/*
 * This file implements assignment from a scalar to an ndarray.
 *
 * Written by Mark Wiebe (mwwiebe@gmail.com)
 * Copyright (c) 2011 by Enthought, Inc.
 *
 * See LICENSE.txt for the license.
 */

#define PY_SSIZE_T_CLEAN
#include <Python.h>

#define NPY_NO_DEPRECATED_API NPY_API_VERSION
#define _MULTIARRAYMODULE
#include <numpy/ndarraytypes.h>

#include "npy_config.h"
#include "npy_pycompat.h"

#include "convert_datatype.h"
#include "methods.h"
#include "shape.h"
#include "lowlevel_strided_loops.h"

#include "array_assign.h"

/*
 * Assigns the scalar value to every element of the destination raw array.
 *
 * Returns 0 on success, -1 on failure.
 */
NPY_NO_EXPORT int
raw_array_assign_scalar(int ndim, npy_intp *shape,
        PyArray_Descr *dst_dtype, char *dst_data, npy_intp *dst_strides,
        PyArray_Descr *src_dtype, char *src_data)
{
    int idim;
    npy_intp shape_it[NPY_MAXDIMS], dst_strides_it[NPY_MAXDIMS];
    npy_intp coord[NPY_MAXDIMS];

    PyArray_StridedUnaryOp *stransfer = NULL;
    NpyAuxData *transferdata = NULL;
    int aligned, needs_api = 0;
    npy_intp src_itemsize = src_dtype->elsize;

    NPY_BEGIN_THREADS_DEF;

    /* Check alignment */
    aligned = raw_array_is_aligned(ndim, dst_data, dst_strides,
                                    dst_dtype->alignment);
    if (!npy_is_aligned(src_data, src_dtype->alignment)) {
        aligned = 0;
    }

    /* Use raw iteration with no heap allocation */
    if (PyArray_PrepareOneRawArrayIter(
                    ndim, shape,
                    dst_data, dst_strides,
                    &ndim, shape_it,
                    &dst_data, dst_strides_it) < 0) {
        return -1;
    }

    /* Get the function to do the casting */
    if (PyArray_GetDTypeTransferFunction(aligned,
                        0, dst_strides_it[0],
                        src_dtype, dst_dtype,
                        0,
                        &stransfer, &transferdata,
                        &needs_api) != NPY_SUCCEED) {
        return -1;
    }

    if (!needs_api) {
        npy_intp nitems = 1, i;
        for (i = 0; i < ndim; i++) {
            nitems *= shape_it[i];
        }
        NPY_BEGIN_THREADS_THRESHOLDED(nitems);
    }

    NPY_RAW_ITER_START(idim, ndim, coord, shape_it) {
        /* Process the innermost dimension */
        stransfer(dst_data, dst_strides_it[0], src_data, 0,
                    shape_it[0], src_itemsize, transferdata);
    } NPY_RAW_ITER_ONE_NEXT(idim, ndim, coord,
                            shape_it, dst_data, dst_strides_it);

    NPY_END_THREADS;

    NPY_AUXDATA_FREE(transferdata);

    return (needs_api && PyErr_Occurred()) ? -1 : 0;
}

/*
 * Assigns the scalar value to every element of the destination raw array
 * where the 'wheremask' value is True.
 *
 * Returns 0 on success, -1 on failure.
 */
NPY_NO_EXPORT int
raw_array_wheremasked_assign_scalar(int ndim, npy_intp *shape,
        PyArray_Descr *dst_dtype, char *dst_data, npy_intp *dst_strides,
        PyArray_Descr *src_dtype, char *src_data,
        PyArray_Descr *wheremask_dtype, char *wheremask_data,
        npy_intp *wheremask_strides)
{
    int idim;
    npy_intp shape_it[NPY_MAXDIMS], dst_strides_it[NPY_MAXDIMS];
    npy_intp wheremask_strides_it[NPY_MAXDIMS];
    npy_intp coord[NPY_MAXDIMS];

    PyArray_MaskedStridedUnaryOp *stransfer = NULL;
    NpyAuxData *transferdata = NULL;
    int aligned, needs_api = 0;
    npy_intp src_itemsize = src_dtype->elsize;

    NPY_BEGIN_THREADS_DEF;

    /* Check alignment */
    aligned = raw_array_is_aligned(ndim, dst_data, dst_strides,
                                    dst_dtype->alignment);
    if (!npy_is_aligned(src_data, src_dtype->alignment)) {
        aligned = 0;
    }

    /* Use raw iteration with no heap allocation */
    if (PyArray_PrepareTwoRawArrayIter(
                    ndim, shape,
                    dst_data, dst_strides,
                    wheremask_data, wheremask_strides,
                    &ndim, shape_it,
                    &dst_data, dst_strides_it,
                    &wheremask_data, wheremask_strides_it) < 0) {
        return -1;
    }

    /* Get the function to do the casting */
    if (PyArray_GetMaskedDTypeTransferFunction(aligned,
                        0, dst_strides_it[0], wheremask_strides_it[0],
                        src_dtype, dst_dtype, wheremask_dtype,
                        0,
                        &stransfer, &transferdata,
                        &needs_api) != NPY_SUCCEED) {
        return -1;
    }

    if (!needs_api) {
        npy_intp nitems = 1, i;
        for (i = 0; i < ndim; i++) {
            nitems *= shape_it[i];
        }
        NPY_BEGIN_THREADS_THRESHOLDED(nitems);
    }

    NPY_RAW_ITER_START(idim, ndim, coord, shape_it) {
        /* Process the innermost dimension */
        stransfer(dst_data, dst_strides_it[0], src_data, 0,
                    (npy_bool *)wheremask_data, wheremask_strides_it[0],
                    shape_it[0], src_itemsize, transferdata);
    } NPY_RAW_ITER_TWO_NEXT(idim, ndim, coord, shape_it,
                            dst_data, dst_strides_it,
                            wheremask_data, wheremask_strides_it);

    NPY_END_THREADS;

    NPY_AUXDATA_FREE(transferdata);

    return (needs_api && PyErr_Occurred()) ? -1 : 0;
}

/*
 * Assigns a scalar value specified by 'src_dtype' and 'src_data'
 * to elements of 'dst'.
 *
 * dst: The destination array.
 * src_dtype: The data type of the source scalar.
 * src_data: The memory element of the source scalar.
 * wheremask: If non-NULL, a boolean mask specifying where to copy.
 * casting: An exception is raised if the assignment violates this
 *          casting rule.
 *
 * This function is implemented in array_assign_scalar.c.
 *
 * Returns 0 on success, -1 on failure.
 */
NPY_NO_EXPORT int
PyArray_AssignRawScalar(PyArrayObject *dst,
                        PyArray_Descr *src_dtype, char *src_data,
                        PyArrayObject *wheremask,
                        NPY_CASTING casting)
{
    int allocated_src_data = 0;
    npy_longlong scalarbuffer[4];

    if (PyArray_FailUnlessWriteable(dst, "assignment destination") < 0) {
        return -1;
    }

    /* Check the casting rule */
    if (!can_cast_scalar_to(src_dtype, src_data,
                            PyArray_DESCR(dst), casting)) {
        PyObject *errmsg;
        errmsg = PyUString_FromString("Cannot cast scalar from ");
        PyUString_ConcatAndDel(&errmsg,
                PyObject_Repr((PyObject *)src_dtype));
        PyUString_ConcatAndDel(&errmsg,
                PyUString_FromString(" to "));
        PyUString_ConcatAndDel(&errmsg,
                PyObject_Repr((PyObject *)PyArray_DESCR(dst)));
        PyUString_ConcatAndDel(&errmsg,
                PyUString_FromFormat(" according to the rule %s",
                        npy_casting_to_string(casting)));
        PyErr_SetObject(PyExc_TypeError, errmsg);
        Py_DECREF(errmsg);
        return -1;
    }

    /*
     * Make a copy of the src data if it's a different dtype than 'dst'
     * or isn't aligned, and the destination we're copying to has
     * more than one element. To avoid having to manage object lifetimes,
     * we also skip this if 'dst' has an object dtype.
     */
    if ((!PyArray_EquivTypes(PyArray_DESCR(dst), src_dtype) ||
                !npy_is_aligned(src_data, src_dtype->alignment)) &&
                    PyArray_SIZE(dst) > 1 &&
                    !PyDataType_REFCHK(PyArray_DESCR(dst))) {
        char *tmp_src_data;

        /*
         * Use a static buffer to store the aligned/cast version,
         * or allocate some memory if more space is needed.
         */
        if (sizeof(scalarbuffer) >= PyArray_DESCR(dst)->elsize) {
            tmp_src_data = (char *)&scalarbuffer[0];
        }
        else {
            tmp_src_data = PyArray_malloc(PyArray_DESCR(dst)->elsize);
            if (tmp_src_data == NULL) {
                PyErr_NoMemory();
                goto fail;
            }
            allocated_src_data = 1;
        }

        if (PyArray_CastRawArrays(1, src_data, tmp_src_data, 0, 0,
                            src_dtype, PyArray_DESCR(dst), 0) != NPY_SUCCEED) {
            src_data = tmp_src_data;
            goto fail;
        }

        /* Replace src_data/src_dtype */
        src_data = tmp_src_data;
        src_dtype = PyArray_DESCR(dst);
    }

    if (wheremask == NULL) {
        /* A straightforward value assignment */
        /* Do the assignment with raw array iteration */
        if (raw_array_assign_scalar(PyArray_NDIM(dst), PyArray_DIMS(dst),
                PyArray_DESCR(dst), PyArray_DATA(dst), PyArray_STRIDES(dst),
                src_dtype, src_data) < 0) {
            goto fail;
        }
    }
    else {
        npy_intp wheremask_strides[NPY_MAXDIMS];

        /* Broadcast the wheremask to 'dst' for raw iteration */
        if (broadcast_strides(PyArray_NDIM(dst), PyArray_DIMS(dst),
                    PyArray_NDIM(wheremask), PyArray_DIMS(wheremask),
                    PyArray_STRIDES(wheremask), "where mask",
                    wheremask_strides) < 0) {
            goto fail;
        }

        /* Do the masked assignment with raw array iteration */
        if (raw_array_wheremasked_assign_scalar(
                PyArray_NDIM(dst), PyArray_DIMS(dst),
                PyArray_DESCR(dst), PyArray_DATA(dst), PyArray_STRIDES(dst),
                src_dtype, src_data,
                PyArray_DESCR(wheremask), PyArray_DATA(wheremask),
                wheremask_strides) < 0) {
            goto fail;
        }
    }

    if (allocated_src_data) {
        PyArray_free(src_data);
    }

    return 0;

fail:
    if (allocated_src_data) {
        PyArray_free(src_data);
    }

    return -1;
}
