import SwiftUI

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

    @State private var selectedRequestID: ApprovalRequest.ID?
    @State private var searchText = ""
    @State private var isSearchPresented = false

    var body: some View {
        Group {
            if usesRegularNavigation {
                RegularHomeContainer(
                    model: model,
                    selectedRequestID: $selectedRequestID,
                    searchText: $searchText,
                    isSearchPresented: $isSearchPresented
                )
            } else {
                CompactHomeContainer(
                    model: model,
                    selectedRequestID: $selectedRequestID,
                    searchText: $searchText,
                    isSearchPresented: $isSearchPresented
                )
            }
        }
        .onAppear(perform: syncSelection)
        .onChange(of: model.requests.map(\.id)) { _, _ in
            syncSelection()
        }
    }

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

    private func syncSelection() {
        if let selectedRequestID,
           model.requests.contains(where: { $0.id == selectedRequestID }) {
            return
        }

        selectedRequestID = model.pendingRequests.first?.id ?? model.requests.first?.id
    }
}

private struct CompactHomeContainer: View {
    @ObservedObject var model: AppViewModel
    @Binding var selectedRequestID: ApprovalRequest.ID?
    @Binding var searchText: String
    @Binding var isSearchPresented: Bool

    var body: some View {
        TabView(selection: $model.selectedSection) {
            ForEach(AppSection.allCases) { section in
                NavigationStack {
                    sectionContent(for: section)
                        .navigationDestination(for: ApprovalRequest.ID.self) { requestID in
                            ApprovalDetailView(model: model, requestID: requestID, dismissOnResolve: true)
                        }
                        .toolbar {
                            if section == .inbox {
                                InboxToolbar(model: model, isSearchPresented: $isSearchPresented)
                            }
                        }
                }
                .tag(section)
                .tabItem {
                    Label(section.title, systemImage: section.systemImage)
                }
            }
        }
        .idpTabBarChrome()
    }

    @ViewBuilder
    private func sectionContent(for section: AppSection) -> some View {
        switch section {
        case .inbox:
            InboxListView(
                model: model,
                selectedRequestID: $selectedRequestID,
                searchText: $searchText,
                isSearchPresented: $isSearchPresented,
                usesSelection: false
            )
        case .notifications:
            NotificationCenterView(model: model)
        case .devices:
            DevicesView(model: model)
        case .identity:
            IdentityView(model: model)
        case .settings:
            SettingsView(model: model)
        }
    }
}

private struct RegularHomeContainer: View {
    @ObservedObject var model: AppViewModel
    @Binding var selectedRequestID: ApprovalRequest.ID?
    @Binding var searchText: String
    @Binding var isSearchPresented: Bool

    var body: some View {
        NavigationSplitView {
            SidebarView(model: model)
                .navigationSplitViewColumnWidth(min: 250, ideal: 280, max: 320)
        } content: {
            contentColumn
        } detail: {
            detailColumn
        }
        .navigationSplitViewStyle(.balanced)
    }

    @ViewBuilder
    private var contentColumn: some View {
        switch model.selectedSection {
        case .inbox:
            InboxListView(
                model: model,
                selectedRequestID: $selectedRequestID,
                searchText: $searchText,
                isSearchPresented: $isSearchPresented,
                usesSelection: true
            )
            .toolbar {
                InboxToolbar(model: model, isSearchPresented: $isSearchPresented)
            }
        case .notifications:
            NotificationCenterView(model: model)
        case .devices:
            DevicesView(model: model)
        case .identity:
            IdentityView(model: model)
        case .settings:
            SettingsView(model: model)
        }
    }

    @ViewBuilder
    private var detailColumn: some View {
        switch model.selectedSection {
        case .inbox:
            ApprovalDetailView(model: model, requestID: selectedRequestID)
        case .notifications:
            EmptyPaneView(
                title: "Notification history",
                message: "Select the inbox to review request context side by side.",
                systemImage: "bell"
            )
        case .devices:
            EmptyPaneView(
                title: "Trusted hardware",
                message: "Device trust and last-seen state appear here while you manage your passport.",
                systemImage: "desktopcomputer"
            )
        case .identity:
            EmptyPaneView(
                title: "Identity overview",
                message: "Your profile, recovery status, and pairing state stay visible here.",
                systemImage: "person.crop.rectangle.stack"
            )
        case .settings:
            EmptyPaneView(
                title: "Preferences",
                message: "Notification delivery and demo controls live in settings.",
                systemImage: "gearshape"
            )
        }
    }
}

struct SidebarView: View {
    @ObservedObject var model: AppViewModel

    var body: some View {
        List {
            ForEach(Array(AppSection.allCases.enumerated()), id: \.element.id) { index, section in
                Button {
                    model.selectedSection = section
                    Haptics.selection()
                } label: {
                    HStack(spacing: 12) {
                        Label(section.title, systemImage: section.systemImage)
                        Spacer()
                        if badgeCount(for: section) > 0 {
                            StatusPill(title: "\(badgeCount(for: section))", color: IdP.tint)
                        }
                    }
                    .padding(.vertical, 6)
                }
                .buttonStyle(.plain)
                .listRowBackground(model.selectedSection == section ? IdP.tint.opacity(0.08) : Color.clear)
                .keyboardShortcut(shortcut(for: index), modifiers: .command)
            }
        }
        .navigationTitle("idp.global")
    }

    private func badgeCount(for section: AppSection) -> Int {
        switch section {
        case .inbox:
            model.pendingRequests.count
        case .notifications:
            model.unreadNotificationCount
        case .devices:
            max((model.profile?.deviceCount ?? 1) - 1, 0)
        case .identity, .settings:
            0
        }
    }

    private func shortcut(for index: Int) -> KeyEquivalent {
        let value = max(1, min(index + 1, 9))
        return KeyEquivalent(Character("\(value)"))
    }
}

private struct InboxToolbar: ToolbarContent {
    @ObservedObject var model: AppViewModel
    @Binding var isSearchPresented: Bool

    var body: some ToolbarContent {
        ToolbarItem(placement: .idpTrailingToolbar) {
            HStack(spacing: 8) {
                Button {
                    isSearchPresented = true
                } label: {
                    Image(systemName: "magnifyingglass")
                        .font(.headline)
                        .foregroundStyle(.primary)
                }
                .accessibilityLabel("Search inbox")

                Button {
                    model.selectedSection = .identity
                } label: {
                    MonogramAvatar(title: model.profile?.name ?? "idp.global", size: 28)
                }
                .accessibilityLabel("Open identity")
            }
            .padding(.horizontal, 10)
            .padding(.vertical, 8)
            .background(
                RoundedRectangle(cornerRadius: 18, style: .continuous)
                    .fill(.clear)
                    .idpGlassChrome()
            )
            .overlay(
                RoundedRectangle(cornerRadius: 18, style: .continuous)
                    .stroke(Color.white.opacity(0.16), lineWidth: 1)
            )
        }
    }
}