using BuildFlow.Infrastructure.AI;
using FluentAssertions;
using Xunit;

namespace BuildFlow.Rag.Tests;

/// <summary>
/// LlmRerankService.ParseOrderedIds 纯解析单测：不依赖 PG/LLM，覆盖围栏容忍与幻觉拒绝。
/// </summary>
public class LlmRerankParsingTests
{
    private static readonly List<(Guid ChunkId, string Content)> Candidates =
    [
        (Guid.NewGuid(), "内容甲"),
        (Guid.NewGuid(), "内容乙"),
        (Guid.NewGuid(), "内容丙"),
    ];

    [Fact]
    public void PlainArray_ParsesInOrder()
    {
        var result = LlmRerankService.ParseOrderedIds("[3,1,2]", Candidates);
        result.Should().NotBeNull();
        result![0].Should().Be(Candidates[2].ChunkId);
        result[1].Should().Be(Candidates[0].ChunkId);
        result[2].Should().Be(Candidates[1].ChunkId);
    }

    [Fact]
    public void JsonFenceAndProse_Tolerated()
    {
        var result = LlmRerankService.ParseOrderedIds("好的，排序结果如下：\n```json\n[2, 1]\n```\n希望有帮助", Candidates);
        result.Should().NotBeNull();
        result![0].Should().Be(Candidates[1].ChunkId);
        result[1].Should().Be(Candidates[0].ChunkId);
    }

    [Fact]
    public void OutOfRangeNumber_RejectedAsNull()
    {
        // 模型幻觉输出编号 4（越界）→ 整体不可信，降级
        LlmRerankService.ParseOrderedIds("[1, 4]", Candidates).Should().BeNull();
        LlmRerankService.ParseOrderedIds("[0, 1]", Candidates).Should().BeNull();
    }

    [Fact]
    public void MalformedText_ReturnsNull()
    {
        LlmRerankService.ParseOrderedIds("无法排序", Candidates).Should().BeNull();
        LlmRerankService.ParseOrderedIds("[1, \"两\"]", Candidates).Should().BeNull();
        LlmRerankService.ParseOrderedIds("[]", Candidates).Should().BeNull();
    }
}