using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using SixLabors.ImageSharp;
using SixLabors.ImageSharp.PixelFormats;
using SixLabors.ImageSharp.Processing;
using MediaToolkit;
using MediaToolkit.Model;
using MediaToolkit.Options;
using VideoAnalysisCore.Common;
using VideoAnalysisCore.AICore.FFMPGE;
using Microsoft.Extensions.Options;
using System.Diagnostics;

namespace VideoChangeDetector
{
    class Program
    {
        static void Main(string[] args)
        {
            var taskID = "665310769946693";
            var inputFile = $"F:\\Learn.VideoAnalysis\\testC\\bin\\Debug\\net8.0\\video\\{taskID}.mp4";
            //inputFile = "F:\\Learn.VideoAnalysis\\testC\\bin\\Debug\\net8.0\\video\\ppt.mp4";
            string tempFrameDir = "temp_frames";
            var intervalSec = 5;
            double threshold = 15.0;

            Stopwatch sw = new Stopwatch();
            sw.Start();
            ExtractVideoFrames(inputFile, tempFrameDir, intervalSec);
            sw.Stop();
            Console.WriteLine("视频切帧总共花费{0}ms.", sw.Elapsed.TotalMilliseconds);
            Stopwatch sw1 = new Stopwatch();
            sw1.Start();
            DetectChanges(tempFrameDir, threshold);
            sw1.Stop();
            Console.WriteLine("视频分析帧总共花费{0}ms.", sw1.Elapsed.TotalMilliseconds);
            Console.WriteLine("处理完成!");
        }
        /// <summary>
        /// 视频切片 
        /// </summary>
        /// <param name="inputPath">输入</param>
        /// <param name="outputDir">输出</param>
        /// <param name="intervalSec">间隔多少秒</param>
        /// <param name="ProcessorCount">线程数</param>
        static void ExtractVideoFrames(string inputPath, string outputDir, int intervalSec, int ProcessorCount = 6)
        {
            Directory.CreateDirectory(outputDir);
            var inputFile = new MediaFile { Filename = inputPath };
            using var engine = new Engine(FFMPGEHandle.FFmpegPath);
            engine.CustomCommand($"-i {inputPath} -vf \"fps=1/{intervalSec},scale=320:180\" {outputDir}/frame_%03d.jpg");
        }
        /// <summary>
        /// 差异比对
        /// </summary>
        /// <param name="frameDir"></param>
        /// <param name="threshold"></param>
        /// <param name="ProcessorCount"></param>
        static void DetectChanges(string frameDir, double threshold,int ProcessorCount = 6)
        {
            var frameFiles = Directory.GetFiles(frameDir, "*.jpg")
                .OrderBy(f => f)
                .ToList();

            Image<Rgb24> prevFrame = null;
            string outputDir = "output";
            Directory.CreateDirectory(outputDir);
            var options = new ParallelOptions { MaxDegreeOfParallelism = ProcessorCount };
            foreach (var frameFile in frameFiles) 
            {
                using (var currFrame = Image.Load<Rgb24>(frameFile))
                {
                    if (prevFrame != null)
                    {
                        double diff = CalculateFrameDifference(prevFrame, currFrame);
                        double timestamp = GetTimestampFromFileName(frameFile) * 5 ;

                        if (diff > threshold)
                        {
                            string outputPath = Path.Combine(outputDir, $"change_{timestamp:0000}.jpg");
                            currFrame.Save(outputPath);
                            Console.WriteLine($"变化帧: {timestamp}秒，差异值: {diff:F2}");
                        }
                        else
                        {
                            Console.WriteLine($"-------: {timestamp}秒，差异值: {diff:F2}");
                        }
                    }
                    prevFrame?.Dispose();
                    prevFrame = currFrame.Clone();
                }
            }
            //Parallel.ForEach(frameFiles, options, frameFile =>
            //{
                
            //});
        }
        /// <summary>
        /// 计算帧差异
        /// </summary>
        /// <param name="img1"></param>
        /// <param name="img2"></param>
        /// <returns></returns>
        static double CalculateFrameDifference(Image<Rgb24> img1, Image<Rgb24> img2)
        {
            // 统一调整为64x64
            var resized1 = img1.Clone(x => x.Resize(96, 96).Grayscale());
            var resized2 = img2.Clone(x => x.Resize(96, 96).Grayscale());

            long diff = 0;
            for (int y = 0; y < resized1.Height; y++)
            {
                for (int x = 0; x < resized1.Width; x++)
                {
                    var pixel1 = resized1[x, y];
                    var pixel2 = resized2[x, y];
                    diff += Math.Abs(pixel1.R - pixel2.R);
                }
            }
            return diff / (double)(resized1.Width * resized1.Height);
        }

        static double GetTimestampFromFileName(string filePath)
        {
            string fileName = Path.GetFileNameWithoutExtension(filePath);
            return double.Parse(fileName.Split('_')[1]);
        }
    }
}