SeemGen/Services/LocalVectorSearchService.cs

using BLAIzor.Models;
using System;
using System.Collections.Generic;
using System.Linq;


namespace BLAIzor.Services
{   
    public class LocalVectorSearchService
    {
        //private List<WebPageContent> _cachedContents = new();
        //private List<HtmlSnippet> _cachedSnippets = new();
        private int _cachedContentVersion = -1;
        private int _cachedSnippetVersion = -1;

        // Inject any needed services (e.g. DbContext, versioning service)
        public LocalVectorSearchService()
        {
        }

        //public void SetContentCache(List<WebPageContent> contents, int contentVersion)
        //{
        //    _cachedContents = contents;
        //    _cachedContentVersion = contentVersion;
        //}

        //public void SetSnippetCache(List<HtmlSnippet> snippets, int snippetVersion)
        //{
        //    _cachedSnippets = snippets;
        //    _cachedSnippetVersion = snippetVersion;
        //}

        public bool IsContentVersionOutdated(int currentVersion)
            => currentVersion != _cachedContentVersion;

        public bool IsSnippetVersionOutdated(int currentVersion)
            => currentVersion != _cachedSnippetVersion;

        public List<WebPageContent> SearchContent(float[] queryVector, List<WebPageContent> cachedContents, int maxResults = 5)
        {
            return cachedContents
                .Select(c => new
                {
                    Content = c,
                    Similarity = CosineSimilarity(queryVector, c.Vectors)
                })
                .OrderByDescending(x => x.Similarity)
                .Take(maxResults)
                .Select(x => x.Content)
                .ToList();
        }

        public List<HtmlSnippet> SearchSnippets(float[] queryVector, List<HtmlSnippet> cachedSnippets, int maxResults = 5)
        {
            return cachedSnippets
                .Select(s => new
                {
                    Snippet = s,
                    Similarity = CosineSimilarity(queryVector, s.Vectors)
                })
                .OrderByDescending(x => x.Similarity)
                .Take(maxResults)
                .Select(x => x.Snippet)
                .ToList();
        }

        private float CosineSimilarity(float[] vectorA, float[] vectorB)
        {
            if (vectorA == null || vectorB == null || vectorA.Length != vectorB.Length)
                return 0f;

            float dot = 0f, magA = 0f, magB = 0f;

            for (int i = 0; i < vectorA.Length; i++)
            {
                dot += vectorA[i] * vectorB[i];
                magA += vectorA[i] * vectorA[i];
                magB += vectorB[i] * vectorB[i];
            }

            if (magA == 0 || magB == 0)
                return 0f;

            return dot / ((float)Math.Sqrt(magA) * (float)Math.Sqrt(magB));
        }
    }
}