package org.simantics.ui.selection;

import java.util.Collection;
import java.util.List;

import org.eclipse.core.commands.ExecutionEvent;
import org.eclipse.jface.viewers.ISelection;
import org.eclipse.ui.handlers.HandlerUtil;
import org.simantics.Simantics;
import org.simantics.db.ReadGraph;
import org.simantics.db.RequestProcessor;
import org.simantics.db.Resource;
import org.simantics.db.common.primitiverequest.IsInstanceOf;
import org.simantics.db.exception.DatabaseException;
import org.simantics.db.layer0.request.VariableURI;
import org.simantics.db.layer0.variable.Variable;
import org.simantics.utils.ui.ISelectionUtils;

public class WorkbenchSelectionUtils {

	public static Resource getPossibleResource(ExecutionEvent event) throws DatabaseException {
		ISelection selection = HandlerUtil.getCurrentSelection(event);
		return getPossibleResource(selection);
	}
	
	public static Variable getPossibleVariable(ExecutionEvent event) throws DatabaseException {
		ISelection selection = HandlerUtil.getCurrentSelection(event);
		return getPossibleVariable(selection);
	}
	
	public static List<WorkbenchSelectionElement> getWorkbenchSelectionElements(ISelection selection) {
	    return ISelectionUtils.filterSelection(selection, WorkbenchSelectionElement.class);
	}

	public static String getPossibleJSON(Object selection) throws DatabaseException {
		if(selection instanceof WorkbenchSelectionElement) return getPossibleJSON((WorkbenchSelectionElement)selection);
		WorkbenchSelectionElement element = ISelectionUtils.filterSingleSelection(selection, WorkbenchSelectionElement.class);
		if(element == null) return null;
		return getPossibleJSON(element);
	}

	public static Resource getPossibleResource(Object selection) throws DatabaseException {
		if(selection instanceof WorkbenchSelectionElement) return getPossibleResource((WorkbenchSelectionElement)selection);
		WorkbenchSelectionElement element = ISelectionUtils.filterSingleSelection(selection, WorkbenchSelectionElement.class);
		if(element == null) return null;
		return getPossibleResource(element);
	}

	public static Variable getPossibleVariable(Object selection) throws DatabaseException {
		if(selection instanceof WorkbenchSelectionElement) return getPossibleVariable((WorkbenchSelectionElement)selection);
		WorkbenchSelectionElement element = ISelectionUtils.filterSingleSelection(selection, WorkbenchSelectionElement.class);
		if(element == null) return null;
		return getPossibleVariable(element);
	}

	public static Variable getPossibleVariable(Object[] selection) throws DatabaseException {
		if(selection.length != 1) return null;
		if(!(selection[0] instanceof WorkbenchSelectionElement)) return null;
		return getPossibleVariable((WorkbenchSelectionElement)selection[0]);
	}

	public static <T> T getPossibleElement(Object[] selection, WorkbenchSelectionContentType<T> contentType) throws DatabaseException {
		if(selection.length != 1) return null;
		if(!(selection[0] instanceof WorkbenchSelectionElement)) return null;
		WorkbenchSelectionElement wse = (WorkbenchSelectionElement)selection[0];
		return wse.getContent(contentType);
	}

//	public static <T> T getPossibleExplorerInput(Object selection) throws DatabaseException {
//		if(selection instanceof WorkbenchSelectionElement) return getPossibleExplorerInput((WorkbenchSelectionElement)selection);
//		WorkbenchSelectionElement element = ISelectionUtils.filterSingleSelection(selection, WorkbenchSelectionElement.class);
//		if(element == null) return null;
//		return getPossibleExplorerInput(element);
//	}

//	public static <T> T getPossibleExplorerColumn(Object selection) throws DatabaseException {
//		if(selection instanceof WorkbenchSelectionElement) return getPossibleExplorerColumn((WorkbenchSelectionElement)selection);
//		WorkbenchSelectionElement element = ISelectionUtils.filterSingleSelection(selection, WorkbenchSelectionElement.class);
//		if(element == null) return null;
//		return getPossibleExplorerColumn(element);
//	}
	
	public static String getPossibleJSON(WorkbenchSelectionElement wse) throws DatabaseException {
		return getPossibleJSON(Simantics.getSession(), wse);
	}

	public static Resource getPossibleResource(WorkbenchSelectionElement wse) throws DatabaseException {
		return getPossibleResource(Simantics.getSession(), wse);
	}

	public static Variable getPossibleVariable(WorkbenchSelectionElement wse) throws DatabaseException {
		return getPossibleVariable(Simantics.getSession(), wse);
	}

	public static Variable getPossibleVariableSCL(ReadGraph graph, WorkbenchSelectionElement wse) throws DatabaseException {
		return getPossibleVariable(graph, wse);
	}

	public static Resource getPossibleResourceSCL(ReadGraph graph, WorkbenchSelectionElement wse) throws DatabaseException {
		return getPossibleResource(graph, wse);
	}

	public static String getPossibleJSON(RequestProcessor processor, Object input) throws DatabaseException {
		Variable var = getPossibleVariable(processor, input);
		if(var != null) {
			String uri = processor.syncRequest(new VariableURI(var));
			return "{ \"type\":\"Variable\", \"uri\" : \"" + uri + "\" }";
		}
		Resource res = getPossibleResource(processor, input);
		if(res != null) {
			return "{ type:\"Resource\" }";
		}
		return "{ type:\"Unknown\" }";
		
	}

	public static Resource getPossibleResource(RequestProcessor processor, Object input) throws DatabaseException {
		return getPossibleResource(processor, input, null);
	}

	public static Resource getPossibleResource(RequestProcessor processor, Object input, Resource type) throws DatabaseException {
	    if(input instanceof Collection && !((Collection<?>)input).isEmpty()) {
	        Object element = ((Collection<?>)input).iterator().next();
	        if(element instanceof Resource)
	            return (Resource)element;
	    }
		Resource resource = getPossibleElement(input, new AnyResource(processor));
		if(resource == null) return resource;
		if(type != null) {
			if(processor.sync(new IsInstanceOf(resource, type))) return resource;
			else return null;
		}
		return resource;
	}

	public static Variable getPossibleVariable(RequestProcessor processor, Object input) throws DatabaseException {
		return getPossibleElement(input, new AnyVariable(processor));
	}

//	@SuppressWarnings("unchecked")
//	public static <T> T getPossibleExplorerInput(WorkbenchSelectionElement input) throws DatabaseException {
//		return ((T)getPossibleElement(input, new ExplorerInputContentType()));
//	}

	public static <T> T getPossibleElement(Object input, WorkbenchSelectionContentType<T> contentType) {
		Object single = getPossibleSingleElement(input);
		if(single == null) return null;
		if(single instanceof WorkbenchSelectionElement) {
			WorkbenchSelectionElement element = (WorkbenchSelectionElement)single;
			return (T)element.getContent(contentType);
		}
		return null;
	}
	
	public static WorkbenchSelectionElement getPossibleSelectionElement(Object input) {
    	if(input instanceof WorkbenchSelectionElement) return (WorkbenchSelectionElement)input;
    	if(input instanceof Collection) {
    		Collection<?> c = (Collection<?>)input;
    		if(c.size() == 1) {
    			Object o = c.iterator().next();
    			if(o instanceof WorkbenchSelectionElement) return (WorkbenchSelectionElement)o;
    		}
    	}
    	return null;
	}

	// Internal helpers
	
    private static Object getPossibleSingleElement(Object input) {
    	if(input instanceof WorkbenchSelectionElement) return input;
    	if(input instanceof Collection) {
    		Collection<?> c = (Collection<?>)input;
    		if(c.size() == 1) return c.iterator().next();
    	} 
    	return null;
    }	
    
	
}