package btools.mapcreator;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.DataInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.util.Arrays;
import java.util.Locale;
import java.util.StringTokenizer;
import java.util.zip.ZipEntry;
import java.util.zip.ZipInputStream;

public class ElevationRasterTileConverter {

  public static final boolean DEBUG = false;

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

  private static final String HGT_FILE_EXT = ".hgt";
  private static final int HGT_BORDER_OVERLAP = 1;
  private static final int HGT_3ASEC_ROWS = 1201; // 3 arc second resolution (90m)
  private static final int HGT_3ASEC_FILE_SIZE = HGT_3ASEC_ROWS * HGT_3ASEC_ROWS * Short.BYTES;
  private static final int HGT_1ASEC_ROWS = 3601; // 1 arc second resolution (30m)
  private static final int SRTM3_ROW_LENGTH = 1200; // number of elevation values per line
  private static final int SRTM1_ROW_LENGTH = 3600;
  private static final boolean SRTM_NO_ZERO = true;

  private int NROWS;
  private int NCOLS;
  private int ROW_LENGTH;
  private short[] imagePixels;

  /**
   * This generates elevation raster files with a 5x5 degree scope
   * The output can be for 1sec (18000x18000 points)
   * or for 3sec (6000x6000 points)
   * When using 1sec input files a not found area can be called from 3sec pool
   * The input can be 1x1 degree 1sec/3sec hgt files (also packed as zip)
   * or 5x5 degree 3sec asc files (delivered as zip)
   * Arguments for single file generation:
   * ElevationRasterTileConverter <srtm-filename | all> <hgt-data-dir> <srtm-output-dir> [arc seconds (1 or 3,default=3)] [hgt-fallback-data-dir]
   * Samples
   * $ ... ElevationRasterTileConverter srtm_34_-1 ./srtm/hgt3sec ./srtm/srtm3_bef
   * $ ... ElevationRasterTileConverter srtm_34_-1 ./srtm/hgt1sec ./srtm/srtm1_bef 1
   * $ ... ElevationRasterTileConverter srtm_34_-1 ./srtm/hgt1sec ./srtm/srtm1_bef 1 ./srtm/hgt3sec
   * <p>
   * Arguments for multi file generation (world wide):
   * $ ... ElevationRasterTileConverter all ./srtm/hgt3sec ./srtm/srtm3_bef
   * $ ... ElevationRasterTileConverter all ./srtm/hgt1sec ./srtm/srtm1_bef 1
   * $ ... ElevationRasterTileConverter all ./srtm/hgt1sec ./srtm/srtm1_bef 1 ./srtm/hgt3sec
   *
   * @param args
   * @throws Exception
   */
  public static void main(String[] args) throws Exception {
    if (args.length == 3 || args.length == 4 || args.length == 5) {
      String filename90 = args[0];
      if ("all".equals(filename90)) {
        //if (DEBUG)
        System.out.println("raster convert all ");
        new ElevationRasterTileConverter().doConvertAll(args[1], args[2], (args.length > 3 ? args[3] : null), (args.length == 5 ? args[4] : null));
        return;
      }
      // old filenames only
      String filename30 = filename90 + ".bef"; //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;
      int row_length = SRTM3_ROW_LENGTH;
      String fallbackdir = null;
      if (args.length > 3) {
        row_length = (Integer.parseInt(args[3]) == 1 ? SRTM1_ROW_LENGTH : SRTM3_ROW_LENGTH);
        fallbackdir = (args.length == 5 ? args[4] : null);
      }
      //if (DEBUG)
      System.out.println("raster convert " + ilon_base + " " + ilat_base + " from " + srtmLonIdx + " " + srtmLatIdx + " f: " + filename90 + " rowl " + row_length);

      new ElevationRasterTileConverter().doConvert(args[1], ilon_base, ilat_base, args[2] + "/" + filename30, row_length, fallbackdir);
    } else {
      System.out.println("usage: java <srtm-filename> <hgt-data-dir> <srtm-output-dir> [arc seconds (1 or 3,default=3)] [hgt-fallback-data-dir]");
      System.out.println("or     java all <hgt-data-dir> <srtm-output-dir> [arc seconds (1 or 3, default=3)] [hgt-fallback-data-dir]");
    }
  }

  private void doConvertAll(String hgtdata, String outdir, String rlen, String hgtfallbackdata) throws Exception {
    int row_length = SRTM3_ROW_LENGTH;
    if (rlen != null) {
      row_length = (Integer.parseInt(rlen) == 1 ? SRTM1_ROW_LENGTH : SRTM3_ROW_LENGTH);
    }
    String filename30;
    for (int ilon_base = -180; ilon_base < 180; ilon_base += 5) {
      for (int ilat_base = 85; ilat_base > -90; ilat_base -= 5) {
        if (PosUnifier.UseRasterRd5FileName) {
          filename30 = genFilenameRd5(ilon_base, ilat_base);
        } else {
          filename30 = genFilenameOld(ilon_base, ilat_base);
        }
        if (DEBUG)
          System.out.println("lidar convert all: " + filename30);
        doConvert(hgtdata, ilon_base, ilat_base, outdir + "/" + filename30, row_length, hgtfallbackdata);
      }
    }
  }

  static String genFilenameOld(int ilon_base, int ilat_base) {
    int srtmLonIdx = ((ilon_base + 180) / 5) + 1;
    int srtmLatIdx = (60 - ilat_base) / 5;
    return String.format(Locale.US, "srtm_%02d_%02d.bef", srtmLonIdx, srtmLatIdx);
  }

  static String genFilenameRd5(int ilon_base, int ilat_base) {
    return String.format("srtm_%s_%s.bef", ilon_base < 0 ? "W" + (-ilon_base) : "E" + ilon_base,
      ilat_base < 0 ? "S" + (-ilat_base) : "N" + ilat_base);
  }

  private void readHgtZip(String filename, int rowOffset, int colOffset, int row_length, int scale) throws Exception {
    ZipInputStream zis = new ZipInputStream(new BufferedInputStream(new FileInputStream(filename)));
    try {
      for (; ; ) {
        ZipEntry ze = zis.getNextEntry();
        if (ze == null) break;
        if (ze.getName().toLowerCase().endsWith(HGT_FILE_EXT)) {
          readHgtFromStream(zis, rowOffset, colOffset, row_length, scale);
          return;
        }
      }
    } finally {
      zis.close();
    }
  }

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

      for (int ic = 0; ic < rowLength; ic++) {
        int col = colOffset + ic * scale;

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

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

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

        if (val == NODATA2) {
          val = NODATA;
        }
        if (scale == 3) {
          setPixel(row, col, val);
          setPixel(row + 1, col, val);
          setPixel(row + 2, col, val);
          setPixel(row, col + 1, val);
          setPixel(row + 1, col + 1, val);
          setPixel(row + 2, col + 1, val);
          setPixel(row, col + 2, val);
          setPixel(row + 1, col + 2, val);
          setPixel(row + 2, col + 2, val);
        } else {
          setPixel(row, col, val);
        }
      }
    }
  }

  private void readHgtFile(File file, int rowOffset, int colOffset, int row_length, int scale)
    throws Exception {

    if (DEBUG)
      System.out.println("read: " + file + " " + row_length);

    FileInputStream fis = new FileInputStream(file);
    try {
      readHgtFromStream(fis, rowOffset, colOffset, row_length, scale);
    } finally {
      fis.close();
    }
  }

  /*
  private void readFallbackFile(File file, int rowOffset, int colOffset, int row_length)
    throws Exception {
    int rowLength;
    int scale;
    if (file.length() > HGT_3ASEC_FILE_SIZE) {
      rowLength = HGT_1ASEC_ROWS;
      scale = 1;
    } else {
      rowLength = HGT_3ASEC_ROWS;
      scale = 3;
    }
    if (DEBUG)
      System.out.println("read fallback: " + file + " " + rowLength);

    FileInputStream fis = new FileInputStream(file);
    try {
      readHgtFromStream(fis, rowOffset, colOffset, rowLength, scale);
    } finally {
      fis.close();
    }
  }
  */

  private void readAscZip(File file, ElevationRaster raster) throws Exception {

    ZipInputStream zis = new ZipInputStream(new BufferedInputStream(new FileInputStream(file)));
    try {
      for (; ; ) {
        ZipEntry ze = zis.getNextEntry();
        if (ze.getName().endsWith(".asc")) {
          readAscFromStream(zis, raster);
          return;
        }
      }
    } finally {
      zis.close();
    }
  }

  private String secondToken(String s) {
    StringTokenizer tk = new StringTokenizer(s, " ");
    tk.nextToken();
    return tk.nextToken();
  }

  private void readAscFromStream(InputStream is, ElevationRaster raster) throws Exception {
    BufferedReader br = new BufferedReader(new InputStreamReader(is));
    int linenr = 0;
    for (; ; ) {
      linenr++;
      if (linenr <= 6) {
        String line = br.readLine();
        if (linenr == 1)
          raster.ncols = Integer.parseInt(secondToken(line));
        else if (linenr == 2)
          raster.nrows = Integer.parseInt(secondToken(line));
        else if (linenr == 3)
          raster.xllcorner = Double.parseDouble(secondToken(line));
        else if (linenr == 4)
          raster.yllcorner = Double.parseDouble(secondToken(line));
        else if (linenr == 5)
          raster.cellsize = Double.parseDouble(secondToken(line));
        else if (linenr == 6) {
          // nodata ignored here ( < -250 assumed nodata... )
          // raster.noDataValue = Short.parseShort( secondToken( line ) );
          raster.eval_array = new short[raster.ncols * raster.nrows];
        }
      } else {
        int row = 0;
        int col = 0;
        int n = 0;
        boolean negative = false;
        for (; ; ) {
          int c = br.read();
          if (c < 0)
            break;
          if (c == ' ') {
            if (negative)
              n = -n;
            short val = n < -250 ? Short.MIN_VALUE : (short) (n);

            raster.eval_array[row * raster.ncols + col] = val;
            if (++col == raster.ncols) {
              col = 0;
              ++row;
            }
            n = 0;
            negative = false;
          } else if (c >= '0' && c <= '9') {
            n = 10 * n + (c - '0');
          } else if (c == '-') {
            negative = true;
          }
        }
        break;
      }
    }
    br.close();
  }


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

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


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

    //List<String> foundList = new ArrayList<>();
    //List<String> notfoundList = new ArrayList<>();

    boolean hgtfound = false;
    boolean ascfound = false;
    String filename = null;
    //if (row_length == SRTM1_ROW_LENGTH)
    {
      // check for sources w/o border
      for (int latIdx = 0; latIdx < 5; latIdx++) {
        int latDegree = latDegreeStart + latIdx;

        for (int lonIdx = 0; lonIdx < 5; lonIdx++) {
          int lonDegree = lonDegreeStart + lonIdx;

          filename = inputDir + "/" + formatLat(latDegree) + formatLon(lonDegree) + ".zip";
          File f = new File(filename);
          if (f.exists() && f.length() > 0) {
            hgtfound = true;
            break;
          }
          filename = filename.substring(0, filename.length() - 4) + ".hgt";
          f = new File(filename);
          if (f.exists() && f.length() > 0) {
            hgtfound = true;
            break;
          }
        }
      }
      if (!hgtfound) {
        filename = inputDir + "/" + genFilenameOld(lonDegreeStart, latDegreeStart).substring(0, 10) + ".zip";
        File f = new File(filename);
        if (f.exists() && f.length() > 0) {
          ascfound = true;
        }
      }
    }
    if (hgtfound) { // init when found
      NROWS = 5 * row_length + 1 + 2 * extraBorder;
      NCOLS = 5 * row_length + 1 + 2 * extraBorder;
      imagePixels = new short[NROWS * NCOLS]; // 650 MB !

      // prefill as NODATA
      Arrays.fill(imagePixels, NODATA);
    } else if (!ascfound) {
      if (DEBUG)
        System.out.println("none data: " + lonDegreeStart + " " + latDegreeStart);
      return;
    }

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

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

          filename = inputDir + "/" + formatLat(latDegree) + formatLon(lonDegree) + ".zip";
          File f = new File(filename);
          if (f.exists() && f.length() > 0) {
            if (DEBUG)
              System.out.println("exist: " + filename);
            readHgtZip(filename, rowOffset, colOffset, row_length + 1, 1);
            continue;
          }
          filename = filename.substring(0, filename.length() - 4) + ".hgt";
          f = new File(filename);
          if (f.exists() && f.length() > 0) {
            if (DEBUG)
              System.out.println("exist: " + filename);
            readHgtFile(f, rowOffset, colOffset, row_length + 1, 1);
            continue;
          } else {
            if (hgtfallbackdata != null) {
              filename = hgtfallbackdata + "/" + formatLat(latDegree) + formatLon(lonDegree) + ".hgt";
              f = new File(filename);
              if (f.exists() && f.length() > 0) {
                readHgtFile(f, rowOffset, colOffset, SRTM3_ROW_LENGTH + 1, 3);
                continue;
              }
              filename = filename.substring(0, filename.length() - 4) + ".zip";
              f = new File(filename);
              if (f.exists() && f.length() > 0) {
                readHgtZip(filename, rowOffset, colOffset, SRTM3_ROW_LENGTH + 1, 3);
              } else {
                if (DEBUG)
                  System.out.println("none : " + filename);
              }
            }

          }
        }
      }

      // post fill zero
      if (SRTM_NO_ZERO) {
        for (int row = 0; row < NROWS; row++) {
          for (int col = 0; col < NCOLS; col++) {
            if (imagePixels[row * NCOLS + col] == 0) imagePixels[row * NCOLS + col] = NODATA;
          }
        }
      }
    }

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


    ElevationRaster raster = new ElevationRaster();
    if (hgtfound) {
      raster.nrows = NROWS;
      raster.ncols = NCOLS;
      raster.halfcol = halfCol5;
      raster.noDataValue = NODATA;
      raster.cellsize = 1. / row_length;
      raster.xllcorner = lonDegreeStart - (0.5 + extraBorder) * raster.cellsize;
      raster.yllcorner = latDegreeStart - (0.5 + extraBorder) * raster.cellsize;
      raster.eval_array = imagePixels;
    }

    if (ascfound) {
      File f = new File(filename);
      readAscZip(f, raster);
    }

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

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

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

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

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

    String s = "E";
    if (lon < 0) {
      lon = -lon;
      s = "W";
    }
    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 ElevationRaster getRaster(File f, double lon, double lat) throws Exception {
    long fileSize;
    InputStream inputStream;

    if (f.getName().toLowerCase().endsWith(".zip")) {
      ZipInputStream zis = new ZipInputStream(new BufferedInputStream(new FileInputStream(f)));
      for (; ; ) {
        ZipEntry ze = zis.getNextEntry();
        if (ze == null) {
          throw new FileNotFoundException(f.getName() + " doesn't contain a " + HGT_FILE_EXT + " file.");
        }
        if (ze.getName().toLowerCase().endsWith(HGT_FILE_EXT)) {
          fileSize = ze.getSize();
          inputStream = zis;
          break;
        }
      }
    } else {
      fileSize = f.length();
      inputStream = new FileInputStream(f);
    }

    int rowLength;
    if (fileSize > HGT_3ASEC_FILE_SIZE) {
      rowLength = HGT_1ASEC_ROWS;
    } else {
      rowLength = HGT_3ASEC_ROWS;
    }

    // stay at 1 deg * 1 deg raster
    NROWS = rowLength;
    NCOLS = rowLength;

    imagePixels = new short[NROWS * NCOLS];

    // prefill as NODATA
    Arrays.fill(imagePixels, NODATA);
    readHgtFromStream(inputStream, 0, 0, rowLength, 1);
    inputStream.close();

    ElevationRaster raster = new ElevationRaster();
    raster.nrows = NROWS;
    raster.ncols = NCOLS;
    raster.halfcol = false; // assume full resolution
    raster.noDataValue = NODATA;
    raster.cellsize = 1. / (double) (rowLength - HGT_BORDER_OVERLAP);
    raster.xllcorner = (int) (lon < 0 ? lon - 1 : lon); //onDegreeStart - raster.cellsize;
    raster.yllcorner = (int) (lat < 0 ? lat - 1 : lat); //latDegreeStart - raster.cellsize;
    raster.eval_array = imagePixels;

    return raster;
  }


}