/*
 * 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.jena.sparql.core.assembler;

import org.apache.jena.assembler.Assembler ;
import org.apache.jena.assembler.ConstAssembler ;
import org.apache.jena.assembler.JA ;
import org.apache.jena.assembler.assemblers.AssemblerGroup ;
import org.apache.jena.query.* ;
import org.apache.jena.rdf.model.Model ;
import org.apache.jena.rdf.model.ModelFactory ;
import org.apache.jena.rdf.model.Resource ;
import org.apache.jena.rdf.model.ResourceFactory ;
import org.apache.jena.riot.RDFDataMgr ;
import org.apache.jena.shared.PrefixMapping ;
import org.apache.jena.sparql.ARQException ;
import org.apache.jena.sparql.util.Context ;
import org.apache.jena.sparql.util.MappingRegistry ;
import org.apache.jena.sparql.util.Symbol ;
import org.apache.jena.sparql.util.TypeNotUniqueException ;
import org.apache.jena.sparql.util.graph.GraphUtils ;
import org.apache.jena.sys.JenaSystem ;
import org.apache.jena.vocabulary.RDFS ;
import static org.apache.jena.sparql.core.assembler.DatasetAssemblerVocab.*;

public class AssemblerUtils
{
    // Wrappers for reading things form a file - assumes one of the thing per file.
    public static PrefixMapping readPrefixMapping(String file)
    {
        PrefixMapping pm = (PrefixMapping)AssemblerUtils.build(file, JA.PrefixMapping) ;
        return pm ;
    }

    private static boolean initialized = false ;

    static { JenaSystem.init() ; }

    static public void init()
    {
        if ( initialized )
            return ;
        initialized = true ;
        registerDataset(tDataset,         new DatasetAssembler());
        registerDataset(tDatasetOne,      new DatasetOneAssembler());
        registerDataset(tDatasetZero,     new DatasetNullAssembler(tDatasetZero));
        registerDataset(tDatasetSink,     new DatasetNullAssembler(tDatasetSink));
        registerDataset(tMemoryDataset,   new InMemDatasetAssembler());
        registerDataset(tDatasetTxnMem,   new InMemDatasetAssembler());

        registerModel(tViewGraph,          new ViewGraphAssembler());
    }

    private static Model modelExtras = ModelFactory.createDefaultModel() ;

    /** Register an assembler that creates a dataset */
    static public void registerDataset(Resource r, Assembler a) {
        register(ConstAssembler.general(), r, a, DatasetAssembler.getType()) ;
    }

    /** Register an assembler that creates a dataset */
    static public void registerModel(Resource r, Assembler a) {
        register(ConstAssembler.general(), r, a, JA.Model) ;
    }

    /** Register an additional assembler */
    static public void register(AssemblerGroup g, Resource r, Assembler a, Resource superType) {
        registerAssembler(g, r, a) ;
        if ( superType != null && ! superType.equals(r) ) {
            // This is called during Jena-wide initialization.
            // Use function for constant (JENA-1294)
           modelExtras.add(r, RDFS.Init.subClassOf(), superType) ;
        }
    }

    /** register */
    public static void registerAssembler(AssemblerGroup group, Resource r, Assembler a) {
        if ( group == null )
            group = ConstAssembler.general();
        group.implementWith(r, a);
        // assemblerAssertions.add(r, RDFS.subClassOf, JA.Object) ;
    }

    public static Model readAssemblerFile(String assemblerFile) {
        Model spec = null ;
        try {
            spec = RDFDataMgr.loadModel(assemblerFile) ;
        } catch (Exception ex)
        { throw new ARQException("Failed reading assembler description: "+ex.getMessage()) ; }
        addRegistered(spec);
        return spec ;
    }

    /** Add any extra information to the model.
     * Such information includes registration of datasets (e.g. TDB1, TDB2)
     * done by {@link #register} ({@link #registerDataset}, {@link #registerModel}.
     * It avoids directly modifying {@link Assembler#general}.
     * @param model
     * @return Model The same model after modification.
     */
    public static Model addRegistered(Model model) {
        model.add(modelExtras) ;
        return model ;
    }

    public static Object build(String assemblerFile, String typeURI) {
        Resource type = ResourceFactory.createResource(typeURI) ;
        return build(assemblerFile, type) ;
    }

    public static Object build(String assemblerFile, Resource type) {
        if ( assemblerFile == null )
            throw new ARQException("No assembler file") ;
        Model spec = readAssemblerFile(assemblerFile) ;

        Resource root = null ;
        try {
            root = GraphUtils.findRootByType(spec, type) ;
            if ( root == null )
                throw new ARQException("No such type: <"+type+">");

        } catch (TypeNotUniqueException ex)
        { throw new ARQException("Multiple types for: "+tDataset) ; }
        return Assembler.general.open(root) ;
    }

    /** Look for and build context declarations.
     * e.g.
     * <pre>
     * root ... ;
     *   ja:context [ ja:cxtName "arq:queryTimeout" ;  ja:cxtValue "10000" ] ;
     *   ...
     * </pre>
     * Short name forms of context parameters can be used.
     * Setting as string "undef" will remove the context setting.
     * Returns null when there is no {@link JA#context} on the resource.
     */
    public static Context parseContext(Resource r)
    {
        if ( ! r.hasProperty(JA.context ) )
            return null;
        Context context = new Context();
        mergeContext(r, context);
        return context;
    }

    /** Look for and merge in context declarations.
     * e.g.
     * <pre>
     * root ... ;
     *   ja:context [ ja:cxtName "arq:queryTimeout" ;  ja:cxtValue "10000" ] ;
     *   ...
     * </pre>
     * Short name forms of context parameters can be used.
     * Setting as string "undef" will remove the context setting.
     */
    public static void mergeContext(Resource r, Context context) {
        String qs = "PREFIX ja: <"+JA.getURI()+">\nSELECT * { ?x ja:context [ ja:cxtName ?name ; ja:cxtValue ?value ] }" ;
        QuerySolutionMap qsm = new QuerySolutionMap() ;
        qsm.add("x", r) ;
        QueryExecution qExec = QueryExecutionFactory.create(qs, r.getModel(), qsm) ;
        ResultSet rs = qExec.execSelect() ;
        while ( rs.hasNext() )
        {
            QuerySolution soln = rs.next() ;
            String name = soln.getLiteral("name").getLexicalForm() ;
            String value = soln.getLiteral("value").getLexicalForm() ;  // Works for numbers as well!
            name = MappingRegistry.mapPrefixName(name) ;
            Symbol symbol = Symbol.create(name) ;
            if ( "undef".equalsIgnoreCase(value) )
                context.remove(symbol) ;
            else
                context.set(symbol, value) ;
        }
    }
}
