import SwiftUI

// MARK: - Skeleton loading row

private struct SkeletonRow: View {
    var delay: Double = 0
    @State private var dimmed = false

    var body: some View {
        HStack(alignment: .top, spacing: 11) {
            RoundedRectangle(cornerRadius: 3)
                .fill(Paper.ink.opacity(0.09))
                .frame(width: 34, height: 46)
            VStack(alignment: .leading, spacing: 7) {
                Capsule()
                    .fill(Paper.ink.opacity(0.09))
                    .frame(maxWidth: .infinity)
                    .frame(height: 15)
                Capsule()
                    .fill(Paper.ink.opacity(0.06))
                    .frame(width: 140, height: 12)
            }
            .padding(.top, 4)
            Spacer()
        }
        .padding(.vertical, 14)
        .opacity(dimmed ? 0.45 : 1)
        .onAppear {
            withAnimation(
                .easeInOut(duration: 0.9)
                .repeatForever(autoreverses: true)
                .delay(delay)
            ) { dimmed = true }
        }
    }
}

// MARK: - Row press ButtonStyle

struct RowPressStyle: ButtonStyle {
    func makeBody(configuration: Configuration) -> some View {
        configuration.label
            .scaleEffect(configuration.isPressed ? 0.97 : 1)
            .opacity(configuration.isPressed ? 0.75 : 1)
            .animation(.spring(duration: 0.18, bounce: 0), value: configuration.isPressed)
    }
}

// MARK: - BookmarksView

struct BookmarksView: View {
    @Bindable var viewModel: BookmarksViewModel
    let onDisconnect: () -> Void

    @State private var showSettings = false
    @State private var showCollections = false
    @State private var showAddBookmark = false
    @State private var editingBookmark: Bookmark?
    @State private var browsingBookmark: Bookmark?
    @State private var showFullPlayer = false
    @State private var showAsk = false
    @State private var readingProgress: [String: Double] = ReadingProgress.all()
    @AppStorage("bookmarksLayout") private var layoutRaw = LibraryLayout.list.rawValue
    @State private var libraryFilters: [LibraryFilter] = [
        LibraryFilter(name: "Everything", tag: nil)
    ]
    @State private var librarySelection: LibraryFilter.ID?
    @State private var showTags = false

    private var layout: LibraryLayout { LibraryLayout(rawValue: layoutRaw) ?? .list }
    private var otherLayout: LibraryLayout { layout == .cards ? .list : .cards }

    var body: some View {
        NavigationStack {
            VStack(spacing: 0) {
                // Both layouts speak the same design now, so the filter strip
                // belongs to the screen rather than to one mode — which also
                // means a tag filter can no longer go invisible when you switch.
                LibraryTagStrip(
                    filters: $libraryFilters,
                    selection: $librarySelection,
                    onChange: applyTagFilter,
                    onBrowseTags: { showTags = true }
                )

                if layout == .cards {
                    LibraryGridView(
                        viewModel: viewModel,
                        onOpen: { browsingBookmark = $0 },
                        onEdit: { editingBookmark = $0 }
                    )
                } else {
                    bookmarkList
                }
            }
            // The large-title area draws from the content behind it, so the
            // paper ground has to reach past the safe area or the library
            // appears to start halfway down a white screen.
            .background(Paper.sheet.ignoresSafeArea())
            .task { librarySelection = librarySelection ?? libraryFilters.first?.id }
            .navigationTitle(viewModel.unreadFilter ? "Unread" : "Bookmarks")
            .navigationBarTitleDisplayMode(.large)
            .toolbar {
                ToolbarItem(placement: .topBarLeading) {
                    Menu {
                        Button {
                            showAsk = true
                        } label: {
                            Label("Ask Your Bookmarks", systemImage: "bubble.left.and.text.bubble.right")
                        }
                        Button {
                            Task { await viewModel.generateSmartCollections() }
                            showCollections = true
                        } label: {
                            Label("Smart Collections", systemImage: "sparkles")
                        }
                        Button {
                            Task { await viewModel.enrichAll() }
                        } label: {
                            Label("Enrich All with AI", systemImage: "wand.and.stars")
                        }
                    } label: {
                        Image(systemName: "sparkles")
                    }
                }
                ToolbarItem(placement: .topBarTrailing) {
                    HStack(spacing: 16) {
                        // Shows where the tap goes, not where you are — a
                        // two-state toggle labelled with its current state
                        // reads as a status light rather than a control.
                        Button { toggleLayout() } label: {
                            Image(systemName: otherLayout.symbol)
                                .contentTransition(.symbolEffect(.replace))
                        }
                        .accessibilityLabel(
                            otherLayout == .cards ? "Show as cards" : "Show as list"
                        )
                        Button { showAddBookmark = true } label: {
                            Image(systemName: "plus")
                        }
                        Button {
                            Task { await viewModel.toggleUnreadFilter() }
                        } label: {
                            Image(systemName: viewModel.unreadFilter
                                  ? "line.3.horizontal.decrease.circle.fill"
                                  : "line.3.horizontal.decrease.circle")
                                .contentTransition(.symbolEffect(.replace))
                        }
                        Button { showSettings = true } label: {
                            Image(systemName: "gearshape")
                        }
                    }
                }
            }
            .overlay {
                if !viewModel.isLoading && viewModel.bookmarks.isEmpty {
                    PaperEmptyState(
                        title: "No Bookmarks",
                        systemImage: "bookmark",
                        message: "Bookmarks you save will appear here."
                    )
                    .transition(.opacity)
                }
            }
            .overlay(alignment: .bottom) {
                VStack(spacing: 8) {
                    if viewModel.podcastGenerator.hasActive {
                        podcastGeneratingBanner
                            .transition(.move(edge: .bottom).combined(with: .opacity))
                    }
                    if !viewModel.podcastPlayer.currentArticleUrl.isEmpty {
                        MiniPlayerView(vm: viewModel.podcastPlayer) {
                            showFullPlayer = true
                        }
                        .transition(.move(edge: .bottom).combined(with: .opacity))
                    }
                    if viewModel.enrichmentProgress > 0 {
                        enrichmentBanner
                    }
                }
                .animation(.spring(duration: 0.3), value: !viewModel.podcastPlayer.currentArticleUrl.isEmpty)
                .animation(.spring(duration: 0.3), value: viewModel.podcastGenerator.hasActive)
                .padding(.bottom, 8)
            }
            .sensoryFeedback(.selection, trigger: browsingBookmark?.id)
        }
        .sheet(isPresented: $showSettings) {
            SettingsView(viewModel: viewModel, onDisconnect: onDisconnect)
        }
        .sheet(isPresented: $showCollections) {
            CollectionsView(viewModel: viewModel)
        }
        .sheet(isPresented: $showAsk) {
            AskView()
        }
        .sheet(isPresented: $showTags) {
            TagsView(
                viewModel: viewModel,
                pinned: Set(libraryFilters.compactMap(\.tag)),
                onPick: pinTag
            )
        }
        .sheet(isPresented: $showAddBookmark) {
            AddBookmarkView(viewModel: viewModel)
        }
        .sheet(item: $editingBookmark) { bookmark in
            EditBookmarkView(viewModel: viewModel, bookmark: bookmark)
        }
        .sheet(item: $browsingBookmark) { bookmark in
            if let url = URL(string: bookmark.url) {
                BrowserView(url: url, title: bookmark.displayTitle, claude: viewModel.claude, podcastPlayer: viewModel.podcastPlayer, podcastGenerator: viewModel.podcastGenerator) {
                    await viewModel.archive(bookmark)
                }
                .bookmarkOnscreen(bookmark)
            }
        }
        .onChange(of: browsingBookmark) { _, new in
            if new == nil { readingProgress = ReadingProgress.all() }
        }
        .sheet(isPresented: $showFullPlayer) {
            PodcastPlayerView(
                vm: viewModel.podcastPlayer,
                articleUrl: viewModel.podcastPlayer.currentArticleUrl,
                articleTitle: viewModel.podcastPlayer.currentArticleTitle,
                claude: viewModel.claude,
                stopOnDismiss: false
            )
        }
        .refreshable {
            await viewModel.load()
        }
        .task {
            if viewModel.bookmarks.isEmpty {
                await viewModel.load()
            }
        }
        .alert("Error", isPresented: Binding(
            get: { viewModel.error != nil },
            set: { if !$0 { viewModel.error = nil } }
        )) {
            Button("OK") { viewModel.error = nil }
        } message: {
            Text(viewModel.error ?? "")
        }
    }

    private var enrichmentBanner: some View {
        HStack(spacing: 10) {
            ProgressView(value: viewModel.enrichmentProgress)
                .progressViewStyle(.linear)
                .tint(Paper.ink)
            Text("Adding AI summaries…")
                .font(PaperType.meta)
                .foregroundStyle(Paper.secondary)
        }
        .padding(.horizontal, 20)
        .padding(.vertical, 12)
        .paperCard(cornerRadius: 12)
        .padding(.horizontal, 16)
    }

    private var podcastGeneratingBanner: some View {
        let jobs = viewModel.podcastGenerator.activeJobs
        return HStack(spacing: 10) {
            Image(systemName: "waveform")
                .font(.system(size: 15, weight: .semibold))
                .foregroundStyle(Paper.accent)
                .symbolEffect(.variableColor.iterative, isActive: true)
            VStack(alignment: .leading, spacing: 2) {
                Text(jobs.count == 1 ? "Generating podcast…" : "Generating \(jobs.count) podcasts…")
                    .font(PaperType.stamp)
                    .foregroundStyle(Paper.ink)
                if let first = jobs.first {
                    Text(first.title.isEmpty ? first.label : first.title)
                        .font(PaperType.micro)
                        .foregroundStyle(Paper.tertiary)
                        .lineLimit(1)
                }
            }
            Spacer()
            if jobs.count == 1, let progress = jobs.first?.progress, progress > 0 {
                ProgressView(value: progress)
                    .progressViewStyle(.linear)
                    .tint(Paper.accent)
                    .frame(width: 44)
            } else {
                ProgressView()
            }
        }
        .padding(.horizontal, 16)
        .padding(.vertical, 10)
        .paperCard(cornerRadius: 12)
        .padding(.horizontal, 16)
    }

    private var bookmarkList: some View {
        List {
            if viewModel.isLoading && viewModel.bookmarks.isEmpty {
                ForEach(0..<3, id: \.self) { i in
                    SkeletonRow(delay: Double(i) * 0.13)
                        .listRowInsets(EdgeInsets(top: 0, leading: 16, bottom: 0, trailing: 16))
                        .listRowSeparator(.visible)
                }
            } else {
                ForEach(viewModel.bookmarks) { bookmark in
                    BookmarkListRow(
                        bookmark: bookmark,
                        viewModel: viewModel,
                        readingProgress: readingProgress[bookmark.url] ?? 0,
                        onOpen: { browsingBookmark = bookmark },
                        onEdit: { editingBookmark = bookmark }
                    )
                    .onAppear { maybeLoadMore(bookmark) }
                }
            }

            if viewModel.isLoadingMore {
                HStack { Spacer(); ProgressView(); Spacer() }
                    .listRowSeparator(.hidden)
                    .listRowBackground(Paper.sheet)
            }
        }
        .listStyle(.plain)
        .scrollContentBackground(.hidden)
        .animation(.spring(duration: 0.35), value: viewModel.bookmarks.isEmpty)
    }

    /// Pin a tag as a filter tab and switch to it. Choosing one that's already
    /// pinned selects that tab instead of adding a duplicate.
    private func pinTag(_ tag: String) {
        if let existing = libraryFilters.first(where: { $0.tag == tag }) {
            librarySelection = existing.id
        } else {
            let new = LibraryFilter(name: tag, tag: tag)
            withAnimation(.spring(duration: 0.35, bounce: 0.1)) {
                libraryFilters.append(new)
                librarySelection = new.id
            }
        }
        applyTagFilter()
    }

    /// Tag tabs filter server-side through linkding's `#tag` search syntax —
    /// filtering the loaded page client-side would only ever search the most
    /// recent 50 of 600+ bookmarks and quietly look empty.
    private func applyTagFilter() {
        let tag = libraryFilters.first { $0.id == librarySelection }?.tag
        viewModel.searchQuery = tag.map { "#\($0)" } ?? ""
        Task { await viewModel.search() }
    }

    private func toggleLayout() {
        withAnimation(.spring(duration: 0.35, bounce: 0.05)) { layoutRaw = otherLayout.rawValue }
    }

    private func maybeLoadMore(_ bookmark: Bookmark) {
        guard let last = viewModel.bookmarks.last, last.id == bookmark.id,
              viewModel.nextPageUrl != nil, !viewModel.isLoadingMore else { return }
        Task { await viewModel.loadMore() }
    }
}