/**
 * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
 */

package net.sourceforge.pmd.lang;

import java.io.File;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * This class can discover the LanguageVersion of a source file. Further, every
 * Language has a default LanguageVersion, which can be temporarily overridden
 * here.
 */
public class LanguageVersionDiscoverer {
    private Map<Language, LanguageVersion> languageToLanguageVersion = new HashMap<>();

    /**
     * Set the given LanguageVersion as the current default for it's Language.
     *
     * @param languageVersion
     *            The new default for the Language.
     * @return The previous default version for the language.
     */
    public LanguageVersion setDefaultLanguageVersion(LanguageVersion languageVersion) {
        LanguageVersion currentLanguageVersion = languageToLanguageVersion.put(languageVersion.getLanguage(),
                languageVersion);
        if (currentLanguageVersion == null) {
            currentLanguageVersion = languageVersion.getLanguage().getDefaultVersion();
        }
        return currentLanguageVersion;
    }

    /**
     * Get the current default LanguageVersion for the given Language.
     *
     * @param language
     *            The Language.
     * @return The current default version for the language.
     */
    public LanguageVersion getDefaultLanguageVersion(Language language) {
        LanguageVersion languageVersion = languageToLanguageVersion.get(language);
        if (languageVersion == null) {
            languageVersion = language.getDefaultVersion();
        }
        return languageVersion;
    }

    /**
     * Get the default LanguageVersion for the first Language of a given source
     * file.
     *
     * @param sourceFile
     *            The file.
     * @return The currently configured LanguageVersion for the source file, or
     *         <code>null</code> if there are no supported Languages for the
     *         file.
     */
    public LanguageVersion getDefaultLanguageVersionForFile(File sourceFile) {
        return getDefaultLanguageVersionForFile(sourceFile.getName());
    }

    /**
     * Get the LanguageVersion for the first Language of a source file with the
     * given name.
     *
     * @param fileName
     *            The file name.
     * @return The currently configured LanguageVersion for the source file or
     *         <code>null</code> if there are no supported Languages for the
     *         file.
     */
    public LanguageVersion getDefaultLanguageVersionForFile(String fileName) {
        List<Language> languages = getLanguagesForFile(fileName);
        LanguageVersion languageVersion = null;
        if (!languages.isEmpty()) {
            languageVersion = getDefaultLanguageVersion(languages.get(0));
        }
        return languageVersion;
    }

    /**
     * Get the Languages of a given source file.
     *
     * @param sourceFile
     *            The file.
     * @return The Languages for the source file, may be empty.
     */
    public List<Language> getLanguagesForFile(File sourceFile) {
        return getLanguagesForFile(sourceFile.getName());
    }

    /**
     * Get the Languages of a given source file.
     *
     * @param fileName
     *            The file name.
     * @return The Languages for the source file, may be empty.
     */
    public List<Language> getLanguagesForFile(String fileName) {
        String extension = getExtension(fileName);
        return LanguageRegistry.findByExtension(extension);
    }

    // Get the extensions from a file
    private String getExtension(String fileName) {
        String extension = null;
        int extensionIndex = 1 + fileName.lastIndexOf('.');
        if (extensionIndex > 0) {
            extension = fileName.substring(extensionIndex);
        }
        return extension;
    }
}