using System;
using System.Windows.Forms;
namespace Netron.Diagramming.Core {
  // ----------------------------------------------------------------------
  /// <summary>
  /// The base class for any tool <see cref="ITool"/>.
  /// </summary>
  // ----------------------------------------------------------------------
  public abstract class AbstractTool : ITool {
    #region Events

    // ------------------------------------------------------------------
    /// <summary>
    /// Occurs when this tool is deactivated.
    /// </summary>
    // ------------------------------------------------------------------
    public event EventHandler<ToolEventArgs> OnToolDeactivate;

    // ------------------------------------------------------------------
    /// <summary>
    /// Occurs when this tool is activated.
    /// </summary>
    // ------------------------------------------------------------------
    public event EventHandler<ToolEventArgs> OnToolActivate;

    #endregion

    #region Fields
    /// <summary>
    /// the Name field
    /// </summary>
    private string mName;
    /// <summary>
    /// the Enabled field
    /// </summary>
    private bool mEnabled = true;
    /// <summary>
    /// a pointer to the controller
    /// </summary>
    private IController mController;
    /// <summary>
    /// the tool's cursor
    /// </summary>
    private Cursor mCursor = Cursors.Default;
    /// <summary>
    /// whether the tool is currently active
    /// </summary>
    private bool mIsActive;
    /// <summary>
    /// keeps a reference to the previous cursor
    /// </summary>
    Cursor previousCursor;
    /// <summary>
    /// the suspend state of the tool
    /// </summary>
    private bool mIsSuspended;
    #endregion

    #region Properties

    /// <summary>
    /// Gets or sets a value indicating whether this instance is suspended. A tool enters in a suspended mode when another tool has been activated and disallows another to continue its normal activity. For example, the <see cref="MoveTool"/> and <see cref="SelectionTool"/> are
    /// mutually exclusive and similarly for the drawing tools and the selection tool.
    /// <para>This suspended state is independent of the <see cref="IsActive"/> and the <see cref="Enabled"/> states.</para>
    /// </summary>
    /// <value>
    /// 	<c>true</c> if this instance is suspended; otherwise, <c>false</c>.
    /// </value>
    public bool IsSuspended {
      get { return mIsSuspended; }
      set { mIsSuspended = value; }
    }

    /// <summary>
    /// Gets or sets a value indicating whether this tool is active.
    /// </summary>
    /// <value><c>true</c> if this instance is active; otherwise, <c>false</c>.</value>
    public bool IsActive {
      get { return mIsActive; }
      set { mIsActive = value; }
    }
    /// <summary>
    /// Gets or sets the name of the tool.
    /// </summary>
    /// <value>The name.</value>
    public string Name {
      get { return mName; }
      set { mName = value; }
    }
    /// <summary>
    /// Gets or sets the controller.
    /// </summary>
    /// <value>The controller.</value>
    public IController Controller {
      get {
        return mController;
      }

      set {
        mController = value;
      }
    }

    /// <summary>
    /// Gets or sets the cursor.
    /// </summary>
    /// <value>The cursor.</value>
    public Cursor Cursor {
      get {
        return mCursor;
      }
      set {
        mCursor = value;
        //prevCursor = Controller.View.CurrentCursor;
        Controller.View.CurrentCursor = value;
      }
    }

    /// <summary>
    /// Gets or sets the Enabled
    /// </summary>
    public bool Enabled {
      get {
        return this.mEnabled;
      }

      set {
        //disable the tool first if it is active
        if (!value && IsActive) {
          DeactivateTool();
        }
        mEnabled = value;
      }
    }

    /// <summary>
    /// Gets a value indicating whether this tool excludes other tools.
    /// </summary>
    /// <value>
    /// 	<c>true</c> if this instance is exclusive; otherwise, <c>false</c>.
    /// </value>
    public virtual bool IsExclusive {
      get {
        return true;
      }
    }

    /// <summary>
    /// Gets or sets a value indicating whether this tool can activated.
    /// </summary>
    /// <value>
    /// 	<c>true</c> if this instance can activate; otherwise, <c>false</c>.
    /// </value>
    public virtual bool CanActivate {
      get {
        if (mEnabled) {
          return !IsActive;
        } else {
          return false;
        }
      }

    }
    #endregion

    #region Constructor
    /// <summary>
    /// Default constructor
    /// </summary>
    /// <param name="name">The name of the tool.</param>
    public AbstractTool(string name) {
      this.mName = name;
    }
    #endregion

    #region Methods

    protected void RestoreCursor() {
      // I ran into an issue where the RectangleTool was activated,
      // nothing drawn, then the EllipseTool was activated.  When
      // the EllipseTool was deactivated the cursor was set to the
      // previous cursor, which was the cursor for the RectangleTool.

      // Update: Rather than fixing it here, I changed 
      // ControllerBase.ActivateTool(string) so it deactivates
      // the current tool first.
      //Controller.View.CurrentCursor = Cursors.Default;

      if (previousCursor != null) {
        if (Controller != null) {
          Controller.View.CurrentCursor = previousCursor;
        }
        previousCursor = null;
      }
    }

    // ------------------------------------------------------------------
    /// <summary>
    /// Raises the <see cref="OnToolActivate"/> event
    /// </summary>
    /// <param name="e">ConnectionCollection event argument</param>
    // ------------------------------------------------------------------
    public virtual void RaiseOnToolActivate(ToolEventArgs e) {
      EventHandler<ToolEventArgs> handler = OnToolActivate;
      if (handler != null) {
        handler(this, e);
      }
    }

    // ------------------------------------------------------------------
    /// <summary>
    /// Raises the <see cref="OnToolDeactivate"/> event.
    /// </summary>
    /// <param name="e">ConnectionCollection event argument</param>
    // ------------------------------------------------------------------
    public virtual void RaiseOnToolDeactivate(ToolEventArgs e) {
      EventHandler<ToolEventArgs> handler = OnToolDeactivate;
      if (handler != null) {
        handler(this, e);
      }
    }

    #region Activation & deactivation

    /// <summary>
    /// Deactivates the tool.
    /// </summary>
    /// <returns></returns>
    public bool DeactivateTool() {
      if (IsActive) {
        OnDeactivateTool();
        IsActive = false;
        RestoreCursor();
        UnsuspendTools();
        RaiseOnToolDeactivate(new ToolEventArgs(this));
        return true;
      }
      return false;
    }

    /// <summary>
    /// Activates the tool.
    /// </summary>
    /// <returns></returns>
    public bool ActivateTool() {
      //halt other actions
      SuspendOtherTools();

      if (Enabled && !IsActive) {
        previousCursor = this.Controller.View.CurrentCursor;
        IsActive = true;
        OnActivateTool();
        RaiseOnToolActivate(new ToolEventArgs(this));
      }
      return IsActive;
    }

    /// <summary>
    /// Suspends the other tools.
    /// </summary>
    public void SuspendOtherTools() {
      foreach (ITool tool in Controller.Tools) {
        if (tool != this)
          tool.IsSuspended = true;
      }
    }

    /// <summary>
    /// Releases the previously suspeneded tools <see cref="SuspendOtherTools"/>
    /// </summary>
    public void UnsuspendTools() {
      foreach (ITool tool in Controller.Tools) {
        tool.IsSuspended = false;
      }
    }

    #endregion

    /// <summary>
    /// Called when the tool is activated.
    /// </summary>
    protected virtual void OnActivateTool() { }

    /// <summary>
    /// Called when the tool is deactivated.
    /// </summary>
    protected virtual void OnDeactivateTool() { }

    /// <summary>
    /// Gets the service object of the specified type.
    /// </summary>
    /// <param name="serviceType">An object that specifies the type of service object to get.</param>
    /// <returns>
    /// A service object of type serviceType.-or- null if there is no service object of type serviceType.
    /// </returns>
    public object GetService(Type serviceType) {
      return null;
    }
    #endregion

  }
}