import SwiftUI

private let kDevUrlKey = "dev_custom_start_url"

/// Debug-only URL switcher. Mirrors Android's DevUrlSettingsActivity.
/// Production builds should never show or use this.
enum DevUrlSettings {
    static var effectiveStartUrl: String? {
        #if DEBUG
        return UserDefaults.standard.string(forKey: kDevUrlKey)?.nonEmpty
        #else
        return nil
        #endif
    }

    static func save(_ url: String) {
        UserDefaults.standard.set(url.trimmingCharacters(in: .whitespaces), forKey: kDevUrlKey)
    }

    static func clear() {
        UserDefaults.standard.removeObject(forKey: kDevUrlKey)
    }
}

#if DEBUG
struct DevUrlSettingsSheet: View {
    @Environment(\.dismiss) private var dismiss
    @State private var input: String = DevUrlSettings.effectiveStartUrl ?? ""

    var body: some View {
        NavigationStack {
            Form {
                Section {
                    TextField("自定义 URL（留空使用默认）", text: $input, axis: .vertical)
                        .keyboardType(.URL)
                        .autocorrectionDisabled()
                        .textInputAutocapitalization(.never)
                        .lineLimit(4)
                } header: {
                    Text("调试用后端地址")
                } footer: {
                    Text("设置后重启 App 生效。留空则使用 AppConfig.startUrl。")
                }

                Section {
                    Button("使用默认地址") {
                        input = ""
                    }
                    .foregroundStyle(.secondary)
                }
            }
            .navigationTitle("开发环境设置")
            .navigationBarTitleDisplayMode(.inline)
            .toolbar {
                ToolbarItem(placement: .confirmationAction) {
                    Button("保存") {
                        let trimmed = input.trimmingCharacters(in: .whitespaces)
                        if trimmed.isEmpty {
                            DevUrlSettings.clear()
                        } else {
                            DevUrlSettings.save(trimmed)
                        }
                        dismiss()
                    }
                }
                ToolbarItem(placement: .cancellationAction) {
                    Button("取消") { dismiss() }
                }
            }
        }
    }
}
#endif

private extension String {
    var nonEmpty: String? { isEmpty ? nil : self }
}