/* === This file is part of Calamares - <http://github.com/calamares> ===
 *
 *   Copyright 2014-2015, Teo Mrnjavac <teo@kde.org>
 *
 *   Calamares is free software: you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation, either version 3 of the License, or
 *   (at your option) any later version.
 *
 *   Calamares is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with Calamares. If not, see <http://www.gnu.org/licenses/>.
 */

#include "ModuleManager.h"

#include "ExecutionViewStep.h"
#include "Module.h"
#include "utils/Logger.h"
#include "utils/YamlUtils.h"
#include "Settings.h"
#include "ViewManager.h"

#include <yaml-cpp/yaml.h>

#include <QApplication>
#include <QDir>
#include <QTimer>

#define MODULE_CONFIG_FILENAME "module.desc"

namespace Calamares
{


ModuleManager* ModuleManager::s_instance = nullptr;


ModuleManager*
ModuleManager::instance()
{
    return s_instance;
}


ModuleManager::ModuleManager( const QStringList& paths, QObject* parent )
    : QObject( parent )
    , m_paths( paths )
{
    Q_ASSERT( !s_instance );
    s_instance = this;
}


ModuleManager::~ModuleManager()
{
    // The map is populated with Module::fromDescriptor(), which allocates on the heap.
    for( auto moduleptr : m_loadedModulesByInstanceKey )
    {
        delete moduleptr;
    }
}


void
ModuleManager::init()
{
    QTimer::singleShot( 0, this, &ModuleManager::doInit );
}


void
ModuleManager::doInit()
{
    // We start from a list of paths in m_paths. Each of those is a directory that
    // might (should) contain Calamares modules of any type/interface.
    // For each modules search path (directory), it is expected that each module
    // lives in its own subdirectory. This subdirectory must have the same name as
    // the module name, and must contain a settings file named module.desc.
    // If at any time the module loading procedure finds something unexpected, it
    // silently skips to the next module or search path. --Teo 6/2014
    for ( const QString& path : m_paths )
    {
        QDir currentDir( path );
        if ( currentDir.exists() && currentDir.isReadable() )
        {
            const QStringList subdirs = currentDir.entryList( QDir::AllDirs | QDir::NoDotAndDotDot );
            for ( const QString& subdir : subdirs )
            {
                currentDir.setPath( path );
                bool success = currentDir.cd( subdir );
                if ( success )
                {
                    QFileInfo descriptorFileInfo( currentDir.absoluteFilePath( MODULE_CONFIG_FILENAME ) );
                    if ( ! ( descriptorFileInfo.exists() && descriptorFileInfo.isReadable() ) )
                    {
                        cDebug() << Q_FUNC_INFO << "unreadable file: "
                                 << descriptorFileInfo.absoluteFilePath();
                        continue;
                    }

                    QFile descriptorFile( descriptorFileInfo.absoluteFilePath() );
                    QVariant moduleDescriptor;
                    if ( descriptorFile.exists() && descriptorFile.open( QFile::ReadOnly | QFile::Text ) )
                    {
                        QByteArray ba = descriptorFile.readAll();
                        try
                        {
                            YAML::Node doc = YAML::Load( ba.constData() );

                            moduleDescriptor = CalamaresUtils::yamlToVariant( doc );
                        }
                        catch ( YAML::Exception& e )
                        {
                            cDebug() << "WARNING: YAML parser error " << e.what();
                            continue;
                        }
                    }


                    if ( moduleDescriptor.isValid() &&
                         !moduleDescriptor.isNull() &&
                         moduleDescriptor.type() == QVariant::Map )
                    {
                        QVariantMap moduleDescriptorMap = moduleDescriptor.toMap();

                        if ( moduleDescriptorMap.value( "name" ) == currentDir.dirName() &&
                             !m_availableDescriptorsByModuleName.contains( moduleDescriptorMap.value( "name" ).toString() ) )
                        {
                            m_availableDescriptorsByModuleName.insert( moduleDescriptorMap.value( "name" ).toString(),
                                                                       moduleDescriptorMap );
                            m_moduleDirectoriesByModuleName.insert( moduleDescriptorMap.value( "name" ).toString(),
                                                                    descriptorFileInfo.absoluteDir().absolutePath() );
                        }
                    }
                }
                else
                {
                    cDebug() << Q_FUNC_INFO << "cannot cd into module directory "
                             << path << "/" << subdir;
                }
            }
        }
        else
        {
            cDebug() << "ModuleManager bad search path" << path;
        }
    }
    // At this point m_availableModules is filled with whatever was found in the
    // search paths.
    checkDependencies();
    emit initDone();
}


QStringList
ModuleManager::loadedInstanceKeys()
{
    return m_loadedModulesByInstanceKey.keys();
}


QVariantMap
ModuleManager::moduleDescriptor( const QString& name )
{
    return m_availableDescriptorsByModuleName.value( name );
}

Module*
ModuleManager::moduleInstance( const QString& instanceKey )
{
    return m_loadedModulesByInstanceKey.value( instanceKey );
}


void
ModuleManager::loadModules()
{
    QTimer::singleShot( 0, this, [ this ]()
    {
        QList< QMap< QString, QString > > customInstances =
                Settings::instance()->customModuleInstances();

        const auto modulesSequence = Settings::instance()->modulesSequence();
        for ( const auto &modulePhase : modulesSequence )
        {
            ModuleAction currentAction = modulePhase.first;

            foreach ( const QString& moduleEntry,
                      modulePhase.second )
            {
                QStringList moduleEntrySplit = moduleEntry.split( '@' );
                QString moduleName;
                QString instanceId;
                QString configFileName;
                if ( moduleEntrySplit.length() < 1 ||
                     moduleEntrySplit.length() > 2 )
                {
                    cDebug() << "Wrong module entry format for module" << moduleEntry << "."
                             << "\nCalamares will now quit.";
                    qApp->exit( 1 );
                    return;
                }
                moduleName = moduleEntrySplit.first();
                instanceId = moduleEntrySplit.last();
                configFileName = QString( "%1.conf" ).arg( moduleName );

                if ( !m_availableDescriptorsByModuleName.contains( moduleName ) ||
                     m_availableDescriptorsByModuleName.value( moduleName ).isEmpty() )
                {
                    cDebug() << "Module" << moduleName << "not found in module search paths."
                             << "\nCalamares will now quit.";
                    qApp->exit( 1 );
                    return;
                }

                auto findCustomInstance =
                        [ customInstances ]( const QString& moduleName,
                                             const QString& instanceId ) -> int
                {
                    for ( int i = 0; i < customInstances.count(); ++i )
                    {
                        auto thisInstance = customInstances[ i ];
                        if ( thisInstance.value( "module" ) == moduleName &&
                             thisInstance.value( "id" ) == instanceId )
                            return i;
                    }
                    return -1;
                };

                if ( moduleName != instanceId ) //means this is a custom instance
                {
                    if ( findCustomInstance( moduleName, instanceId ) > -1 )
                    {
                        configFileName = customInstances[ findCustomInstance( moduleName, instanceId ) ].value( "config" );
                    }
                    else //ought to be a custom instance, but cannot find instance entry
                    {
                        cDebug() << "Custom instance" << moduleEntry << "not found in custom instances section."
                                 << "\nCalamares will now quit.";
                        qApp->exit( 1 );
                        return;
                    }
                }

                // So now we can assume that the module entry is at least valid,
                // that we have a descriptor on hand (and therefore that the
                // module exists), and that the instance is either default or
                // defined in the custom instances section.
                // We still don't know whether the config file for the entry
                // exists and is valid, but that's the only thing that could fail
                // from this point on. -- Teo 8/2015

                QString instanceKey = QString( "%1@%2" )
                                      .arg( moduleName )
                                      .arg( instanceId );

                Module* thisModule =
                    m_loadedModulesByInstanceKey.value( instanceKey, nullptr );
                if ( thisModule && !thisModule->isLoaded() )
                {
                    cDebug() << "Module" << instanceKey << "exists but not loaded."
                             << "\nCalamares will now quit.";
                    qApp->exit( 1 );
                    return;
                }

                if ( thisModule && thisModule->isLoaded() )
                {
                    cDebug() << "Module" << instanceKey << "already loaded.";
                }
                else
                {
                    thisModule =
                        Module::fromDescriptor( m_availableDescriptorsByModuleName.value( moduleName ),
                                                instanceId,
                                                configFileName,
                                                m_moduleDirectoriesByModuleName.value( moduleName ) );
                    if ( !thisModule )
                    {
                        cDebug() << "Module" << instanceKey << "cannot be created from descriptor.";
                        Q_ASSERT( thisModule );
                        continue;
                    }
                    // If it's a ViewModule, it also appends the ViewStep to the ViewManager.
                    thisModule->loadSelf();
                    m_loadedModulesByInstanceKey.insert( instanceKey, thisModule );
                    Q_ASSERT( thisModule->isLoaded() );
                    if ( !thisModule->isLoaded() )
                    {
                        cDebug() << "Module" << moduleName << "loading FAILED";
                        continue;
                    }
                }

                // At this point we most certainly have a pointer to a loaded module in
                // thisModule. We now need to enqueue jobs info into an EVS.
                if ( currentAction == Calamares::Exec )
                {
                    ExecutionViewStep* evs =
                        qobject_cast< ExecutionViewStep* >(
                            Calamares::ViewManager::instance()->viewSteps().last() );
                    if ( !evs ) // If the last step is not an EVS, we must create it.
                    {
                        evs = new ExecutionViewStep( ViewManager::instance() );
                        ViewManager::instance()->addViewStep( evs );
                    }

                    evs->appendJobModuleInstanceKey( instanceKey );
                }
            }
        }
        emit modulesLoaded();
    } );
}


void
ModuleManager::checkDependencies()
{
    // This goes through the map of available modules, and deletes those whose
    // dependencies are not met, if any.
    bool somethingWasRemovedBecauseOfUnmetDependencies = false;
    forever
    {
        for ( auto it = m_availableDescriptorsByModuleName.begin();
              it != m_availableDescriptorsByModuleName.end(); ++it )
        {
            foreach ( const QString& depName,
                      (*it).value( "requiredModules" ).toStringList() )
            {
                if ( !m_availableDescriptorsByModuleName.contains( depName ) )
                {
                    somethingWasRemovedBecauseOfUnmetDependencies = true;
                    m_availableDescriptorsByModuleName.erase( it );
                    break;
                }
            }
            if ( somethingWasRemovedBecauseOfUnmetDependencies )
                break;
        }
        if ( !somethingWasRemovedBecauseOfUnmetDependencies )
            break;
    }
}


}