//
//  LocationReportHistoryViewModel.swift
//  suixinkan
//

import Foundation

/// 位置上报历史 ViewModel，对齐 Android `LocationReportHistoryViewModel`。
final class LocationReportHistoryViewModel {

    private(set) var reportList: [LocationReportHistoryItem] = []
    private(set) var selectedFilter: LocationReportFilterType = .all
    private(set) var isRefreshing = false
    private(set) var canLoadMore = false
    private(set) var startDate: Date?
    private(set) var endDate: Date?

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

    private let appStore: AppStore
    private var currentPage = 1
    private let pageSize = 10
    private var isLoading = false

    init(appStore: AppStore = .shared) {
        self.appStore = appStore
    }

    var startDateText: String { formattedDate(startDate) }
    var endDateText: String { formattedDate(endDate) }
    var hasDateFilter: Bool { startDate != nil || endDate != nil }

    /// 加载历史上报列表。
    func loadReportList(api: HomeAPI, refresh: Bool = false) async {
        guard !isLoading || refresh else { return }
        let staffId = appStore.userId.trimmingCharacters(in: .whitespacesAndNewlines)
        guard !staffId.isEmpty else {
            onShowMessage?("获取用户ID失败")
            return
        }

        if refresh {
            currentPage = 1
            isRefreshing = true
            notifyStateChange()
        }
        isLoading = true
        defer {
            isLoading = false
            isRefreshing = false
            notifyStateChange()
        }

        do {
            let response = try await api.locationReportList(
                staffId: staffId,
                page: currentPage,
                pageSize: pageSize,
                type: selectedFilter.typeCode,
                startDate: apiDateString(startDate),
                endDate: apiDateString(endDate)
            )
            if refresh || currentPage == 1 {
                reportList = response.list
            } else {
                reportList.append(contentsOf: response.list)
            }
            currentPage += 1
            canLoadMore = reportList.count < response.total
            notifyStateChange()
        } catch is CancellationError {
            return
        } catch {
            onShowMessage?(error.localizedDescription)
        }
    }

    func selectFilter(_ filter: LocationReportFilterType, api: HomeAPI) async {
        selectedFilter = filter
        currentPage = 1
        await loadReportList(api: api, refresh: true)
    }

    func setDateRange(start: Date?, end: Date?, api: HomeAPI) async {
        startDate = start
        endDate = end
        currentPage = 1
        await loadReportList(api: api, refresh: true)
    }

    func clearDateRange(api: HomeAPI) async {
        startDate = nil
        endDate = nil
        currentPage = 1
        await loadReportList(api: api, refresh: true)
    }

    func loadMoreIfNeeded(currentIndex: Int, api: HomeAPI) async {
        guard canLoadMore, !isLoading else { return }
        guard currentIndex >= reportList.count - 2 else { return }
        await loadReportList(api: api, refresh: false)
    }

    private func apiDateString(_ date: Date?) -> String? {
        guard let date else { return nil }
        let formatter = DateFormatter()
        formatter.locale = Locale(identifier: "zh_CN")
        formatter.dateFormat = "yyyy-MM-dd"
        return formatter.string(from: date)
    }

    private func formattedDate(_ date: Date?) -> String {
        guard let date else { return "请选择" }
        let formatter = DateFormatter()
        formatter.locale = Locale(identifier: "zh_CN")
        formatter.dateFormat = "yyyy-MM-dd"
        return formatter.string(from: date)
    }

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