/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.apache.maven.settings.building;

import javax.inject.Inject;
import javax.inject.Named;
import javax.inject.Singleton;

import java.io.File;
import java.io.IOException;
import java.io.StringReader;
import java.io.StringWriter;
import java.util.Collections;
import java.util.List;
import java.util.Map;

import org.apache.maven.building.FileSource;
import org.apache.maven.building.Source;
import org.apache.maven.settings.Settings;
import org.apache.maven.settings.TrackableBase;
import org.apache.maven.settings.io.SettingsParseException;
import org.apache.maven.settings.io.SettingsReader;
import org.apache.maven.settings.io.SettingsWriter;
import org.apache.maven.settings.merge.MavenSettingsMerger;
import org.apache.maven.settings.validation.SettingsValidator;
import org.codehaus.plexus.interpolation.EnvarBasedValueSource;
import org.codehaus.plexus.interpolation.InterpolationException;
import org.codehaus.plexus.interpolation.InterpolationPostProcessor;
import org.codehaus.plexus.interpolation.PropertiesBasedValueSource;
import org.codehaus.plexus.interpolation.RegexBasedInterpolator;

/**
 * Builds the effective settings from a user settings file and/or a global settings file.
 *
 * @author Benjamin Bentmann
 */
@Named
@Singleton
public class DefaultSettingsBuilder implements SettingsBuilder {

    private SettingsReader settingsReader;

    private SettingsWriter settingsWriter;

    private SettingsValidator settingsValidator;

    private final MavenSettingsMerger settingsMerger = new MavenSettingsMerger();

    @Inject
    public DefaultSettingsBuilder(
            SettingsReader settingsReader, SettingsWriter settingsWriter, SettingsValidator settingsValidator) {
        this.settingsReader = settingsReader;
        this.settingsWriter = settingsWriter;
        this.settingsValidator = settingsValidator;
    }

    public DefaultSettingsBuilder setSettingsReader(SettingsReader settingsReader) {
        this.settingsReader = settingsReader;
        return this;
    }

    public DefaultSettingsBuilder setSettingsWriter(SettingsWriter settingsWriter) {
        this.settingsWriter = settingsWriter;
        return this;
    }

    public DefaultSettingsBuilder setSettingsValidator(SettingsValidator settingsValidator) {
        this.settingsValidator = settingsValidator;
        return this;
    }

    @Override
    public SettingsBuildingResult build(SettingsBuildingRequest request) throws SettingsBuildingException {
        DefaultSettingsProblemCollector problems = new DefaultSettingsProblemCollector(null);

        Source globalSettingsSource =
                getSettingsSource(request.getGlobalSettingsFile(), request.getGlobalSettingsSource());
        Settings globalSettings = readSettings(globalSettingsSource, request, problems);

        Source userSettingsSource = getSettingsSource(request.getUserSettingsFile(), request.getUserSettingsSource());
        Settings userSettings = readSettings(userSettingsSource, request, problems);

        settingsMerger.merge(userSettings, globalSettings, TrackableBase.GLOBAL_LEVEL);

        problems.setSource("");

        userSettings = interpolate(userSettings, request, problems);

        // for the special case of a drive-relative Windows path, make sure it's absolute to save plugins from trouble
        String localRepository = userSettings.getLocalRepository();
        if (localRepository != null && localRepository.length() > 0) {
            File file = new File(localRepository);
            if (!file.isAbsolute() && file.getPath().startsWith(File.separator)) {
                userSettings.setLocalRepository(file.getAbsolutePath());
            }
        }

        if (hasErrors(problems.getProblems())) {
            throw new SettingsBuildingException(problems.getProblems());
        }

        return new DefaultSettingsBuildingResult(userSettings, problems.getProblems());
    }

    private boolean hasErrors(List<SettingsProblem> problems) {
        if (problems != null) {
            for (SettingsProblem problem : problems) {
                if (SettingsProblem.Severity.ERROR.compareTo(problem.getSeverity()) >= 0) {
                    return true;
                }
            }
        }

        return false;
    }

    private Source getSettingsSource(File settingsFile, Source settingsSource) {
        if (settingsSource != null) {
            return settingsSource;
        } else if (settingsFile != null && settingsFile.exists()) {
            return new FileSource(settingsFile);
        }
        return null;
    }

    private Settings readSettings(
            Source settingsSource, SettingsBuildingRequest request, DefaultSettingsProblemCollector problems) {
        if (settingsSource == null) {
            return new Settings();
        }

        problems.setSource(settingsSource.getLocation());

        Settings settings;

        try {
            Map<String, ?> options = Collections.singletonMap(SettingsReader.IS_STRICT, Boolean.TRUE);

            try {
                settings = settingsReader.read(settingsSource.getInputStream(), options);
            } catch (SettingsParseException e) {
                options = Collections.singletonMap(SettingsReader.IS_STRICT, Boolean.FALSE);

                settings = settingsReader.read(settingsSource.getInputStream(), options);

                problems.add(
                        SettingsProblem.Severity.WARNING, e.getMessage(), e.getLineNumber(), e.getColumnNumber(), e);
            }
        } catch (SettingsParseException e) {
            problems.add(
                    SettingsProblem.Severity.FATAL,
                    "Non-parseable settings " + settingsSource.getLocation() + ": " + e.getMessage(),
                    e.getLineNumber(),
                    e.getColumnNumber(),
                    e);
            return new Settings();
        } catch (IOException e) {
            problems.add(
                    SettingsProblem.Severity.FATAL,
                    "Non-readable settings " + settingsSource.getLocation() + ": " + e.getMessage(),
                    -1,
                    -1,
                    e);
            return new Settings();
        }

        settingsValidator.validate(settings, problems);

        return settings;
    }

    private Settings interpolate(
            Settings settings, SettingsBuildingRequest request, SettingsProblemCollector problems) {
        StringWriter writer = new StringWriter(1024 * 4);

        try {
            settingsWriter.write(writer, null, settings);
        } catch (IOException e) {
            throw new IllegalStateException("Failed to serialize settings to memory", e);
        }

        String serializedSettings = writer.toString();

        RegexBasedInterpolator interpolator = new RegexBasedInterpolator();

        interpolator.addValueSource(new PropertiesBasedValueSource(request.getUserProperties()));

        interpolator.addValueSource(new PropertiesBasedValueSource(request.getSystemProperties()));

        try {
            interpolator.addValueSource(new EnvarBasedValueSource());
        } catch (IOException e) {
            problems.add(
                    SettingsProblem.Severity.WARNING,
                    "Failed to use environment variables for interpolation: " + e.getMessage(),
                    -1,
                    -1,
                    e);
        }

        interpolator.addPostProcessor(new InterpolationPostProcessor() {
            @Override
            public Object execute(String expression, Object value) {
                if (value != null) {
                    // we're going to parse this back in as XML so we need to escape XML markup
                    value = value.toString()
                            .replace("&", "&amp;")
                            .replace("<", "&lt;")
                            .replace(">", "&gt;");
                    return value;
                }
                return null;
            }
        });

        try {
            serializedSettings = interpolator.interpolate(serializedSettings, "settings");
        } catch (InterpolationException e) {
            problems.add(
                    SettingsProblem.Severity.ERROR, "Failed to interpolate settings: " + e.getMessage(), -1, -1, e);

            return settings;
        }

        Settings result;
        try {
            Map<String, ?> options = Collections.singletonMap(SettingsReader.IS_STRICT, Boolean.FALSE);
            result = settingsReader.read(new StringReader(serializedSettings), options);
        } catch (IOException e) {
            problems.add(
                    SettingsProblem.Severity.ERROR, "Failed to interpolate settings: " + e.getMessage(), -1, -1, e);
            return settings;
        }

        return result;
    }
}
