import LChatCore
import SwiftUI
import WebKit

// 🤖 A GROUP chat's shared app surface: the selected added app's interface,
// rendered by the shared embed page (FeedWebCache) — seeded with this thread's
// key plus the app to show (app != nil). ONE cached page serves
// all the group's apps; switching apps is a JS call into it
// (WebBridge.setGroupApp), never a reload. NativeChatScreen swaps this in for
// the native feed when the header's view picker chooses an app.
struct GroupAppPane: View {
    @ObservedObject private var bridge: WebBridge
    let instance: SavedInstance
    let thread: ChatThread
    let myUserId: String
    let instanceKeyB64: String?
    let app: String

    @MainActor
    init(instance: SavedInstance, thread: ChatThread, myUserId: String,
         instanceKeyB64: String?, app: String) {
        self.instance = instance
        self.thread = thread
        self.myUserId = myUserId
        self.instanceKeyB64 = instanceKeyB64
        self.app = app
        bridge = FeedWebCache.shared.bridge(for: instance, thread: thread,
                                            myUserId: myUserId,
                                            instanceKeyB64: instanceKeyB64, app: app)
    }

    var body: some View {
        VStack(spacing: 0) {
            AppUpdateBar(bridge: bridge)
            ZStack {
                GroupAppWebView(instance: instance, thread: thread, myUserId: myUserId,
                                instanceKeyB64: instanceKeyB64, app: app)
                if !bridge.pageReady {
                    WebLoadingVeil().transition(.opacity)
                }
            }
        }
        .animation(.easeOut(duration: 0.25), value: bridge.pageReady)
        // Re-assert the selection on every appearance/switch. The boot seed
        // carries the app chosen at page-creation time; a still-booting page
        // ignores the JS no-op, so the ready flip re-asserts once more.
        .onAppear { bridge.setGroupApp(app) }
        .onChange(of: app) { _, newApp in bridge.setGroupApp(newApp) }
        .onChange(of: bridge.pageReady) { _, ready in
            if ready { bridge.setGroupApp(app) }
        }
    }
}

private struct GroupAppWebView: UIViewRepresentable {
    let instance: SavedInstance
    let thread: ChatThread
    let myUserId: String
    let instanceKeyB64: String?
    let app: String

    func makeUIView(context: Context) -> WKWebView {
        FeedWebCache.shared.webView(for: instance, thread: thread, myUserId: myUserId,
                                    instanceKeyB64: instanceKeyB64, app: app)
    }

    func updateUIView(_ web: WKWebView, context: Context) {}
}