import SwiftUI

/// Shared native chat history and composer. History stays visible while the
/// signaling stream reconnects; only sending depends on current admission.
@MainActor public struct ChatView: View {
  @ObservedObject private var call: Call
  @StateObject private var draft: ChatDraft

  public init(call: Call, draft: ChatDraft? = nil) {
    self.call = call
    _draft = StateObject(wrappedValue: draft ?? ChatDraft())
  }

  public var body: some View {
    VStack(alignment: .leading, spacing: 12) {
      ScrollViewReader { proxy in
        ScrollView {
          VStack(alignment: .leading, spacing: 8) {
            if call.chat.isEmpty {
              Text("Messages sent during this call appear here.")
                .foregroundStyle(.secondary)
            }
            ForEach(Array(call.chat.enumerated()), id: \.offset) { _, line in
              Text(line).textSelection(.enabled)
                .padding(10).frame(maxWidth: .infinity, alignment: .leading)
                .background(.quaternary.opacity(0.5), in: RoundedRectangle(cornerRadius: 10))
            }
            Color.clear.frame(height: 1).id("chat-bottom")
          }.frame(maxWidth: .infinity, alignment: .leading)
        }
        .accessibilityIdentifier("chatHistory")
        .defaultScrollAnchor(.bottom)
        .onAppear { proxy.scrollTo("chat-bottom", anchor: .bottom) }
        .onChange(of: call.chat) { _, _ in
          proxy.scrollTo("chat-bottom", anchor: .bottom)
        }
      }
      if call.reconnecting {
        Text("Reconnecting. You can send again when the call reconnects.")
          .font(.footnote).foregroundStyle(.secondary)
      }
      HStack {
        TextField("Message to everyone", text: $draft.text)
          .textFieldStyle(.roundedBorder)
          .accessibilityIdentifier("chatComposer")
          .onSubmit(send)
        Button("Send", systemImage: "arrow.up.circle.fill", action: send)
          .buttonStyle(.borderedProminent)
          .disabled(draft.text.isEmpty || call.state?.phase != "admitted")
      }
    }
  }

  private func send() {
    guard call.state?.phase == "admitted" else { return }
    if call.sendChat(draft.text) { draft.text = "" }
  }
}