//
// (C) Copyright 2003-2016 by Autodesk, Inc.
//
// Permission to use, copy, modify, and distribute this software in
// object code form for any purpose and without fee is hereby granted,
// provided that the above copyright notice appears in all copies and
// that both that copyright notice and the limited warranty and
// restricted rights notice below appear in all supporting
// documentation.
//
// AUTODESK PROVIDES THIS PROGRAM "AS IS" AND WITH ALL FAULTS.
// AUTODESK SPECIFICALLY DISCLAIMS ANY IMPLIED WARRANTY OF
// MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. AUTODESK, INC.
// DOES NOT WARRANT THAT THE OPERATION OF THE PROGRAM WILL BE
// UNINTERRUPTED OR ERROR FREE.
//
// Use, duplication, or disclosure by the U.S. Government is subject to
// restrictions set forth in FAR 52.227-19 (Commercial Computer
// Software - Restricted Rights) and DFAR 252.227-7013(c)(1)(ii)
// (Rights in Technical Data and Computer Software), as applicable.
//
using System;
using System.Windows.Forms;
using System.Collections;
using System.Reflection;
using System.IO;
using System.Collections.Generic;

using Autodesk.Revit;
using Autodesk.Revit.DB;
using Autodesk.Revit.UI;
using Autodesk.Revit.DB.Mechanical;
using Autodesk.Revit.DB.Plumbing;
using Autodesk.Revit.UI.Selection;
using Application = Autodesk.Revit.ApplicationServices.Application;
using Element = Autodesk.Revit.DB.Element;
using System.Diagnostics;

namespace Revit.SDK.Samples.TraverseSystem.CS
{
  /// <summary>
  /// Implements the Revit add-in interface IExternalCommand
  /// </summary>
  [Autodesk.Revit.Attributes.Transaction( Autodesk.Revit.Attributes.TransactionMode.Manual )]
  [Autodesk.Revit.Attributes.Regeneration( Autodesk.Revit.Attributes.RegenerationOption.Manual )]
  [Autodesk.Revit.Attributes.Journaling( Autodesk.Revit.Attributes.JournalingMode.NoCommandData )]
  public class Command : IExternalCommand
  {
    /// <summary>
    /// Implement this method as an external command for Revit.
    /// </summary>
    /// <param name="commandData">An object that is passed to the external application 
    /// which contains data related to the command, 
    /// such as the application object and active view.</param>
    /// <param name="message">A message that can be set by the external application 
    /// which will be displayed if a failure or cancellation is returned by 
    /// the external command.</param>
    /// <param name="elements">A set of elements to which the external application 
    /// can add elements that are to be highlighted in case of failure or cancellation.</param>
    /// <returns>Return the status of the external command. 
    /// A result of Succeeded means that the API external method functioned as expected. 
    /// Cancelled can be used to signify that the user cancelled the external operation 
    /// at some point. Failure should be returned if the application is unable to proceed with 
    /// the operation.</returns>
    public virtual Autodesk.Revit.UI.Result Execute( ExternalCommandData commandData
        , ref string message, Autodesk.Revit.DB.ElementSet elements )
    {
      try
      {
        // Verify if the active document is null
        UIDocument activeDoc = commandData.Application.ActiveUIDocument;
        if( activeDoc == null )
        {
          TaskDialog.Show( "No Active Document", "There's no active document in Revit.", TaskDialogCommonButtons.Ok );
          return Autodesk.Revit.UI.Result.Failed;
        }

        // Verify the number of selected elements
        ElementSet selElements = new ElementSet();
        foreach( ElementId elementId in activeDoc.Selection.GetElementIds() )
        {
          selElements.Insert( activeDoc.Document.GetElement( elementId ) );
        }
        if( selElements.Size != 1 )
        {
          message = "Please select ONLY one element from current project.";
          return Autodesk.Revit.UI.Result.Failed;
        }

        // Get the selected element
        Element selectedElement = null;
        foreach( Element element in selElements )
        {
          selectedElement = element;
          break;
        }

        // Get the expected mechanical or piping system from selected element
        // Some elements in a non-well-connected system may get lost when traversing 
        //the system in the direction of flow; and
        // flow direction of elements in a non-well-connected system may not be right, 
        // therefore the sample will only support well-connected system.
        MEPSystem system = ExtractMechanicalOrPipingSystem( selectedElement );
        if( system == null )
        {
          message = "The selected element does not belong to any well-connected mechanical or piping system. " +
              "The sample will not support well-connected systems for the following reasons: " +
              Environment.NewLine +
              "- Some elements in a non-well-connected system may get lost when traversing the system in the " +
              "direction of flow" + Environment.NewLine +
              "- Flow direction of elements in a non-well-connected system may not be right";
          return Autodesk.Revit.UI.Result.Failed;
        }

        // Traverse the system and dump the traversal into an XML file
        TraversalTree tree = new TraversalTree( activeDoc.Document, system );
        tree.Traverse();
        String fileName;
        fileName = Path.Combine( Path.GetDirectoryName( Assembly.GetExecutingAssembly().Location ), "traversal.xml" );
        tree.DumpIntoXML( fileName );
        Process.Start( fileName );

        return Autodesk.Revit.UI.Result.Succeeded;
      }
      catch( Exception ex )
      {
        message = ex.Message;
        return Autodesk.Revit.UI.Result.Failed;
      }
    }

    /// <summary>
    /// Get the mechanical or piping system from selected element
    /// </summary>
    /// <param name="selectedElement">Selected element</param>
    /// <returns>The extracted mechanical or piping system. Null if no expected system is found.</returns>
    private MEPSystem ExtractMechanicalOrPipingSystem( Element selectedElement )
    {
      MEPSystem system = null;

      if( selectedElement is MEPSystem )
      {
        if( selectedElement is MechanicalSystem || selectedElement is PipingSystem )
        {
          system = selectedElement as MEPSystem;
          return system;
        }
      }
      else // Selected element is not a system
      {
        FamilyInstance fi = selectedElement as FamilyInstance;
        //
        // If selected element is a family instance, iterate its connectors and get the expected system
        if( fi != null )
        {
          MEPModel mepModel = fi.MEPModel;
          ConnectorSet connectors = null;
          try
          {
            connectors = mepModel.ConnectorManager.Connectors;
          }
          catch( System.Exception )
          {
            system = null;
          }

          system = ExtractSystemFromConnectors( connectors );
        }
        else
        {
          //
          // If selected element is a MEPCurve (e.g. pipe or duct), 
          // iterate its connectors and get the expected system
          MEPCurve mepCurve = selectedElement as MEPCurve;
          if( mepCurve != null )
          {
            ConnectorSet connectors = null;
            connectors = mepCurve.ConnectorManager.Connectors;
            system = ExtractSystemFromConnectors( connectors );
          }
        }
      }

      return system;
    }

    /// <summary>
    /// Get the mechanical or piping system from the connectors of selected element
    /// </summary>
    /// <param name="connectors">Connectors of selected element</param>
    /// <returns>The found mechanical or piping system</returns>
    static private MEPSystem ExtractSystemFromConnectors( ConnectorSet connectors )
    {
      MEPSystem system = null;

      if( connectors == null || connectors.Size == 0 )
      {
        return null;
      }

      // Get well-connected mechanical or piping systems from each connector
      List<MEPSystem> systems = new List<MEPSystem>();
      foreach( Connector connector in connectors )
      {
        MEPSystem tmpSystem = connector.MEPSystem;
        if( tmpSystem == null )
        {
          continue;
        }

        MechanicalSystem ms = tmpSystem as MechanicalSystem;
        if( ms != null )
        {
          if( ms.IsWellConnected )
          {
            systems.Add( tmpSystem );
          }
        }
        else
        {
          PipingSystem ps = tmpSystem as PipingSystem;
          if( ps != null && ps.IsWellConnected )
          {
            systems.Add( tmpSystem );
          }
        }
      }

      // If more than one system is found, get the system contains the most elements
      int countOfSystem = systems.Count;
      if( countOfSystem != 0 )
      {
        int countOfElements = 0;
        foreach( MEPSystem sys in systems )
        {
          if( sys.Elements.Size > countOfElements )
          {
            system = sys;
            countOfElements = sys.Elements.Size;
          }
        }
      }

      return system;
    }
  }
}