import SwiftUI

struct SendMessageFormView: View {
    @Environment(\.dismiss) private var dismiss
    @ObservedObject var model: MessagesViewModel
    @State private var phoneNumber = ""
    @State private var content = ""
    @State private var validationMessage: String?

    private var trimmedPhoneNumber: String {
        phoneNumber.trimmingCharacters(in: .whitespacesAndNewlines)
    }

    private var trimmedContent: String {
        content.trimmingCharacters(in: .whitespacesAndNewlines)
    }

    private var canSend: Bool {
        !trimmedPhoneNumber.isEmpty && !trimmedContent.isEmpty
    }

    var body: some View {
        NavigationStack {
            ZStack {
                AITheme.canvas.ignoresSafeArea()
                ScrollView {
                    VStack(spacing: 12) {
                        AICard {
                            VStack(alignment: .leading, spacing: 14) {
                                Picker("实例", selection: Binding(
                                    get: { model.selectedInstanceID ?? model.instances.first?.id },
                                    set: { model.selectedInstanceID = $0 }
                                )) {
                                    ForEach(model.instances) { instance in
                                        Text(instance.name).tag(Optional(instance.id))
                                    }
                                }
                                .pickerStyle(.menu)

                                TextField("收件号码", text: $phoneNumber)
                                    .textFieldStyle(AIFieldStyle())

                                TextField("消息内容", text: $content, axis: .vertical)
                                    .textFieldStyle(.plain)
                                    .padding(.horizontal, 12)
                                    .frame(minHeight: AITheme.buttonHeight)
                                    .background(AITheme.canvas)
                                    .clipShape(RoundedRectangle(cornerRadius: AITheme.buttonRadius))
                                    .overlay {
                                        RoundedRectangle(cornerRadius: AITheme.buttonRadius)
                                            .strokeBorder(AITheme.line)
                                    }
                                    .lineLimit(4...8)
                            }
                        }
                        if let validationMessage {
                            Text(validationMessage)
                                .font(.subheadline)
                                .foregroundStyle(AITheme.danger)
                                .frame(maxWidth: .infinity, alignment: .leading)
                        }
                    }
                    .padding(16)
                }
            }
            .navigationTitle("发送消息")
            .toolbar {
                ToolbarItem(placement: .cancellationAction) {
                    Button("取消") { dismiss() }
                        .buttonStyle(AIButtonStyle(kind: .secondary, size: .regular))
                }
                ToolbarItem(placement: .confirmationAction) {
                    Button("发送") { send() }
                        .buttonStyle(AIButtonStyle(kind: .primary, size: .regular))
                        .disabled(!canSend)
                }
            }
        }
    }

    private func send() {
        Task {
            do {
                try await model.send(phoneNumber: trimmedPhoneNumber, content: trimmedContent)
                phoneNumber = ""
                content = ""
                validationMessage = nil
                dismiss()
            } catch {
                validationMessage = "发送失败，请检查号码、内容和实例登录状态。"
            }
        }
    }
}