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/* 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.activiti.engine.impl.bpmn.diagram;

import java.io.InputStream;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.activiti.bpmn.model.Activity;
import org.activiti.bpmn.model.BaseElement;
import org.activiti.bpmn.model.BoundaryEvent;
import org.activiti.bpmn.model.BpmnModel;
import org.activiti.bpmn.model.BusinessRuleTask;
import org.activiti.bpmn.model.CallActivity;
import org.activiti.bpmn.model.EndEvent;
import org.activiti.bpmn.model.ErrorEventDefinition;
import org.activiti.bpmn.model.EventGateway;
import org.activiti.bpmn.model.EventSubProcess;
import org.activiti.bpmn.model.ExclusiveGateway;
import org.activiti.bpmn.model.FlowElement;
import org.activiti.bpmn.model.FlowElementsContainer;
import org.activiti.bpmn.model.FlowNode;
import org.activiti.bpmn.model.Gateway;
import org.activiti.bpmn.model.GraphicInfo;
import org.activiti.bpmn.model.InclusiveGateway;
import org.activiti.bpmn.model.IntermediateCatchEvent;
import org.activiti.bpmn.model.Lane;
import org.activiti.bpmn.model.ManualTask;
import org.activiti.bpmn.model.MultiInstanceLoopCharacteristics;
import org.activiti.bpmn.model.ParallelGateway;
import org.activiti.bpmn.model.Pool;
import org.activiti.bpmn.model.Process;
import org.activiti.bpmn.model.ReceiveTask;
import org.activiti.bpmn.model.ScriptTask;
import org.activiti.bpmn.model.SendTask;
import org.activiti.bpmn.model.SequenceFlow;
import org.activiti.bpmn.model.ServiceTask;
import org.activiti.bpmn.model.SignalEventDefinition;
import org.activiti.bpmn.model.StartEvent;
import org.activiti.bpmn.model.SubProcess;
import org.activiti.bpmn.model.Task;
import org.activiti.bpmn.model.ThrowEvent;
import org.activiti.bpmn.model.TimerEventDefinition;
import org.activiti.bpmn.model.UserTask;

/**
 * Class to generate an image based the diagram interchange information in a
 * BPMN 2.0 process.
 * 
 * @author Joram Barrez
 */
public class ProcessDiagramGenerator {

  protected static final Map, ActivityDrawInstruction> activityDrawInstructions = new HashMap, ActivityDrawInstruction>();
  
  // The instructions on how to draw a certain construct is
  // created statically and stored in a map for performance.
  static {
    // start event
    activityDrawInstructions.put(StartEvent.class, new ActivityDrawInstruction() {

      public void draw(ProcessDiagramCanvas processDiagramCanvas, BpmnModel bpmnModel, FlowNode flowNode) {
        GraphicInfo graphicInfo = bpmnModel.getGraphicInfo(flowNode.getId());
        StartEvent startEvent = (StartEvent) flowNode;
        if (startEvent.getEventDefinitions() != null && startEvent.getEventDefinitions().size() > 0) {
         if (startEvent.getEventDefinitions().get(0) instanceof TimerEventDefinition) {
           processDiagramCanvas.drawTimerStartEvent((int) graphicInfo.getX(), (int) graphicInfo.getY(), (int) graphicInfo.getWidth(), (int) graphicInfo.getHeight());
         } else if (startEvent.getEventDefinitions().get(0) instanceof ErrorEventDefinition) {
           processDiagramCanvas.drawErrorStartEvent((int) graphicInfo.getX(), (int) graphicInfo.getY(), (int) graphicInfo.getWidth(), (int) graphicInfo.getHeight());
         }
        } else {
          processDiagramCanvas.drawNoneStartEvent((int) graphicInfo.getX(), (int) graphicInfo.getY(), (int) graphicInfo.getWidth(), (int) graphicInfo.getHeight());
        }
      }
    });

    // signal catch
    activityDrawInstructions.put(IntermediateCatchEvent.class, new ActivityDrawInstruction() {
      
      public void draw(ProcessDiagramCanvas processDiagramCanvas, BpmnModel bpmnModel, FlowNode flowNode) {
        GraphicInfo graphicInfo = bpmnModel.getGraphicInfo(flowNode.getId());
        IntermediateCatchEvent intermediateCatchEvent = (IntermediateCatchEvent) flowNode;
        if (intermediateCatchEvent.getEventDefinitions() != null && intermediateCatchEvent.getEventDefinitions().size() > 0) {
          if (intermediateCatchEvent.getEventDefinitions().get(0) instanceof SignalEventDefinition) {
            processDiagramCanvas.drawCatchingSignalEvent(flowNode.getName(), (int) graphicInfo.getX(), (int) graphicInfo.getY(), (int) graphicInfo.getWidth(), (int) graphicInfo.getHeight(), false);
          } else if (intermediateCatchEvent.getEventDefinitions().get(0) instanceof TimerEventDefinition) {
            processDiagramCanvas.drawCatchingTimerEvent(flowNode.getName(), (int) graphicInfo.getX(), (int) graphicInfo.getY(), (int) graphicInfo.getWidth(), (int) graphicInfo.getHeight(), false);
          }
        }
      }
    });
    
    // signal throw
    activityDrawInstructions.put(ThrowEvent.class, new ActivityDrawInstruction() {
      
      public void draw(ProcessDiagramCanvas processDiagramCanvas, BpmnModel bpmnModel, FlowNode flowNode) {
        GraphicInfo graphicInfo = bpmnModel.getGraphicInfo(flowNode.getId());
        ThrowEvent throwEvent = (ThrowEvent) flowNode;
        if (throwEvent.getEventDefinitions() != null && throwEvent.getEventDefinitions().size() > 0) {
          if (throwEvent.getEventDefinitions().get(0) instanceof SignalEventDefinition) {
            processDiagramCanvas.drawThrowingSignalEvent((int) graphicInfo.getX(), (int) graphicInfo.getY(), (int) graphicInfo.getWidth(), (int) graphicInfo.getHeight());
          }
        } else {
          processDiagramCanvas.drawThrowingNoneEvent((int) graphicInfo.getX(), (int) graphicInfo.getY(), (int) graphicInfo.getWidth(), (int) graphicInfo.getHeight());
        }
      }
    });
    
    // end event
    activityDrawInstructions.put(EndEvent.class, new ActivityDrawInstruction() {

      public void draw(ProcessDiagramCanvas processDiagramCanvas, BpmnModel bpmnModel, FlowNode flowNode) {
        GraphicInfo graphicInfo = bpmnModel.getGraphicInfo(flowNode.getId());
        EndEvent endEvent = (EndEvent) flowNode;
        if (endEvent.getEventDefinitions() != null && endEvent.getEventDefinitions().size() > 0) {
          if (endEvent.getEventDefinitions().get(0) instanceof ErrorEventDefinition) {
            processDiagramCanvas.drawErrorEndEvent(flowNode.getName(), (int) graphicInfo.getX(), (int) graphicInfo.getY(), (int) graphicInfo.getWidth(), (int) graphicInfo.getHeight());
          }
        } else {
          processDiagramCanvas.drawNoneEndEvent((int) graphicInfo.getX(), (int) graphicInfo.getY(), (int) graphicInfo.getWidth(), (int) graphicInfo.getHeight());
        }
      }
    });

    // task
    activityDrawInstructions.put(Task.class, new ActivityDrawInstruction() {

      public void draw(ProcessDiagramCanvas processDiagramCanvas, BpmnModel bpmnModel, FlowNode flowNode) {
        GraphicInfo graphicInfo = bpmnModel.getGraphicInfo(flowNode.getId());
        processDiagramCanvas.drawTask(flowNode.getName(), (int) graphicInfo.getX(), (int) graphicInfo.getY(), (int) graphicInfo.getWidth(), (int) graphicInfo.getHeight());
      }
    });

    // user task
    activityDrawInstructions.put(UserTask.class, new ActivityDrawInstruction() {

      public void draw(ProcessDiagramCanvas processDiagramCanvas, BpmnModel bpmnModel, FlowNode flowNode) {
        GraphicInfo graphicInfo = bpmnModel.getGraphicInfo(flowNode.getId());
        processDiagramCanvas.drawUserTask(flowNode.getName(), (int) graphicInfo.getX(), (int) graphicInfo.getY(), (int) graphicInfo.getWidth(), (int) graphicInfo.getHeight());
      }
    });

    // script task
    activityDrawInstructions.put(ScriptTask.class, new ActivityDrawInstruction() {

      public void draw(ProcessDiagramCanvas processDiagramCanvas, BpmnModel bpmnModel, FlowNode flowNode) {
        GraphicInfo graphicInfo = bpmnModel.getGraphicInfo(flowNode.getId());
        processDiagramCanvas.drawScriptTask(flowNode.getName(), (int) graphicInfo.getX(), (int) graphicInfo.getY(), (int) graphicInfo.getWidth(), (int) graphicInfo.getHeight());
      }
    });

    // service task
    activityDrawInstructions.put(ServiceTask.class, new ActivityDrawInstruction() {

      public void draw(ProcessDiagramCanvas processDiagramCanvas, BpmnModel bpmnModel, FlowNode flowNode) {
        GraphicInfo graphicInfo = bpmnModel.getGraphicInfo(flowNode.getId());
        processDiagramCanvas.drawServiceTask(flowNode.getName(), (int) graphicInfo.getX(), (int) graphicInfo.getY(), (int) graphicInfo.getWidth(), (int) graphicInfo.getHeight());
      }
    });

    // receive task
    activityDrawInstructions.put(ReceiveTask.class, new ActivityDrawInstruction() {

      public void draw(ProcessDiagramCanvas processDiagramCanvas, BpmnModel bpmnModel, FlowNode flowNode) {
        GraphicInfo graphicInfo = bpmnModel.getGraphicInfo(flowNode.getId());
        processDiagramCanvas.drawReceiveTask(flowNode.getName(), (int) graphicInfo.getX(), (int) graphicInfo.getY(), (int) graphicInfo.getWidth(), (int) graphicInfo.getHeight());
      }
    });

    // send task
    activityDrawInstructions.put(SendTask.class, new ActivityDrawInstruction() {

      public void draw(ProcessDiagramCanvas processDiagramCanvas, BpmnModel bpmnModel, FlowNode flowNode) {
        GraphicInfo graphicInfo = bpmnModel.getGraphicInfo(flowNode.getId());
        processDiagramCanvas.drawSendTask(flowNode.getName(), (int) graphicInfo.getX(), (int) graphicInfo.getY(), (int) graphicInfo.getWidth(), (int) graphicInfo.getHeight());
      }
    });

    // manual task
    activityDrawInstructions.put(ManualTask.class, new ActivityDrawInstruction() {

      public void draw(ProcessDiagramCanvas processDiagramCanvas, BpmnModel bpmnModel, FlowNode flowNode) {
        GraphicInfo graphicInfo = bpmnModel.getGraphicInfo(flowNode.getId());
        processDiagramCanvas.drawManualTask(flowNode.getName(), (int) graphicInfo.getX(), (int) graphicInfo.getY(), (int) graphicInfo.getWidth(), (int) graphicInfo.getHeight());
      }
    });
    
    // businessRuleTask task
    activityDrawInstructions.put(BusinessRuleTask.class, new ActivityDrawInstruction() {

      public void draw(ProcessDiagramCanvas processDiagramCanvas, BpmnModel bpmnModel, FlowNode flowNode) {
        GraphicInfo graphicInfo = bpmnModel.getGraphicInfo(flowNode.getId());
        processDiagramCanvas.drawBusinessRuleTask(flowNode.getName(), (int) graphicInfo.getX(), (int) graphicInfo.getY(), (int) graphicInfo.getWidth(), (int) graphicInfo.getHeight());
      }
    });

    // exclusive gateway
    activityDrawInstructions.put(ExclusiveGateway.class, new ActivityDrawInstruction() {

      public void draw(ProcessDiagramCanvas processDiagramCanvas, BpmnModel bpmnModel, FlowNode flowNode) {
        GraphicInfo graphicInfo = bpmnModel.getGraphicInfo(flowNode.getId());
        processDiagramCanvas.drawExclusiveGateway((int) graphicInfo.getX(), (int) graphicInfo.getY(), (int) graphicInfo.getWidth(), (int) graphicInfo.getHeight());
      }
    });

    // inclusive gateway
    activityDrawInstructions.put(InclusiveGateway.class, new ActivityDrawInstruction() {

      public void draw(ProcessDiagramCanvas processDiagramCanvas, BpmnModel bpmnModel, FlowNode flowNode) {
        GraphicInfo graphicInfo = bpmnModel.getGraphicInfo(flowNode.getId());
        processDiagramCanvas.drawInclusiveGateway((int) graphicInfo.getX(), (int) graphicInfo.getY(), (int) graphicInfo.getWidth(), (int) graphicInfo.getHeight());
      }
    });

    // parallel gateway
    activityDrawInstructions.put(ParallelGateway.class, new ActivityDrawInstruction() {

      public void draw(ProcessDiagramCanvas processDiagramCanvas, BpmnModel bpmnModel, FlowNode flowNode) {
        GraphicInfo graphicInfo = bpmnModel.getGraphicInfo(flowNode.getId());
        processDiagramCanvas.drawParallelGateway((int) graphicInfo.getX(), (int) graphicInfo.getY(), (int) graphicInfo.getWidth(), (int) graphicInfo.getHeight());
      }
    });
    
    // event based gateway
    activityDrawInstructions.put(EventGateway.class, new ActivityDrawInstruction() {

      public void draw(ProcessDiagramCanvas processDiagramCanvas, BpmnModel bpmnModel, FlowNode flowNode) {
        GraphicInfo graphicInfo = bpmnModel.getGraphicInfo(flowNode.getId());
        processDiagramCanvas.drawEventBasedGateway((int) graphicInfo.getX(), (int) graphicInfo.getY(), (int) graphicInfo.getWidth(), (int) graphicInfo.getHeight());
      }
    });
    

    // Boundary timer
    activityDrawInstructions.put(BoundaryEvent.class, new ActivityDrawInstruction() {

      public void draw(ProcessDiagramCanvas processDiagramCanvas, BpmnModel bpmnModel, FlowNode flowNode) {
        GraphicInfo graphicInfo = bpmnModel.getGraphicInfo(flowNode.getId());
        BoundaryEvent boundaryEvent = (BoundaryEvent) flowNode;
        if (boundaryEvent.getEventDefinitions() != null && boundaryEvent.getEventDefinitions().size() > 0) {
          if (boundaryEvent.getEventDefinitions().get(0) instanceof TimerEventDefinition) {
            
            processDiagramCanvas.drawCatchingTimerEvent(flowNode.getName(), (int) graphicInfo.getX(), 
                    (int) graphicInfo.getY(), (int) graphicInfo.getWidth(), (int) graphicInfo.getHeight(), boundaryEvent.isCancelActivity());
            
          } else if (boundaryEvent.getEventDefinitions().get(0) instanceof ErrorEventDefinition) {
            
            processDiagramCanvas.drawCatchingErrorEvent((int) graphicInfo.getX(), (int) graphicInfo.getY(),
                    (int) graphicInfo.getWidth(), (int) graphicInfo.getHeight(), boundaryEvent.isCancelActivity());
            
          } else if (boundaryEvent.getEventDefinitions().get(0) instanceof SignalEventDefinition) {
            processDiagramCanvas.drawCatchingSignalEvent(flowNode.getName(), (int) graphicInfo.getX(), 
                    (int) graphicInfo.getY(), (int) graphicInfo.getWidth(), (int) graphicInfo.getHeight(), boundaryEvent.isCancelActivity());
          }
        }
        
      }
    });

    // subprocess
    activityDrawInstructions.put(SubProcess.class, new ActivityDrawInstruction() {

      public void draw(ProcessDiagramCanvas processDiagramCanvas, BpmnModel bpmnModel, FlowNode flowNode) {
        GraphicInfo graphicInfo = bpmnModel.getGraphicInfo(flowNode.getId());
        if (!graphicInfo.isExpanded()) {
          processDiagramCanvas.drawCollapsedSubProcess(flowNode.getName(), (int) graphicInfo.getX(), 
                  (int) graphicInfo.getY(), (int) graphicInfo.getWidth(), (int) graphicInfo.getHeight(), false);
        } else {
          processDiagramCanvas.drawExpandedSubProcess(flowNode.getName(), (int) graphicInfo.getX(), 
                  (int) graphicInfo.getY(), (int) graphicInfo.getWidth(), (int) graphicInfo.getHeight(), false);
        }
      }
    });
    
    // Event subprocess
    activityDrawInstructions.put(EventSubProcess.class, new ActivityDrawInstruction() {

      public void draw(ProcessDiagramCanvas processDiagramCanvas, BpmnModel bpmnModel, FlowNode flowNode) {
        GraphicInfo graphicInfo = bpmnModel.getGraphicInfo(flowNode.getId());
        if (!graphicInfo.isExpanded()) {
          processDiagramCanvas.drawCollapsedSubProcess(flowNode.getName(), (int) graphicInfo.getX(), 
                  (int) graphicInfo.getY(), (int) graphicInfo.getWidth(), (int) graphicInfo.getHeight(), true);
        } else {
          processDiagramCanvas.drawExpandedSubProcess(flowNode.getName(), (int) graphicInfo.getX(), 
                  (int) graphicInfo.getY(), (int) graphicInfo.getWidth(), (int) graphicInfo.getHeight(), true);
        }
      }
    });

    // call activity
    activityDrawInstructions.put(CallActivity.class, new ActivityDrawInstruction() {

      public void draw(ProcessDiagramCanvas processDiagramCanvas, BpmnModel bpmnModel, FlowNode flowNode) {
        GraphicInfo graphicInfo = bpmnModel.getGraphicInfo(flowNode.getId());
        processDiagramCanvas.drawCollapsedCallActivity(flowNode.getName(), (int) graphicInfo.getX(), 
                (int) graphicInfo.getY(), (int) graphicInfo.getWidth(), (int) graphicInfo.getHeight());
      }
    });

  }

  /**
   * Generates a PNG diagram image of the given process definition, using the
   * diagram interchange information of the process.
   */
  public static InputStream generatePngDiagram(BpmnModel bpmnModel) {
    return generateDiagram(bpmnModel, "png", Collections. emptyList());
  }
  
  /**
   * Generates a JPG diagram image of the given process definition, using the
   * diagram interchange information of the process.
   */
  public static InputStream generateJpgDiagram(BpmnModel bpmnModel) {
    return generateDiagram(bpmnModel, "jpg", Collections. emptyList());
  }

  protected static ProcessDiagramCanvas generateDiagram(BpmnModel bpmnModel, List highLightedActivities) {
	  return generateDiagram(bpmnModel, highLightedActivities, Collections. emptyList());
  }
  
  protected static ProcessDiagramCanvas generateDiagram(BpmnModel bpmnModel, List highLightedActivities, List highLightedFlows) {
    ProcessDiagramCanvas processDiagramCanvas = initProcessDiagramCanvas(bpmnModel);
    
//    // Draw pool shape, if process is participant in collaboration
    for (Pool pool : bpmnModel.getPools()) {
      GraphicInfo graphicInfo = bpmnModel.getGraphicInfo(pool.getId());
      processDiagramCanvas.drawPoolOrLane(pool.getName(), (int) graphicInfo.getX(), (int) graphicInfo.getY(), 
              (int) graphicInfo.getWidth(),  (int) graphicInfo.getHeight());
    }
    
    // Draw lanes
    for (Process process : bpmnModel.getProcesses()) {
      for (Lane lane : process.getLanes()) {
        GraphicInfo graphicInfo = bpmnModel.getGraphicInfo(lane.getId());
        processDiagramCanvas.drawPoolOrLane(lane.getName(), (int) graphicInfo.getX(), (int) graphicInfo.getY(), 
                (int) graphicInfo.getWidth(),  (int) graphicInfo.getHeight());
      }
    }
    
    // Draw activities and their sequence-flows
    for (FlowNode flowNode : bpmnModel.getProcesses().get(0).findFlowElementsOfType(FlowNode.class)) {
      drawActivity(processDiagramCanvas, bpmnModel, flowNode, highLightedActivities, highLightedFlows);
    }
    return processDiagramCanvas;
  }
  
  public static InputStream generateDiagram(BpmnModel bpmnModel, String imageType, List highLightedActivities) {
    ProcessDiagramCanvas canvas = generateDiagram(bpmnModel, highLightedActivities, Collections. emptyList());
    return canvas.generateImage(imageType);
  }
  
  public static InputStream generateDiagram(BpmnModel bpmnModel, String imageType, List highLightedActivities, List highLightedFlows) {
    return generateDiagram(bpmnModel, highLightedActivities, highLightedFlows).generateImage(imageType);
  }

  protected static void drawActivity(ProcessDiagramCanvas processDiagramCanvas, BpmnModel bpmnModel, FlowNode flowNode, List highLightedActivities, List highLightedFlows) {
    
    ActivityDrawInstruction drawInstruction = activityDrawInstructions.get(flowNode.getClass());
    if (drawInstruction != null) {

      drawInstruction.draw(processDiagramCanvas, bpmnModel, flowNode);

      // Gather info on the multi instance marker
      boolean multiInstanceSequential = false, multiInstanceParallel = false, collapsed = false;
      if (flowNode instanceof Activity) {
        Activity activity = (Activity) flowNode;
        MultiInstanceLoopCharacteristics multiInstanceLoopCharacteristics = activity.getLoopCharacteristics();
        if (multiInstanceLoopCharacteristics != null) {
          multiInstanceSequential = multiInstanceLoopCharacteristics.isSequential();
          multiInstanceParallel = !multiInstanceSequential;
        }
      }

      // Gather info on the collapsed marker
      GraphicInfo graphicInfo = bpmnModel.getGraphicInfo(flowNode.getId()); 
      if (flowNode instanceof SubProcess) {
        collapsed = !graphicInfo.isExpanded();
      } else if (flowNode instanceof CallActivity) {
        collapsed = true;
      }

      // Actually draw the markers
      processDiagramCanvas.drawActivityMarkers((int) graphicInfo.getX(), (int) graphicInfo.getY(),(int) graphicInfo.getWidth(), (int) graphicInfo.getHeight(), 
              multiInstanceSequential, multiInstanceParallel, collapsed);

      // Draw highlighted activities
      if (highLightedActivities.contains(flowNode.getId())) {
        drawHighLight(processDiagramCanvas, bpmnModel.getGraphicInfo(flowNode.getId()));
      }

    }

    // Outgoing transitions of activity
    for (SequenceFlow sequenceFlow : flowNode.getOutgoingFlows()) {
      List graphicInfoList = bpmnModel.getFlowLocationGraphicInfo(sequenceFlow.getId());
      for (int i=1; i waypoints = ((TransitionImpl) sequenceFlow).getWaypoints();
//      int xPoints[]= new int[waypoints.size()/2];
//      int yPoints[]= new int[waypoints.size()/2];
//      for (int i=0, j=0; i < waypoints.size(); i+=2, j++) { // waypoints.size()
//                                                      // minimally 4: x1, y1,
//                                                      // x2, y2
//      	xPoints[j] = waypoints.get(i);
//      	yPoints[j] = waypoints.get(i+1);
//      }
//      processDiagramCanvas.drawSequenceflow(xPoints, yPoints, drawConditionalIndicator, isDefault, highLighted);
//    }

    // Nested elements
    if (flowNode instanceof FlowElementsContainer) {
      for (FlowElement nestedFlowElement : ((FlowElementsContainer) flowNode).getFlowElements()) {
        if (nestedFlowElement instanceof FlowNode) {
          drawActivity(processDiagramCanvas, bpmnModel, (FlowNode) nestedFlowElement, highLightedActivities, highLightedFlows);
        }
      }
    }
  }

  private static void drawHighLight(ProcessDiagramCanvas processDiagramCanvas, GraphicInfo graphicInfo) {
    processDiagramCanvas.drawHighLight((int) graphicInfo.getX(), (int) graphicInfo.getY(), (int) graphicInfo.getWidth(), (int) graphicInfo.getHeight());

  }

  protected static ProcessDiagramCanvas initProcessDiagramCanvas(BpmnModel bpmnModel) {
    
    // We need to calculate maximum values to know how big the image will be in its entirety
    double minX = Double.MAX_VALUE;
    double maxX = 0;
    double minY = Double.MAX_VALUE;
    double maxY = 0;

    for (Pool pool : bpmnModel.getPools()) {
      GraphicInfo graphicInfo = bpmnModel.getGraphicInfo(pool.getId());
      minX = graphicInfo.getX();
      maxX = graphicInfo.getX() + graphicInfo.getWidth();
      minY = graphicInfo.getY();
      maxY = graphicInfo.getY() + graphicInfo.getHeight();
    }
    
    List flowNodes = gatherAllFlowNodes(bpmnModel);
    for (FlowNode flowNode : flowNodes) {

      GraphicInfo flowNodeGraphicInfo = bpmnModel.getGraphicInfo(flowNode.getId());
      
      // width
      if (flowNodeGraphicInfo.getX() + flowNodeGraphicInfo.getWidth() > maxX) {
        maxX = flowNodeGraphicInfo.getX() + flowNodeGraphicInfo.getWidth();
      }
      if (flowNodeGraphicInfo.getX() < minX) {
        minX = flowNodeGraphicInfo.getX();
      }
      // height
      if (flowNodeGraphicInfo.getY() + flowNodeGraphicInfo.getHeight() > maxY) {
        maxY = flowNodeGraphicInfo.getY() + flowNodeGraphicInfo.getHeight();
      }
      if (flowNodeGraphicInfo.getY() < minY) {
        minY = flowNodeGraphicInfo.getY();
      }

      for (SequenceFlow sequenceFlow : flowNode.getOutgoingFlows()) {
        List graphicInfoList = bpmnModel.getFlowLocationGraphicInfo(sequenceFlow.getId());
        for (GraphicInfo graphicInfo : graphicInfoList) {
          // width
          if (graphicInfo.getX() > maxX) {
            maxX = graphicInfo.getX();
          }
          if (graphicInfo.getX() < minX) {
            minX = graphicInfo.getX();
          }
          // height
          if (graphicInfo.getY() > maxY) {
            maxY = graphicInfo.getY();
          }
          if (graphicInfo.getY()< minY) {
            minY = graphicInfo.getY();
          }
        }
      }
    }
    
    int nrOfLanes = 0;
    for (Process process : bpmnModel.getProcesses()) {
      for (Lane l : process.getLanes()) {
        
        nrOfLanes++;
        
        GraphicInfo graphicInfo = bpmnModel.getGraphicInfo(l.getId());
        // // width
        if (graphicInfo.getX() + graphicInfo.getWidth() > maxX) {
          maxX = graphicInfo.getX() + graphicInfo.getWidth();
        }
        if (graphicInfo.getX() < minX) {
          minX = graphicInfo.getX();
        }
        // height
        if (graphicInfo.getY() + graphicInfo.getHeight() > maxY) {
          maxY = graphicInfo.getY() + graphicInfo.getHeight();
        }
        if (graphicInfo.getY() < minY) {
          minY = graphicInfo.getY();
        }
      }
    }
    
    // Special case, see http://jira.codehaus.org/browse/ACT-1431
    if (flowNodes.size() == 0 && bpmnModel.getPools().size() == 0 && nrOfLanes == 0) {
      // Nothing to show
      minX = 0;
      minY = 0;
    }
    
    return new ProcessDiagramCanvas((int) maxX + 10,(int) maxY + 10, (int) minX, (int) minY);
  }
  
  protected static List gatherAllFlowNodes(BpmnModel bpmnModel) {
    List flowNodes = new ArrayList();
    for (Process process : bpmnModel.getProcesses()) {
      flowNodes.addAll(gatherAllFlowNodes(process));
    }
    return flowNodes;
  }
  
  protected static List gatherAllFlowNodes(FlowElementsContainer flowElementsContainer) {
    List flowNodes = new ArrayList();
    for (FlowElement flowElement : flowElementsContainer.getFlowElements()) {
      if (flowElement instanceof FlowNode) {
        flowNodes.add((FlowNode) flowElement);
      }
      if (flowElement instanceof FlowElementsContainer) {
        flowNodes.addAll(gatherAllFlowNodes((FlowElementsContainer) flowElement));
      }
    }
    return flowNodes;
  }

  protected interface ActivityDrawInstruction {

    void draw(ProcessDiagramCanvas processDiagramCanvas, BpmnModel bpmnModel, FlowNode flowNode);

  }

}