/*
 * Copyright 2009 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.initialization;

import org.gradle.StartParameter;
import org.gradle.api.initialization.ProjectDescriptor;
import org.gradle.api.internal.GradleInternal;
import org.gradle.api.internal.SettingsInternal;
import org.gradle.api.internal.initialization.ClassLoaderScope;
import org.gradle.initialization.buildsrc.BuildSourceBuilder;

import java.io.File;

/**
 * Handles locating and processing setting.gradle files.  Also deals with the buildSrc module, since that modules is
 * found after settings is located, but needs to be built before settings is processed.
 */
public class SettingsHandler {
    private ISettingsFinder settingsFinder;
    private SettingsProcessor settingsProcessor;
    private BuildSourceBuilder buildSourceBuilder;

    public SettingsHandler(ISettingsFinder settingsFinder, SettingsProcessor settingsProcessor,
                           BuildSourceBuilder buildSourceBuilder) {
        this.settingsFinder = settingsFinder;
        this.settingsProcessor = settingsProcessor;
        this.buildSourceBuilder = buildSourceBuilder;
    }

    public SettingsInternal findAndLoadSettings(GradleInternal gradle) {
        StartParameter startParameter = gradle.getStartParameter();
        SettingsInternal settings = findSettingsAndLoadIfAppropriate(gradle, startParameter);

        ProjectSpec spec = ProjectSpecs.forStartParameter(startParameter, settings);

        if (spec.containsProject(settings.getProjectRegistry())) {
            setDefaultProject(spec, settings);
            return settings;
        }

        // Try again with empty settings
        StartParameter noSearchParameter = startParameter.newInstance();
        noSearchParameter.useEmptySettings();
        settings = findSettingsAndLoadIfAppropriate(gradle, noSearchParameter);

        // Set explicit build file, if required
        if (noSearchParameter.getBuildFile() != null) {
            ProjectDescriptor rootProject = settings.getRootProject();
            rootProject.setBuildFileName(noSearchParameter.getBuildFile().getName());
        }
        setDefaultProject(spec, settings);

        return settings;
    }

    private void setDefaultProject(ProjectSpec spec, SettingsInternal settings) {
        settings.setDefaultProject(spec.selectProject(settings.getProjectRegistry()));
    }

    /**
     * Finds the settings.gradle for the given startParameter, and loads it if contains the project selected by the
     * startParameter, or if the startParameter explicitly specifies a settings script.  If the settings file is not
     * loaded (executed), then a null is returned.
     */
    private SettingsInternal findSettingsAndLoadIfAppropriate(GradleInternal gradle,
                                                              StartParameter startParameter) {
        SettingsLocation settingsLocation = findSettings(startParameter);

        // We found the desired settings file, now build the associated buildSrc before loading settings.  This allows
        // the settings script to reference classes in the buildSrc.
        StartParameter buildSrcStartParameter = startParameter.newBuild();
        buildSrcStartParameter.setCurrentDir(new File(settingsLocation.getSettingsDir(), BaseSettings.DEFAULT_BUILD_SRC_DIR));
        ClassLoaderScope buildSourceClassLoader = buildSourceBuilder.buildAndCreateClassLoader(buildSrcStartParameter);

        return settingsProcessor.process(gradle, settingsLocation, buildSourceClassLoader, startParameter);
    }

    private SettingsLocation findSettings(StartParameter startParameter) {
        return settingsFinder.find(startParameter);
    }
}

