/*
 *  Copyright (c) 2004-2005 The Trustees of Indiana University and Indiana
 *                          University Research and Technology
 *                          Corporation.  All rights reserved.
 *  Copyright (c) 2004-2016 The University of Tennessee and The University
 *                          of Tennessee Research Foundation.  All rights
 *                          reserved.
 *  Copyright (c) 2004-2005 High Performance Computing Center Stuttgart,
 *                          University of Stuttgart.  All rights reserved.
 *  Copyright (c) 2004-2005 The Regents of the University of California.
 *                          All rights reserved.
 *  Copyright (c) 2008-2016 University of Houston. All rights reserved.
 *  $COPYRIGHT$
 *
 *  Additional copyrights may follow
 *
 *  $HEADER$
 */

#include "ompi_config.h"

#include "ompi/communicator/communicator.h"
#include "ompi/info/info.h"
#include "ompi/file/file.h"
#include "ompi/mca/fs/fs.h"
#include "ompi/mca/fs/base/base.h"
#include "ompi/mca/fcoll/fcoll.h"
#include "ompi/mca/fcoll/base/base.h"
#include "ompi/mca/fbtl/fbtl.h"
#include "ompi/mca/fbtl/base/base.h"

#include "common_ompio.h"
#include "ompi/mca/io/ompio/io_ompio.h"
#include "ompi/mca/io/ompio/io_ompio_request.h"
#include "math.h"
#include <unistd.h>

/* Read and write routines are split into two interfaces.
**   The
**   mca_io_ompio_file_read/write[_at]
**
** routines are the ones registered with the ompio modules.
** The
**
** mca_common_ompio_file_read/write[_at]
**
** routesin are used e.g. from the shared file pointer modules.
** The main difference is, that the first one takes an ompi_file_t
** as a file pointer argument, while the second uses the ompio internal
** mca_io_ompio_file_t structure.
*/

int mca_common_ompio_file_read (mca_io_ompio_file_t *fh,
			      void *buf,
			      int count,
			      struct ompi_datatype_t *datatype,
			      ompi_status_public_t *status)
{
    int ret = OMPI_SUCCESS;

    size_t total_bytes_read = 0;       /* total bytes that have been read*/
    size_t bytes_per_cycle = 0;        /* total read in each cycle by each process*/
    int index = 0;
    int cycles = 0;

    uint32_t iov_count = 0;
    struct iovec *decoded_iov = NULL;

    size_t max_data=0, real_bytes_read=0;
    ssize_t ret_code=0;
    int i = 0; /* index into the decoded iovec of the buffer */
    int j = 0; /* index into the file vie iovec */

    if ( 0 == count ) {
	if ( MPI_STATUS_IGNORE != status ) {
	    status->_ucount = 0;
	}
	return ret;
    }

    if (fh->f_amode & MPI_MODE_WRONLY){
      printf("Improper use of FILE Mode, Using WRONLY for Read!\n");
      ret = OMPI_ERROR;
      return ret;
    }

    ompi_io_ompio_decode_datatype (fh,
                                   datatype,
                                   count,
                                   buf,
                                   &max_data,
                                   &decoded_iov,
                                   &iov_count);

    if ( -1 == mca_io_ompio_cycle_buffer_size ) {
	bytes_per_cycle = max_data;
    }
    else {
	bytes_per_cycle = mca_io_ompio_cycle_buffer_size;
    }
    cycles = ceil((float)max_data/bytes_per_cycle);

#if 0
	printf ("Bytes per Cycle: %d   Cycles: %d max_data:%d \n",bytes_per_cycle, cycles, max_data);
#endif

    j = fh->f_index_in_file_view;

    for (index = 0; index < cycles; index++) {

	mca_common_ompio_build_io_array ( fh,
                                          index,
                                          cycles,
                                          bytes_per_cycle,
                                          max_data,
                                          iov_count,
                                          decoded_iov,
                                          &i,
                                          &j,
                                          &total_bytes_read);

        if (fh->f_num_of_io_entries) {
            ret_code = fh->f_fbtl->fbtl_preadv (fh);
	    if ( 0<= ret_code ) {
		real_bytes_read+=(size_t)ret_code;
	    }
        }

        fh->f_num_of_io_entries = 0;
        if (NULL != fh->f_io_array) {
            free (fh->f_io_array);
            fh->f_io_array = NULL;
        }
    }

    if (NULL != decoded_iov) {
        free (decoded_iov);
        decoded_iov = NULL;
    }

    if ( MPI_STATUS_IGNORE != status ) {
	status->_ucount = real_bytes_read;
    }

    return ret;
}

int mca_common_ompio_file_read_at (mca_io_ompio_file_t *fh,
				 OMPI_MPI_OFFSET_TYPE offset,
				 void *buf,
				 int count,
				 struct ompi_datatype_t *datatype,
				 ompi_status_public_t * status)
{
    int ret = OMPI_SUCCESS;
    OMPI_MPI_OFFSET_TYPE prev_offset;

    mca_common_ompio_file_get_position (fh, &prev_offset );

    mca_common_ompio_set_explicit_offset (fh, offset);
    ret = mca_common_ompio_file_read (fh,
				    buf,
				    count,
				    datatype,
				    status);

    // An explicit offset file operation is not suppsed to modify
    // the internal file pointer. So reset the pointer
    // to the previous value
    mca_common_ompio_set_explicit_offset (fh, prev_offset);

    return ret;
}


int mca_common_ompio_file_iread (mca_io_ompio_file_t *fh,
			       void *buf,
			       int count,
			       struct ompi_datatype_t *datatype,
			       ompi_request_t **request)
{
    int ret = OMPI_SUCCESS;
    mca_ompio_request_t *ompio_req=NULL;

    ompio_req = OBJ_NEW(mca_ompio_request_t);
    ompio_req->req_type = MCA_OMPIO_REQUEST_READ;
    ompio_req->req_ompi.req_state = OMPI_REQUEST_ACTIVE;

    if ( 0 == count ) {
	ompio_req->req_ompi.req_status.MPI_ERROR = OMPI_SUCCESS;
	ompio_req->req_ompi.req_status._ucount = 0;
	ompi_request_complete (&ompio_req->req_ompi, false);
        *request = (ompi_request_t *) ompio_req;

	return OMPI_SUCCESS;
    }

    if ( NULL != fh->f_fbtl->fbtl_ipreadv ) {
	// This fbtl has support for non-blocking operations

	size_t total_bytes_read = 0;       /* total bytes that have been read*/
	uint32_t iov_count = 0;
	struct iovec *decoded_iov = NULL;

	size_t max_data = 0;
	int i = 0; /* index into the decoded iovec of the buffer */
	int j = 0; /* index into the file vie iovec */

	ompi_io_ompio_decode_datatype (fh,
				       datatype,
				       count,
				       buf,
				       &max_data,
				       &decoded_iov,
				       &iov_count);

	// Non-blocking operations have to occur in a single cycle
	j = fh->f_index_in_file_view;

	mca_common_ompio_build_io_array ( fh,
                                          0,         // index
                                          1,         // no. of cyces
                                          max_data,  // setting bytes per cycle to match data
                                          max_data,
                                          iov_count,
                                          decoded_iov,
                                          &i,
                                          &j,
                                          &total_bytes_read);

	if (fh->f_num_of_io_entries) {
	  fh->f_fbtl->fbtl_ipreadv (fh, (ompi_request_t *) ompio_req);
	}

	if ( false == mca_io_ompio_progress_is_registered ) {
            // Lazy initialization of progress function to minimize impact
            // on other ompi functionality in case its not used.
            opal_progress_register (mca_io_ompio_component_progress);
            mca_io_ompio_progress_is_registered=true;
        }

	fh->f_num_of_io_entries = 0;
	if (NULL != fh->f_io_array) {
	    free (fh->f_io_array);
	    fh->f_io_array = NULL;
	}

	if (NULL != decoded_iov) {
	    free (decoded_iov);
	    decoded_iov = NULL;
	}
    }
    else {
	// This fbtl does not  support non-blocking operations
	ompi_status_public_t status;
	ret = mca_common_ompio_file_read (fh, buf, count, datatype, &status);

	ompio_req->req_ompi.req_status.MPI_ERROR = ret;
	ompio_req->req_ompi.req_status._ucount = status._ucount;
	ompi_request_complete (&ompio_req->req_ompi, false);
    }

    *request = (ompi_request_t *) ompio_req;
    return ret;
}


int mca_common_ompio_file_iread_at (mca_io_ompio_file_t *fh,
				  OMPI_MPI_OFFSET_TYPE offset,
				  void *buf,
				  int count,
				  struct ompi_datatype_t *datatype,
				  ompi_request_t **request)
{
    int ret = OMPI_SUCCESS;
    OMPI_MPI_OFFSET_TYPE prev_offset;
    mca_common_ompio_file_get_position (fh, &prev_offset );

    mca_common_ompio_set_explicit_offset (fh, offset);
    ret = mca_common_ompio_file_iread (fh,
				    buf,
				    count,
				    datatype,
				    request);

    /* An explicit offset file operation is not suppsed to modify
    ** the internal file pointer. So reset the pointer
    ** to the previous value
    ** It is OK to reset the position already here, althgouth
    ** the operation might still be pending/ongoing, since
    ** the entire array of <offset, length, memaddress> have
    ** already been constructed in the file_iread operation
    */
    mca_common_ompio_set_explicit_offset (fh, prev_offset);

    return ret;
}


/* Infrastructure for collective operations  */
int mca_common_ompio_file_read_at_all (mca_io_ompio_file_t *fh,
				     OMPI_MPI_OFFSET_TYPE offset,
				     void *buf,
				     int count,
				     struct ompi_datatype_t *datatype,
				     ompi_status_public_t * status)
{
    int ret = OMPI_SUCCESS;
    OMPI_MPI_OFFSET_TYPE prev_offset;
    mca_common_ompio_file_get_position (fh, &prev_offset );

    mca_common_ompio_set_explicit_offset (fh, offset);
    ret = fh->f_fcoll->fcoll_file_read_all (fh,
                                            buf,
                                            count,
                                            datatype,
                                            status);

    mca_common_ompio_set_explicit_offset (fh, prev_offset);
    return ret;
}

int mca_common_ompio_file_iread_at_all (mca_io_ompio_file_t *fp,
				      OMPI_MPI_OFFSET_TYPE offset,
				      void *buf,
				      int count,
				      struct ompi_datatype_t *datatype,
				      ompi_request_t **request)
{
    int ret = OMPI_SUCCESS;
    OMPI_MPI_OFFSET_TYPE prev_offset;

    mca_common_ompio_file_get_position (fp, &prev_offset );
    mca_common_ompio_set_explicit_offset (fp, offset);

    if ( NULL != fp->f_fcoll->fcoll_file_iread_all ) {
	ret = fp->f_fcoll->fcoll_file_iread_all (fp,
						 buf,
						 count,
						 datatype,
						 request);
    }
    else {
	/* this fcoll component does not support non-blocking
	   collective I/O operations. WE fake it with
	   individual non-blocking I/O operations. */
	ret = mca_common_ompio_file_iread ( fp, buf, count, datatype, request );
    }


    mca_common_ompio_set_explicit_offset (fp, prev_offset);
    return ret;
}

int mca_common_ompio_set_explicit_offset (mca_io_ompio_file_t *fh,
                                          OMPI_MPI_OFFSET_TYPE offset)
{
    int i = 0;
    int k = 0;

    if ( fh->f_view_size  > 0 ) {
	/* starting offset of the current copy of the filew view */
	fh->f_offset = (fh->f_view_extent *
			((offset*fh->f_etype_size) / fh->f_view_size)) + fh->f_disp;


	/* number of bytes used within the current copy of the file view */
	fh->f_total_bytes = (offset*fh->f_etype_size) % fh->f_view_size;
	i = fh->f_total_bytes;


	/* Initialize the block id and the starting offset of the current block
	   within the current copy of the file view to zero */
	fh->f_index_in_file_view = 0;
	fh->f_position_in_file_view = 0;

	/* determine block id that the offset is located in and
	   the starting offset of that block */
	k = fh->f_decoded_iov[fh->f_index_in_file_view].iov_len;
	while (i >= k) {
	    fh->f_position_in_file_view = k;
	    fh->f_index_in_file_view++;
	    k += fh->f_decoded_iov[fh->f_index_in_file_view].iov_len;
	}
    }

    return OMPI_SUCCESS;
}