import SwiftUI
import AppKit

/// The top bar panel shown from the menu bar hamburger icon.
struct TopBarView: View {
    @ObservedObject var model: AppListModel
    @ObservedObject var menuBar: MenuBarItemManager
    @ObservedObject var hider: MenuBarHider

    var body: some View {
        VStack(spacing: 0) {
            header
            Divider()
            ScrollView {
                VStack(alignment: .leading, spacing: 0) {
                    menuBarSection

                    Divider().padding(.vertical, 4)

                    section(title: "Apps", apps: model.regularApps, emptyText: "No apps running")

                    Divider().padding(.vertical, 4)

                    backgroundSection
                }
                .padding(.vertical, 4)
            }
            .frame(maxHeight: 420)

            Divider()
            footer
        }
        .frame(width: 320)
        .onAppear {
            model.refresh()
            menuBar.refresh()
        }
    }

    private var header: some View {
        HStack(spacing: 8) {
            Image(systemName: "line.3.horizontal")
                .foregroundStyle(.secondary)
            Text("SimpleTopBar")
                .font(.headline)
            Spacer()
            Button {
                model.refresh()
                menuBar.refresh()
            } label: {
                Image(systemName: "arrow.clockwise")
            }
            .buttonStyle(.plain)
            .help("Refresh")
        }
        .padding(.horizontal, 12)
        .padding(.vertical, 8)
    }

    /// The hamburger tray: every other app's menu bar item lives here.
    private var menuBarSection: some View {
        VStack(alignment: .leading, spacing: 0) {
            HStack(spacing: 6) {
                Text("MENU BAR")
                    .font(.caption2)
                    .fontWeight(.semibold)
                    .foregroundStyle(.secondary)
                Spacer()
                Text("\(menuBar.items.count)")
                    .font(.caption2)
                    .foregroundStyle(.tertiary)
                    .padding(.horizontal, 6)
                    .padding(.vertical, 1)
                    .background(Capsule().fill(Color.secondary.opacity(0.15)))
            }
            .padding(.horizontal, 12)
            .padding(.top, 4)
            .padding(.bottom, 4)

            if !menuBar.authorized {
                VStack(alignment: .leading, spacing: 4) {
                    Text("Grant Accessibility to collect and open menu bar items.")
                        .font(.caption)
                        .foregroundStyle(.secondary)
                    Button("Grant Accessibility…") {
                        AccessibilityPermission.request()
                        menuBar.refresh()
                    }
                    .buttonStyle(.borderedProminent)
                    .controlSize(.small)
                }
                .padding(.horizontal, 12)
                .padding(.vertical, 4)
            } else if menuBar.items.isEmpty {
                Text("No menu bar items found")
                    .font(.caption)
                    .foregroundStyle(.tertiary)
                    .padding(.horizontal, 12)
                    .padding(.vertical, 4)
            } else {
                LazyVGrid(columns: [GridItem(.adaptive(minimum: 34), spacing: 6)], spacing: 6) {
                    ForEach(menuBar.items) { item in
                        MenuBarTile(item: item, menuBar: menuBar)
                    }
                }
                .padding(.horizontal, 12)
            }

            if menuBar.authorized {
                Toggle(isOn: $hider.enabled) {
                    Text("Hide items from the menu bar")
                        .font(.caption)
                }
                .toggleStyle(.switch)
                .controlSize(.mini)
                .padding(.horizontal, 12)
                .padding(.top, 6)
                .help("Best-effort: pushes other apps' icons off the menu bar so they only live here. Apple's Spotlight, Clock, Battery and Control Center stay pinned on the right and cannot be moved by any third-party app.")
            }
        }
    }

    private func section(title: String, apps: [RunningApp], emptyText: String) -> some View {
        VStack(alignment: .leading, spacing: 0) {
            Text(title.uppercased())
                .font(.caption2)
                .fontWeight(.semibold)
                .foregroundStyle(.secondary)
                .padding(.horizontal, 12)
                .padding(.top, 4)
                .padding(.bottom, 2)

            if apps.isEmpty {
                Text(emptyText)
                    .font(.caption)
                    .foregroundStyle(.tertiary)
                    .padding(.horizontal, 12)
                    .padding(.vertical, 4)
            } else {
                ForEach(apps) { app in
                    AppRow(app: app, model: model)
                }
            }
        }
    }

    /// Collapsible dropdown for background apps. When collapsed it is a single
    /// header row; when expanded it reveals a limited number of apps and hides
    /// the overflow behind "Show N more".
    private var backgroundSection: some View {
        VStack(alignment: .leading, spacing: 0) {
            Button {
                model.toggleBackgroundExpanded()
            } label: {
                HStack(spacing: 6) {
                    Image(systemName: model.backgroundExpanded ? "chevron.down" : "chevron.right")
                        .font(.caption2)
                        .foregroundStyle(.secondary)
                        .frame(width: 10)
                    Text("Background Apps")
                        .font(.caption2)
                        .fontWeight(.semibold)
                        .foregroundStyle(.secondary)
                    Spacer()
                    Text("\(model.backgroundApps.count)")
                        .font(.caption2)
                        .foregroundStyle(.tertiary)
                        .padding(.horizontal, 6)
                        .padding(.vertical, 1)
                        .background(Capsule().fill(Color.secondary.opacity(0.15)))
                }
                .contentShape(Rectangle())
            }
            .buttonStyle(.plain)
            .padding(.horizontal, 12)
            .padding(.vertical, 4)
            .help(model.backgroundExpanded ? "Collapse background apps" : "Expand background apps")

            if model.backgroundExpanded {
                if model.backgroundApps.isEmpty {
                    Text("No background apps")
                        .font(.caption)
                        .foregroundStyle(.tertiary)
                        .padding(.horizontal, 12)
                        .padding(.vertical, 4)
                } else {
                    ForEach(model.visibleBackgroundApps) { app in
                        AppRow(app: app, model: model)
                    }

                    if model.canShowMoreBackgroundApps {
                        Button {
                            model.showMoreBackgroundApps()
                        } label: {
                            Label(
                                "Show \(model.hiddenBackgroundCount) more",
                                systemImage: "ellipsis.circle"
                            )
                            .font(.caption)
                        }
                        .buttonStyle(.plain)
                        .foregroundStyle(.secondary)
                        .padding(.horizontal, 12)
                        .padding(.vertical, 4)
                    }
                }
            }
        }
    }

    private var footer: some View {
        HStack(spacing: 8) {
            Text("\(model.regularApps.count) apps · \(model.backgroundApps.count) background")
                .font(.caption2)
                .foregroundStyle(.tertiary)
            Spacer()
            Button(LoginItem.isEnabled ? "Disable Launch at Login" : "Launch at Login") {
                if !LoginItem.toggle() {
                    let alert = NSAlert()
                    alert.messageText = "Could not update Launch at Login"
                    alert.informativeText = "Launch at Login requires a signed app bundle in /Applications. It is not available when running via `swift run`."
                    alert.alertStyle = .warning
                    alert.addButton(withTitle: "OK")
                    alert.runModal()
                }
            }
            .font(.caption2)
            .buttonStyle(.plain)

            Button("Quit") { NSApp.terminate(nil) }
                .font(.caption2)
                .buttonStyle(.plain)
                .keyboardShortcut("q")
        }
        .padding(.horizontal, 12)
        .padding(.vertical, 6)
    }
}

private struct MenuBarTile: View {
    let item: MenuBarItem
    @ObservedObject var menuBar: MenuBarItemManager

    var body: some View {
        Button {
            menuBar.press(item)
        } label: {
            Image(nsImage: item.appIcon)
                .resizable()
                .frame(width: 20, height: 20)
                .padding(6)
                .background(
                    RoundedRectangle(cornerRadius: 6)
                        .fill(Color.secondary.opacity(0.12))
                )
        }
        .buttonStyle(.plain)
        .help("\(item.appName) — \(item.title)")
    }
}

private struct AppRow: View {
    let app: RunningApp
    @ObservedObject var model: AppListModel

    var body: some View {
        Button {
            model.activate(app)
        } label: {
            HStack(spacing: 8) {
                Image(nsImage: app.icon)
                    .resizable()
                    .frame(width: 18, height: 18)
                Text(app.name)
                    .font(.system(size: 12))
                    .lineLimit(1)
                    .truncationMode(.middle)
                if app.isActive {
                    Image(systemName: "circle.fill")
                        .font(.system(size: 5))
                        .foregroundStyle(Color.accentColor)
                }
                Spacer(minLength: 0)
            }
            .contentShape(Rectangle())
            .padding(.horizontal, 12)
            .padding(.vertical, 3)
            .opacity(app.isHidden ? 0.55 : 1)
        }
        .buttonStyle(.plain)
        .help("Activate \(app.name)")
        .contextMenu {
            Button("Activate") { model.activate(app) }
            Button(app.isHidden ? "Unhide" : "Hide") { model.toggleHidden(app) }
            Divider()
            Button("Quit \(app.name)") { model.quit(app) }
        }
    }
}