using System;
using System.IO;
using System.Text;
using System.Text.RegularExpressions;
using System.Drawing;
using System.Windows.Forms;
using System.Runtime.InteropServices;
using System.Security.Cryptography;
using System.Xml;
using System.Xml.Serialization;

unsafe class J2000 {
	const int J2K_MAXRLVLS=33;
	const int J2K_MAXBANDS=3*J2K_MAXRLVLS+1;

	public class Math {
		static public int ceildiv(int a, int b) {
			return (a+b-1)/b;
		}
	}

	[StructLayout(LayoutKind.Sequential)]
	public struct j2k_comp_t {
		public int dx, dy; 
		public int prec; 
		public int sgnd; 
		public int *data; 
	};

	[StructLayout(LayoutKind.Sequential)]
	public struct j2k_image_t {
		public int x0, y0;
		public int x1, y1; 
		public int numcomps; 
		public j2k_comp_t *comps; 
	};

	[StructLayout(LayoutKind.Sequential)]
	public struct j2k_stepsize_t {
		public int expn;
		public int mant; 
	};

	[StructLayout(LayoutKind.Sequential)]
	public struct j2k_tccp_t {
		public int csty; 
		public int numresolutions; 
		public int cblkw; 
		public int cblkh; 
		public int cblksty; 
		public int qmfbid; 
		public int qntstypublic ; 
		[MarshalAs(UnmanagedType.ByValArray, SizeConst=J2K_MAXBANDS)]
		public j2k_stepsize_t[] stepsizes; 
		public int numgbits; 
		public int roishift; 
		[MarshalAs(UnmanagedType.ByValArray, SizeConst=J2K_MAXRLVLS)]
		public int[] prcw; 
		[MarshalAs(UnmanagedType.ByValArray, SizeConst=J2K_MAXRLVLS)]
		public int[] prch; 
	};

	[StructLayout(LayoutKind.Sequential)]
	public struct j2k_poc_t {
		public int resno0, compno0; 
		public int layno1, resno1, compno1;
		public int prg;
	};

	[StructLayout(LayoutKind.Sequential)]
	public struct j2k_tcp_t {
		public int csty; 
		public int prg; 
		public int numlayers; 
		public int mct; 
		[MarshalAs(UnmanagedType.ByValArray, SizeConst=32)]
		public int[] rates; 
		public int numpocs; 
		[MarshalAs(UnmanagedType.ByValArray, SizeConst=32)]
		public j2k_poc_t[] pocs; 
		public j2k_tccp_t *tccps; 
	}

	[StructLayout(LayoutKind.Sequential)]
	public struct j2k_cp_t {
		public int tx0, ty0; 
		public int tdx, tdy; 
		public int tw, th;
		public j2k_tcp_t *tcps; 
	}

	[DllImport("libj2k.dll", EntryPoint="j2k_decode")]
	static extern int j2k_decode(byte *src, int len, j2k_image_t **i, j2k_cp_t **cp);

	static public j2k_image_t* Decode(byte[] src)	{
		j2k_image_t *img;
		j2k_cp_t *cp;
		fixed (byte *p=src) {
			j2k_decode(p, src.Length, &img, &cp);
		}
		return img;
	}

	static public Bitmap BitmapFromComp(j2k_image_t *img, int compno, out string hash) {
		j2k_comp_t *comp=&img->comps[compno];
		int w=Math.ceildiv(img->x1-img->x0, comp->dx);
		int h=Math.ceildiv(img->y1-img->y0, comp->dy);
		int prec=comp->prec;
		bool sgnd=comp->sgnd!=0;
		Bitmap bmp=new Bitmap(w, h);

		HashAlgorithm md5=new MD5CryptoServiceProvider();
		CryptoStream cs=new CryptoStream(Stream.Null, md5, CryptoStreamMode.Write);
		BinaryWriter bw=new BinaryWriter(cs);

		for (int j=0; j<h; j++) {
			for (int i=0; i<w; i++) {
				int v, c;
				v=comp->data[i+j*w];
				if (sgnd) c=(int)(128+v*127.0/(1<<(prec-1)));
				else c=(int)(v*255.0/(1<<prec));
				bmp.SetPixel(i, j, Color.FromArgb(255, c, c, c));
				bw.Write(v);
			}
		}
		bw.Close();
		hash=Convert.ToBase64String(md5.Hash);
		return bmp;
	}
}

unsafe class J2KView:Form {
	J2000.j2k_image_t *img;
	public static int Main(string[] args) {
		try {
			Application.Run(new J2KView(args[0]));
		}
		catch (Exception e) {
			Console.WriteLine(e.Message);
			Console.ReadLine();
		}
		return 0;
	}

	string[] hash;
	TabControl tc;

	public J2KView(string filename) {
		FileStream fs=new FileStream(filename, FileMode.Open, FileAccess.Read);
		BinaryReader br=new BinaryReader(fs);
		byte[] src=new byte[fs.Length];
		br.Read(src, 0, src.Length);
		img=J2000.Decode(src);
		Text="J2000.J2KView";
		tc=new TabControl();
		Controls.Add(tc);
		System.Console.WriteLine("numcomps="+img->numcomps);
		hash=new string[img->numcomps];
		for (int i=0; i<img->numcomps; i++) {
			TabPage tp=new TabPage();
			tp.Text="c"+i;
			tc.Controls.Add(tp);
			PictureBox pb=new PictureBox();
			pb.Image=J2000.BitmapFromComp(img, i, out hash[i]);
			pb.SizeMode=PictureBoxSizeMode.AutoSize;
			tp.Controls.Add(pb);
			tp.AutoScroll=true;
			ContextMenu cm=new ContextMenu();
			cm.MenuItems.Add("&MD5", new EventHandler(PrintHashCode));
			cm.MenuItems.Add("&PSNR", new EventHandler(PrintPSNR));
			tp.ContextMenu=cm;
		}
		tc.Dock=DockStyle.Fill;
	}
	
	private void PrintHashCode(object sender, EventArgs e) {
		MessageBox.Show(hash[tc.SelectedIndex], "MD5");
	}

	private void PrintPSNR(object sender, EventArgs e) {
		OpenFileDialog d=new OpenFileDialog();	
		d.Filter="PGX files (*.pgx)|*.pgx";
		if (d.ShowDialog()!=DialogResult.OK) return;
		try {
			double psnr=CalcPSNR(tc.SelectedIndex, d.FileName);
			MessageBox.Show(20*Math.Log10(psnr)+" dB", "PSNR");
		}
		catch (Exception ex) {
			MessageBox.Show("Failed to compute PSNR. "+ex.Message, "Error");
		}
	}

	private static string ReadLine(BinaryReader br) {
		StringBuilder sb=new StringBuilder();
		char c;
		while ((c=br.ReadChar())!='\n') {
			sb.Append(c);	
		}
		return sb.ToString();
	}


	private double CalcPSNR(int compno, string filename) {
		J2000.j2k_comp_t *comp=&img->comps[compno];
		FileStream f=new FileStream(filename, FileMode.Open, FileAccess.Read, FileShare.Read);
		BinaryReader br=new BinaryReader(f);
		Regex r=new Regex(@"[\s]+");
		string[] head=r.Split(ReadLine(br));
		if (head[0]!="PG") throw new Exception("Not a PGX file");
		bool bigendian=head[1]=="ML";
		int prec=Math.Abs(int.Parse(head[2]));
		bool sgnd=int.Parse(head[2])<0;
		int w=int.Parse(head[3]);
		int h=int.Parse(head[4]);
		if (prec!=comp->prec) throw new Exception("Precision mismatch");
		if (sgnd!=(comp->sgnd!=0)) throw new Exception("Signedness mismatch");
		if (w!=J2000.Math.ceildiv(img->x1-img->x0, comp->dx) || h!=J2000.Math.ceildiv(img->y1-img->y0, comp->dy)) throw new Exception("Dimensions mismatch");
		double s=0, n=0;
		for (int j=0; j<h; j++) {
			for (int i=0; i<w; i++) {
				int v1, v2;
				v1=comp->data[i+j*w];
				if (prec<=8) {
					v2=sgnd?(int)br.ReadSByte():(int)br.ReadByte(); 
				}
				else if (prec<=16) {
					v2=sgnd?(int)br.ReadInt16():(int)br.ReadUInt16(); 
					if (bigendian) v2=System.Net.IPAddress.HostToNetworkOrder((short)v2);
				}
				else {
					v2=sgnd?(int)br.ReadInt32():(int)br.ReadUInt32(); 
					if (bigendian) v2=System.Net.IPAddress.HostToNetworkOrder(v2);
				}
				s+=Math.Pow((double)v1, 2);
				n+=Math.Pow((double)(v1-v2), 2);
			}
		}
		double psnr=Math.Sqrt(s/n);
		return psnr;
	}
}