/*
 * This file is part of McIDAS-V
 *
 * Copyright 2007-2016
 * Space Science and Engineering Center (SSEC)
 * University of Wisconsin - Madison
 * 1225 W. Dayton Street, Madison, WI 53706, USA
 * https://www.ssec.wisc.edu/mcidas
 * 
 * All Rights Reserved
 * 
 * McIDAS-V is built on Unidata's IDV and SSEC's VisAD libraries, and
 * some McIDAS-V source code is based on IDV and VisAD source code.  
 * 
 * McIDAS-V is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 * 
 * McIDAS-V is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser Public License
 * along with this program.  If not, see http://www.gnu.org/licenses.
 */

package edu.wisc.ssec.mcidasv.data;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;

import java.util.ArrayList;
import java.util.List;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import ucar.unidata.geoloc.projection.UtmProjection;

/**
 * Representation of an ENVI header file.
 */
public class EnviInfo extends HeaderInfo {

    /** The url */
    private String dataFile = "";
    private boolean isEnvi = false;
    private boolean hasBounds = false;
    private static final Logger logger = LoggerFactory.getLogger(EnviInfo.class);

    // Map Info header field indices 
    // See www.exelisvis.com/docs/ENVIHeaderFiles.html 
    // for a description of this information
    enum MapInfoIndex {

        MAP_INFO_IDX_PROJ_NAME(0),
        MAP_INFO_IDX_X_REF(1),
        MAP_INFO_IDX_Y_REF(2),
        MAP_INFO_IDX_EASTING(3),
        MAP_INFO_IDX_NORTHING(4),
        MAP_INFO_IDX_X_SIZE(5),
        MAP_INFO_IDX_Y_SIZE(6),
        MAP_INFO_IDX_ZONE(7),
        MAP_INFO_IDX_N_OR_S(8),
        MAP_INFO_IDX_DATUM(9),
        MAP_INFO_IDX_UNITS(10);

        private final int index;

        private MapInfoIndex(int idx) {
            index = idx;
        }

        public int getIndex() {
            return index;
        }
    }

    /**
     * Ctor for xml encoding
     */
    public EnviInfo() {}

    /**
     * CTOR
     *
     * @param thisFile File to use. Cannot be {@code null}.
     */
    public EnviInfo(File thisFile) {
        this(thisFile.getAbsolutePath());
    }

    /**
     * CTOR
     *
     * @param filename The filename
     */
    public EnviInfo(String filename) {
        super(filename);
        this.dataFile = filename.replace(".hdr", ".img");
    }

    /**
     * Is the file an ENVI header file?
     * 
     * @return {@code true} if the file appears to be an ENVI header file.
     */
    public boolean isEnviHeader() {
        parseHeader();
        return isEnvi;
    }

    /**
     * Can we find a matching ENVI data file?
     * 
     * @return {@code true} if {@link #dataFile} exists.
     */
    public boolean hasEnviData() {
        File testFile = new File(dataFile);
        if (testFile.exists()) {
            return true;
        } else {
            return false;
        }
    }

    /**
     * Is this a navigation header file?
     * 
     * @return {@code true} if {@link #dataFile} contains latitude and 
     *         longitude bands, {@code false} otherwise.
     */
    public boolean isNavHeader() {
        parseHeader();
        List bandNames = getParameter(BANDNAMES, new ArrayList());
        if (bandNames == null) {
            return false;
        }
        if (bandNames.contains("Latitude") && bandNames.contains("Longitude")) {
            return true;
        }
        return false;
    }

    /**
     * Get the latitude band number.
     * 
     * @return Either the latitude band number or {code -1}. 
     */
    public int getLatBandNum() {
        parseHeader();
        List bandNames = getParameter(BANDNAMES, new ArrayList());
        for (int i = 0; i < bandNames.size(); i++) {
            if (bandNames.get(i).equals("Latitude")) {
                return i + 1;
            }
        }
        return -1;
    }

    /**
     * 
     *
     * @return Either the latitude band file or an empty {@code String}.
     */
    public String getLatBandFile() {
        parseHeader();
        List bandFiles = getParameter(BANDFILES, new ArrayList());
        int bandNum = getLatBandNum();
        if (bandNum < 0) {
            return "";
        }
        return (String)(bandFiles.get(bandNum - 1));
    }

    /**
     * Get the longitude band number.
     * 
     * @return Either the longitude band number or {@code -1}.
     */
    public int getLonBandNum() {
        parseHeader();
        List bandNames = getParameter(BANDNAMES, new ArrayList());
        for (int i = 0; i < bandNames.size(); i++) {
            if (bandNames.get(i).equals("Longitude")) {
                return i + 1;
            }
        }
        return -1;
    }

    /**
     * 
     * 
     * @return Either the longitude band file or an empty {@code String}.
     */
    public String getLonBandFile() {
        parseHeader();
        List bandFiles = getParameter(BANDFILES, new ArrayList());
        int bandNum = getLonBandNum();
        if (bandNum < 0) {
            return "";
        }
        return (String)(bandFiles.get(bandNum - 1));
    }

//    /**
//     * Return a FlatField representing the data
//     */
//      public FlatField getDataField() {
//
//      }

//    /**
//     * Return a Gridded2DSet representing navigation
//     */
//      public Gridded2DSet getNavField() {
//
//      }

    /**
     * Returns whether or not there are bounds.
     * 
     * @return Whether or not there are bounds.
     */
    public boolean isHasBounds() {
        return hasBounds;
    }

    /**
     * Control whether or not there are bounds.
     * 
     * @param hasBounds Whether or not there are bounds.
     */
    public void setHasBounds(boolean hasBounds) {
        this.hasBounds = hasBounds;
    }

    /**
     * Parse a potential ENVI header file.
     */
    protected void parseHeader() {
        if (haveParsed()) {
            return;
        }
        if (!doesExist()) {
            isEnvi = false;
            return;
        }

        try {
            BufferedReader br = new BufferedReader(new FileReader(getFilename()));
            String line;
            String parameter = "";
            String value = "";
            boolean inValue = false;

            List<String> bandNames = new ArrayList<>();
            List bandFiles = new ArrayList();

            while ((line = br.readLine()) != null) {
                if (line.trim().equals("ENVI")) {
                    isEnvi = true;
                    continue;
                }
                if (!isEnvi) {
                    break;
                }

                int indexOfEquals = line.indexOf("=");
                int indexOfOpen = line.indexOf("{");
                int indexOfClose = line.indexOf("}");
                if (indexOfEquals >= 0) {
                    parameter = line.substring(0, indexOfEquals).trim();
                    value = "";
                    inValue = false;
                }
                if (indexOfOpen >= 0) {
                    if (indexOfClose >= 0) {
                        value += line.substring(indexOfOpen+1, indexOfClose).trim();
                        inValue = false;
                    } else {
                        value += line.substring(indexOfOpen+1).trim();
                        inValue = true;
                        continue;
                    }
                } else if (inValue) {
                    if (indexOfClose >= 0) {
                        value += line.substring(0, indexOfClose).trim();
                        inValue = false;
                    } else {
                        value += line.trim();
                        continue;
                    }
                } else {
                    value += line.substring(indexOfEquals + 1).trim();
                }

                if (parameter.equals("")) {
                    continue;
                }

                if (parameter.equals("description")) {
                    setParameter(DESCRIPTION, value);
                }

                // TJJ Apr 2014
                // NOTE: method signatures in parent class should be modified or extended
                // I had to pass in an Integer object here in order to be able to retrieve
                // anything other than default values later (both "lines" and "samples")

                else if (parameter.equals("samples")) {
                    setParameter(ELEMENTS, new Integer(value));
                } else if (parameter.equals("lines")) {
                    setParameter(LINES, new Integer(value));
                } else if (parameter.equals("header offset")) {
                    setParameter(OFFSET, Integer.parseInt(value));
                } else if (parameter.equals("data type")) {
                    setParameter(DATATYPE, Integer.parseInt(value));
                } else if (parameter.equals("data ignore value") ||
                    parameter.equals("bad value")) {
                    setParameter(MISSINGVALUE, Float.parseFloat(value));
                } else if (parameter.equals("interleave")) {
                    setParameter(INTERLEAVE, value.toUpperCase());
                } else if (parameter.equals("map info")) {
                    logger.debug("Parsing Map Info, value: " + value);

                    ArrayList<String> mapInfo = new ArrayList<>();
                    String[] mapInfoSplit = value.split(",");
                    for (int i = 0; i < mapInfoSplit.length; i++) {
                        mapInfo.add(mapInfoSplit[i].trim());
                    }

                    // See www.exelisvis.com/docs/ENVIHeaderFiles.html 
                    // for a description of this information
                    // this code handles UTM files

                    String projName = mapInfo.get(MapInfoIndex.MAP_INFO_IDX_PROJ_NAME.getIndex());

                    if (projName.equals("UTM")) {

                        // zone and hemisphere
                        int utmZone = Integer.parseInt(mapInfo.get(MapInfoIndex.MAP_INFO_IDX_ZONE.getIndex()));
                        boolean utmN = false;
                        if (mapInfo.get(MapInfoIndex.MAP_INFO_IDX_N_OR_S.getIndex()).equals("North")) utmN = true;
                        UtmProjection utmp = new UtmProjection(utmZone, utmN);

                        // Java UTM class default units km, adjust if necessary
                        float distFactor = 1.0f;
                        if (mapInfo.get(MapInfoIndex.MAP_INFO_IDX_UNITS.getIndex()).contains("Meters")) distFactor = 1000.0f;

                        // figure out Lat/Lon bounding box from Northing/Easting,
                        // resolution, and grid size
                        float upperLeftX = Float.parseFloat(mapInfo.get(MapInfoIndex.MAP_INFO_IDX_EASTING.getIndex())) / distFactor;
                        float upperLeftY = Float.parseFloat(mapInfo.get(MapInfoIndex.MAP_INFO_IDX_NORTHING.getIndex())) / distFactor;

                        // lines and samples were already seen
                        int numLines = getParameter(LINES, 0);
                        int numSamples = getParameter(ELEMENTS, 0);

                        float xMag = Float.parseFloat(mapInfo.get(MapInfoIndex.MAP_INFO_IDX_X_SIZE.getIndex()));
                        float yMag = Float.parseFloat(mapInfo.get(MapInfoIndex.MAP_INFO_IDX_Y_SIZE.getIndex()));

                        float lowerRightX = upperLeftX + ((numSamples * xMag) / distFactor);
                        float lowerRightY = upperLeftY + ((numLines * yMag) / distFactor);

                        float [][] from = new float[2][2];
                        from [0][0] = upperLeftX;
                        from [1][0] = upperLeftY;
                        from [0][1] = lowerRightX;
                        from [1][1] = lowerRightY;
                        float [][] to = new float[2][2];
                        to = utmp.projToLatLon(from, to);

                        // Need to check and see if we are correct in assuming which one is upper left
                        if (to[0][0] > to[0][1]) {
                            setParameter("BOUNDS.ULLAT", "" + to[0][0]);
                            setParameter("BOUNDS.ULLON", "" + to[1][0]);
                            setParameter("BOUNDS.LRLAT", "" + to[0][1]);
                            setParameter("BOUNDS.LRLON", "" + to[1][1]);
                        } else {
                            from [0][0] = upperLeftX;
                            from [1][0] = upperLeftY - ((numLines * yMag) / distFactor);
                            from [0][1] = lowerRightX;
                            from [1][1] = lowerRightY - ((numLines * yMag) / distFactor);
                            to = utmp.projToLatLon(from, to);
                            setParameter("BOUNDS.ULLAT", "" + to[0][1]);
                            setParameter("BOUNDS.ULLON", "" + to[1][0]);
                            setParameter("BOUNDS.LRLAT", "" + to[0][0]);
                            setParameter("BOUNDS.LRLON", "" + to[1][1]);
                        }
                        hasBounds = true;
                    }
                } else if (parameter.equals("byte order")) {
                    boolean bigEndian = false;
                    if (value.equals("1")) {
                        bigEndian = true;
                    }
                    setParameter(BIGENDIAN, bigEndian);
                } else if (parameter.equals("bands")) {
                    if (bandNames.size() <= 0 && bandFiles.size() <= 0) {
                        int bandCount = Integer.parseInt(value);
                        for (int i = 0; i < bandCount; i++) {
                            bandNames.add("Band " + i+1);
                            bandFiles.add(dataFile);
                        }
                        setParameter(BANDNAMES, bandNames);
                        setParameter(BANDFILES, bandFiles);
                    }
                } else if (parameter.equals("band names")) {
                    bandNames = new ArrayList<>();
                    bandFiles = new ArrayList<String>();
                    String[] bandNamesSplit = value.split(",");
                    for (int i = 0; i < bandNamesSplit.length; i++) {
                        bandNames.add(bandNamesSplit[i].trim());
                        bandFiles.add(dataFile);
                    }
                    setParameter(BANDNAMES, bandNames);
                    setParameter(BANDFILES, bandFiles);
                }

            }
            br.close();
        } catch (IOException ioe) {
            ioe.printStackTrace();
        }
    }
}