using System;

using UnityEngine;

namespace Framework.Geometry.Lines {

  /// <summary>Line segment that connects two points together</summary>
  public struct Segment3 {

    /// <summary>Point the line segment begins at</summary>
    public Vector3 From;
    /// <summary>Point the line segment ends at</summary>
    public Vector3 To;

    /// <summary>Initializes a new line segment between the provided points</summary>
    /// <param name="fromX">X coordinate the line segment will begin at</param>
    /// <param name="fromY">Y coordinate the line segment will begin at</param>
    /// <param name="fromZ">Z coordinate the line segment will begin at</param>
    /// <param name="toX">X coordinate the line segment will end at</param>
    /// <param name="toY">Y coordinate the line segment will end at</param>
    /// <param name="toZ">Z coordinate the line segment will end at</param>
    public Segment3(float fromX, float fromY, float fromZ, float toX, float toY, float toZ) {
      this.From = new Vector3(fromX, fromY, fromZ);
      this.To = new Vector3(toX, toY, toZ);
    }

    /// <summary>Initializes a new line segment between the provided points</summary>
    /// <param name="from">Point the line segment will begin at</param>
    /// <param name="to">Point the line segment will end at</param>
    public Segment3(Vector3 from, Vector3 to) {
      this.From = from;
      this.To = to;
    }

    /// <summary>Length of the line segment</summary>
    public float Length {
      get { return (this.To - this.From).magnitude; }
    }

    /// <summary>Squared length of the line segment (faster to calculate than Length)</summary>
    public float SquaredLength {
      get { return (this.To - this.From).sqrMagnitude; }
    }

    /// <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 Segment3)) {
        return false;
      }

      Segment3 other = (Segment3)otherObject;
      return (
        (this.From == other.From) &&
        (this.To == other.To)
      );
    }

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

    /// <summary>Interpolates along a line segment</summary>
    /// <param name="from">Point at which the line segment begins</param>
    /// <param name="to">Point at which the line segment ends</param>
    /// <param name="t">Interpolation time</param>
    /// <returns>The interpolated point</returns>
    public static Vector3 Interpolate(Vector3 from, Vector3 to, float t) {
      return (to - from) * t + from;
    }

  }

} // namespace Framework.Geometry.Lines