Initial project import

2026-07-24 23:11:20 +08:00
commit 6396eabb87
372 changed files with 49682 additions and 0 deletions
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+using System.Data;
+using MiaoJiZhang.Domain.Entities;
+using MiaoJiZhang.Domain.Enums;
+using MiaoJiZhang.Infrastructure.Persistence;
+using Microsoft.EntityFrameworkCore;
+
+namespace MiaoJiZhang.Api.Services;
+
+public sealed record AiChatQuotaStatus(
+    int Limit,
+    int Used,
+    int Remaining,
+    AiQuotaPeriod Period,
+    DateTime WindowStartedAt,
+    DateTime ResetAt,
+    bool Allowed);
+
+public sealed class AiChatQuotaService(AppDbContext db)
+{
+    public async Task<AiChatQuotaStatus> TryConsumeAsync(
+        long userId,
+        CancellationToken ct = default)
+    {
+        await using var transaction = await db.Database.BeginTransactionAsync(
+            IsolationLevel.Serializable,
+            ct);
+        var user = await db.Users.SingleAsync(item => item.Id == userId, ct);
+        var status = GetStatus(user);
+        if (!status.Allowed)
+        {
+            await transaction.CommitAsync(ct);
+            return status;
+        }
+
+        if (user.AiChatWindowStartedAt != status.WindowStartedAt)
+        {
+            user.AiChatWindowStartedAt = status.WindowStartedAt;
+            user.AiChatUsed = 0;
+        }
+        user.AiChatUsed++;
+        await db.SaveChangesAsync(ct);
+        await transaction.CommitAsync(ct);
+        return GetStatus(user) with { Allowed = true };
+    }
+
+    public static AiChatQuotaStatus GetStatus(User user)
+    {
+        var (start, end) = CurrentWindow(user.AiChatPeriod);
+        var used = user.AiChatWindowStartedAt == start
+            ? Math.Max(0, user.AiChatUsed)
+            : 0;
+        var limit = Math.Max(0, user.AiChatLimit);
+        var remaining = limit == 0 ? -1 : Math.Max(0, limit - used);
+        return new AiChatQuotaStatus(
+            limit,
+            used,
+            remaining,
+            user.AiChatPeriod,
+            start,
+            end,
+            limit == 0 || used < limit);
+    }
+
+    public static (DateTime Start, DateTime End) CurrentWindow(
+        AiQuotaPeriod period)
+    {
+        var now = ChinaClock.Now;
+        var start = period switch
+        {
+            AiQuotaPeriod.Week => now.Date.AddDays(-(now.DayOfWeek == DayOfWeek.Sunday
+                ? 6
+                : (int)now.DayOfWeek - 1)),
+            AiQuotaPeriod.Month => new DateTime(now.Year, now.Month, 1),
+            _ => now.Date,
+        };
+        var end = period switch
+        {
+            AiQuotaPeriod.Week => start.AddDays(7),
+            AiQuotaPeriod.Month => start.AddMonths(1),
+            _ => start.AddDays(1),
+        };
+        return (ChinaClock.ToUtc(start), ChinaClock.ToUtc(end));
+    }
+
+    public static bool TryParsePeriod(string? value, out AiQuotaPeriod period)
+    {
+        period = value?.Trim().ToLowerInvariant() switch
+        {
+            "week" => AiQuotaPeriod.Week,
+            "month" => AiQuotaPeriod.Month,
+            _ => AiQuotaPeriod.Day,
+        };
+        return value?.Trim().ToLowerInvariant() is "day" or "week" or "month";
+    }
+
+    public static string PeriodKey(AiQuotaPeriod period) =>
+        period.ToString().ToLowerInvariant();
+}