namespace Server.Controllers;

using System.Reflection;
using System.Text.Json;
using AdaptiveExpressions;
using ElmahCore;
using Microsoft.AspNetCore.Mvc;
using Server.Exceptions;
using Server.Helper;
using Shared.Models;

[ApiController]
[Route("[controller]")]
public class ServerController : ControllerBase
{
    private readonly ILogger<ServerController> _logger;
    private readonly IConfiguration _config;
    private AIProvider _aIProvider;
    private readonly SearchdomainManager _searchdomainManager;

    public ServerController(ILogger<ServerController> logger, IConfiguration config, AIProvider aIProvider, SearchdomainManager searchdomainManager)
    {
        _logger = logger;
        _config = config;
        _aIProvider = aIProvider;
        _searchdomainManager = searchdomainManager;
    }

    /// <summary>
    /// Lists the models available to the server
    /// </summary>
    /// <remarks>
    /// Returns ALL models available to the server - not only the embedding models.
    /// </remarks>
    [HttpGet("Models")]
    public ActionResult<ServerGetModelsResult> GetModels()
    {
        try
        {
            string[] models = _aIProvider.GetModels();
            return new ServerGetModelsResult() { Models = models, Success = true };
        } catch (Exception ex)
        {
            _logger.LogError("Unable to get models due to exception {ex.Message} - {ex.StackTrace}", [ex.Message, ex.StackTrace]);
            return new ServerGetModelsResult() { Success = false, Message = ex.Message};
        }
    }

    /// <summary>
    /// Gets the total memory size of the embedding cache
    /// </summary>
    [HttpGet("EmbeddingCache/Size")]
    public ActionResult<ServerGetEmbeddingCacheSizeResult> GetEmbeddingCacheSize()
    {
        long size = 0;
        long elementCount = 0;
        long embeddingsCount = 0;
        LRUCache<string, Dictionary<string, float[]>> embeddingCache = _searchdomainManager.embeddingCache;
        var cacheListField = embeddingCache.GetType()
            .GetField("_cacheList", BindingFlags.Instance | BindingFlags.NonPublic) ?? throw new InvalidOperationException("_cacheList field not found"); // TODO Remove this unsafe reflection atrocity
        LinkedList<string> cacheListOriginal = (LinkedList<string>)cacheListField.GetValue(embeddingCache)!;
        LinkedList<string> cacheList = new(cacheListOriginal);

        foreach (string key in cacheList)
        {
            if (!embeddingCache.TryGet(key, out var entry))
                continue;

            // estimate size
            size += EstimateEntrySize(key, entry);
            elementCount++;
            embeddingsCount += entry.Keys.Count;
        }
        return new ServerGetEmbeddingCacheSizeResult() { Success = true, SizeInBytes = size, MaxElementCount = _searchdomainManager.EmbeddingCacheMaxCount, ElementCount = elementCount, EmbeddingsCount = embeddingsCount};
    }

    private static long EstimateEntrySize(string key, Dictionary<string, float[]> value)
    {
        int stringOverhead = MemorySizes.Align(MemorySizes.ObjectHeader + sizeof(int));
        int arrayOverhead = MemorySizes.ArrayHeader;
        int dictionaryOverhead = MemorySizes.ObjectHeader;
        long size = 0;

        size += stringOverhead + key.Length * sizeof(char);
        size += dictionaryOverhead;

        foreach (var kv in value)
        {
            size += stringOverhead + kv.Key.Length * sizeof(char);
            size += arrayOverhead + kv.Value.Length * sizeof(float);
        }

        return size;
    }
}