/*******************************************************************************
 * Copyright (c) 2015-2018 Skymind, Inc.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Apache License, Version 2.0 which is available at
 * https://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.
 *
 * SPDX-License-Identifier: Apache-2.0
 ******************************************************************************/

package org.nd4j.linalg.cpu.nativecpu.blas;

import lombok.val;
import org.nd4j.linalg.api.blas.impl.BaseLapack;
import org.nd4j.linalg.api.buffer.DataType;
import org.nd4j.linalg.api.ndarray.INDArray;
import org.nd4j.linalg.factory.Nd4j;
import org.nd4j.linalg.indexing.INDArrayIndex;
import org.nd4j.linalg.indexing.NDArrayIndex;
import org.bytedeco.javacpp.DoublePointer;
import org.bytedeco.javacpp.FloatPointer;
import org.bytedeco.javacpp.IntPointer;

import org.nd4j.linalg.api.blas.BlasException ;

import static org.bytedeco.openblas.global.openblas.*;

/**
 * CPU lapack implementation
 */
public class CpuLapack extends BaseLapack {
    protected static int getColumnOrder(INDArray A) {
        return A.ordering() == 'f' ? LAPACK_COL_MAJOR : LAPACK_ROW_MAJOR;
    }

    protected static int getLda(INDArray A) {
        // FIXME: int cast
        return A.ordering() == 'f' ? (int) A.rows() : (int) A.columns();
    }
//=========================    
// L U DECOMP
    @Override
    public void sgetrf(int M, int N, INDArray A, INDArray IPIV, INDArray INFO) {
        int status = LAPACKE_sgetrf(getColumnOrder(A), M, N, 
            (FloatPointer)A.data().addressPointer(), 
            getLda(A), (IntPointer)IPIV.data().addressPointer()
            );
        if( status < 0 ) {
            throw new BlasException( "Failed to execute sgetrf", status ) ;
        }
    }

    @Override
    public void dgetrf(int M, int N, INDArray A, INDArray IPIV, INDArray INFO) {
        int status = LAPACKE_dgetrf(getColumnOrder(A), M, N, (DoublePointer)A.data().addressPointer(), 
            getLda(A), (IntPointer)IPIV.data().addressPointer()
            );
        if( status < 0 ) {
            throw new BlasException( "Failed to execute dgetrf", status ) ;
        }
    }

//=========================    
// Q R DECOMP
    @Override
    public void sgeqrf(int M, int N, INDArray A, INDArray R, INDArray INFO) {
        INDArray tau = Nd4j.create(DataType.FLOAT, N ) ;

        int status = LAPACKE_sgeqrf(getColumnOrder(A), M, N, 
             (FloatPointer)A.data().addressPointer(), getLda(A),
             (FloatPointer)tau.data().addressPointer()
             );
        if( status != 0 ) {
            throw new BlasException( "Failed to execute sgeqrf", status ) ;
        }

        // Copy R ( upper part of Q ) into result
        if( R != null ) {
            R.assign( A.get( NDArrayIndex.interval( 0, A.columns() ), NDArrayIndex.all() ) ) ; 
			INDArrayIndex ix[] = new INDArrayIndex[ 2 ] ;

			for( int i=1 ; i<Math.min( A.rows(), A.columns() ) ; i++ ) {
				ix[0] = NDArrayIndex.point( i ) ;
				ix[1] = NDArrayIndex.interval( 0, i ) ;				
				R.put(ix, 0) ;
			}
        }

        status = LAPACKE_sorgqr( getColumnOrder(A), M, N, N, 
             (FloatPointer)A.data().addressPointer(), getLda(A),
             (FloatPointer)tau.data().addressPointer()
             );
        if( status != 0 ) {
            throw new BlasException( "Failed to execute sorgqr", status ) ;
        }
    }

    @Override
    public void dgeqrf(int M, int N, INDArray A, INDArray R, INDArray INFO)  {
        INDArray tau = Nd4j.create(DataType.DOUBLE, N ) ;

        int status = LAPACKE_dgeqrf(getColumnOrder(A), M, N,
             (DoublePointer)A.data().addressPointer(), getLda(A),
             (DoublePointer)tau.data().addressPointer()
             );
        if( status != 0 ) {
            throw new BlasException( "Failed to execute dgeqrf", status ) ;
        }
        
        // Copy R ( upper part of Q ) into result
        if( R != null ) {
            R.assign( A.get( NDArrayIndex.interval( 0, A.columns() ), NDArrayIndex.all() ) ) ; 
			INDArrayIndex ix[] = new INDArrayIndex[ 2 ] ;
			
			for( int i=1 ; i<Math.min( A.rows(), A.columns() ) ; i++ ) {
				ix[0] = NDArrayIndex.point( i ) ;
				ix[1] = NDArrayIndex.interval( 0, i ) ;				
				R.put(ix, 0) ;
			}
        }

        status = LAPACKE_dorgqr( getColumnOrder(A), M, N, N, 
             (DoublePointer)A.data().addressPointer(), getLda(A),
             (DoublePointer)tau.data().addressPointer()
             );
        if( status != 0 ) {
            throw new BlasException( "Failed to execute dorgqr", status ) ;
        }
    }


//=========================    
// CHOLESKY DECOMP
    @Override
    public void spotrf(byte uplo, int N, INDArray A, INDArray INFO) {
        int status = LAPACKE_spotrf(getColumnOrder(A), uplo, N, 
                        (FloatPointer)A.data().addressPointer(), getLda(A) );
        if( status != 0 ) {
            throw new BlasException( "Failed to execute spotrf", status ) ;
        }
        if( uplo == 'U' ) {			
			INDArrayIndex ix[] = new INDArrayIndex[ 2 ] ;
			for( int i=1 ; i<Math.min( A.rows(), A.columns() ) ; i++ ) {
				ix[0] = NDArrayIndex.point( i ) ;
				ix[1] = NDArrayIndex.interval( 0, i ) ;				
				A.put(ix, 0) ;
			}            
        } else {
            INDArrayIndex ix[] = new INDArrayIndex[ 2 ] ;
            for( int i=0 ; i<Math.min( A.rows(), A.columns()-1 ) ; i++ ) {
                ix[0] = NDArrayIndex.point( i ) ;
                ix[1] = NDArrayIndex.interval( i+1, A.columns() ) ;
                A.put(ix, 0) ;
            }        
        }
    }

    @Override
    public void dpotrf(byte uplo, int N, INDArray A, INDArray INFO) {
        int status = LAPACKE_dpotrf(getColumnOrder(A), uplo, N, 
                    (DoublePointer)A.data().addressPointer(), getLda(A) );
        if( status != 0 ) {
            throw new BlasException( "Failed to execute dpotrf", status ) ;
        }
        if( uplo == 'U' ) {			
			INDArrayIndex ix[] = new INDArrayIndex[ 2 ] ;
			for( int i=1 ; i<Math.min( A.rows(), A.columns() ) ; i++ ) {
				ix[0] = NDArrayIndex.point( i ) ;
				ix[1] = NDArrayIndex.interval( 0, i ) ;				
				A.put(ix, 0) ;
			}            
        } else {
            INDArrayIndex ix[] = new INDArrayIndex[ 2 ] ;
            for( int i=0 ; i<Math.min( A.rows(), A.columns()-1 ) ; i++ ) {
                ix[0] = NDArrayIndex.point( i ) ;
                ix[1] = NDArrayIndex.interval( i+1, A.columns() ) ;
                A.put(ix, 0) ;
            }        
        }
    }



//=========================    
// U S V' DECOMP  (aka SVD)
    @Override
    public void sgesvd(byte jobu, byte jobvt, int M, int N, INDArray A, INDArray S, INDArray U, INDArray VT,
                    INDArray INFO) {
        INDArray superb = Nd4j.create(DataType.FLOAT, M < N ? M : N ) ;
        int status = LAPACKE_sgesvd(getColumnOrder(A), jobu, jobvt, M, N, 
                        (FloatPointer)A.data().addressPointer(), getLda(A),
                        (FloatPointer)S.data().addressPointer(), 
                        U == null ? null : (FloatPointer)U.data().addressPointer(), U == null ? 1 : getLda(U),
                        VT == null ? null : (FloatPointer)VT.data().addressPointer(), VT == null ? 1 : getLda(VT), 
                        (FloatPointer)superb.data().addressPointer() 
                        );
        if( status != 0 ) {
            throw new BlasException( "Failed to execute sgesvd", status ) ;
        }
    }

    @Override
    public void dgesvd(byte jobu, byte jobvt, int M, int N, INDArray A, INDArray S, INDArray U, INDArray VT,
                    INDArray INFO) {
        INDArray superb = Nd4j.create(DataType.DOUBLE, M < N ? M : N ) ;
        int status = LAPACKE_dgesvd(getColumnOrder(A), jobu, jobvt, M, N, 
                        (DoublePointer)A.data().addressPointer(), getLda(A),
                        (DoublePointer)S.data().addressPointer(), 
                        U == null ? null : (DoublePointer)U.data().addressPointer(), U == null ? 1 : getLda(U),
                        VT == null ? null : (DoublePointer)VT.data().addressPointer(), VT == null ? 1 : getLda(VT), 
                        (DoublePointer)superb.data().addressPointer() 
                        ) ;
        if( status != 0 ) {
            throw new BlasException( "Failed to execute dgesvd", status ) ;
        }
    }


//=========================    
// syev EigenValue/Vectors
//
    @Override
    public int ssyev( char jobz, char uplo, int N, INDArray A, INDArray R ) {
	FloatPointer fp = new FloatPointer(1) ;
	int status = LAPACKE_ssyev_work( getColumnOrder(A), (byte)jobz, (byte)uplo, 
					N, (FloatPointer)A.data().addressPointer(), getLda(A),
					(FloatPointer)R.data().addressPointer(), fp, -1 ) ;
	if( status == 0 ) {
		int lwork = (int)fp.get() ;
		INDArray work = Nd4j.createArrayFromShapeBuffer(Nd4j.getDataBufferFactory().createFloat(lwork),
		                Nd4j.getShapeInfoProvider().createShapeInformation(new long[] {lwork}, A.dataType()).getFirst());

		status = LAPACKE_ssyev( getColumnOrder(A), (byte)jobz, (byte)uplo, N, 
		            (FloatPointer)A.data().addressPointer(), getLda(A),
			    (FloatPointer)work.data().addressPointer() ) ;
		if( status == 0 ) {
			R.assign(work.get(NDArrayIndex.interval(0,N))) ;
		}
	}
	return status ;
    }


    public int dsyev( char jobz, char uplo, int N, INDArray A, INDArray R ) {

	DoublePointer dp = new DoublePointer(1) ;
	int status = LAPACKE_dsyev_work( getColumnOrder(A), (byte)jobz, (byte)uplo, 
					N, (DoublePointer)A.data().addressPointer(), getLda(A),
					(DoublePointer)R.data().addressPointer(), dp, -1 ) ;
	if( status == 0 ) {
		int lwork = (int)dp.get() ;
		INDArray work = Nd4j.createArrayFromShapeBuffer(Nd4j.getDataBufferFactory().createDouble(lwork),
		                Nd4j.getShapeInfoProvider().createShapeInformation(new long[] {lwork}, A.dataType()).getFirst());

		status = LAPACKE_dsyev( getColumnOrder(A), (byte)jobz, (byte)uplo, N, 
		            (DoublePointer)A.data().addressPointer(), getLda(A),
			    (DoublePointer)work.data().addressPointer() ) ;

		if( status == 0 ) {
			R.assign( work.get( NDArrayIndex.interval(0,N) ) ) ;
		}
	}
	return status ;
    }




    /**
     * Generate inverse given LU decomp
     *
     * @param N
     * @param A
     * @param lda
     * @param IPIV
     * @param WORK
     * @param lwork
     * @param INFO
     */
    @Override
    public void getri(int N, INDArray A, int lda, int[] IPIV, INDArray WORK, int lwork, int INFO) {

    }
}
