/*
 *    GeoTools - The Open Source Java GIS Toolkit
 *    http://geotools.org
 *
 *    (C) 2017, Open Source Geospatial Foundation (OSGeo)
 *
 *    This library is free software; you can redistribute it and/or
 *    modify it under the terms of the GNU Lesser General Public
 *    License as published by the Free Software Foundation;
 *    version 2.1 of the License.
 *
 *    This library 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 General Public License for more details.
 */
package org.geotools.mbstyle;

import org.geotools.mbstyle.layer.MBLayer;
import org.geotools.mbstyle.parse.MBFormatException;
import org.geotools.mbstyle.parse.MBStyleParser;
import org.geotools.styling.FeatureTypeStyle;
import org.geotools.styling.NamedLayer;
import org.geotools.styling.StyledLayer;
import org.geotools.styling.StyledLayerDescriptor;
import org.json.simple.parser.ParseException;
import org.opengis.style.Style;

import java.io.IOException;
import java.io.InputStream;
import java.io.Reader;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

/**
 * MapBox Style facade offering utility methods for quickly working with JSON and converting to
 * {@link StyledLayerDescriptor}.
 * 
 * @author Jody Garnett (Boundless)
 */
public class MapBoxStyle {

    /**
     * Read in the provided JSON as a {@link StyledLayerDescriptor}.
     * 
     * @param reader
     * @return generated style
     */
    public static StyledLayerDescriptor parse(Reader reader) throws IOException, ParseException {
        MBStyleParser parser = new MBStyleParser();
        MBStyle style = parser.parse(reader);

        StyledLayerDescriptor sld = style.transform();
        return sld;
    }

    /**
     * Read in the provided JSON as a {@link StyledLayerDescriptor}.
     * 
     * @param stream
     * @return generated style
     */
    public static StyledLayerDescriptor parse(InputStream stream) throws IOException, ParseException {
        MBStyleParser parser = new MBStyleParser();
        MBStyle style = parser.parse(stream);

        StyledLayerDescriptor sld = style.transform();
        return sld;
    }
    
    /**
     * Validate ability to read json, and parse each layer.
     * @param reader Reader for reading the style
     * @return List of parse exceptions found. If this list is empty, the style is valid.
     */
    public static List<Exception> validate(Reader reader) {
        List<Exception> problems = new ArrayList<Exception>();
        MBStyleParser parser = new MBStyleParser();
        MBStyle style;
        try {
            style = parser.parse(reader);
        } catch (Exception invalid) {
            problems.add( invalid );
            return problems;
        }
        List<MBLayer> layers = Collections.emptyList();
        
        try {
            layers = style.layers();
            if (layers.isEmpty()) {
                problems.add( new MBFormatException("No layers defined"));
            }
        }
        catch (MBFormatException layersUnavailable){
            problems.add( layersUnavailable );
        }
        boolean hasVisibleLayer = false;
        for (MBLayer layer : layers) {
            if (!layer.visibility()) {
                continue;
            }
            try {
                List<FeatureTypeStyle> featureTypeStyle = layer.transform(style);
                if (featureTypeStyle != null) {
                    hasVisibleLayer = true;
                }
            } catch (Exception invalid) {
                problems.add((MBFormatException) new MBFormatException(
                        "Layer " + layer.getId() + ":" + invalid.getMessage()).initCause(invalid));
                return problems;
            }
        }
        if (!hasVisibleLayer) {
            problems.add( new MBFormatException("No layers were visible"));
        }
        else {
            try {
                StyledLayerDescriptor sld = style.transform();
                // quick sanity check on results sld files
                // if we get any problems downstream in rendering add additional checks here
                if( sld.getStyledLayers().length == 0 ){
                    problems.add(new MBFormatException("Generated sld for "+sld.getName()+" is empty."));
                }
                else {
                    for( StyledLayer layer : sld.getStyledLayers()){
                        if( layer instanceof NamedLayer ){
                            NamedLayer named = (NamedLayer) layer;
                            if( named.styles().isEmpty() ){
                                problems.add(new MBFormatException("Generated named layer for "+named.getName()+" is empty."));
                            }
                            else {
                                for( Style layerStyle : named.styles()){
                                    if( layerStyle instanceof FeatureTypeStyle){
                                        FeatureTypeStyle fts = (FeatureTypeStyle) layerStyle;
                                        if( fts.rules().isEmpty()){
                                            problems.add(new MBFormatException("Generated feature type style "+fts.getName()+" is empty."));
                                        }
                                    }
                                }
                            }
                        }
                    }
                }
            } catch (MBFormatException invalid) {
                // we could not parse out an sld due to a well-known problem
                problems.add(invalid);
            } catch (Exception problem) {
                // we could not parse out sld due to an unexpected problem
                problems.add((MBFormatException) new MBFormatException(
                        "Style " + style.getName() + ":" + problem.getMessage()).initCause(problem));
            }
        }
        return problems;
    }
}