using System;

namespace Framework.Geometry.Lines.Intersection {

  /// <summary>Contact invervals between a line and another shape</summary>
  public struct LineContacts {

    /// <summary>A line contacts instance for reporting no contacts</summary>
    public static readonly LineContacts None = new LineContacts(float.NaN, float.NaN);

    /// <summary>Time the first contact was made</summary>
    public float EntryTime;
    /// <summary>Time the last contact occurred</summary>
    public float ExitTime;

    /// <summary>Initializes a new contact point</summary>
    /// <param name="touchTime">Time the contact was made at</param>
    public LineContacts(float touchTime) :
      this(touchTime, touchTime) { }

    /// <summary>Initializes a new contact point</summary>
    /// <param name="entryTime">Time the first contact was made at</param>
    /// <param name="exitTime">Time the last contact has occured</param>
    public LineContacts(float entryTime, float exitTime) {
      this.EntryTime = entryTime;
      this.ExitTime = exitTime;
    }

    /// <summary>Whether a contact is stored in the line contacts instance</summary>
    public bool HasContact {
      get { return (!float.IsNaN(this.EntryTime) && !float.IsNaN(this.ExitTime)); }
    }

    /// <summary>
    ///   Determines whether this instance is identical to another instance
    /// </summary>
    /// <param name="otherObject">Other instance of compare against</param>
    /// <returns>True if both instances are identical</returns>
    public override bool Equals(object otherObject) {
      if(!(otherObject is LineContacts)) {
        return false;
      }

      LineContacts other = (LineContacts)otherObject;
      return
        (this.EntryTime == other.EntryTime) &&
        (this.ExitTime == other.ExitTime);
    }

    /// <summary>Returns a hash code for the instance</summary>
    /// <returns>The instance's hash code</returns>
    public override int GetHashCode() {
      return this.EntryTime.GetHashCode() ^ this.ExitTime.GetHashCode();
    }

  }

} // namespace Framework.Geometry.Lines.Intersection