using System;

namespace Netron.Diagramming.Core.Layout.Force {
  /// <summary>
  /// Interface for force functions in a force simulation.
  /// </summary>
  public interface IForce {
    /// <summary>
    /// Initialize this force function.
    /// </summary>
    /// <param name="fsim"> the encompassing ForceSimulator</param>     
    void Init(ForceSimulator fsim);

    /// <summary>
    /// Returns the number of parameters (e.g., gravitational constant or
    /// spring force coefficient) affecting this force function. 
    /// </summary>
    int ParameterCount { get; }

    /// <summary>
    /// Returns the specified, numbered parameter.
    /// </summary>
    /// <param name="i">i the index of the parameter to return</param>
    /// <returns>the parameter value</returns>
    float GetParameter(int i);

    /// <summary>
    /// Get the suggested minimum value for a parameter. This value is not
    /// strictly enforced, but is used by interface components that allow force
    /// parameters to be varied.
    /// </summary>
    /// <param name="param">the parameter index</param>
    /// <returns>the suggested minimum value.</returns>
    float GetMinValue(int param);

    /// <summary>
    /// Get the suggested maximum value for a parameter. This value is not
    /// strictly enforced, but is used by interface components that allow force
    /// parameters to be varied.
    /// </summary>
    /// <param name="param">the parameter index</param>
    /// <returns>the suggested maximum value.</returns>
    float GetMaxValue(int param);

    /// <summary>
    /// Gets the text name of the requested parameter.
    /// </summary>
    /// <param name="i"> the index of the parameter</param>
    /// <returns>a String containing the name of this parameter</returns>
    String GetParameterName(int i);

    /// <summary>
    /// Sets the specified parameter value.
    /// </summary>
    /// <param name="i">  the index of the parameter</param>
    /// <param name="val">the new value of the parameter</param>
    void SetParameter(int i, float val);

    /// <summary>
    /// Set the suggested minimum value for a parameter. This value is not
    /// strictly enforced, but is used by interface components that allow force
    /// parameters to be varied.
    /// </summary>
    /// <param name="i">the parameter index</param>
    /// <param name="val">the suggested minimum value to use</param>
    void SetMinValue(int i, float val);

    /// <summary>
    /// Set the suggested maximum value for a parameter. This value is not
    /// strictly enforced, but is used by interface components that allow force
    /// parameters to be varied.
    /// </summary>
    /// <param name="i">the parameter index</param>
    /// <param name="val">the suggested maximum value to use</param>
    void SetMaxValue(int i, float val);

    /// <summary>
    /// Indicates if this force function will compute forces on Spring instances.   
    /// </summary>
    /// <returns>
    /// 	<c>true</c> if this force function processes Spring instances; otherwise, <c>false</c>.
    /// </returns>
    bool IsSpringForce { get; }

    /// <summary>
    /// Indicates if this force function will compute forces on ForceItem instances
    /// </summary>
    /// <returns>
    /// 	<c>true</c> if this force function processes IForce instances; otherwise, <c>false</c>.
    /// </returns>
    bool IsItemForce { get; }

    /// <summary>
    /// Updates the force calculation on the given ForceItem
    /// </summary>
    /// <param name="item"> the ForceItem on which to compute updated forces</param>
    void GetForce(ForceItem item);

    /// <summary>
    /// Updates the force calculation on the given Spring. The ForceItems
    /// attached to Spring will have their force values updated appropriately.
    /// </summary>
    /// <param name="spring">spring the Spring on which to compute updated forces</param>
    void GetForce(Spring spring);

  }

}