ChatTemplateDropdownView.swift

import ConversationServiceProvider
import AppKit
import SwiftUI

public struct ChatTemplateDropdownView: View {
    @Binding var templates: [ChatTemplate]
    let onSelect: (ChatTemplate) -> Void
    @State private var selectedIndex = 0
    @State private var frameHeight: CGFloat = 0
    @State private var localMonitor: Any? = nil

    public var body: some View {
        VStack(alignment: .leading, spacing: 0) {
            ForEach(Array(templates.enumerated()), id: \.element.id) { index, template in
                HStack {
                    Text("/" + template.id)
                        .hoverPrimaryForeground(isHovered: selectedIndex == index)
                    Spacer()
                    Text(template.shortDescription)
                        .hoverSecondaryForeground(isHovered: selectedIndex == index)
                }
                .padding(.horizontal, 8)
                .padding(.vertical, 6)
                .contentShape(Rectangle())
                .onTapGesture {
                    onSelect(template)
                }
                .hoverBackground(isHovered: selectedIndex == index)
                .onHover { isHovered in
                    if isHovered {
                        selectedIndex = index
                    }
                }
            }
        }
        .background(
            GeometryReader { geometry in
                Color.clear
                    .onAppear { frameHeight = geometry.size.height }
                    .onChange(of: geometry.size.height) { newHeight in
                        frameHeight = newHeight
                    }
            }
        )
        .background(.ultraThickMaterial)
        .cornerRadius(6)
        .shadow(radius: 2)
        .overlay(
            RoundedRectangle(cornerRadius: 6)
                .stroke(Color(nsColor: .separatorColor), lineWidth: 1)
        )
        .frame(maxWidth: .infinity)
        .offset(y: -1 * frameHeight)
        .onChange(of: templates) { _ in
            selectedIndex = 0
        }
        .onAppear {
            selectedIndex = 0
            localMonitor = NSEvent.addLocalMonitorForEvents(matching: .keyDown) { event in
                switch event.keyCode {
                case 126: // Up arrow
                    moveSelection(up: true)
                case 125: // Down arrow
                    moveSelection(up: false)
                case 36: // Return key
                    handleEnter()
                case 48: // Tab key
                    handleTab()
                    return nil // not forwarding the Tab Event which will replace the typed message to "\t"
                default:
                    break
                }
                return event
            }
        }
        .onDisappear {
            if let monitor = localMonitor {
                NSEvent.removeMonitor(monitor)
                localMonitor = nil
            }
        }
    }

    private func moveSelection(up: Bool) {
        guard !templates.isEmpty else { return }
        let lowerBound = 0
        let upperBound = templates.count - 1
        let newIndex = selectedIndex + (up ? -1 : 1)
        selectedIndex = newIndex < lowerBound ? upperBound : (newIndex > upperBound ? lowerBound : newIndex)
    }
    
    private func handleEnter() {
        handleTemplateSelection()
    }
    
    private func handleTab() {
        handleTemplateSelection()
    }
    
    private func handleTemplateSelection() {
        if templates.count > 0 && selectedIndex < templates.count {
            onSelect(templates[selectedIndex])
        }
    }
}