import SwiftUI

struct ConnectView: View {
    @StateObject private var vm = ConnectViewModel()
    @State private var navigateToDashboard = false
    @FocusState private var focused: ConnectField?

    var body: some View {
        NavigationStack {
            ZStack {
                Color.white.ignoresSafeArea()

                ScrollView {
                    VStack(spacing: 0) {
                        // Logo
                        Image("nas_logo_clean")
                            .resizable()
                            .scaledToFit()
                            .frame(width: 44, height: 44)
                            .clipShape(RoundedRectangle(cornerRadius: 11, style: .continuous))
                            .padding(.top, 44)
                            .padding(.bottom, 24)

                        // Protocol picker
                        HStack(spacing: 0) {
                            ForEach(NASProtocol.allCases, id: \.self) { proto in
                                Button {
                                    withAnimation(.spring(response: 0.25, dampingFraction: 0.8)) {
                                        vm.selectedProtocol = proto
                                    }
                                } label: {
                                    Text(proto.rawValue)
                                        .font(.system(size: 13, weight: .medium))
                                        .foregroundStyle(vm.selectedProtocol == proto ? AppTheme.ink : AppTheme.inkTertiary)
                                        .frame(maxWidth: .infinity)
                                        .padding(.vertical, 8)
                                        .background(
                                            RoundedRectangle(cornerRadius: 8, style: .continuous)
                                                .fill(vm.selectedProtocol == proto ? Color.white : Color.clear)
                                                .shadow(
                                                    color: vm.selectedProtocol == proto ? .black.opacity(0.07) : .clear,
                                                    radius: 4, x: 0, y: 1
                                                )
                                        )
                                }
                                .buttonStyle(PlainButtonStyle())
                            }
                        }
                        .padding(4)
                        .background(AppTheme.surfaceSunken)
                        .clipShape(RoundedRectangle(cornerRadius: 11, style: .continuous))
                        .padding(.horizontal, AppTheme.hPad)
                        .padding(.bottom, 16)

                        // Form card
                        VStack(spacing: 0) {
                            formField(
                                icon: "network",
                                placeholder: "IP address or hostname",
                                text: $vm.host,
                                field: .host,
                                keyboard: .URL
                            )
                            hairline
                            formField(
                                icon: "person",
                                placeholder: "Username",
                                text: $vm.username,
                                field: .username,
                                keyboard: .emailAddress
                            )
                            hairline
                            secureField(
                                icon: "lock",
                                placeholder: "Password",
                                text: $vm.password,
                                field: .password
                            )
                            hairline
                            folderRow
                        }
                        .background(Color.white)
                        .clipShape(RoundedRectangle(cornerRadius: AppTheme.radius, style: .continuous))
                        .overlay(
                            RoundedRectangle(cornerRadius: AppTheme.radius, style: .continuous)
                                .stroke(
                                    vm.isConnected ? AppTheme.positive.opacity(0.4) :
                                    vm.verifyError != nil ? AppTheme.destructive.opacity(0.4) :
                                    AppTheme.cardBorderColor,
                                    lineWidth: vm.isConnected || vm.verifyError != nil ? 1 : 0.5
                                )
                        )
                        .shadow(color: AppTheme.cardShadow, radius: 12, x: 0, y: 2)
                        .padding(.horizontal, AppTheme.hPad)
                        .animation(.spring(response: 0.3, dampingFraction: 0.8), value: vm.isConnected)
                        .animation(.spring(response: 0.3, dampingFraction: 0.8), value: vm.verifyError != nil)

                        // Feedback
                        Group {
                            if let error = vm.verifyError {
                                HStack(spacing: 6) {
                                    Image(systemName: "exclamationmark.circle")
                                        .font(.system(size: 13))
                                    Text(error)
                                        .font(AppTheme.caption())
                                }
                                .foregroundStyle(AppTheme.destructive)
                                .padding(.top, 10)
                                .padding(.horizontal, AppTheme.hPad)
                                .transition(.opacity.combined(with: .move(edge: .top)))
                            } else if vm.isConnected {
                                HStack(spacing: 6) {
                                    Image(systemName: "checkmark.circle")
                                        .font(.system(size: 13))
                                    Text("Connected successfully")
                                        .font(AppTheme.caption())
                                }
                                .foregroundStyle(AppTheme.positive)
                                .padding(.top, 10)
                                .padding(.horizontal, AppTheme.hPad)
                                .transition(.opacity.combined(with: .move(edge: .top)))
                            }
                        }
                        .animation(.spring(response: 0.3, dampingFraction: 0.8), value: vm.verifyError)
                        .animation(.spring(response: 0.3, dampingFraction: 0.8), value: vm.isConnected)

                        // Button — below the card with deliberate gap
                        Spacer().frame(height: 20)

                        Button(action: {
                            if vm.isConnected { navigateToDashboard = true }
                            else { Task { await vm.verify() } }
                        }) {
                            Group {
                                if vm.isVerifying {
                                    ProgressView().tint(.white)
                                } else {
                                    Text(vm.isConnected ? "Continue" : "Connect")
                                }
                            }
                        }
                        .buttonStyle(PrimaryButtonStyle(
                            color: vm.isConnected ? AppTheme.positive : AppTheme.ink
                        ))
                        .padding(.horizontal, AppTheme.hPad)
                        .disabled(!vm.canConnect)
                        .animation(.spring(response: 0.3, dampingFraction: 0.8), value: vm.isConnected)

                        Spacer().frame(height: 40)
                    }
                }
            }
            .navigationTitle("Connect to NAS")
            .navigationBarTitleDisplayMode(.inline)
            .navigationDestination(isPresented: $navigateToDashboard) { MainTabView() }
            .sheet(isPresented: $vm.showFolderBrowser) {
                if let conn = ConnectionStore.shared.savedConnection {
                    BrowseView(connection: conn, selectedPath: $vm.remotePath)
                }
            }
        }
    }

    // MARK: — Sub-views

    private var hairline: some View {
        Rectangle()
            .fill(AppTheme.separator)
            .frame(height: 0.5)
            .padding(.leading, 44)
    }

    private var folderRow: some View {
        Button(action: { if vm.isConnected { vm.showFolderBrowser = true } }) {
            HStack(spacing: 12) {
                Image(systemName: "folder")
                    .font(.system(size: 14, weight: .regular))
                    .foregroundStyle(vm.isConnected ? AppTheme.inkSecondary : AppTheme.inkQuaternary)
                    .frame(width: 20)
                Text(vm.remotePath == "/" ? "Destination folder" : vm.remotePath)
                    .font(AppTheme.body())
                    .foregroundStyle(vm.remotePath == "/" ? AppTheme.inkTertiary : AppTheme.ink)
                    .lineLimit(1)
                Spacer()
                Image(systemName: "chevron.right")
                    .font(.system(size: 12, weight: .medium))
                    .foregroundStyle(AppTheme.inkQuaternary)
            }
            .padding(.horizontal, 16)
            .padding(.vertical, 14)
        }
        .buttonStyle(ScaleButtonStyle())
    }

    private func formField(
        icon: String,
        placeholder: String,
        text: Binding<String>,
        field: ConnectField,
        keyboard: UIKeyboardType
    ) -> some View {
        HStack(spacing: 12) {
            Image(systemName: icon)
                .font(.system(size: 14, weight: .regular))
                .foregroundStyle(AppTheme.inkSecondary)
                .frame(width: 20)
            TextField(placeholder, text: text)
                .font(AppTheme.body())
                .foregroundStyle(AppTheme.ink)
                .keyboardType(keyboard)
                .autocorrectionDisabled()
                .textInputAutocapitalization(.never)
                .focused($focused, equals: field)
        }
        .padding(.horizontal, 16)
        .padding(.vertical, 14)
    }

    private func secureField(
        icon: String,
        placeholder: String,
        text: Binding<String>,
        field: ConnectField
    ) -> some View {
        HStack(spacing: 12) {
            Image(systemName: icon)
                .font(.system(size: 14, weight: .regular))
                .foregroundStyle(AppTheme.inkSecondary)
                .frame(width: 20)
            SecureField(placeholder, text: text)
                .font(AppTheme.body())
                .foregroundStyle(AppTheme.ink)
                .focused($focused, equals: field)
        }
        .padding(.horizontal, 16)
        .padding(.vertical, 14)
    }
}