using BuildFlow.Domain.Interfaces;

namespace BuildFlow.Rag.Tests.Stub;

/// <summary>
/// Stub IEmbeddingService:返回固定维度(768)的向量,与 DB vector(768) 列匹配。
/// 维度由 embeddinggemma-300m 决定。所有文本返回相同向量(测试场景下足够)。
/// </summary>
public sealed class StubEmbeddingService : IEmbeddingService
{
    /// <summary>向量维度,匹配 document_chunks.embedding vector(768)。</summary>
    public const int Dimensions = 768;

    /// <summary>是否返回空向量(用于测试零分块路径)。</summary>
    public bool ReturnEmpty { get; init; }

    private static float[] BuildVector()
    {
        var v = new float[Dimensions];
        for (var i = 0; i < Dimensions; i++)
            v[i] = (i % 10) / 10f;
        return v;
    }

    public Task<float[]> EmbedAsync(string text, CancellationToken ct = default)
        => Task.FromResult(ReturnEmpty ? [] : BuildVector());

    public Task<List<float[]>> EmbedBatchAsync(List<string> texts, CancellationToken ct = default)
    {
        if (ReturnEmpty)
            return Task.FromResult(new List<float[]>());

        var vector = BuildVector();
        return Task.FromResult(texts.Select(_ => vector).ToList());
    }
}