import SwiftUI

let dashboardAccent = AppTheme.accent
let dashboardGold = AppTheme.warmAccent

extension View {
    @ViewBuilder
    func inlineNavigationTitleOnIOS() -> some View {
        #if os(iOS)
        navigationBarTitleDisplayMode(.inline)
        #else
        self
        #endif
    }

    @ViewBuilder
    func cleanTabBarOnIOS() -> some View {
        #if os(iOS)
        toolbarBackground(.visible, for: .tabBar)
            .toolbarBackground(AppTheme.chromeFill, for: .tabBar)
        #else
        self
        #endif
    }
}

struct HomeRootView: View {
    @ObservedObject var model: AppViewModel
    @State private var notificationBellFrame: CGRect?

    var body: some View {
        Group {
            if usesCompactNavigation {
                CompactHomeContainer(model: model)
            } else {
                RegularHomeContainer(model: model)
            }
        }
        .onPreferenceChange(NotificationBellFrameKey.self) { notificationBellFrame = $0 }
        .overlay(alignment: .topLeading) {
            if usesCompactNavigation {
                NotificationBellBadgeOverlay(
                    unreadCount: model.unreadNotificationCount,
                    bellFrame: notificationBellFrame
                )
                .ignoresSafeArea()
            }
        }
        .sheet(isPresented: $model.isNotificationCenterPresented) {
            NotificationCenterSheet(model: model)
        }
    }

    private var usesCompactNavigation: Bool {
        #if os(iOS)
        true
        #else
        false
        #endif
    }
}

private struct CompactHomeContainer: View {
    @ObservedObject var model: AppViewModel
    @Environment(\.horizontalSizeClass) private var horizontalSizeClass

    var body: some View {
        TabView(selection: $model.selectedSection) {
            ForEach(AppSection.allCases) { section in
                NavigationStack {
                    HomeSectionScreen(model: model, section: section, compactLayout: compactLayout)
                        .navigationTitle(section.title)
                        .inlineNavigationTitleOnIOS()
                        .toolbar {
                            DashboardToolbar(model: model)
                        }
                }
                .tag(section)
                .tabItem {
                    Label(section.title, systemImage: section.systemImage)
                }
            }
        }
        .cleanTabBarOnIOS()
    }

    private var compactLayout: Bool {
        #if os(iOS)
        horizontalSizeClass == .compact
        #else
        false
        #endif
    }
}

private struct RegularHomeContainer: View {
    @ObservedObject var model: AppViewModel

    var body: some View {
        NavigationSplitView {
            Sidebar(model: model)
                .navigationSplitViewColumnWidth(min: 240, ideal: 280, max: 320)
        } detail: {
            HomeSectionScreen(model: model, section: model.selectedSection, compactLayout: false)
                .navigationTitle(model.selectedSection.title)
                .toolbar {
                    DashboardToolbar(model: model)
                }
        }
        .navigationSplitViewStyle(.balanced)
    }
}

private struct DashboardToolbar: ToolbarContent {
    @ObservedObject var model: AppViewModel

    var body: some ToolbarContent {
        ToolbarItemGroup(placement: .primaryAction) {
            NotificationBellButton(model: model)
        }
    }
}

struct NotificationBellFrameKey: PreferenceKey {
    static var defaultValue: CGRect? = nil

    static func reduce(value: inout CGRect?, nextValue: () -> CGRect?) {
        value = nextValue() ?? value
    }
}

private struct NotificationBellBadgeOverlay: View {
    let unreadCount: Int
    let bellFrame: CGRect?

    var body: some View {
        GeometryReader { proxy in
            if unreadCount > 0, let bellFrame {
                let rootFrame = proxy.frame(in: .global)

                Text("\(min(unreadCount, 9))")
                    .font(.caption2.weight(.bold))
                    .foregroundStyle(.white)
                    .frame(minWidth: 18, minHeight: 18)
                    .padding(.horizontal, 3)
                    .background(Color.orange, in: Capsule())
                    .position(
                        x: bellFrame.maxX - rootFrame.minX - 2,
                        y: bellFrame.minY - rootFrame.minY + 2
                    )
            }
        }
        .allowsHitTesting(false)
    }
}

private struct HomeSectionScreen: View {
    @ObservedObject var model: AppViewModel
    let section: AppSection
    let compactLayout: Bool

    @State private var focusedRequest: ApprovalRequest?
    @State private var isOTPPresented = false
    @StateObject private var identifyReader = NFCIdentifyReader()

    var body: some View {
        AppScrollScreen(
            compactLayout: compactLayout,
            bottomPadding: compactLayout ? AppLayout.compactBottomDockPadding : AppLayout.regularBottomPadding
        ) {
            HomeTopActions(
                model: model,
                identifyReader: identifyReader,
                onScanQR: { model.isScannerPresented = true },
                onShowOTP: { isOTPPresented = true }
            )

            switch section {
            case .overview:
                OverviewPanel(model: model, compactLayout: compactLayout)
            case .requests:
                RequestsPanel(model: model, compactLayout: compactLayout, onOpenRequest: { focusedRequest = $0 })
            case .activity:
                ActivityPanel(model: model, compactLayout: compactLayout)
            case .account:
                AccountPanel(model: model, compactLayout: compactLayout)
            }
        }
        .task {
            identifyReader.onAuthenticationRequestDetected = { request in
                Task {
                    await model.identifyWithNFC(request)
                }
            }

            identifyReader.onError = { message in
                model.errorMessage = message
            }
        }
        .sheet(item: $focusedRequest) { request in
            RequestDetailSheet(request: request, model: model)
        }
        .sheet(isPresented: $model.isScannerPresented) {
            QRScannerSheet(
                seededPayload: model.session?.pairingCode ?? model.suggestedPairingPayload,
                title: "Scan proof QR",
                description: "Use the camera to scan an idp.global QR challenge from the site or device asking you to prove that it is really you.",
                navigationTitle: "Scan Proof QR",
                onCodeScanned: { payload in
                    Task {
                        await model.identifyWithPayload(payload, transport: .qr)
                    }
                }
            )
        }
        .sheet(isPresented: $isOTPPresented) {
            if let session = model.session {
                OneTimePasscodeSheet(session: session)
            }
        }
    }
}

private struct HomeTopActions: View {
    @ObservedObject var model: AppViewModel
    @ObservedObject var identifyReader: NFCIdentifyReader
    let onScanQR: () -> Void
    let onShowOTP: () -> Void

    var body: some View {
        LazyVGrid(columns: columns, spacing: 12) {
            identifyButton
            qrButton
            otpButton
        }
    }

    private var columns: [GridItem] {
        Array(repeating: GridItem(.flexible(), spacing: 12), count: 3)
    }

    private var identifyButton: some View {
        Button {
            identifyReader.beginScanning()
        } label: {
            AppActionTile(
                title: identifyReader.isScanning ? "Scanning NFC" : "Tap NFC",
                systemImage: "dot.radiowaves.left.and.right",
                tone: dashboardAccent,
                isBusy: identifyReader.isScanning || model.isIdentifying
            )
        }
        .buttonStyle(.plain)
        .disabled(identifyReader.isScanning || !identifyReader.isSupported || model.isIdentifying)
    }

    private var qrButton: some View {
        Button {
            onScanQR()
        } label: {
            AppActionTile(
                title: "Scan QR",
                systemImage: "qrcode.viewfinder",
                tone: dashboardAccent
            )
        }
        .buttonStyle(.plain)
    }

    private var otpButton: some View {
        Button {
            onShowOTP()
        } label: {
            AppActionTile(
                title: "OTP",
                systemImage: "number.square.fill",
                tone: dashboardGold
            )
        }
        .buttonStyle(.plain)
    }
}

private struct Sidebar: View {
    @ObservedObject var model: AppViewModel

    var body: some View {
        List {
            Section {
                SidebarStatusCard(
                    profile: model.profile,
                    pendingCount: model.pendingRequests.count,
                    unreadCount: model.unreadNotificationCount
                )
            }

            Section("Workspace") {
                ForEach(AppSection.allCases) { section in
                    Button {
                        model.selectedSection = section
                    } label: {
                        HStack {
                            Label(section.title, systemImage: section.systemImage)
                            Spacer()
                            if badgeCount(for: section) > 0 {
                                AppStatusTag(title: "\(badgeCount(for: section))", tone: dashboardAccent)
                            }
                        }
                    }
                    .buttonStyle(.plain)
                    .listRowBackground(
                        model.selectedSection == section
                            ? dashboardAccent.opacity(0.10)
                            : Color.clear
                    )
                }
            }
        }
        .navigationTitle("idp.global")
    }

    private func badgeCount(for section: AppSection) -> Int {
        switch section {
        case .overview:
            0
        case .requests:
            model.pendingRequests.count
        case .activity:
            model.unreadNotificationCount
        case .account:
            0
        }
    }
}

private struct SidebarStatusCard: View {
    let profile: MemberProfile?
    let pendingCount: Int
    let unreadCount: Int

    var body: some View {
        VStack(alignment: .leading, spacing: 10) {
            Text("Digital Passport")
                .font(.headline)

            Text(profile?.handle ?? "No passport active")
                .foregroundStyle(.secondary)

            HStack(spacing: 8) {
                AppStatusTag(title: "\(pendingCount) pending", tone: dashboardAccent)
                AppStatusTag(title: "\(unreadCount) unread", tone: dashboardGold)
            }
        }
        .padding(.vertical, 6)
    }
}