Linter.java

package org.thewonderlemming.c4plantuml.linter;

import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.nio.file.Path;
import java.util.Collections;
import java.util.HashSet;
import java.util.Set;

import org.antlr.v4.runtime.tree.ParseTree;
import org.antlr.v4.runtime.tree.ParseTreeWalker;
import org.thewonderlemming.c4plantuml.commons.Reporter;
import org.thewonderlemming.c4plantuml.grammars.SourceType;
import org.thewonderlemming.c4plantuml.linter.rules.AbstractLintingRule;

/**
 * A linting engine that parses C4 files and passes the result {@link ParseTree} to a set of
 * {@link AbstractLintingRule}.
 *
 * @author thewonderlemming
 *
 */
public class Linter {

    private final Set<AbstractLintingRule> activeRules = new HashSet<>();

    private final Reporter reporter;


    /**
     * returns a new instance of {@link LinterBuilder} since the default constructor is protected.
     *
     * @return a new builder instance.
     */
    public static LinterBuilder builder() {
        return new LinterBuilder();
    }

    /**
     * Default constructor.
     *
     * @param reporter the reporter to report linting errors to.
     * @param activeRules the set of {@link AbstractLintingRule} to use.
     */
    protected Linter(final Reporter reporter, final Set<AbstractLintingRule> activeRules) {

        this.reporter = reporter;
        this.activeRules.addAll(activeRules);
    }

    /**
     * Returns the set of active {@link AbstractLintingRule} to be used on parsed files.
     *
     * @return the set of active {@link AbstractLintingRule} to use.
     */
    public Set<AbstractLintingRule> getActiveRules() {
        return Collections.unmodifiableSet(this.activeRules);
    }

    /**
     * Same as {@link Linter#lint(Path, Charset)} but with UTF-8 as default {@link Charset}.
     *
     * @see Linter#lint(Path, Charset)
     *
     * @param c4SourceFile the C4 file to process.
     */
    public void lint(final Path c4SourceFile) {
        lint(c4SourceFile, StandardCharsets.UTF_8);
    }

    /**
     * Parses a C4 file and if no error occurs, passes the resulting {@link ParseTree} through every active
     * {@link AbstractLintingRule}.
     * <p>
     * Any syntax error in the file will be reported to a {@link LinterSyntaxErrorListener}.
     * <p>
     * Linting errors will be reported to the instance {@link Reporter}.
     *
     * @param c4SourceFile the C4 source file to process.
     * @param charset the {@link Charset} of the file.
     */
    public void lint(final Path c4SourceFile, final Charset charset) {

        SourceType
            .getSourceTypeFromFilename(c4SourceFile)
                .ifPresent(sourceType -> {

                    final LinterSyntaxErrorListener errorListener = new LinterSyntaxErrorListener();

                    sourceType
                        .createParser(c4SourceFile, charset, errorListener)
                            .ifPresent(parser -> this.activeRules
                                .stream()
                                    .filter(rule -> rule.acceptableParsersTypes().contains(parser.getClass()))
                                    .forEach(rule -> {

                                        errorListener.registerRule(rule);

                                        rule
                                            .selectParseTree(parser)
                                                .ifPresent(tree -> {
                                                    rule
                                                        .createParseTreeListener(this.reporter, parser.getClass())
                                                            .ifPresent(
                                                                listener -> new ParseTreeWalker().walk(listener, tree));

                                                    rule.wrapUp();
                                                });

                                        errorListener.unregisterRule(rule);
                                    }));
                });
    }
}