import SwiftUI
import OrgSocialKit

struct TimelineView: View {
    @State private var viewModel = TimelineViewModel()
    @State private var showCompose = false
    @State private var showSearch = false
    @State private var followCoordinator = FollowCoordinator.shared
    @AppStorage("useRelay") private var useRelay = true
    @AppStorage("showAllRelayFeeds") private var showAllRelayFeeds = false
    @Binding var selectedTab: RootTab

    init(selectedTab: Binding<RootTab> = .constant(.timeline)) {
        self._selectedTab = selectedTab
    }

    var body: some View {
        NavigationStack {
            Group {
                if viewModel.isLoading && viewModel.posts.isEmpty {
                    loadingView
                } else if let error = viewModel.errorMessage, viewModel.posts.isEmpty {
                    errorView(error)
                } else if viewModel.posts.isEmpty {
                    emptyStateView
                } else {
                    postList
                }
            }
            .navigationTitle("")
            .navigationBarTitleDisplayMode(.inline)
            .toolbar { toolbar }
            .navigationDestination(for: URL.self) { ProfileView(feedURL: $0) }
            .navigationDestination(for: ThreadRoute.self) {
                ThreadView(postURL: $0.postURL, relayURL: $0.relayURL)
            }
            .sheet(isPresented: $showCompose) {
                ComposeView(onPosted: {
                    Task { await viewModel.mergeOwnFeed() }
                })
            }
            .sheet(isPresented: $showSearch) {
                SearchView()
            }
            .task { await viewModel.load() }
            .onChange(of: followCoordinator.feedVersion) { _, _ in
                // Any own-feed mutation elsewhere (follow toggle, post edit/delete,
                // profile edit) while this tab stayed mounted; reload.
                Task { await viewModel.load() }
            }
        }
    }

    // MARK: - Subviews

    private var loadingView: some View {
        VStack(spacing: 16) {
            ProgressView()
            Text("Loading timeline from relay…")
                .font(.subheadline)
                .foregroundStyle(.secondary)
        }
        .frame(maxWidth: .infinity, maxHeight: .infinity)
    }

    private func errorView(_ message: String) -> some View {
        ContentUnavailableView {
            Label("No Posts", systemImage: "antenna.radiowaves.left.and.right.slash")
        } description: {
            Text(message)
        } actions: {
            Button("Retry") { Task { await viewModel.load() } }
                .buttonStyle(.bordered)
        }
    }

    @ViewBuilder
    private var emptyStateView: some View {
        // Wrap in a ScrollView so `.refreshable` works while the timeline is empty.
        ScrollView {
            ContentUnavailableView {
                Label("No posts yet", systemImage: "tray")
            } description: {
                if useRelay && !showAllRelayFeeds {
                    Text("Your follow list is empty or the feeds you follow haven't posted recently. Find people in Discover, or turn on Show all relay feeds in Settings to see everyone.")
                } else if !useRelay {
                    Text("Timeline is running in offline mode. Add #+FOLLOW: entries to your profile to see posts.")
                } else {
                    Text("The relay hasn't returned any posts. Pull to refresh or try again later.")
                }
            } actions: {
                VStack(spacing: 10) {
                    if useRelay && !showAllRelayFeeds {
                        Button {
                            selectedTab = .discover
                        } label: {
                            Label("Find people in Discover", systemImage: "globe")
                        }
                        .buttonStyle(.borderedProminent)

                        Button {
                            showAllRelayFeeds = true
                            Task { await viewModel.load() }
                        } label: {
                            Label("Show all relay feeds", systemImage: "dot.radiowaves.left.and.right")
                        }
                        .buttonStyle(.bordered)
                    } else {
                        Button("Retry") { Task { await viewModel.load() } }
                            .buttonStyle(.bordered)
                    }
                }
            }
            .frame(minHeight: 500)
        }
        .refreshable { await viewModel.load() }
    }

    private var postList: some View {
        // ScrollView + LazyVStack instead of List: SwiftUI's List auto-fires the first
        // NavigationLink inside a row on any tap, which pushed a stray Profile/Thread
        // onto the stack every time an action button was tapped.
        ScrollView {
            LazyVStack(spacing: 0) {
                ForEach(viewModel.posts, id: \.stableID) { post in
                    PostRowView(post: post,
                                onDelete: { viewModel.removePost(timestamp: post.timestamp) },
                                onEdit: { result in viewModel.applyEdit(timestamp: post.timestamp, result: result) })
                        .padding(.horizontal, 16)
                        .padding(.vertical, 12)
                    Divider().padding(.leading, 16).background(Color.secondary.opacity(0.2))
                }
            }
        }
        .refreshable { await viewModel.load() }
        .overlay(alignment: .bottom) {
            if viewModel.isLoading && !viewModel.posts.isEmpty {
                HStack(spacing: 8) {
                    ProgressView().scaleEffect(0.8)
                    Text("Refreshing…").font(.caption).foregroundStyle(.secondary)
                }
                .padding(.horizontal, 16).padding(.vertical, 8)
                .background(.thinMaterial, in: Capsule())
                .padding(.bottom, 12)
            }
        }
    }

    @ToolbarContentBuilder
    private var toolbar: some ToolbarContent {
        ToolbarItem(placement: .principal) {
            LogoView(size: 30)
                .allowsHitTesting(false)
                .accessibilityHidden(true)
        }
        ToolbarItem(placement: .navigationBarTrailing) {
            Button { showSearch = true } label: {
                Image(systemName: "magnifyingglass")
            }
            .disabled(!useRelay)
        }
        ToolbarItem(placement: .navigationBarTrailing) {
            Button {
                showCompose = true
            } label: {
                Image(systemName: "square.and.pencil")
                    .fontWeight(.semibold)
            }
        }
    }
}