import SwiftUI

struct BrowseView: View {
    let connection: NASConnection
    @Binding var selectedPath: String
    @Environment(\.dismiss) private var dismiss

    @State private var currentPath: String = "/"
    @State private var items: [NASItem] = []
    @State private var isLoading = false
    @State private var error: String? = nil
    @State private var showCreateFolder = false
    @State private var newFolderName = ""

    var body: some View {
        NavigationStack {
            ZStack {
                AppTheme.background.ignoresSafeArea()

                VStack(spacing: 0) {
                    // Path breadcrumb bar
                    HStack(spacing: 6) {
                        Image(systemName: "externaldrive")
                            .font(.system(size: 11, weight: .medium))
                            .foregroundStyle(AppTheme.inkTertiary)
                        Text(currentPath)
                            .font(.system(size: 12, weight: .regular))
                            .foregroundStyle(AppTheme.inkSecondary)
                            .lineLimit(1)
                            .truncationMode(.middle)
                        Spacer()
                    }
                    .padding(.horizontal, AppTheme.cardPad)
                    .padding(.vertical, 10)
                    .background(AppTheme.surfaceSunken)

                    Rectangle()
                        .fill(AppTheme.separator)
                        .frame(height: 0.5)

                    if isLoading {
                        loadingState
                    } else if let err = error {
                        errorState(err)
                    } else if items.isEmpty {
                        emptyState
                    } else {
                        folderList
                    }
                }
            }
            .navigationTitle("Choose folder")
            .navigationBarTitleDisplayMode(.inline)
            .toolbar {
                ToolbarItem(placement: .navigationBarLeading) {
                    Button("Cancel") { dismiss() }
                        .font(AppTheme.body())
                        .foregroundStyle(AppTheme.inkSecondary)
                }
                ToolbarItem(placement: .navigationBarTrailing) {
                    Button {
                        newFolderName = ""
                        showCreateFolder = true
                    } label: {
                        Image(systemName: "folder.badge.plus")
                            .foregroundStyle(AppTheme.inkSecondary)
                    }
                    .disabled(currentPath == "/" && connection.nasProtocol == .smb)
                }
            }
            .safeAreaInset(edge: .bottom) {
                selectButton
            }
            .alert("New folder", isPresented: $showCreateFolder) {
                TextField("Folder name", text: $newFolderName)
                Button("Create") { Task { await createFolder() } }
                Button("Cancel", role: .cancel) {}
            }
        }
        .task { await loadItems(path: currentPath) }
        .refreshable { await loadItems(path: currentPath) }
    }

    // MARK: — Sub-views

    private var loadingState: some View {
        VStack {
            Spacer()
            VStack(spacing: 12) {
                ProgressView()
                    .tint(AppTheme.inkTertiary)
                    .scaleEffect(1.1)
                Text("Loading…")
                    .font(AppTheme.caption())
                    .foregroundStyle(AppTheme.inkTertiary)
            }
            Spacer()
        }
    }

    private func errorState(_ message: String) -> some View {
        VStack {
            Spacer()
            VStack(spacing: 20) {
                // Icon
                ZStack {
                    Circle()
                        .fill(AppTheme.surfaceSunken)
                        .frame(width: 64, height: 64)
                    Image(systemName: "wifi.exclamationmark")
                        .font(.system(size: 24, weight: .light))
                        .foregroundStyle(AppTheme.inkSecondary)
                }

                VStack(spacing: 6) {
                    Text("Could not load folder")
                        .font(.system(size: 15, weight: .semibold))
                        .foregroundStyle(AppTheme.ink)
                    Text(message)
                        .font(AppTheme.caption())
                        .foregroundStyle(AppTheme.inkTertiary)
                        .multilineTextAlignment(.center)
                        .padding(.horizontal, 40)
                }

                Button(action: { Task { await loadItems(path: currentPath) } }) {
                    HStack(spacing: 6) {
                        Image(systemName: "arrow.clockwise")
                            .font(.system(size: 12, weight: .medium))
                        Text("Try again")
                            .font(.system(size: 13, weight: .medium))
                    }
                    .foregroundStyle(AppTheme.ink)
                    .padding(.horizontal, 16)
                    .padding(.vertical, 8)
                    .background(AppTheme.surfaceSunken)
                    .clipShape(RoundedRectangle(cornerRadius: 8, style: .continuous))
                }
                .buttonStyle(ScaleButtonStyle())
            }
            Spacer()
        }
    }

    private var emptyState: some View {
        VStack {
            Spacer()
            VStack(spacing: 10) {
                Image(systemName: "folder")
                    .font(.system(size: 28, weight: .ultraLight))
                    .foregroundStyle(AppTheme.inkQuaternary)
                Text("Empty folder")
                    .font(AppTheme.caption())
                    .foregroundStyle(AppTheme.inkTertiary)
            }
            Spacer()
        }
    }

    private var folderList: some View {
        List {
            if currentPath != "/" {
                Button(action: navigateUp) {
                    HStack(spacing: 10) {
                        Image(systemName: "arrow.up")
                            .font(.system(size: 13, weight: .medium))
                            .foregroundStyle(AppTheme.inkSecondary)
                            .frame(width: 22)
                        Text("Parent folder")
                            .font(AppTheme.body())
                            .foregroundStyle(AppTheme.inkSecondary)
                        Spacer()
                    }
                    .padding(.horizontal, 16)
                    .padding(.vertical, 13)
                }
                .buttonStyle(ScaleButtonStyle())
                .listRowInsets(EdgeInsets())
                .listRowSeparator(.hidden)
                .listRowBackground(Color.clear)
            }

            ForEach(items) { item in
                FolderRow(
                    item: item,
                    isSelected: selectedPath == item.path
                ) {
                    if item.isDirectory {
                        navigate(to: item.path)
                    } else {
                        selectedPath = item.path
                    }
                }
                .contextMenu {
                    if item.isDirectory {
                        Button {
                            navigate(to: item.path)
                        } label: {
                            Label("Open Folder", systemImage: "folder")
                        }
                        Button {
                            selectedPath = item.path
                        } label: {
                            Label("Select This Folder", systemImage: "checkmark.circle")
                        }
                    } else {
                        Button {
                            // Placeholder: Make available offline
                        } label: {
                            Label("Make Available Offline", systemImage: "arrow.down.circle")
                        }
                    }
                    Button(role: .destructive) {
                        // Placeholder: context-sensitive action
                    } label: {
                        Label("More Info", systemImage: "info.circle")
                    }
                }
                .listRowInsets(EdgeInsets())
                .listRowSeparator(.hidden)
                .listRowBackground(Color.clear)
            }
        }
        .listStyle(.plain)
        .background(AppTheme.background)
    }

    private var selectButton: some View {
        VStack(spacing: 0) {
            Rectangle()
                .fill(AppTheme.separator)
                .frame(height: 0.5)

            HStack(spacing: 12) {
                // Current path chip
                HStack(spacing: 5) {
                    Image(systemName: "folder.fill")
                        .font(.system(size: 11, weight: .medium))
                        .foregroundStyle(selectedPath == currentPath ? AppTheme.interactive : AppTheme.inkQuaternary)
                    Text(currentPath == "/" ? "Root" : (currentPath as NSString).lastPathComponent)
                        .font(.system(size: 12, weight: .medium))
                        .foregroundStyle(selectedPath == currentPath ? AppTheme.interactive : AppTheme.inkTertiary)
                        .lineLimit(1)
                }
                .padding(.horizontal, 10)
                .padding(.vertical, 6)
                .background(
                    RoundedRectangle(cornerRadius: 7, style: .continuous)
                        .fill(selectedPath == currentPath ? AppTheme.interactive.opacity(0.1) : AppTheme.surfaceSunken)
                )

                Spacer()

                Button(action: {
                    selectedPath = currentPath
                    dismiss()
                }) {
                    Text("Select")
                        .font(.system(size: 14, weight: .semibold))
                        .foregroundStyle(AppTheme.inkInverse)
                        .padding(.horizontal, 20)
                        .padding(.vertical, 10)
                        .background(currentPath == "/" && connection.nasProtocol == .smb ? AppTheme.inkQuaternary : AppTheme.ink)
                        .clipShape(RoundedRectangle(cornerRadius: 10, style: .continuous))
                }
                .buttonStyle(ScaleButtonStyle())
                .disabled(currentPath == "/" && connection.nasProtocol == .smb)
            }
            .padding(.horizontal, AppTheme.hPad)
            .padding(.vertical, 12)
            .background(AppTheme.background)
        }
    }

    // MARK: — Data

    private func loadItems(path: String) async {
        isLoading = true
        error = nil
        items = []
        do {
            let s: any NASTransferProtocol = connection.nasProtocol == .smb ? SMBService() : SFTPService()
            try await s.connect(to: connection.host, port: connection.port,
                                username: connection.username, password: connection.password)
            if path == "/" && connection.nasProtocol == .smb {
                let shareNames = try await s.listShares()
                items = shareNames.map { name in
                    NASItem(name: name, path: "/\(name)", isDirectory: true, size: 0, modifiedDate: nil)
                }
            } else {
                items = try await s.listDirectory(at: path).filter { $0.isDirectory }
            }
            s.disconnect()
        } catch let e as BackupError {
            self.error = e.errorDescription
        } catch {
            self.error = error.localizedDescription
        }
        isLoading = false
    }

    private func navigate(to path: String) {
        currentPath = path
        Task { await loadItems(path: path) }
    }

    private func navigateUp() {
        let parent = (currentPath as NSString).deletingLastPathComponent
        navigate(to: parent.isEmpty ? "/" : parent)
    }

    private func createFolder() async {
        guard !newFolderName.isEmpty else { return }
        let newPath = currentPath == "/" ? "/\(newFolderName)" : "\(currentPath)/\(newFolderName)"
        do {
            let s: any NASTransferProtocol = connection.nasProtocol == .smb ? SMBService() : SFTPService()
            try await s.connect(to: connection.host, port: connection.port,
                                username: connection.username, password: connection.password)
            try await s.createDirectory(at: newPath)
            s.disconnect()
            await loadItems(path: currentPath)
        } catch {}
    }
}