package org.simantics.district.network.ui.contributions;

import java.util.Collection;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ExecutionException;
import java.util.stream.Collectors;

import javax.inject.Named;

import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.Status;
import org.eclipse.core.runtime.jobs.Job;
import org.eclipse.e4.core.di.annotations.CanExecute;
import org.eclipse.e4.core.di.annotations.Execute;
import org.eclipse.e4.ui.services.IServiceConstants;
import org.eclipse.jface.dialogs.Dialog;
import org.eclipse.jface.layout.GridDataFactory;
import org.eclipse.jface.viewers.ISelection;
import org.eclipse.swt.SWT;
import org.eclipse.swt.layout.GridData;
import org.eclipse.swt.layout.GridLayout;
import org.eclipse.swt.widgets.Combo;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Group;
import org.eclipse.swt.widgets.Label;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.ui.dialogs.SelectionStatusDialog;
import org.eclipse.ui.progress.UIJob;
import org.simantics.DatabaseJob;
import org.simantics.Simantics;
import org.simantics.db.ReadGraph;
import org.simantics.db.Resource;
import org.simantics.db.WriteGraph;
import org.simantics.db.common.NamedResource;
import org.simantics.db.common.request.IndexRoot;
import org.simantics.db.common.request.ReadRequest;
import org.simantics.db.common.request.UniqueRead;
import org.simantics.db.common.request.WriteRequest;
import org.simantics.db.common.utils.NameUtils;
import org.simantics.db.exception.DatabaseException;
import org.simantics.db.exception.ServiceException;
import org.simantics.db.exception.ValidationException;
import org.simantics.db.layer0.SelectionHints;
import org.simantics.db.procedure.Procedure;
import org.simantics.db.request.Read;
import org.simantics.district.network.DistrictNetworkUtil;
import org.simantics.district.network.ontology.DistrictNetworkResource;
import org.simantics.district.network.ui.function.Functions;
import org.simantics.district.network.ui.internal.Activator;
import org.simantics.utils.ui.ISelectionUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class ChangeMappingTypeHandler {

    private static final Logger LOGGER = LoggerFactory.getLogger(ChangeMappingTypeHandler.class);

    @CanExecute
    public boolean canExecute(@Named(IServiceConstants.ACTIVE_SELECTION) ISelection selection) {
        List<Resource> elements = ISelectionUtils.getPossibleKeys(selection, SelectionHints.KEY_MAIN, Resource.class);
        if (elements.size() < 1)
            return false;
        try {
            return Simantics.getSession().syncRequest(new Read<Boolean>() {

                @Override
                public Boolean perform(ReadGraph graph) throws DatabaseException {
                    DistrictNetworkResource DN = DistrictNetworkResource.getInstance(graph);
                    for (Resource selection : elements) {
                        if (!graph.isInstanceOf(selection, DN.Element)) {
                            return false;
                        }
                    }
                    return true;
                }
            });
        } catch (DatabaseException e) {
            LOGGER.error("Could not evaluate if mapping can be changed for selection {}", elements, e);
            return false;
        }
    }

    @Execute
    public void execute(@Named(IServiceConstants.ACTIVE_SELECTION) Object selection) {
        final List<Resource> elements = ISelectionUtils.getPossibleKeys(selection, SelectionHints.KEY_MAIN, Resource.class);
//        if (elements.size() < 1)
//            return;
        
        CompletableFuture<Map<NamedResource, Collection<NamedResource>>> result = new CompletableFuture<>();
        Simantics.getSession().asyncRequest(new UniqueRead<Map<NamedResource, Collection<NamedResource>>>() {
            
            @Override
            public Map<NamedResource, Collection<NamedResource>> perform(ReadGraph graph) throws DatabaseException {
                DistrictNetworkResource DN = DistrictNetworkResource.getInstance(graph);
                
                Map<NamedResource, Collection<NamedResource>> currents = new HashMap<>();
                for (Resource element : elements) {
                    Resource currentMapping = graph.getPossibleObject(element, DN.HasMapping);
                    NamedResource mapping = new NamedResource(NameUtils.getSafeName(graph, currentMapping), currentMapping);
                    currents.compute(mapping, (t, u) -> {
                        if (u == null)
                            u = new HashSet<>();
                        try {
                            u.add(new NamedResource(NameUtils.getSafeName(graph, element), element));
                        } catch (ValidationException | ServiceException e) {
                            LOGGER.error("Could not compute name for {}", element, e);
                        }
                        return u;
                    });
                }
                return currents;
            }
        }, new Procedure<Map<NamedResource, Collection<NamedResource>>>() {

            @Override
            public void execute(Map<NamedResource, Collection<NamedResource>> results) {
                result.complete(results);
            }

            @Override
            public void exception(Throwable t) {
                LOGGER.error("Could not compute mappings for selection {}", elements, t);
                result.completeExceptionally(t);
            }
        });
        
        UIJob uiJob = new UIJob("Change mappings..") {
            
            @Override
            public IStatus runInUIThread(IProgressMonitor monitor) {
                SelectMappingDialog dialog = new SelectMappingDialog(getDisplay().getActiveShell(), result);
                if (dialog.open() != Dialog.OK)
                    return Status.OK_STATUS;
                
                Map<Resource, Collection<NamedResource>> results = dialog.getResults();
                Job job = new DatabaseJob("Join selected vertices") {
                    
                    @Override
                    protected IStatus run(IProgressMonitor monitor) {
                        try {
                            Simantics.getSession().syncRequest(new WriteRequest() {
                                
                                @Override
                                public void perform(WriteGraph graph) throws DatabaseException {
                                    for (Map.Entry<Resource, Collection<NamedResource>> entry : results.entrySet()) {
                                        List<Resource> elements = entry.getValue().stream()
                                            .map(NamedResource::getResource)
                                            .collect(Collectors.toList());
                                        DistrictNetworkUtil.changeMappingType(graph, entry.getKey(), elements);
                                    }
                                }
                            });
                        } catch (DatabaseException e) {
                            return new Status(IStatus.ERROR, Activator.PLUGIN_ID, getName() + " failed.", e);
                        }
                        return Status.OK_STATUS;
                    }
                };
                job.setUser(true);
                job.schedule();
                return Status.OK_STATUS;
            }
        };
        uiJob.setUser(true);
        uiJob.schedule();
    }
    
    private static class SelectMappingDialog extends SelectionStatusDialog {

        private Map<NamedResource, Combo> mappingCombos = new HashMap<>();
        
        private Composite composite;
        
        private CompletableFuture<Map<NamedResource, Collection<NamedResource>>> elements;
        
        private Map<NamedResource, Map<String, Resource>> possibleMappings = new HashMap<>();
        
        protected SelectMappingDialog(Shell parentShell, CompletableFuture<Map<NamedResource, Collection<NamedResource>>> elements) {
            super(parentShell);
            this.elements = elements;
            setTitle("Change mappings");
        }

        @Override
        protected Control createDialogArea(Composite parent) {
            composite = (Composite) super.createDialogArea(parent);
            
            createMappingsGroup(composite);
            
            // compute default values
            Simantics.getSession().asyncRequest(new ReadRequest() {

                @Override
                public void run(ReadGraph graph) throws DatabaseException {
                    DistrictNetworkResource DN = DistrictNetworkResource.getInstance(graph);
                    try {
                        for (Map.Entry<NamedResource, Collection<NamedResource>> entry : elements.get().entrySet()) {
                            NamedResource currentMapping = entry.getKey();
                            Resource resource = entry.getValue().iterator().next().getResource();
                            Resource indexRoot = graph.sync(new IndexRoot(resource));
                            if (graph.isInstanceOf(currentMapping.getResource(), DN.Mapping_VertexMapping)) {
                                possibleMappings.put(currentMapping, Functions.getVertexMappings(graph, indexRoot));
                            } else if (graph.isInstanceOf(currentMapping.getResource(), DN.Mapping_EdgeMapping)) {
                                possibleMappings.put(currentMapping, Functions.getEdgeMappings(graph, indexRoot));
                            }
                        }
                    } catch (InterruptedException | ExecutionException e) {
                        e.printStackTrace();
                    }
                    composite.getDisplay().asyncExec(() -> {
                        for (Map.Entry<NamedResource, Map<String, Resource>> entry : possibleMappings.entrySet()) {
                            NamedResource key = entry.getKey();
                            Map<String, Resource> value = entry.getValue();
                            Combo combo = mappingCombos.get(key);
                            combo.setItems(value.keySet().toArray(new String[value.size()]));
                            combo.select(0);
                        }
                    });
                }
            });
            return composite;
        }

        private Map<Resource, Collection<NamedResource>> results = new HashMap<>();
        
        @Override
        protected void computeResult() {
            Map<NamedResource, Collection<NamedResource>> currentElements = null;
            try {
                currentElements = elements.get();
            } catch (InterruptedException | ExecutionException e) {
                LOGGER.error("Could not get currentElements", e);
                throw new RuntimeException("Could not get currentElements", e);
            }
            for (Map.Entry<NamedResource, Combo> combos : mappingCombos.entrySet()) {
                NamedResource resource = combos.getKey();
                Combo c = combos.getValue();
                String item = c.getItem(c.getSelectionIndex());
                Collection<NamedResource> collection = currentElements.get(resource);
                Map<String, Resource> map = possibleMappings.get(resource);
                Resource newMapping = map.get(item);
                results.compute(newMapping, (t, u) -> {
                    if (u == null) {
                        u = new HashSet<>();
                    }
                    u.addAll(collection);
                    return u;
                });
            }
        }

        public Map<Resource, Collection<NamedResource>> getResults() {
            return results;
        }

        private void createMappingsGroup(Composite parent) {
            try {
                for (Map.Entry<NamedResource, Collection<NamedResource>> entry : elements.get().entrySet()) {
                    
                    NamedResource currentMapping = entry.getKey();
                    
                    Collection<NamedResource> mappedElements = entry.getValue();
                    
                    Group group= new Group(parent, SWT.NONE);
                    group.setFont(parent.getFont());
                    group.setText(currentMapping.getName() + " currently mapped to " + mappedElements.size() + " elements");
                    GridDataFactory.fillDefaults().grab(true, false).applyTo(group);
                    group.setLayout(new GridLayout(1, false));
                    
                    Composite cmposite = new Composite(group, SWT.NONE);
                    cmposite.setLayoutData(new GridData(SWT.FILL, SWT.TOP, true, false));
                    cmposite.setLayout(new GridLayout(2, false));
                    
                    Label vertexMappingLabel = new Label(cmposite, SWT.NONE);
                    vertexMappingLabel.setText("New mapping type");

                    Combo c = new Combo(cmposite, SWT.READ_ONLY | SWT.BORDER);
                    GridDataFactory.fillDefaults().grab(true, false).applyTo(c);
                    mappingCombos.put(entry.getKey(), c);
                }
            } catch (InterruptedException | ExecutionException e) {
                e.printStackTrace();
            }
        }
    }
}