//
//  TaskOrderSelectViewModel.swift
//  suixinkan
//

import Foundation

/// 任务关联订单选择 ViewModel，对齐 Android `OrderSelectViewModel`。
final class TaskOrderSelectViewModel {

    private(set) var orders: [AvailableOrder] = []
    private(set) var selectedOrderNumber: String?
    private(set) var isLoading = false

    var onStateChange: (() -> Void)?
    var onShowMessage: ((String) -> Void)?

    private let appStore: AppStore

    init(appStore: AppStore = .shared, initialOrderNumber: String? = nil) {
        self.appStore = appStore
        let trimmed = initialOrderNumber?.trimmingCharacters(in: .whitespacesAndNewlines) ?? ""
        selectedOrderNumber = trimmed.isEmpty ? nil : trimmed
    }

    /// 拉取可选订单列表。
    func loadOrders(api: TaskAPI) async {
        isLoading = true
        notifyStateChange()
        defer {
            isLoading = false
            notifyStateChange()
        }

        let scenicId = appStore.currentScenicId
        guard scenicId > 0 else {
            orders = []
            onShowMessage?("请先选择景区")
            return
        }

        do {
            orders = try await api.availableOrders(scenicId: scenicId)
        } catch is CancellationError {
            return
        } catch {
            orders = []
            onShowMessage?(error.localizedDescription)
        }
    }

    /// 切换订单选中状态，再次点击同一项则取消。
    func toggleSelection(orderNumber: String) {
        if selectedOrderNumber == orderNumber {
            selectedOrderNumber = nil
        } else {
            selectedOrderNumber = orderNumber
        }
        notifyStateChange()
    }

    /// 确认选择并返回订单号。
    func confirmedOrderNumber() -> String? {
        selectedOrderNumber
    }

    private func notifyStateChange() {
        onStateChange?()
    }
}