using Microsoft.Extensions.Options;
using MyAgent.Core;
using Xunit;

namespace MyAgent.Tests.Core;

public sealed class SessionManagerTests
{
    [Fact]
    public async Task DebounceAsync_TwoRapidMessagesProduceOneStableBatch()
    {
        var manager = CreateManager();
        var now = DateTimeOffset.Now;
        var first = manager.DebounceAsync(CreateMessage("1", "第一条", now));
        await Task.Delay(10);
        var second = manager.DebounceAsync(CreateMessage("2", "第二条", now.AddMilliseconds(10)));

        Assert.Null(await first);
        var batch = await second;
        Assert.NotNull(batch);
        Assert.Equal(2, batch!.Messages.Count);
        Assert.Contains("第一条", batch.MergedText);
        Assert.Contains("第二条", batch.MergedText);
    }

    [Fact]
    public async Task DebounceAsync_CompletedBatchIsConsumed()
    {
        var manager = CreateManager();
        var first = await manager.DebounceAsync(CreateMessage("1", "第一轮", DateTimeOffset.Now));
        var second = await manager.DebounceAsync(CreateMessage("2", "第二轮", DateTimeOffset.Now.AddSeconds(1)));

        Assert.Single(first!.Messages);
        Assert.Single(second!.Messages);
        Assert.Equal("第二轮", second.MergedText);
    }

    [Fact]
    public async Task DebounceAsync_CallerCancellationDoesNotLeaveBrokenPendingState()
    {
        var manager = CreateManager();
        using var cancellation = new CancellationTokenSource();
        var cancelled = manager.DebounceAsync(CreateMessage("1", "取消", DateTimeOffset.Now), cancellation.Token);
        cancellation.Cancel();

        await Assert.ThrowsAnyAsync<OperationCanceledException>(() => cancelled);
        var next = await manager.DebounceAsync(CreateMessage("2", "下一条", DateTimeOffset.Now.AddSeconds(1)));

        Assert.NotNull(next);
        Assert.Single(next!.Messages);
    }

    [Fact]
    public async Task DebounceAsync_DifferentUsersReplyingToSameMessageStayIsolated()
    {
        var manager = CreateManager();
        var firstMessage = CreateMessage("1", "用户一", DateTimeOffset.Now, "1", "root");
        var secondMessage = CreateMessage("2", "用户二", DateTimeOffset.Now, "2", "root");

        var first = manager.DebounceAsync(firstMessage);
        var second = manager.DebounceAsync(secondMessage);
        var batches = await Task.WhenAll(first, second);

        Assert.All(batches, batch => Assert.Single(batch!.Messages));
        Assert.NotEqual(batches[0]!.ThreadId, batches[1]!.ThreadId);
    }

    private static SessionManager CreateManager()
    {
        var options = Options.Create(new ShirobotOptions
        {
            Fusion = new FusionOptions
            {
                DebounceMs = 40,
                SameUserMergeWindowSec = 8,
                MaxMergedMessages = 8
            }
        });
        return new SessionManager(options, TimeProvider.System);
    }

    private static IncomingMessage CreateMessage(string id, string text, DateTimeOffset at, string userId = "1", string? replyToMessageId = null) => new()
    {
        MessageId = id,
        GroupId = "1",
        UserId = userId,
        Text = text,
        CreatedAt = at,
        ReplyToMessageId = replyToMessageId
    };
}