package won.matcher.utils.tensor;

import org.springframework.core.io.Resource;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.Collection;
import java.util.LinkedList;
import java.util.stream.Collectors;

/**
 * Loads all SPARQL "*.rq" files from a specified directory and executes them (using time range parameters) on a
 * SPARQL endpoint. The result {@link TensorEntry} objects from all queries are returned.
 *
 * Created by hfriedrich on 21.04.2017.
 */
public class TensorEntryAllGenerator implements TensorEntryGenerator {

    private String sparqlEndpoint;
    private String queryDirectory;
    private long from;
    private long to;

    public TensorEntryAllGenerator(String queryDirectory, String sparqlEndpoint, long fromDate, long toDate) {

        this.queryDirectory = queryDirectory;
        this.sparqlEndpoint = sparqlEndpoint;
        from = fromDate;
        to = toDate;
    }

    @Override
    public Collection<TensorEntry> generateTensorEntries() throws IOException {

        Collection<TensorEntry> tensorEntries = new LinkedList<>();
        Collection<TensorEntrySparqlGenerator> queryGenerators = new LinkedList<>();

        // read all sparql queries from target directory and configure them with variable bindings
        PathMatchingResourcePatternResolver resolver = new PathMatchingResourcePatternResolver();
        Resource[] resources = resolver.getResources("classpath:" + queryDirectory + "/*.rq");

        for (Resource resource : resources) {
            String query = readFromInputStream(resource.getInputStream());
            TensorEntrySparqlGenerator queryGen = new TensorEntrySparqlGenerator(sparqlEndpoint, query);
            queryGen.addVariableBinding("from", Long.valueOf(from));
            queryGen.addVariableBinding("to", Long.valueOf(to));
            queryGenerators.add(queryGen);
        }

        // execute all sparql query generators
        for (TensorEntrySparqlGenerator queryGen : queryGenerators) {
            tensorEntries.addAll(queryGen.generateTensorEntries());
        }

        return tensorEntries;
    }

    public static String readFromInputStream(InputStream input) throws IOException {
        try (BufferedReader buffer = new BufferedReader(new InputStreamReader(input, "UTF-8"))) {
            return buffer.lines().collect(Collectors.joining("\n"));
        }
    }
}