/*
    * Licensed to the Apache Software Foundation (ASF) under one or more
    * contributor license agreements.  See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * The ASF licenses this file to You under the Apache License, Version 2.0
    * (the "License"); you may not use this file except in compliance with
    * the License.  You may obtain a copy of the License at
    *
    *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.apache.commons.geometry.io.euclidean.threed.txt;
  
  import java.io.Writer;
  import java.util.Iterator;
  import java.util.List;
  import java.util.stream.Stream;
  
  import org.apache.commons.geometry.euclidean.internal.EuclideanUtils;
  import org.apache.commons.geometry.euclidean.threed.BoundarySource3D;
  import org.apache.commons.geometry.euclidean.threed.PlaneConvexSubset;
  import org.apache.commons.geometry.euclidean.threed.Triangle3D;
  import org.apache.commons.geometry.euclidean.threed.Vector3D;
  import org.apache.commons.geometry.io.core.utils.AbstractTextFormatWriter;
  import org.apache.commons.geometry.io.euclidean.threed.FacetDefinition;
  
  /** Class for writing 3D facet geometry in a simple human-readable text format. The
   * format simply consists of sequences of decimal numbers defining the vertices of each
   * facet, with one facet defined per line. Facet vertices are defined by listing their
   * {@code x}, {@code y}, and {@code z} components in that order. At least 3 vertices are
   * required for each facet but more can be specified. The facet normal is defined implicitly
   * from the facet vertices using the right-hand rule (i.e. vertices are arranged counter-clockwise).
   *
   * <p>Delimiters can be configured for both {@link #getVertexComponentSeparator() vertex components} and
   * {@link #getVertexSeparator() vertices}. This allows a wide range of outputs to be configured, from standard
   * {@link #csvFormat(Writer) CSV format} to formats designed for easy human readability.</p>
   *
   * <p><strong>Examples</strong></p>
   * <p>The examples below demonstrate output from two square facets using different writer
   * configurations.</p>
   *
   * <p><em>Default</em></p>
   * <p>The default writer configuration uses distinct vertex and vertex component separators to make it
   * easier to visually distinguish vertices. Comments are supported and facets are allowed to have
   * any geometrically valid number of vertices. This format is designed for human readability and ease
   * of editing.</p>
   * <pre>
   * # two square facets
   * 0 0 0; 1 0 0; 1 1 0; 0 1 0
   * 0 0 0; 0 1 0; 0 1 1; 0 0 1
   * </pre>
   *
   * <p><em>CSV</em></p>
   * <p>The example below uses a comma as both the vertex and vertex component separators to produce
   * a standard CSV format. The facet vertex count is set to 3 to ensure that each row has the same number
   * of columns and all numbers are written with at least a single fraction digit to ensure proper interpretation
   * as floating point data. Comments are not supported. This configuration is produced by the
   * {@link #csvFormat(Writer)} factory method.</p>
   * <pre>
   * 0.0,0.0,0.0,1.0,0.0,0.0,1.0,1.0,0.0
   * 0.0,0.0,0.0,1.0,1.0,0.0,0.0,1.0,0.0
   * 0.0,0.0,0.0,0.0,1.0,0.0,0.0,1.0,1.0
   * 0.0,0.0,0.0,0.0,1.0,1.0,0.0,0.0,1.0
   * </pre>
   *
   * @see TextFacetDefinitionReader
   */
  public class TextFacetDefinitionWriter extends AbstractTextFormatWriter {
  
      /** Vertex and vertex component separator used in the CSV format. */
      static final String CSV_SEPARATOR = ",";
  
      /** Number of vertices required per facet in the CSV format. */
      static final int CSV_FACET_VERTEX_COUNT = 3;
  
      /** Default vertex component separator. */
      static final String DEFAULT_VERTEX_COMPONENT_SEPARATOR = " ";
  
      /** Default vertex separator. */
      static final String DEFAULT_VERTEX_SEPARATOR = "; ";
  
      /** Default facet vertex count. */
      static final int DEFAULT_FACET_VERTEX_COUNT = -1;
  
      /** Default comment token. */
      private static final String DEFAULT_COMMENT_TOKEN = "# ";
  
      /** String used to separate vertex components, ie, x, y, z values. */
      private String vertexComponentSeparator = DEFAULT_VERTEX_COMPONENT_SEPARATOR;
  
      /** String used to separate vertices. */
      private String vertexSeparator = DEFAULT_VERTEX_SEPARATOR;
  
      /** Number of vertices required per facet; will be -1 if disabled. */
     private int facetVertexCount = DEFAULT_FACET_VERTEX_COUNT;
 
     /** Comment start token; may be null. */
     private String commentToken = DEFAULT_COMMENT_TOKEN;
 
     /** Construct a new instance that writes facet information to the given writer.
      * @param writer writer to write output to
      */
     public TextFacetDefinitionWriter(final Writer writer) {
         super(writer);
     }
 
     /** Get the string used to separate vertex components (ie, individual x, y, z values).
      * The default value is {@value #DEFAULT_VERTEX_COMPONENT_SEPARATOR}.
      * @return string used to separate vertex components
      */
     public String getVertexComponentSeparator() {
         return vertexComponentSeparator;
     }
 
     /** Set the string used to separate vertex components (ie, individual x, y, z values).
      * @param sep string used to separate vertex components
      */
     public void setVertexComponentSeparator(final String sep) {
         this.vertexComponentSeparator = sep;
     }
 
     /** Get the string used to separate facet vertices. The default value is {@value #DEFAULT_VERTEX_SEPARATOR}.
      * @return string used to separate facet vertices
      */
     public String getVertexSeparator() {
         return vertexSeparator;
     }
 
     /** Set the string used to separate facet vertices.
      * @param sep string used to separate facet vertices
      */
     public void setVertexSeparator(final String sep) {
         this.vertexSeparator = sep;
     }
 
     /** Get the number of vertices required per facet or {@code -1} if no specific
      * number is required. The default value is {@value #DEFAULT_FACET_VERTEX_COUNT}.
      * @return the number of vertices required per facet or {@code -1} if any geometricallly
      *      valid number is allowed (ie, any number greater than or equal to 3)
      */
     public int getFacetVertexCount() {
         return facetVertexCount;
     }
 
     /** Set the number of vertices required per facet. This can be used to enforce a consistent
      * format in the output. Set to {@code -1} to allow any geometrically valid number of vertices
      * (ie, any number greater than or equal to 3).
      * @param vertexCount number of vertices required per facet or {@code -1} to allow any number
      * @throws IllegalArgumentException if the argument would produce invalid geometries (ie, is
      *      greater than -1 and less than 3)
      */
     public void setFacetVertexCount(final int vertexCount) {
         if (vertexCount > -1 &&  vertexCount < 3) {
             throw new IllegalArgumentException("Facet vertex count must be less than 0 or greater than 2; was " +
                     vertexCount);
         }
 
         this.facetVertexCount = Math.max(-1, vertexCount);
     }
 
     /** Get the string used to begin comment lines in the output.
      * The default value is {@value #DEFAULT_COMMENT_TOKEN}
      * @return the string used to begin comment lines in the output; may be null
      */
     public String getCommentToken() {
         return commentToken;
     }
 
     /** Set the string used to begin comment lines in the output. Set to null to disable the
      * use of comments.
      * @param commentToken comment token string
      * @throws IllegalArgumentException if the argument is empty or begins with whitespace
      */
     public void setCommentToken(final String commentToken) {
         if (commentToken != null) {
             if (commentToken.isEmpty()) {
                 throw new IllegalArgumentException("Comment token cannot be empty");
             } else if (Character.isWhitespace(commentToken.charAt(0))) {
                 throw new IllegalArgumentException("Comment token cannot begin with whitespace");
             }
 
         }
 
         this.commentToken = commentToken;
     }
 
     /** Write a comment to the output.
      * @param comment comment string to write
      * @throws IllegalStateException if the configured {@link #getCommentToken() comment token} is null
      * @throws java.io.UncheckedIOException if an I/O error occurs
      */
     public void writeComment(final String comment) {
         if (commentToken == null) {
             throw new IllegalStateException("Cannot write comment: no comment token configured");
         }
 
         if (comment != null) {
             for (final String line : comment.split("\\R")) {
                 write(commentToken + line);
                 writeNewLine();
             }
         }
     }
 
     /** Write a blank line to the output.
      * @throws java.io.UncheckedIOException if an I/O error occurs
      */
     public void writeBlankLine() {
         writeNewLine();
     }
 
     /** Write all boundaries in the argument to the output. If the
      * {@link #getFacetVertexCount() facet vertex count} has been set to {@code 3}, then each
      * boundary is converted to triangles before being written. Otherwise, the boundaries are
      * written as-is.
      * @param src object providing the boundaries to write
      * @throws IllegalArgumentException if any boundary has infinite size or a
      *      {@link #getFacetVertexCount() facet vertex count} has been configured and a boundary
      *      cannot be represented using the required number of vertices
      * @throws java.io.UncheckedIOException if an I/O error occurs
      */
     public void write(final BoundarySource3D src) {
         try (Stream<PlaneConvexSubset> stream = src.boundaryStream()) {
             final Iterator<PlaneConvexSubset> it = stream.iterator();
             while (it.hasNext()) {
                 write(it.next());
             }
         }
     }
 
     /** Write the vertices defining the argument to the output. If the
      * {@link #getFacetVertexCount() facet vertex count} has been set to {@code 3}, then the convex subset
      * is converted to triangles before being written to the output. Otherwise, the argument
      * vertices are written as-is.
      * @param convexSubset convex subset to write
      * @throws IllegalArgumentException if the argument has infinite size or a
      *      {@link #getFacetVertexCount() facet vertex count} has been configured and the number of required
      *      vertices does not match the number present in the argument
      * @throws java.io.UncheckedIOException if an I/O error occurs
      */
     public void write(final PlaneConvexSubset convexSubset) {
         if (convexSubset.isInfinite()) {
             throw new IllegalArgumentException("Cannot write infinite convex subset");
         }
 
         if (facetVertexCount == EuclideanUtils.TRIANGLE_VERTEX_COUNT) {
             // force conversion to triangles
             for (final Triangle3D tri : convexSubset.toTriangles()) {
                 write(tri.getVertices());
             }
         } else {
             // write as-is; callers are responsible for making sure that the number of
             // vertices matches the required number for the writer
             write(convexSubset.getVertices());
         }
     }
 
     /** Write the vertices in the argument to the output.
      * @param facet facet containing the vertices to write
      * @throws IllegalArgumentException if a {@link #getFacetVertexCount() facet vertex count}
      *      has been configured and the number of required vertices does not match the number
      *      present in the argument
      * @throws java.io.UncheckedIOException if an I/O error occurs
      */
     public void write(final FacetDefinition facet) {
         write(facet.getVertices());
     }
 
     /** Write a list of vertices defining a facet as a single line of text to the output. Vertex components
      * (ie, individual x, y, z values) are separated with the configured
      * {@link #getVertexComponentSeparator() vertex component separator} and vertices are separated with the
      * configured {@link #getVertexSeparator() vertex separator}.
      * @param vertices vertices to write
      * @throws IllegalArgumentException if the vertex list contains less than 3 vertices or a
      *      {@link #getFacetVertexCount() facet vertex count} has been configured and the number of required
      *      vertices does not match the number given
      * @throws java.io.UncheckedIOException if an I/O error occurs
      * @see #getVertexComponentSeparator()
      * @see #getVertexSeparator()
      * @see #getFacetVertexCount()
      */
     public void write(final List<Vector3D> vertices) {
         final int size = vertices.size();
         if (size < EuclideanUtils.TRIANGLE_VERTEX_COUNT) {
             throw new IllegalArgumentException("At least " + EuclideanUtils.TRIANGLE_VERTEX_COUNT +
                     " vertices are required per facet; found " + size);
         } else if (facetVertexCount > -1 && size != facetVertexCount) {
             throw new IllegalArgumentException("Writer requires " + facetVertexCount +
                     " vertices per facet; found " + size);
         }
 
         final Iterator<Vector3D> it = vertices.iterator();
 
         write(it.next());
         while (it.hasNext()) {
             write(vertexSeparator);
             write(it.next());
         }
 
         writeNewLine();
     }
 
     /** Write a single vertex to the output.
      * @param vertex vertex to write
      * @throws java.io.UncheckedIOException if an I/O error occurs
      */
     private void write(final Vector3D vertex) {
         write(vertex.getX());
         write(vertexComponentSeparator);
         write(vertex.getY());
         write(vertexComponentSeparator);
         write(vertex.getZ());
     }
 
     /** Construct a new instance configured to write CSV output to the given writer.
      * The returned instance has the following configuration:
      * <ul>
      *  <li>Vertex separator and vertex components separator are set to the "," string.</li>
      *  <li>Comments are disabled (i.e., comment token is set to null).</li>
      *  <li>Facet vertex count is set to 3 to ensure a consistent number of columns.</li>
      * </ul>
      * This configuration produces output similar to the following:
      * <pre>
      * 0.0,0.0,0.0,1.0,0.0,0.0,1.0,1.0,0.0
      * 0.0,0.0,0.0,1.0,1.0,0.0,0.0,1.0,0.0
      * </pre>
      *
      * @param writer writer to write output to
      * @return a new facet definition writer configured to produce CSV output
      */
     public static TextFacetDefinitionWriter csvFormat(final Writer writer) {
         final TextFacetDefinitionWriter fdWriter = new TextFacetDefinitionWriter(writer);
 
         fdWriter.setVertexComponentSeparator(CSV_SEPARATOR);
         fdWriter.setVertexSeparator(CSV_SEPARATOR);
         fdWriter.setFacetVertexCount(CSV_FACET_VERTEX_COUNT);
         fdWriter.setCommentToken(null);
 
         return fdWriter;
     }
 }