Backend-Api/ProgramManager/src/Infrastructure/GozareshgirProgramManager.Infrastructure/Services/FileManagement/ThumbnailGeneratorService.cs

using GozareshgirProgramManager.Application.Services.FileManagement;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.Configuration;
using SixLabors.ImageSharp;
using SixLabors.ImageSharp.Processing;
using SixLabors.ImageSharp.Formats.Jpeg;

namespace GozareshgirProgramManager.Infrastructure.Services.FileManagement;

/// <summary>
/// سرویس تولید thumbnail با استفاده از ImageSharp
/// </summary>
public class ThumbnailGeneratorService : IThumbnailGeneratorService
{
    private readonly string _thumbnailBasePath;
    private readonly string _baseUrl;

    public ThumbnailGeneratorService(IConfiguration configuration,
        IHttpContextAccessor httpContextAccessor)
    {
        _thumbnailBasePath = configuration["FileStorage:ThumbnailPath"] 
                            ?? Path.Combine(Directory.GetCurrentDirectory(), "storage", "Thumbnails");
        var request = httpContextAccessor.HttpContext?.Request;

        if (request != null)
        {
            _baseUrl = $"{request.Scheme}://{request.Host}/storage";
        }
        else
        {
            _baseUrl = configuration["FileStorage:BaseUrl"] ?? "http://localhost:5000/storage";
        }

        if (!Directory.Exists(_thumbnailBasePath))
        {
            Directory.CreateDirectory(_thumbnailBasePath);
        }
    }

    public async Task<(string ThumbnailPath, string ThumbnailUrl)?> GenerateImageThumbnailAsync(
        string imagePath,
        string category,
        int width = 200, 
        int height = 200)
    {
        try
        {
            if (!File.Exists(imagePath))
            {
                return null;
            }

            // بارگذاری تصویر
            using var image = await Image.LoadAsync(imagePath);

            // Resize با حفظ نسبت
            image.Mutate(x => x.Resize(new ResizeOptions
            {
                Size = new Size(width, height),
                Mode = ResizeMode.Max
            }));

            // نام فایل thumbnail
            var fileName = Path.GetFileNameWithoutExtension(imagePath);
            var extension = Path.GetExtension(imagePath);
            var thumbnailFileName = $"{fileName}_thumb{extension}";

            // دریافت مسیر و URL توسط متد private
            var (thumbnailPath, thumbnailUrl) = GetThumbnailPathAndUrl(thumbnailFileName, category);

            // ذخیره thumbnail با کیفیت 80
            await image.SaveAsync(thumbnailPath, new JpegEncoder { Quality = 80 });


            return (thumbnailPath, thumbnailUrl);
        }
        catch (Exception)
        {
            // در صورت خطا null برمی‌گردانیم
            return null;
        }
    }

    public async Task<(string ThumbnailPath, string ThumbnailUrl)?> GenerateVideoThumbnailAsync(string videoPath, string category = "general")
    {
        // TODO: برای Video thumbnail باید از FFmpeg استفاده کنیم
        // فعلاً یک placeholder image برمی‌گردانیم
        await Task.CompletedTask;
        return null;
    }

    public Task DeleteThumbnailAsync(string thumbnailPath)
    {
        if (File.Exists(thumbnailPath))
        {
            File.Delete(thumbnailPath);
        }

        return Task.CompletedTask;
    }

    public async Task<(int Width, int Height)?> GetImageDimensionsAsync(string imagePath)
    {
        try
        {
            if (!File.Exists(imagePath))
            {
                return null;
            }

            var imageInfo = await Image.IdentifyAsync(imagePath);
            return (imageInfo.Width, imageInfo.Height);
        }
        catch (Exception)
        {
            return null;
        }
    }

    /// <summary>
    /// دریافت مسیر فیزیکی و URL برای thumbnail بر اساس category
    /// </summary>
    private (string ThumbnailPath, string ThumbnailUrl) GetThumbnailPathAndUrl(string thumbnailFileName, string category)
    {
        var categoryFolder = string.IsNullOrWhiteSpace(category) ? "general" : category;
        var categoryPath = Path.Combine(Directory.GetCurrentDirectory(), "storage", categoryFolder);
        
        if (!Directory.Exists(categoryPath))
        {
            Directory.CreateDirectory(categoryPath);
        }

        var thumbnailSubPath = Path.Combine(categoryPath, "Thumbnails");
        if (!Directory.Exists(thumbnailSubPath))
        {
            Directory.CreateDirectory(thumbnailSubPath);
        }

        var thumbnailPath = Path.Combine(thumbnailSubPath, thumbnailFileName);
        var thumbnailUrl = $"{_baseUrl}/{categoryFolder}/thumbnails/{thumbnailFileName}";

        return (thumbnailPath, thumbnailUrl);
    }
}