/*
 * 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
 *
 *   https://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.
 *
 *   SPDX-License-Identifier: Apache-2.0
 */

package org.apache.jena.fuseki.validation.html;

import static org.apache.jena.fuseki.validation.html.ValidatorHtmlLib.finishFixed;
import static org.apache.jena.fuseki.validation.html.ValidatorHtmlLib.output;
import static org.apache.jena.fuseki.validation.html.ValidatorHtmlLib.printHead;
import static org.apache.jena.fuseki.validation.html.ValidatorHtmlLib.serviceLog;
import static org.apache.jena.fuseki.validation.html.ValidatorHtmlLib.setHeaders;
import static org.apache.jena.fuseki.validation.html.ValidatorHtmlLib.startFixed;

import java.io.IOException;

import jakarta.servlet.ServletOutputStream;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;

import org.apache.jena.query.Query;
import org.apache.jena.query.QueryFactory;
import org.apache.jena.query.Syntax;
import org.apache.jena.sparql.ARQException;
import org.apache.jena.sparql.algebra.Algebra;
import org.apache.jena.sparql.algebra.Op;
import org.apache.jena.sparql.serializer.SerializationContext;

public class QueryValidatorHTML {
    private QueryValidatorHTML() {}

    static final String paramLineNumbers = "linenumbers";
    static final String paramFormat      = "outputFormat";
    static final String paramQuery       = "query";
    static final String paramSyntax      = "languageSyntax";

    public static void executeHTML(HttpServletRequest httpRequest, HttpServletResponse httpResponse) {
        try {
            String[] args = httpRequest.getParameterValues(paramQuery);

            if ( args == null || args.length == 0 ) {
                httpResponse.sendError(HttpServletResponse.SC_BAD_REQUEST, "No query parameter to validator");
                return;
            }

            if ( args.length > 1 ) {
                httpResponse.sendError(HttpServletResponse.SC_BAD_REQUEST, "Too many query parameters");
                return;
            }

            final String queryString = httpRequest.getParameter(paramQuery).replaceAll("(\r|\n| )*$", "");

            String querySyntax = httpRequest.getParameter(paramSyntax);
            if ( querySyntax == null || querySyntax.equals("") )
                querySyntax = "SPARQL";

            Syntax language = Syntax.lookup(querySyntax);
            if ( language == null ) {
                httpResponse.sendError(HttpServletResponse.SC_BAD_REQUEST, "Unknown syntax: " + querySyntax);
                return;
            }

            String lineNumbersArg = httpRequest.getParameter(paramLineNumbers);

            String a[] = httpRequest.getParameterValues(paramFormat);

            boolean outputSPARQL = false;
            boolean outputPrefix = false;
            boolean outputAlgebra = false;
            boolean outputQuads = false;
            boolean outputOptimized = false;
            boolean outputOptimizedQuads = false;

            if ( a != null ) {
                for ( String anA : a ) {
                    if ( anA.equals("sparql") ) {
                        outputSPARQL = true;
                    }
                    if ( anA.equals("prefix") ) {
                        outputPrefix = true;
                    }
                    if ( anA.equals("algebra") ) {
                        outputAlgebra = true;
                    }
                    if ( anA.equals("quads") ) {
                        outputQuads = true;
                    }
                    if ( anA.equals("opt") ) {
                        outputOptimized = true;
                    }
                    if ( anA.equals("optquads") ) {
                        outputOptimizedQuads = true;
                    }
                }
            }

            // if ( ! outputSPARQL && ! outputPrefix )
            //     outputSPARQL = true;

            boolean lineNumbers = true;

            if ( lineNumbersArg != null )
                lineNumbers = lineNumbersArg.equalsIgnoreCase("true") || lineNumbersArg.equalsIgnoreCase("yes");

            setHeaders(httpResponse);

            ServletOutputStream outStream = httpResponse.getOutputStream();

            outStream.println("<html>");

            printHead(outStream, "SPARQL Query Validation Report");

            outStream.println("<body>");
            outStream.println("<h1>SPARQL Query Validator</h1>");
            // Print query as received
            outStream.println("<p>Input:</p>");
            output(outStream, (out) -> out.print(queryString), lineNumbers);

            // Attempt to parse it.
            Query query = null;
            try {
                query = QueryFactory.create(queryString, "http://example/base/", language);
            } catch (ARQException ex) {
                // Over generous exception (should be QueryException)
                // but this makes the code robust.
                outStream.println("<p>Syntax error:</p>");
                startFixed(outStream);
                outStream.println(ex.getMessage());
                finishFixed(outStream);
            } catch (RuntimeException ex) {
                outStream.println("<p>Internal error:</p>");
                startFixed(outStream);
                outStream.println(ex.getMessage());
                finishFixed(outStream);
            }

            if ( query != null ) {
                if ( outputSPARQL )
                    outputSyntax(outStream, query, lineNumbers);

                if ( outputAlgebra )
                    outputAlgebra(outStream, query, lineNumbers);

                if ( outputQuads )
                    outputAlgebraQuads(outStream, query, lineNumbers);

                if ( outputOptimized )
                    outputAlgebraOpt(outStream, query, lineNumbers);

                if ( outputOptimizedQuads )
                    outputAlgebraOptQuads(outStream, query, lineNumbers);
            }

            outStream.println("</body>");
            outStream.println("</html>");

        } catch (Exception ex) {
            serviceLog.warn("Exception in doGet", ex);
        }
    }

    private static void outputSyntax(ServletOutputStream outStream, final Query query, boolean lineNumbers) throws IOException {
        output(outStream, (out) -> query.serialize(out), lineNumbers);
    }

    private static void outputAlgebra(ServletOutputStream outStream, final Query query, boolean lineNumbers) throws IOException {
        outStream.println("<p>Algebra structure:</p>");
        final Op op = Algebra.compile(query);   // No optimization
        outputQueryOp(outStream, query, op, lineNumbers);
    }

    private static void outputAlgebraOpt(ServletOutputStream outStream, final Query query, boolean lineNumbers) throws IOException {
        outStream.println("<p>Algebra, with general triple optimizations:</p>");
        final Op op = Algebra.optimize(Algebra.compile(query));
        outputQueryOp(outStream, query, op, lineNumbers);
    }

    private static void outputAlgebraQuads(ServletOutputStream outStream, final Query query, boolean lineNumbers) throws IOException {
        outStream.println("<p>Quad structure:</p>");
        final Op op = Algebra.toQuadForm(Algebra.compile(query));
        outputQueryOp(outStream, query, op, lineNumbers);
    }

    private static void outputAlgebraOptQuads(ServletOutputStream outStream, final Query query, boolean lineNumbers) throws IOException {
        outStream.println("<p>Algebra, with general quads optimizations:</p>");
        final Op op = Algebra.optimize(Algebra.toQuadForm(Algebra.compile(query)));
        outputQueryOp(outStream, query, op, lineNumbers);
    }

    private static void outputQueryOp(ServletOutputStream outStream, Query query, final Op op, boolean lineNumbers) throws IOException {
        final SerializationContext sCxt = new SerializationContext(query);
        output(outStream, out -> op.output(out, sCxt), lineNumbers);
    }
}
