using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using AIFotoONLUS.Core;
using ImageCatalog_2.Models;
using Microsoft.Extensions.Logging;

namespace ImageCatalog_2.Services;

public class AiExtractionService : IAiExtractionService
{
    private readonly ILogger<AiExtractionService> _logger;

    public AiExtractionService(ILogger<AiExtractionService> logger)
    {
        _logger = logger;
    }

    public async Task RunAsync(
        AiExtractionRequest request,
        CancellationToken token,
        Func<AiResultItem, Task> onResult,
        Func<double, Task> onProgress)
    {
        var searchOption = request.Recursive ? SearchOption.AllDirectories : SearchOption.TopDirectoryOnly;

        var imageFiles = Directory.EnumerateFiles(request.SearchRoot, "*.*", searchOption)
            .Where(f => f.EndsWith(".jpg", StringComparison.OrdinalIgnoreCase)
                     || f.EndsWith(".jpeg", StringComparison.OrdinalIgnoreCase)
                     || f.EndsWith(".png", StringComparison.OrdinalIgnoreCase)
                     || f.EndsWith(".bmp", StringComparison.OrdinalIgnoreCase)
                     || f.EndsWith(".gif", StringComparison.OrdinalIgnoreCase))
            .Where(f => request.IncludeThumbnails || !Path.GetFileName(f).StartsWith("tn_", StringComparison.OrdinalIgnoreCase))
            .ToList();

        var extractedResults = new List<AiResultItem>();
        var modelConfiguration = BuildModelConfiguration(request.ModelsFolderPath, request.UseGpu);

        using var engine = new NumberRecognitionEngine(modelConfiguration, _logger);

        var processed = 0;
        var total = imageFiles.Count;
        var failed = 0;
        Exception? firstFailure = null;

        foreach (var file in imageFiles)
        {
            token.ThrowIfCancellationRequested();

            var extracted = string.Empty;

            try
            {
                extracted = engine.ProcessImage(file).Text;
            }
            catch (Exception ex)
            {
                failed++;
                firstFailure ??= ex;
                _logger.LogWarning(ex, "Error processing AI OCR for {File}", file);
            }

            var result = new AiResultItem { Path = file, Text = extracted };
            extractedResults.Add(result);
            await onResult(result).ConfigureAwait(false);

            processed++;
            var percent = total > 0 ? (processed * 100.0 / total) : 100.0;
            await onProgress(percent).ConfigureAwait(false);
        }

        if (imageFiles.Count > 0 && failed == imageFiles.Count)
        {
            throw new InvalidOperationException($"AI OCR failed for all {imageFiles.Count} image(s). See previous log entries for details.", firstFailure);
        }

        if (!string.IsNullOrWhiteSpace(request.CsvOutputPath))
        {
            try
            {
                var dir = Path.GetDirectoryName(request.CsvOutputPath) ?? string.Empty;
                if (!string.IsNullOrWhiteSpace(dir) && !Directory.Exists(dir))
                {
                    Directory.CreateDirectory(dir);
                }

                using var sw = new StreamWriter(request.CsvOutputPath, false, Encoding.UTF8);
                sw.WriteLine("Path,Text");
                foreach (var r in extractedResults)
                {
                    var csvFileName = Path.GetFileName(r.Path ?? string.Empty);
                    var safeText = (r.Text ?? string.Empty).Replace("\"", "\"\"");
                    sw.WriteLine($"\"{csvFileName}\",\"{safeText}\"");
                }
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Failed to write CSV to {CsvOutputPath}", request.CsvOutputPath);
            }
        }
    }

    private static ModelConfiguration BuildModelConfiguration(string modelsFolderPath, bool useGpu)
    {
        if (string.IsNullOrWhiteSpace(modelsFolderPath))
        {
            throw new InvalidOperationException("AI models folder is not configured.");
        }

        var modelsRoot = Path.GetFullPath(modelsFolderPath.Trim().Trim('"'));
        if (!Directory.Exists(modelsRoot))
        {
            throw new DirectoryNotFoundException($"AI models folder not found: {modelsRoot}");
        }

        return new ModelConfiguration
        {
            DetectionCfg = Path.Combine(modelsRoot, "detection.cfg"),
            DetectionWeights = Path.Combine(modelsRoot, "detection.weights"),
            RecognitionCfg = Path.Combine(modelsRoot, "recognition.cfg"),
            RecognitionWeights = Path.Combine(modelsRoot, "recognition.weights"),
            UseGpu = useGpu
        };
    }
}