import SwiftUI

struct ContentView: View {
    @Environment(AppState.self) private var appState
    @Environment(\.horizontalSizeClass) private var horizontalSizeClass

    enum Tab: String, Hashable, CaseIterable {
        case home = "Home"
        case pin = "Pin"
        case compose = "Compose"
        case more = "More"

        var icon: String {
            switch self {
            case .home: return "house.fill"
            case .pin: return "pin.fill"
            case .compose: return "square.and.pencil"
            case .more: return "ellipsis.circle.fill"
            }
        }
    }

    @State private var selectedTab: Tab = .home

    var body: some View {
        Group {
            if horizontalSizeClass == .regular {
                iPadLayout
            } else {
                iPhoneLayout
            }
        }
        .overlay {
            if appState.isLocked {
                lockScreen
            }
        }
    }

    private var iPhoneLayout: some View {
        TabView(selection: $selectedTab) {
            NavigationStack { HomeView() }
                .tabItem { Label("Home", systemImage: "house.fill") }
                .tag(Tab.home)

            NavigationStack { PinView() }
                .tabItem { Label("Pin", systemImage: "pin.fill") }
                .tag(Tab.pin)

            NavigationStack { ComposeListView() }
                .tabItem { Label("Compose", systemImage: "square.and.pencil") }
                .tag(Tab.compose)

            NavigationStack { MoreView() }
                .tabItem { Label("More", systemImage: "ellipsis.circle.fill") }
                .tag(Tab.more)
        }
    }

    private var iPadLayout: some View {
        NavigationSplitView {
            iPadSidebar
        } detail: {
            iPadDetail
        }
    }

    private var iPadSidebar: some View {
        VStack(spacing: 4) {
            ForEach(Tab.allCases, id: \.self) { tab in
                iPadSidebarButton(tab: tab)
            }
            Spacer()
        }
        .padding(.top, 8)
        .navigationTitle("Proxy")
    }

    private func iPadSidebarButton(tab: Tab) -> some View {
        Button {
            selectedTab = tab
        } label: {
            Label(tab.rawValue, systemImage: tab.icon)
                .frame(maxWidth: .infinity, alignment: .leading)
                .padding(.horizontal, 20)
                .padding(.vertical, 14)
                .background(
                    selectedTab == tab ? Color.accentColor.opacity(0.12) : Color.clear,
                    in: RoundedRectangle(cornerRadius: 10)
                )
                .foregroundStyle(selectedTab == tab ? Color.accentColor : Color.primary)
        }
        .buttonStyle(.plain)
        .padding(.horizontal, 12)
    }

    @ViewBuilder
    private var iPadDetail: some View {
        NavigationStack {
            switch selectedTab {
            case .home: HomeView()
            case .pin: PinView()
            case .compose: ComposeListView()
            case .more: MoreView()
            }
        }
    }

    private var lockScreen: some View {
        ZStack {
            Color(.systemBackground).ignoresSafeArea()
            VStack(spacing: 24) {
                Image(systemName: "lock.fill")
                    .font(.system(size: 48))
                    .foregroundStyle(.secondary)
                Text("Unlock Proxy")
                    .font(.title2.weight(.semibold))
                Button {
                    appState.authenticate()
                } label: {
                    Text("Unlock")
                        .font(.headline)
                        .frame(maxWidth: 300)
                        .padding()
                        .background(.blue, in: RoundedRectangle(cornerRadius: 12))
                        .foregroundStyle(.white)
                }
            }
        }
        .onAppear { appState.authenticate() }
    }
}