                                    }
                                }
                            }
                        }
                        .buttonStyle(PlainButtonStyle())
                        .listRowInsets(EdgeInsets(top: 8, leading: 16, bottom: 8, trailing: 16))
                        .listRowSeparator(.hidden)
                        .listRowBackground(Color(R.color.bookmark_list_bg))
                    }
                }
                .listStyle(.plain)
                .background(Color(R.color.bookmark_list_bg))
                .scrollContentBackground(.hidden)
                .refreshable {
                    await viewModel.refreshBookmarks()
                }
                .overlay {
                    if viewModel.bookmarks?.bookmarks.isEmpty == true && !viewModel.isLoading {
                        ContentUnavailableView(
                            "No bookmarks",
                            systemImage: "bookmark",
                            description: Text(
                                "No bookmarks found in \(state.displayName.lowercased())."
                            )
                        )
                    }
                }
            }

            // FAB Button - only show for "Unread"
            if state == .unread || state == .all {
                VStack {
                    Spacer()
                    HStack {
                        Spacer()

                        Button(action: {
                            showingAddBookmark = true
                        }) {
                            Image(systemName: "plus")
                                .font(.title2)
                                .fontWeight(.semibold)
                                .foregroundColor(.white)
                                .frame(width: 56, height: 56)
                                .background(Color.accentColor)
                                .clipShape(Circle())
                                .shadow(color: .black.opacity(0.25), radius: 6, x: 0, y: 3)
                        }
                        .padding(.trailing, 20)
                        .padding(.bottom, 20)
                    }
                }
            }
        }
        .navigationDestination(
            item: Binding<String?>(
                get: { selectedBookmarkId },
                set: { selectedBookmarkId = $0 }
            )
        ) { bookmarkId in
            BookmarkDetailView(bookmarkId: bookmarkId)
        }
        .sheet(isPresented: $showingAddBookmark) {
            AddBookmarkView(prefilledURL: shareURL, prefilledTitle: shareTitle)
        }
        .sheet(
            isPresented: $viewModel.showingAddBookmarkFromShare,
            content: {
                AddBookmarkView(prefilledURL: shareURL, prefilledTitle: shareTitle)
            }
        )
        .alert(item: $bookmarkToDelete) { bookmark in
            Alert(
                title: Text("Delete Bookmark"),
                message: Text("Are you sure you want to delete this bookmark? This action cannot be undone."),
                primaryButton: .destructive(Text("Delete")) {
                    Task {
                        await viewModel.deleteBookmark(bookmark: bookmark)
                    }
                },
                secondaryButton: .cancel()
            )
        }
        .onAppear {
            Task {
                await viewModel.loadBookmarks(state: state, type: type, tag: tag)
            }
        }
        .onChange(of: showingAddBookmark) { oldValue, newValue in
            // Refresh bookmarks when sheet is dismissed
            if oldValue && !newValue {
                Task {
                    // Wait a bit for the server to process the new bookmark
                    try? await Task.sleep(nanoseconds: 1_000_000_000) // 1 second
                    
                    await viewModel.refreshBookmarks()
                }
            }
        }
    }
}

#Preview {
    BookmarksView(
        viewModel: .init(MockUseCaseFactory()),
        state: .archived,
        type: [.article],
        selectedBookmark: .constant(nil),
        tag: nil)
}