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 Wi-Fi, Spotlight, Clock, Battery and Control Center stay visible; macOS won't let any third-party app move them.")
            }
        }
    }

    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: {
            // Preserve the symbol's aspect ratio: forcing wide symbols like the
            // battery into a square stretches them into a blocky shape.
            Image(nsImage: item.icon)
                .resizable()
                .scaledToFit()
                .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) }
        }
    }
}