/*******************************************************************************
 * Copyright 2011 See AUTHORS file.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *   http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 ******************************************************************************/

package com.badlogic.gdx.math;

import java.io.Serializable;

import com.badlogic.gdx.utils.GdxRuntimeException;

/** A 3x3 <a href="http://en.wikipedia.org/wiki/Row-major_order#Column-major_order">column major</a> matrix; useful for 2D transforms.
 *
 * @author mzechner */
public class Matrix3 implements Serializable {
	private static final long serialVersionUID = 7907569533774959788L;
	private final static float DEGREE_TO_RAD = (float)Math.PI / 180;
	public static final int M00 = 0;
	public static final int M01 = 3;
	public static final int M02 = 6;
	public static final int M10 = 1;
	public static final int M11 = 4;
	public static final int M12 = 7;
	public static final int M20 = 2;
	public static final int M21 = 5;
	public static final int M22 = 8;
	public float[] val = new float[9];
	private float[] tmp = new float[9];

	public Matrix3 () {
		idt();
	}

	public Matrix3 (Matrix3 matrix) {
		set(matrix);
	}

	/** Sets this matrix to the identity matrix
	 * @return This matrix for the purpose of chaining operations. */
	public Matrix3 idt () {
		val[M00] = 1;
		val[M10] = 0;
		val[M20] = 0;
		val[M01] = 0;
		val[M11] = 1;
		val[M21] = 0;
		val[M02] = 0;
		val[M12] = 0;
		val[M22] = 1;
		return this;
	}

	/** Postmultiplies this matrix with the provided matrix and stores the result in this matrix. For example:
	 *
	 * <pre>
	 * A.mul(B) results in A := AB
	 * </pre>
	 * @param m Matrix to multiply by.
	 * @return This matrix for the purpose of chaining operations together. */
	public Matrix3 mul (Matrix3 m) {
		float v00 = val[M00] * m.val[M00] + val[M01] * m.val[M10] + val[M02] * m.val[M20];
		float v01 = val[M00] * m.val[M01] + val[M01] * m.val[M11] + val[M02] * m.val[M21];
		float v02 = val[M00] * m.val[M02] + val[M01] * m.val[M12] + val[M02] * m.val[M22];

		float v10 = val[M10] * m.val[M00] + val[M11] * m.val[M10] + val[M12] * m.val[M20];
		float v11 = val[M10] * m.val[M01] + val[M11] * m.val[M11] + val[M12] * m.val[M21];
		float v12 = val[M10] * m.val[M02] + val[M11] * m.val[M12] + val[M12] * m.val[M22];

		float v20 = val[M20] * m.val[M00] + val[M21] * m.val[M10] + val[M22] * m.val[M20];
		float v21 = val[M20] * m.val[M01] + val[M21] * m.val[M11] + val[M22] * m.val[M21];
		float v22 = val[M20] * m.val[M02] + val[M21] * m.val[M12] + val[M22] * m.val[M22];

		val[M00] = v00;
		val[M10] = v10;
		val[M20] = v20;
		val[M01] = v01;
		val[M11] = v11;
		val[M21] = v21;
		val[M02] = v02;
		val[M12] = v12;
		val[M22] = v22;

		return this;
	}

	/** Sets this matrix to a rotation matrix that will rotate any vector in counter-clockwise direction around the z-axis.
	 * @param degrees the angle in degrees.
	 * @return This matrix for the purpose of chaining operations. */
	public Matrix3 setToRotation (float degrees) {
		float angle = DEGREE_TO_RAD * degrees;
		float cos = (float)Math.cos(angle);
		float sin = (float)Math.sin(angle);

		this.val[M00] = cos;
		this.val[M10] = sin;
		this.val[M20] = 0;

		this.val[M01] = -sin;
		this.val[M11] = cos;
		this.val[M21] = 0;

		this.val[M02] = 0;
		this.val[M12] = 0;
		this.val[M22] = 1;

		return this;
	}

	/** Sets this matrix to a translation matrix.
	 * @param x the translation in x
	 * @param y the translation in y
	 * @return This matrix for the purpose of chaining operations. */
	public Matrix3 setToTranslation (float x, float y) {
		this.val[M00] = 1;
		this.val[M10] = 0;
		this.val[M20] = 0;

		this.val[M01] = 0;
		this.val[M11] = 1;
		this.val[M21] = 0;

		this.val[M02] = x;
		this.val[M12] = y;
		this.val[M22] = 1;

		return this;
	}

	/** Sets this matrix to a translation matrix.
	 * @param translation The translation vector.
	 * @return This matrix for the purpose of chaining operations. */
	public Matrix3 setToTranslation (Vector2 translation) {
		this.val[M00] = 1;
		this.val[M10] = 0;
		this.val[M20] = 0;

		this.val[M01] = 0;
		this.val[M11] = 1;
		this.val[M21] = 0;

		this.val[M02] = translation.x;
		this.val[M12] = translation.y;
		this.val[M22] = 1;

		return this;
	}

	/** Sets this matrix to a scaling matrix.
	 * 
	 * @param scaleX the scale in x
	 * @param scaleY the scale in y
	 * @return This matrix for the purpose of chaining operations. */
	public Matrix3 setToScaling (float scaleX, float scaleY) {
		val[M00] = scaleX;
		val[M10] = 0;
		val[M20] = 0;
		val[M01] = 0;
		val[M11] = scaleY;
		val[M21] = 0;
		val[M02] = 0;
		val[M12] = 0;
		val[M22] = 1;
		return this;
	}

	public String toString () {
		return "[" + val[0] + "|" + val[3] + "|" + val[6] + "]\n" + "[" + val[1] + "|" + val[4] + "|" + val[7] + "]\n" + "["
				+ val[2] + "|" + val[5] + "|" + val[8] + "]";
	}

	/** @return The determinant of this matrix */
	public float det () {
		return val[M00] * val[M11] * val[M22] + val[M01] * val[M12] * val[M20] + val[M02] * val[M10] * val[M21] - val[M00]
			* val[M12] * val[M21] - val[M01] * val[M10] * val[M22] - val[M02] * val[M11] * val[M20];
	}

	/** Inverts this matrix given that the determinant is != 0.
	 * @return This matrix for the purpose of chaining operations.
	 * @throws GdxRuntimeException if the matrix is singular (not invertible) */
	public Matrix3 inv () {
		float det = det();
		if (det == 0) throw new GdxRuntimeException("Can't invert a singular matrix");

		float inv_det = 1.0f / det;

		tmp[M00] = val[M11] * val[M22] - val[M21] * val[M12];
		tmp[M10] = val[M20] * val[M12] - val[M10] * val[M22];
		tmp[M20] = val[M10] * val[M21] - val[M20] * val[M11];
		tmp[M01] = val[M21] * val[M02] - val[M01] * val[M22];
		tmp[M11] = val[M00] * val[M22] - val[M20] * val[M02];
		tmp[M21] = val[M20] * val[M01] - val[M00] * val[M21];
		tmp[M02] = val[M01] * val[M12] - val[M11] * val[M02];
		tmp[M12] = val[M10] * val[M02] - val[M00] * val[M12];
		tmp[M22] = val[M00] * val[M11] - val[M10] * val[M01];

		val[M00] = inv_det * tmp[M00];
		val[M10] = inv_det * tmp[M10];
		val[M20] = inv_det * tmp[M20];
		val[M01] = inv_det * tmp[M01];
		val[M11] = inv_det * tmp[M11];
		val[M21] = inv_det * tmp[M21];
		val[M02] = inv_det * tmp[M02];
		val[M12] = inv_det * tmp[M12];
		val[M22] = inv_det * tmp[M22];

		return this;
	}

	/** Copies the values from the provided matrix to this matrix.
	 * @param mat The matrix to copy.
	 * @return This matrix for the purposes of chaining. */
	public Matrix3 set (Matrix3 mat) {
		System.arraycopy(mat.val, 0, val, 0, val.length);
		return this;
	}

	/** Sets this 3x3 matrix to the top left 3x3 corner of the provided 4x4 matrix.
	 * @param mat The matrix whose top left corner will be copied. This matrix will not be modified.
	 * @return This matrix for the purpose of chaining operations. */
	public Matrix3 set (Matrix4 mat) {
		val[M00] = mat.val[Matrix4.M00];
		val[M10] = mat.val[Matrix4.M10];
		val[M20] = mat.val[Matrix4.M20];
		val[M01] = mat.val[Matrix4.M01];
		val[M11] = mat.val[Matrix4.M11];
		val[M21] = mat.val[Matrix4.M21];
		val[M02] = mat.val[Matrix4.M02];
		val[M12] = mat.val[Matrix4.M12];
		val[M22] = mat.val[Matrix4.M22];
		return this;
	}

	/** Adds a translational component to the matrix in the 3rd column. The other columns are untouched.
	 * @param vector The translation vector.
	 * @return This matrix for the purpose of chaining. */
	public Matrix3 trn (Vector2 vector) {
		val[M02] += vector.x;
		val[M12] += vector.y;
		return this;
	}

	/** Adds a translational component to the matrix in the 3rd column. The other columns are untouched.
	 * @param x The x-component of the translation vector.
	 * @param y The y-component of the translation vector.
	 * @return This matrix for the purpose of chaining. */
	public Matrix3 trn (float x, float y) {
		val[M02] += x;
		val[M12] += y;
		return this;
	}

	/** Adds a translational component to the matrix in the 3rd column. The other columns are untouched.
	 * @param vector The translation vector. (The z-component of the vector is ignored because this is a 3x3 matrix)
	 * @return This matrix for the purpose of chaining. */
	public Matrix3 trn (Vector3 vector) {
		val[M02] += vector.x;
		val[M12] += vector.y;
		return this;
	}

	/** Postmultiplies this matrix by a translation matrix. Postmultiplication is also used by OpenGL ES' 1.x
	 * glTranslate/glRotate/glScale.
	 * @param x The x-component of the translation vector.
	 * @param y The y-component of the translation vector.
	 * @return This matrix for the purpose of chaining. */
	public Matrix3 translate (float x, float y) {
		tmp[M00] = 1;
		tmp[M10] = 0;
		tmp[M20] = 0;

		tmp[M01] = 0;
		tmp[M11] = 1;
		tmp[M21] = 0;

		tmp[M02] = x;
		tmp[M12] = y;
		tmp[M22] = 1;
		mul(val, tmp);
		return this;
	}

	/** Postmultiplies this matrix by a translation matrix. Postmultiplication is also used by OpenGL ES' 1.x
	 * glTranslate/glRotate/glScale.
	 * @param translation The translation vector.
	 * @return This matrix for the purpose of chaining. */
	public Matrix3 translate (Vector2 translation) {
		tmp[M00] = 1;
		tmp[M10] = 0;
		tmp[M20] = 0;

		tmp[M01] = 0;
		tmp[M11] = 1;
		tmp[M21] = 0;

		tmp[M02] = translation.x;
		tmp[M12] = translation.y;
		tmp[M22] = 1;
		mul(val, tmp);
		return this;
	}

	/** Postmultiplies this matrix with a (counter-clockwise) rotation matrix. Postmultiplication is also used by OpenGL ES' 1.x
	 * glTranslate/glRotate/glScale.
	 * @param degrees The angle in degrees
	 * @return This matrix for the purpose of chaining. */
	public Matrix3 rotate (float degrees) {
		if (degrees == 0) return this;
		degrees = DEGREE_TO_RAD * degrees;
		float cos = (float)Math.cos(degrees);
		float sin = (float)Math.sin(degrees);

		tmp[M00] = cos;
		tmp[M10] = sin;
		tmp[M20] = 0;

		tmp[M01] = -sin;
		tmp[M11] = cos;
		tmp[M21] = 0;

		tmp[M02] = 0;
		tmp[M12] = 0;
		tmp[M22] = 1;
		mul(val, tmp);
		return this;
	}

	/** Postmultiplies this matrix with a scale matrix. Postmultiplication is also used by OpenGL ES' 1.x
	 * glTranslate/glRotate/glScale.
	 * @param scaleX The scale in the x-axis.
	 * @param scaleY The scale in the y-axis.
	 * @return This matrix for the purpose of chaining. */
	public Matrix3 scale (float scaleX, float scaleY) {
		tmp[M00] = scaleX;
		tmp[M10] = 0;
		tmp[M20] = 0;
		tmp[M01] = 0;
		tmp[M11] = scaleY;
		tmp[M21] = 0;
		tmp[M02] = 0;
		tmp[M12] = 0;
		tmp[M22] = 1;
		mul(val, tmp);
		return this;
	}

	/** Postmultiplies this matrix with a scale matrix. Postmultiplication is also used by OpenGL ES' 1.x
	 * glTranslate/glRotate/glScale.
	 * @param scale The vector to scale the matrix by.
	 * @return This matrix for the purpose of chaining. */
	public Matrix3 scale (Vector2 scale) {
		tmp[M00] = scale.x;
		tmp[M10] = 0;
		tmp[M20] = 0;
		tmp[M01] = 0;
		tmp[M11] = scale.y;
		tmp[M21] = 0;
		tmp[M02] = 0;
		tmp[M12] = 0;
		tmp[M22] = 1;
		mul(val, tmp);
		return this;
	}

	/** Get the values in this matrix.
	 * @return The float values that make up this matrix in column-major order. */
	public float[] getValues () {
		return val;
	}

	/** Scale the matrix in the both the x and y components by the scalar value.
	 * @param scale The single value that will be used to scale both the x and y components.
	 * @return This matrix for the purpose of chaining methods together. */
	public Matrix3 scl (float scale) {
		val[M00] *= scale;
		val[M11] *= scale;
		return this;
	}

	/** Scale this matrix using the x and y components of the vector but leave the rest of the matrix alone.
	 * @param scale The {@link Vector3} to use to scale this matrix.
	 * @return This matrix for the purpose of chaining methods together. */
	public Matrix3 scl (Vector2 scale) {
		val[M00] *= scale.x;
		val[M11] *= scale.y;
		return this;
	}

	/** Scale this matrix using the x and y components of the vector but leave the rest of the matrix alone.
	 * @param scale The {@link Vector3} to use to scale this matrix. The z component will be ignored.
	 * @return This matrix for the purpose of chaining methods together. */
	public Matrix3 scl (Vector3 scale) {
		val[M00] *= scale.x;
		val[M11] *= scale.y;
		return this;
	}

	/** Transposes the current matrix.
	 * @return This matrix for the purpose of chaining methods together. */
	public Matrix3 transpose () {
		// Where MXY you do not have to change MXX
		float v01 = val[M10];
		float v02 = val[M20];
		float v10 = val[M01];
		float v12 = val[M21];
		float v20 = val[M02];
		float v21 = val[M12];
		val[M01] = v01;
		val[M02] = v02;
		val[M10] = v10;
		val[M12] = v12;
		val[M20] = v20;
		val[M21] = v21;
		return this;
	}

	/** Multiplies matrix a with matrix b in the following manner:
	 * 
	 * <pre>
	 * mul(A, B) => A := AB
	 * </pre>
	 * @param mata The float array representing the first matrix. Must have at least 9 elements.
	 * @param matb The float array representing the second matrix. Must have at least 9 elements. */
	private static void mul (float[] mata, float[] matb) {
		float v00 = mata[M00] * matb[M00] + mata[M01] * matb[M10] + mata[M02] * matb[M20];
		float v01 = mata[M00] * matb[M01] + mata[M01] * matb[M11] + mata[M02] * matb[M21];
		float v02 = mata[M00] * matb[M02] + mata[M01] * matb[M12] + mata[M02] * matb[M22];

		float v10 = mata[M10] * matb[M00] + mata[M11] * matb[M10] + mata[M12] * matb[M20];
		float v11 = mata[M10] * matb[M01] + mata[M11] * matb[M11] + mata[M12] * matb[M21];
		float v12 = mata[M10] * matb[M02] + mata[M11] * matb[M12] + mata[M12] * matb[M22];

		float v20 = mata[M20] * matb[M00] + mata[M21] * matb[M10] + mata[M22] * matb[M20];
		float v21 = mata[M20] * matb[M01] + mata[M21] * matb[M11] + mata[M22] * matb[M21];
		float v22 = mata[M20] * matb[M02] + mata[M21] * matb[M12] + mata[M22] * matb[M22];

		mata[M00] = v00;
		mata[M10] = v10;
		mata[M20] = v20;
		mata[M01] = v01;
		mata[M11] = v11;
		mata[M21] = v21;
		mata[M02] = v02;
		mata[M12] = v12;
		mata[M22] = v22;
	}
}
