/*
 * 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 java.io.File;
import java.net.URLClassLoader;

/**
 * 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);

        File explicitProjectDir = startParameter.getProjectDir();
        File explicitBuildFile = startParameter.getBuildFile();
        ProjectSpec spec = explicitBuildFile != null
                ? new BuildFileProjectSpec(explicitBuildFile)
                : explicitProjectDir == null ? new DefaultProjectSpec(startParameter.getCurrentDir()) : new ProjectDirectoryProjectSpec(explicitProjectDir);

        if (!spec.containsProject(settings.getProjectRegistry())) {
            // The settings we found did not include the desired default project. Try again with an empty settings file.

            StartParameter noSearchParameter = startParameter.newInstance();
            noSearchParameter.useEmptySettings();
            settings = findSettingsAndLoadIfAppropriate(gradle, noSearchParameter);
            if (settings == null) // not using an assert to make sure it is not disabled
            {
                throw new InternalError("Empty settings file does not contain expected project.");
            }

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

        gradle.getScriptClassLoader().addParent(settings.getClassLoader());
        return settings;
    }

    /**
     * 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));
        URLClassLoader buildSourceClassLoader = buildSourceBuilder.buildAndCreateClassLoader(buildSrcStartParameter);

        return loadSettings(gradle, settingsLocation, buildSourceClassLoader, startParameter);
    }

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

    private SettingsInternal loadSettings(GradleInternal gradle, SettingsLocation settingsLocation,
                                          URLClassLoader buildSourceClassLoader, StartParameter startParameter) {
        return settingsProcessor.process(gradle, settingsLocation, buildSourceClassLoader, startParameter);
    }
}

