package btools.mapcreator;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.DataInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.zip.ZipEntry;
import java.util.zip.ZipInputStream;

public class ConvertLidarTile {
  public static int NROWS;
  public static int NCOLS;

  public static final short NODATA2 = -32767; // hgt-formats nodata
  public static final short NODATA = Short.MIN_VALUE;

  static short[] imagePixels;

  private static void readHgtZip(String filename, int rowOffset, int colOffset) throws Exception {
    ZipInputStream zis = new ZipInputStream(new BufferedInputStream(new FileInputStream(filename)));
    try {
      for (; ; ) {
        ZipEntry ze = zis.getNextEntry();
        if (ze.getName().endsWith(".hgt")) {
          readHgtFromStream(zis, rowOffset, colOffset);
          return;
        }
      }
    } finally {
      zis.close();
    }
  }

  private static void readHgtFromStream(InputStream is, int rowOffset, int colOffset)
    throws Exception {
    DataInputStream dis = new DataInputStream(new BufferedInputStream(is));
    for (int ir = 0; ir < 1201; ir++) {
      int row = rowOffset + ir;

      for (int ic = 0; ic < 1201; ic++) {
        int col = colOffset + ic;

        int i1 = dis.read(); // msb first!
        int i0 = dis.read();

        if (i0 == -1 || i1 == -1)
          throw new RuntimeException("unexcepted end of file reading hgt entry!");

        short val = (short) ((i1 << 8) | i0);

        if (val == NODATA2) {
          val = NODATA;
        }

        setPixel(row, col, val);
      }
    }
  }


  private static void setPixel(int row, int col, short val) {
    if (row >= 0 && row < NROWS && col >= 0 && col < NCOLS) {
      imagePixels[row * NCOLS + col] = val;
    }
  }

  private static short getPixel(int row, int col) {
    if (row >= 0 && row < NROWS && col >= 0 && col < NCOLS) {
      return imagePixels[row * NCOLS + col];
    }
    return NODATA;
  }


  public static void doConvert(String inputDir, int lonDegreeStart, int latDegreeStart, String outputFile) throws Exception {
    int extraBorder = 0;

    NROWS = 5 * 1200 + 1 + 2 * extraBorder;
    NCOLS = 5 * 1200 + 1 + 2 * extraBorder;

    imagePixels = new short[NROWS * NCOLS]; // 650 MB !

    // prefill as NODATA
    for (int row = 0; row < NROWS; row++) {
      for (int col = 0; col < NCOLS; col++) {
        imagePixels[row * NCOLS + col] = NODATA;
      }
    }

    for (int latIdx = -1; latIdx <= 5; latIdx++) {
      int latDegree = latDegreeStart + latIdx;
      int rowOffset = extraBorder + (4 - latIdx) * 1200;

      for (int lonIdx = -1; lonIdx <= 5; lonIdx++) {
        int lonDegree = lonDegreeStart + lonIdx;
        int colOffset = extraBorder + lonIdx * 1200;

        String filename = inputDir + "/" + formatLat(latDegree) + formatLon(lonDegree) + ".zip";
        File f = new File(filename);
        if (f.exists() && f.length() > 0) {
          System.out.println("exist: " + filename);
          readHgtZip(filename, rowOffset, colOffset);
        } else {
          System.out.println("none : " + filename);
        }
      }
    }

    boolean halfCol5 = false; // no halfcol tiles in lidar data (?)


    SrtmRaster raster = new SrtmRaster();
    raster.nrows = NROWS;
    raster.ncols = NCOLS;
    raster.halfcol = halfCol5;
    raster.noDataValue = NODATA;
    raster.cellsize = 1 / 1200.;
    raster.xllcorner = lonDegreeStart - (0.5 + extraBorder) * raster.cellsize;
    raster.yllcorner = latDegreeStart - (0.5 + extraBorder) * raster.cellsize;
    raster.eval_array = imagePixels;

    // encode the raster
    OutputStream os = new BufferedOutputStream(new FileOutputStream(outputFile));
    new RasterCoder().encodeRaster(raster, os);
    os.close();

    // decode the raster
    InputStream is = new BufferedInputStream(new FileInputStream(outputFile));
    SrtmRaster raster2 = new RasterCoder().decodeRaster(is);
    is.close();

    short[] pix2 = raster2.eval_array;
    if (pix2.length != imagePixels.length)
      throw new RuntimeException("length mismatch!");

    // compare decoding result
    for (int row = 0; row < NROWS; row++) {
      int colstep = halfCol5 ? 2 : 1;
      for (int col = 0; col < NCOLS; col += colstep) {
        int idx = row * NCOLS + col;
        short p2 = pix2[idx];
        if (p2 != imagePixels[idx]) {
          throw new RuntimeException("content mismatch: p2=" + p2 + " p1=" + imagePixels[idx]);
        }
      }
    }
  }

  private static String formatLon(int lon) {
    if (lon >= 180)
      lon -= 180; // TODO: w180 oder E180 ?

    String s = "E";
    if (lon < 0) {
      lon = -lon;
      s = "E";
    }
    String n = "000" + lon;
    return s + n.substring(n.length() - 3);
  }

  private static String formatLat(int lat) {
    String s = "N";
    if (lat < 0) {
      lat = -lat;
      s = "S";
    }
    String n = "00" + lat;
    return s + n.substring(n.length() - 2);
  }

  public static void main(String[] args) throws Exception {
    String filename90 = args[0];
    String filename30 = filename90.substring(0, filename90.length() - 3) + "bef";

    int srtmLonIdx = Integer.parseInt(filename90.substring(5, 7).toLowerCase());
    int srtmLatIdx = Integer.parseInt(filename90.substring(8, 10).toLowerCase());

    int ilon_base = (srtmLonIdx - 1) * 5 - 180;
    int ilat_base = 150 - srtmLatIdx * 5 - 90;

    doConvert(args[1], ilon_base, ilat_base, filename30);
  }

}