29WxOrder/OrderSupportTicket/Services/WorkOrderCacheService.cs

using OrderSupportTicket.Models;
using OrderSupportTicket.Models.Api;
using System;
using System.Collections.Generic;
using System.Globalization;
using System.IO;
using System.Linq;

namespace OrderSupportTicket.Services;

/// <summary>
/// 工单列表本地缓存的读取与未读比较。
/// </summary>
public sealed class WorkOrderCacheService
{
    private const string ConfigName = "ordersupportticket";
    private static readonly object SyncRoot = new object();

    /// <summary>
    /// 读取指定账号的工单列表缓存。
    /// </summary>
    public WorkOrderListCache Load(string userName)
    {
        if (string.IsNullOrWhiteSpace(userName))
            return null;

        try
        {
            lock (SyncRoot)
            {
                var path = NaiBa.Util.Helper.ConfigHelper.GetConfigUserPath(ConfigName);
                if (!File.Exists(path))
                    return null;

                var cache = NaiBa.Util.Helper.ConfigHelper
                    .LoadConfig<WorkOrderListCache>(ConfigName);
                if (cache?.Items == null)
                    return null;
                if (!string.Equals(cache.UserName, userName, StringComparison.Ordinal))
                    return null;

                return cache;
            }
        }
        catch
        {
            // 本地缓存损坏或读取失败时按无缓存处理。
            return null;
        }
    }

    /// <summary>
    /// 保存工单列表缓存。
    /// </summary>
    public void Save(WorkOrderListCache cache)
    {
        if (cache == null)
            throw new ArgumentNullException(nameof(cache));
        if (string.IsNullOrWhiteSpace(cache.UserName))
            throw new ArgumentException("缓存缺少登录账号。", nameof(cache));

        lock (SyncRoot)
        {
            NaiBa.Util.Helper.ConfigHelper.SaveConfig(ConfigName, cache);
        }
    }

    /// <summary>
    /// 根据服务端工单列表和历史缓存计算每个工单的未读消息数。
    /// 返回值的键为 "appId|wechatOrderId"。
    /// </summary>
    public Dictionary<string, int> BuildUnreadMap(
        IEnumerable<WorkOrderSummaryDto> workOrders,
        WorkOrderListCache cache)
    {
        var result = new Dictionary<string, int>(StringComparer.Ordinal);
        var savedItems = (cache?.Items ?? new List<WorkOrderListCacheItem>())
            .Where(item => item != null && !string.IsNullOrWhiteSpace(item.OrderId))
            .GroupBy(item => item.OrderId, StringComparer.Ordinal)
            .ToDictionary(
                group => group.Key,
                group => group.First(),
                StringComparer.Ordinal);
        var hasSavedCache = cache?.Items != null && cache.Items.Count > 0;

        foreach (var dto in workOrders ?? Enumerable.Empty<WorkOrderSummaryDto>())
        {
            if (dto == null
                || string.IsNullOrWhiteSpace(dto.AppId)
                || string.IsNullOrWhiteSpace(dto.WechatOrderId))
            {
                continue;
            }

            var hasNewMessage = !hasSavedCache;
            if (hasSavedCache)
            {
                if (savedItems.TryGetValue(dto.WechatOrderId, out var saved))
                {
                    hasNewMessage = ParseTimestamp(dto.LastMessageAt) > saved.LastMessageAt;
                }
                else
                {
                    // 缓存中没有该工单，说明是新增工单。
                    hasNewMessage = true;
                }
            }

            if (!hasNewMessage)
                continue;

            // 有历史基线时，时间更新但服务端未读数为 0 也按 1 条提示；
            // 首次运行没有基线时只信任服务端未读数，避免把历史工单全部标成未读。
            var unreadCount = hasSavedCache
                ? Math.Max(1, dto.UnreadCount)
                : dto.UnreadCount;
            if (unreadCount <= 0)
                continue;

            result[BuildTicketKey(dto.AppId, dto.WechatOrderId)] = unreadCount;
        }

        return result;
    }

    /// <summary>
    /// 构建工单实时通知使用的唯一键。
    /// </summary>
    public static string BuildTicketKey(string appId, string wechatOrderId)
    {
        return appId + "|" + wechatOrderId;
    }

    /// <summary>
    /// 解析服务端 ISO 8601 时间字符串。
    /// </summary>
    public static DateTimeOffset ParseTimestamp(string value)
    {
        if (DateTimeOffset.TryParse(
            value,
            CultureInfo.InvariantCulture,
            DateTimeStyles.AssumeUniversal,
            out var parsed))
        {
            return parsed;
        }
        return default;
    }
}