/*
 * Copyright 2017 the original author or authors.
 *
 * Licensed 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.gradle.internal.scripts;

import org.gradle.scripts.ScriptingLanguage;

import javax.annotation.Nullable;
import java.io.File;
import java.util.ArrayList;
import java.util.List;

import static java.util.Collections.emptyList;
import static org.gradle.internal.FileUtils.hasExtension;

public class DefaultScriptFileResolver implements ScriptFileResolver {

    private static final String[] EXTENSIONS = scriptingLanguageExtensions();

    @Nullable
    private final ScriptFileResolvedListener scriptFileResolvedListener;

    public DefaultScriptFileResolver(@Nullable ScriptFileResolvedListener scriptFileResolvedListener) {
        this.scriptFileResolvedListener = scriptFileResolvedListener;
    }

    public DefaultScriptFileResolver() {
        this.scriptFileResolvedListener = null;
    }

    @Override
    public File resolveScriptFile(File dir, String basename) {
        for (String extension : EXTENSIONS) {
            File candidate = new File(dir, basename + extension);
            if (isCandidateFile(candidate)) {
                return candidate;
            }
        }
        return null;
    }

    private boolean isCandidateFile(File candidate) {
        notifyListener(candidate);
        return candidate.isFile();
    }

    @Override
    public List<File> findScriptsIn(File dir) {
        File[] candidates = dir.listFiles();
        if (candidates == null || candidates.length == 0) {
            return emptyList();
        }
        List<File> found = new ArrayList<File>(candidates.length);
        for (File candidate : candidates) {
            if (candidate.isFile() && hasScriptExtension(candidate)) {
                found.add(candidate);
            }
        }
        return found;
    }


    private void notifyListener(File scriptFile) {
        if (scriptFileResolvedListener != null) {
            scriptFileResolvedListener.onScriptFileResolved(scriptFile);
        }
    }

    private boolean hasScriptExtension(File file) {
        for (String extension : EXTENSIONS) {
            if (hasExtension(file, extension)) {
                return true;
            }
        }
        return false;
    }

    private static String[] scriptingLanguageExtensions() {
        List<ScriptingLanguage> scriptingLanguages = ScriptingLanguages.all();
        String[] extensions = new String[scriptingLanguages.size()];
        for (int i = 0; i < extensions.length; i++) {
            extensions[i] = scriptingLanguages.get(i).getExtension();
        }
        return extensions;
    }
}
