import SwiftUI
import XuqmSDK

struct ChatView: View {
    let targetId: String
    let targetName: String
    let currentUserId: String

    @StateObject private var viewModel = ChatViewModel()
    @State private var scrollToBottom = false

    var body: some View {
        VStack(spacing: 0) {
            if viewModel.connectionStatus != "已连接" {
                Text(viewModel.connectionStatus)
                    .font(.caption)
                    .foregroundStyle(.white)
                    .padding(.vertical, 4)
                    .frame(maxWidth: .infinity)
                    .background(viewModel.connectionStatus.contains("错误") ? Color.red : Color.orange)
            }

            ScrollViewReader { proxy in
                ScrollView {
                    LazyVStack(spacing: 8) {
                        ForEach(viewModel.messages.reversed(), id: \.id) { message in
                            MessageBubble(message: message, currentUserId: currentUserId)
                                .id(message.id)
                                .rotationEffect(.degrees(180))
                        }

                        if viewModel.isLoading {
                            ProgressView()
                                .padding()
                                .rotationEffect(.degrees(180))
                        }
                    }
                    .padding()
                    .rotationEffect(.degrees(180))
                }
                .onChange(of: viewModel.messages.count) { _ in
                    if let first = viewModel.messages.first {
                        withAnimation {
                            proxy.scrollTo(first.id, anchor: .bottom)
                        }
                    }
                }
            }

            Divider()

            HStack(spacing: 12) {
                TextField("输入消息…", text: $viewModel.inputText, axis: .vertical)
                    .textFieldStyle(.roundedBorder)
                    .lineLimit(1...4)

                Button {
                    viewModel.sendText()
                } label: {
                    Image(systemName: "paperplane.fill")
                        .foregroundStyle(viewModel.inputText.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty ? Color.gray : Color.accentColor)
                }
                .disabled(viewModel.inputText.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty)
            }
            .padding()
        }
        .navigationTitle(targetName)
        #if os(iOS)
        .navigationBarTitleDisplayMode(.inline)
        #endif
        .onAppear {
            viewModel.setup(targetId: targetId, chatType: .single)
            viewModel.markRead()
        }
    }
}

struct MessageBubble: View {
    let message: ImMessage
    let currentUserId: String

    private var isOwn: Bool {
        message.fromUserId == currentUserId
    }

    var body: some View {
        HStack {
            if isOwn { Spacer(minLength: 40) }

            VStack(alignment: isOwn ? .trailing : .leading, spacing: 2) {
                Text(parseMessageText(message))
                    .padding(.horizontal, 12)
                    .padding(.vertical, 8)
                    .background(isOwn ? Color.accentColor.opacity(0.15) : Color.gray.opacity(0.2))
                    .clipShape(RoundedRectangle(cornerRadius: 16))
                    .foregroundStyle(.primary)

                HStack(spacing: 4) {
                    if isOwn {
                        Text(statusLabel(message.status))
                            .font(.caption2)
                            .foregroundStyle(.secondary)
                    }
                    Text(formatConversationTime(message.createdAt))
                        .font(.caption2)
                        .foregroundStyle(.secondary)
                }
            }

            if !isOwn { Spacer(minLength: 40) }
        }
    }
}