/*
 *    GeoTools - The Open Source Java GIS Toolkit
 *    http://geotools.org
 *
 *    (C) 2015, Open Source Geospatial Foundation (OSGeo)
 *
 * Copyright (c) 2016 Vivid Solutions.
 *
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * and Eclipse Distribution License v. 1.0 which accompanies this distribution.
 * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v20.html
 * and the Eclipse Distribution License is available at
 *
 * http://www.eclipse.org/org/documents/edl-v10.php.
 */
package org.geotools.geometry.jts;

import java.io.IOException;
import java.util.ArrayList;
import java.util.EnumSet;
import java.util.List;
import org.locationtech.jts.geom.Coordinate;
import org.locationtech.jts.geom.CoordinateSequence;
import org.locationtech.jts.geom.CoordinateSequenceFactory;
import org.locationtech.jts.geom.CoordinateSequences;
import org.locationtech.jts.geom.Geometry;
import org.locationtech.jts.geom.GeometryCollection;
import org.locationtech.jts.geom.GeometryFactory;
import org.locationtech.jts.geom.LineString;
import org.locationtech.jts.geom.LinearRing;
import org.locationtech.jts.geom.MultiLineString;
import org.locationtech.jts.geom.MultiPoint;
import org.locationtech.jts.geom.MultiPolygon;
import org.locationtech.jts.geom.Point;
import org.locationtech.jts.geom.Polygon;
import org.locationtech.jts.geom.PrecisionModel;
import org.locationtech.jts.io.ByteArrayInStream;
import org.locationtech.jts.io.ByteOrderDataInStream;
import org.locationtech.jts.io.ByteOrderValues;
import org.locationtech.jts.io.InStream;
import org.locationtech.jts.io.Ordinate;
import org.locationtech.jts.io.ParseException;
import org.locationtech.jts.io.WKBWriter;

/**
 * Reads a {@link Geometry}from a byte stream in Well-Known Binary format. Supports use of an {@link InStream}, which
 * allows easy use with arbitrary byte stream sources.
 *
 * <p>This class reads the format describe in {@link WKBWriter}. It partially handles the <b>Extended WKB</b> format
 * used by PostGIS, by parsing and storing optional SRID values. If a SRID is not specified in an element geometry, it
 * is inherited from the parent's SRID. The default SRID value is 0.
 *
 * <p>Although not defined in the WKB specification, empty points are handled if they are represented as a Point with
 * <code>NaN</code> X and Y ordinates.
 *
 * <p>The reader repairs structurally-invalid input (specifically, LineStrings and LinearRings which contain too few
 * points have vertices added, and non-closed rings are closed).
 *
 * <p>The reader handles most errors caused by malformed or malicious WKB data. It checks for obviously excessive values
 * of the fields <code>numElems</code>, <code>numRings</code>, and <code>numCoords</code>. It also checks that the
 * reader does not read beyond the end of the data supplied. A {@link ParseException} is thrown if this situation is
 * detected.
 *
 * <p>This class is designed to support reuse of a single instance to read multiple geometries. This class is not
 * thread-safe; each thread should create its own instance.
 *
 * <p>As of version 1.15, the reader can read geometries following the OGC 06-103r4 Simple Features Access 1.2.1
 * specification, which aligns with the ISO 19125 standard. This format is used by Spatialite and Geopackage.
 *
 * <p>The difference between PostGIS EWKB format and the new ISO/OGC specification is that Z and M coordinates are
 * detected with a bit mask on the higher byte in the former case (0x80 for Z and 0x40 for M) while new OGC
 * specification use specific int ranges for 2D geometries, Z geometries (2D code+1000), M geometries (2D code+2000) and
 * ZM geometries (2D code+3000).
 *
 * <p>Note that the {@link WKBWriter} is not changed and still writes the PostGIS EWKB geometry format.
 *
 * @see WKBWriter for a formal format specification
 */
public class WKBReader {
    /**
     * Converts a hexadecimal string to a byte array. The hexadecimal digit symbols are case-insensitive.
     *
     * @param hex a string containing hex digits
     * @return an array of bytes with the value of the hex string
     */
    public static byte[] hexToBytes(String hex) {
        int byteLen = hex.length() / 2;
        byte[] bytes = new byte[byteLen];

        for (int i = 0; i < hex.length() / 2; i++) {
            int i2 = 2 * i;
            if (i2 + 1 > hex.length()) throw new IllegalArgumentException("Hex string has odd length");

            int nib1 = hexToInt(hex.charAt(i2));
            int nib0 = hexToInt(hex.charAt(i2 + 1));
            byte b = (byte) ((nib1 << 4) + (byte) nib0);
            bytes[i] = b;
        }
        return bytes;
    }

    private static int hexToInt(char hex) {
        int nib = Character.digit(hex, 16);
        if (nib < 0) throw new IllegalArgumentException("Invalid hex digit: '" + hex + "'");
        return nib;
    }

    private static final String INVALID_GEOM_TYPE_MSG = "Invalid geometry type encountered in ";

    private static final String FIELD_NUMCOORDS = "numCoords";

    private static final String FIELD_NUMRINGS = "numRings";

    private static final String FIELD_NUMELEMS = "numElems";

    private CurvedGeometryFactory factory;
    private CoordinateSequenceFactory csFactory;
    private PrecisionModel precisionModel;
    // default dimension - will be set on read
    private int inputDimension = 2;
    /**
     * true if structurally invalid input should be reported rather than repaired. At some point this could be made
     * client-controllable.
     */
    private boolean isStrict = false;

    private ByteOrderDataInStream dis = new ByteOrderDataInStream();
    private double[] ordValues;

    private int maxNumFieldValue;

    public WKBReader() {
        this(new GeometryFactory());
    }

    public WKBReader(GeometryFactory geometryFactory) {
        this.factory = getCurvedGeometryFactory(geometryFactory);
        precisionModel = factory.getPrecisionModel();
        csFactory = factory.getCoordinateSequenceFactory();
    }

    /**
     * Reads a single {@link Geometry} in WKB format from a byte array.
     *
     * @param bytes the byte array to read from
     * @return the geometry read
     * @throws ParseException if the WKB is ill-formed
     */
    public Geometry read(byte[] bytes) throws ParseException {
        // possibly reuse the ByteArrayInStream?
        // don't throw IOExceptions, since we are not doing any I/O
        try {
            return read(new ByteArrayInStream(bytes), bytes.length / 8);
        } catch (IOException ex) {
            throw new RuntimeException("Unexpected IOException caught: " + ex.getMessage());
        }
    }

    /**
     * Reads a {@link Geometry} in binary WKB format from an {@link InStream}.
     *
     * @param is the stream to read from
     * @return the Geometry read
     * @throws IOException if the underlying stream creates an error
     * @throws ParseException if the WKB is ill-formed
     */
    public Geometry read(InStream is) throws IOException, ParseException {
        // can't tell size of InStream, but MAX_VALUE should be safe
        return read(is, Integer.MAX_VALUE);
    }

    private Geometry read(InStream is, int maxCoordNum) throws IOException, ParseException {
        /**
         * This puts an upper bound on the allowed value in coordNum fields. It avoids OOM exceptions due to malformed
         * input.
         */
        this.maxNumFieldValue = maxCoordNum;
        dis.setInStream(is);
        return readGeometry(0);
    }

    private int readNumField(String fieldName) throws IOException, ParseException {
        // num field is unsigned int, but Java has only signed int
        int num = dis.readInt();
        if (num < 0 || num > maxNumFieldValue) {
            throw new ParseException(fieldName + " value is too large");
        }
        return num;
    }

    private Geometry readGeometry(int SRID) throws IOException, ParseException {

        // determine byte order
        byte byteOrderWKB = dis.readByte();

        // always set byte order, since it may change from geometry to geometry
        if (byteOrderWKB == WKBConstants.wkbNDR) {
            dis.setOrder(ByteOrderValues.LITTLE_ENDIAN);
        } else if (byteOrderWKB == WKBConstants.wkbXDR) {
            dis.setOrder(ByteOrderValues.BIG_ENDIAN);
        } else if (isStrict) {
            throw new ParseException("Unknown geometry byte order (not NDR or XDR): " + byteOrderWKB);
        }
        // if not strict and not XDR or NDR, then we just use the dis default set at the
        // start of the geometry (if a multi-geometry).  This  allows WBKReader to work
        // with Spatialite native BLOB WKB, as well as other WKB variants that might just
        // specify endian-ness at the start of the multigeometry.

        int typeInt = dis.readInt();

        /**
         * To get geometry type mask out EWKB flag bits, and use only low 3 digits of type word. This supports both EWKB
         * and ISO/OGC.
         */
        int geometryType = (typeInt & 0xffff) % 1000;

        // handle 3D and 4D WKB geometries
        // geometries with Z coordinates have the 0x80 flag (postgis EWKB)
        // or are in the 1000 range (Z) or in the 3000 range (ZM) of geometry type (ISO/OGC 06-103r4)
        boolean hasZ =
                ((typeInt & 0x80000000) != 0 || (typeInt & 0xffff) / 1000 == 1 || (typeInt & 0xffff) / 1000 == 3);
        // geometries with M coordinates have the 0x40 flag (postgis EWKB)
        // or are in the 1000 range (M) or in the 3000 range (ZM) of geometry type (ISO/OGC 06-103r4)
        boolean hasM =
                ((typeInt & 0x40000000) != 0 || (typeInt & 0xffff) / 1000 == 2 || (typeInt & 0xffff) / 1000 == 3);
        // System.out.println(typeInt + " - " + geometryType + " - hasZ:" + hasZ);
        inputDimension = 2 + (hasZ ? 1 : 0) + (hasM ? 1 : 0);

        EnumSet<Ordinate> ordinateFlags = EnumSet.of(Ordinate.X, Ordinate.Y);
        if (hasZ) {
            ordinateFlags.add(Ordinate.Z);
        }
        if (hasM) {
            ordinateFlags.add(Ordinate.M);
        }

        // determine if SRIDs are present (EWKB only)
        boolean hasSRID = (typeInt & 0x20000000) != 0;
        if (hasSRID) {
            SRID = dis.readInt();
        }

        // only allocate ordValues buffer if necessary
        if (ordValues == null || ordValues.length < inputDimension) ordValues = new double[inputDimension];

        Geometry geom = null;
        switch (geometryType) {
            case WKBConstants.wkbPoint:
                geom = readPoint(ordinateFlags);
                break;
            case WKBConstants.wkbLineString:
                geom = readLineString(ordinateFlags);
                break;
            case WKBConstants.wkbPolygon:
                geom = readPolygon(ordinateFlags);
                break;
            case WKBConstants.wkbMultiPoint:
                geom = readMultiPoint(SRID);
                break;
            case WKBConstants.wkbMultiCurve:
            case WKBConstants.wkbMultiLineString:
                geom = readMultiLineString(SRID);
                break;
            case WKBConstants.wkbMultiPolygon:
            case WKBConstants.wkbMultiSurface:
                geom = readMultiPolygon(SRID);
                break;
            case WKBConstants.wkbGeometryCollection:
                geom = readGeometryCollection(SRID);
                break;
            case WKBConstants.wkbCircularString:
                geom = readCircularString(ordinateFlags);
                break;
            case WKBConstants.wkbCompoundCurve:
                geom = readCompoundCurve(SRID);
                break;
            case WKBConstants.wkbCurvePolygon:
                geom = readCurvePolygon(SRID);
                break;
            default:
                throw new ParseException("Unknown WKB type " + geometryType);
        }
        setSRID(geom, SRID);
        return geom;
    }

    /**
     * Sets the SRID, if it was specified in the WKB
     *
     * @param g the geometry to update
     * @return the geometry with an updated SRID value, if required
     */
    private Geometry setSRID(Geometry g, int SRID) {
        if (SRID != 0) g.setSRID(SRID);
        return g;
    }

    private Point readPoint(EnumSet<Ordinate> ordinateFlags) throws IOException, ParseException {
        CoordinateSequence pts = readCoordinateSequence(1, ordinateFlags);
        // If X and Y are NaN create a empty point
        if (Double.isNaN(pts.getX(0)) || Double.isNaN(pts.getY(0))) {
            return factory.createPoint();
        }
        return factory.createPoint(pts);
    }

    private LineString readLineString(EnumSet<Ordinate> ordinateFlags) throws IOException, ParseException {
        int size = readNumField(FIELD_NUMCOORDS);
        CoordinateSequence pts = readCoordinateSequenceLineString(size, ordinateFlags);
        return factory.createLineString(pts);
    }

    private Geometry readCircularString(EnumSet<Ordinate> ordinateFlags) throws IOException, ParseException {
        int size = dis.readInt();
        CoordinateSequence pts = readCoordinateSequenceCircularString(size, ordinateFlags);
        return factory.createCurvedGeometry(pts);
    }

    private Geometry readCompoundCurve(int SRID) throws IOException, ParseException {
        int numGeom = dis.readInt();
        List<LineString> geoms = new ArrayList<>();
        for (int i = 0; i < numGeom; i++) {
            Geometry g = readGeometry(SRID);
            if (!(g instanceof LineString)) throw new ParseException(INVALID_GEOM_TYPE_MSG + "CompoundCurve");
            geoms.add((LineString) g);
        }
        return factory.createCurvedGeometry(geoms);
    }

    private LinearRing readLinearRing(EnumSet<Ordinate> ordinateFlags) throws IOException, ParseException {
        int size = readNumField(FIELD_NUMCOORDS);
        CoordinateSequence pts = readCoordinateSequenceRing(size, ordinateFlags);
        return factory.createLinearRing(pts);
    }

    private Polygon readPolygon(EnumSet<Ordinate> ordinateFlags) throws IOException, ParseException {
        int numRings = readNumField(FIELD_NUMRINGS);
        LinearRing[] holes = null;
        if (numRings > 1) holes = new LinearRing[numRings - 1];

        // empty polygon
        if (numRings <= 0) return factory.createPolygon();

        LinearRing shell = readLinearRing(ordinateFlags);
        for (int i = 0; i < numRings - 1; i++) {
            holes[i] = readLinearRing(ordinateFlags);
        }
        return factory.createPolygon(shell, holes);
    }

    protected Polygon readCurvePolygon(int SRID) throws IOException, ParseException {
        int numRings = dis.readInt();
        LinearRing[] holes = null;
        if (numRings > 1) holes = new LinearRing[numRings - 1];

        LinearRing shell = readRing(SRID);
        for (int i = 0; i < numRings - 1; i++) {
            holes[i] = readRing(SRID);
        }
        return factory.createPolygon(shell, holes);
    }

    private LinearRing readRing(int SRID) throws IOException, ParseException {
        LineString ls = (LineString) readGeometry(SRID);
        if (!(ls instanceof LinearRing)) {
            if (!ls.isClosed()) {
                if (ls instanceof CompoundCurve) {
                    CompoundCurve cc = (CompoundCurve) ls;
                    List<LineString> components = cc.getComponents();
                    Coordinate start = components.get(0).getCoordinateN(0);
                    LineString lastGeom = components.get(components.size() - 1);
                    Coordinate end = lastGeom.getCoordinateN((lastGeom.getNumPoints() - 1));
                    components.add(factory.createLineString(new Coordinate[] {start, end}));
                    ls = factory.createCurvedGeometry(components);
                } else {
                    Coordinate start = ls.getCoordinateN(0);
                    Coordinate end = ls.getCoordinateN((ls.getNumPoints() - 1));
                    // turn it into a compound and add the segment that closes it
                    LineString closer = factory.createLineString(new Coordinate[] {start, end});
                    ls = factory.createCurvedGeometry(ls, closer);
                }
            } else {
                if (ls instanceof CompoundCurve) {
                    // this case should never happen, but let's be robust against
                    // alternative geometry factories not behaving as expected
                    CompoundCurve cc = (CompoundCurve) ls;
                    ls = new CompoundRing(cc.getComponents(), cc.getFactory(), cc.getTolerance());
                } else {
                    ls = new LinearRing(ls.getCoordinateSequence(), ls.getFactory());
                }
            }
        }

        return (LinearRing) ls;
    }

    private MultiPoint readMultiPoint(int SRID) throws IOException, ParseException {
        int numGeom = readNumField(FIELD_NUMELEMS);
        Point[] geoms = new Point[numGeom];
        for (int i = 0; i < numGeom; i++) {
            Geometry g = readGeometry(SRID);
            if (!(g instanceof Point)) throw new ParseException(INVALID_GEOM_TYPE_MSG + "MultiPoint");
            geoms[i] = (Point) g;
        }
        return factory.createMultiPoint(geoms);
    }

    private MultiLineString readMultiLineString(int SRID) throws IOException, ParseException {
        int numGeom = readNumField(FIELD_NUMELEMS);
        LineString[] geoms = new LineString[numGeom];
        for (int i = 0; i < numGeom; i++) {
            Geometry g = readGeometry(SRID);
            if (!(g instanceof LineString)) throw new ParseException(INVALID_GEOM_TYPE_MSG + "MultiLineString");
            geoms[i] = (LineString) g;
        }
        return factory.createMultiLineString(geoms);
    }

    private MultiPolygon readMultiPolygon(int SRID) throws IOException, ParseException {
        int numGeom = readNumField(FIELD_NUMELEMS);
        Polygon[] geoms = new Polygon[numGeom];

        for (int i = 0; i < numGeom; i++) {
            Geometry g = readGeometry(SRID);
            if (!(g instanceof Polygon)) throw new ParseException(INVALID_GEOM_TYPE_MSG + "MultiPolygon");
            geoms[i] = (Polygon) g;
        }
        return factory.createMultiPolygon(geoms);
    }

    private GeometryCollection readGeometryCollection(int SRID) throws IOException, ParseException {
        int numGeom = readNumField(FIELD_NUMELEMS);
        Geometry[] geoms = new Geometry[numGeom];
        for (int i = 0; i < numGeom; i++) {
            geoms[i] = readGeometry(SRID);
        }
        return factory.createGeometryCollection(geoms);
    }

    private CoordinateSequence readCoordinateSequence(int size, EnumSet<Ordinate> ordinateFlags)
            throws IOException, ParseException {
        CoordinateSequence seq = csFactory.create(size, inputDimension, ordinateFlags.contains(Ordinate.M) ? 1 : 0);
        int targetDim = seq.getDimension();
        if (targetDim > inputDimension) targetDim = inputDimension;
        for (int i = 0; i < size; i++) {
            readCoordinate();
            for (int j = 0; j < targetDim; j++) {
                seq.setOrdinate(i, j, ordValues[j]);
            }
        }
        return seq;
    }

    private CoordinateSequence readCoordinateSequenceCircularString(int size, EnumSet<Ordinate> ordinateFlags)
            throws IOException, ParseException {
        CoordinateSequence seq = readCoordinateSequence(size, ordinateFlags);
        if (isStrict) return seq;
        if (seq.size() == 0 || seq.size() >= 3) return seq;
        return CoordinateSequences.extend(csFactory, seq, 3);
    }

    private CoordinateSequence readCoordinateSequenceLineString(int size, EnumSet<Ordinate> ordinateFlags)
            throws IOException, ParseException {
        CoordinateSequence seq = readCoordinateSequence(size, ordinateFlags);
        if (isStrict) return seq;
        if (seq.size() == 0 || seq.size() >= 2) return seq;
        return CoordinateSequences.extend(csFactory, seq, 2);
    }

    private CoordinateSequence readCoordinateSequenceRing(int size, EnumSet<Ordinate> ordinateFlags)
            throws IOException, ParseException {
        CoordinateSequence seq = readCoordinateSequence(size, ordinateFlags);
        if (isStrict) return seq;
        if (CoordinateSequences.isRing(seq)) return seq;
        return CoordinateSequences.ensureValidRing(csFactory, seq);
    }

    /**
     * Reads a coordinate value with the specified dimensionality. Makes the X and Y ordinates precise according to the
     * precision model in use.
     *
     * @throws ParseException
     */
    private void readCoordinate() throws IOException, ParseException {
        for (int i = 0; i < inputDimension; i++) {
            if (i <= 1) {
                ordValues[i] = precisionModel.makePrecise(dis.readDouble());
            } else {
                ordValues[i] = dis.readDouble();
            }
        }
    }

    /**
     * Casts the provided geometry factory to a curved one if possible, or wraps it into one with infinite tolerance
     * (the linearization will happen using the default base segments number set in {@link CircularArc}
     */
    private CurvedGeometryFactory getCurvedGeometryFactory(GeometryFactory gf) {
        CurvedGeometryFactory curvedFactory;
        if (gf instanceof CurvedGeometryFactory) {
            curvedFactory = (CurvedGeometryFactory) gf;
        } else {
            curvedFactory = new CurvedGeometryFactory(gf, Double.MAX_VALUE);
        }
        return curvedFactory;
    }
}
