""" Ops for downsampling images.

Planned: 
DownsampleFactorMax, DownsampleAvg, DownsampleSoftmax.

"""
#This file should move along with conv.py

from theano import gof, Op, tensor, Variable, Apply
import numpy, theano
import __builtin__

def max_pool2D(*args, **kwargs):
    import sys
    print >> sys.stderr, "DEPRECATION: max_pool2D renamed to max_pool_2d"
    return max_pool_2d(*args, **kwargs)

def max_pool_2d(input, ds, ignore_border=False):
    """
    Takes as input a N-D tensor, where N >= 2. It downscales the input image by
    the specified factor, by keeping only the maximum value of non-overlapping
    patches of size (ds[0],ds[1])

    :type input: N-D theano tensor of input images. 
    :param input: input images. Max pooling will be done over the 2 last dimensions.
    :type ds: tuple of length 2
    :param ds: factor by which to downscale. (2,2) will halve the image in each dimension.
    :param ignore_border: boolean value. When True, (5,5) input with ds=(2,2) will generate a
      (2,2) output. (3,3) otherwise.
    """
    if input.ndim < 2:
        raise NotImplementedError('max_pool_2d requires a dimension >= 2')

    # extract image dimensions
    img_shape = input.shape[-2:]

    # count the number of "leading" dimensions, store as dmatrix
    batch_size = tensor.prod(input.shape[:-2])
    batch_size = tensor.shape_padright(batch_size,1)

    # store as 4D tensor with shape: (batch_size,1,height,width)
    new_shape = tensor.cast(tensor.join(0, batch_size, 
        tensor.as_tensor([1,]), img_shape), 'int64')
    input_4D = tensor.reshape(input, new_shape, ndim=4)

    # downsample mini-batch of images
    op = DownsampleFactorMax(ds, ignore_border)
    output = op(input_4D)

    # restore to original shape
    outshp = tensor.join(0, input.shape[:-2], output.shape[-2:])
    return tensor.reshape(output, outshp, ndim=input.ndim)


class DownsampleFactorMax(Op):
    """
    For N-dimensional tensors, consider that the last two dimensions span images.  
    This Op downsamples these images by a factor ds, by taking the max over non-
    overlapping rectangular regions.
    """

    @staticmethod
    def out_shape(imgshape, ds, ignore_border=False):
        """Return the shape of the output from this op, for input of given shape and flags.

        :param imgshape: the shape of a tensor of images. The last two elements are interpreted
        as the number of rows, and the number of cols.
        :type imgshape: tuple, list, or similar.

        :param ds: downsample factor over rows and columns
        :type ds: list or tuple of two ints

        :param ignore_border: if ds doesn't divide imgshape, do we include an extra row/col of
        partial downsampling (False) or ignore it (True).
        :type ignore_border: bool

        :rtype: list
        :returns: the shape of the output from this op, for input of given shape.  This will
        have the same length as imgshape, but with last two elements reduced as per the
        downsampling & ignore_border flags.  
        """
        if len(imgshape) < 2:
            raise TypeError('imgshape must have at least two elements (rows, cols)')
        r, c = imgshape[-2:]
        rval = list(imgshape[:-2])+[ r/ds[0], c/ds[1]]
        if not ignore_border:
            if r % ds[0]:
                rval[-2] += 1
            if c % ds[1]:
                rval[-1] += 1
        return rval

    def __init__(self, ds, ignore_border=False):
        """
        :param ds: downsample factor over rows and columns
        :type ds: list or tuple of two ints

        :param ignore_border: if ds doesn't divide imgshape, do we include an extra row/col of
        partial downsampling (False) or ignore it (True).
        :type ignore_border: bool

        TODO: why is poolsize an op parameter here?
        """
        self.ds = tuple(ds)
        self.ignore_border = ignore_border

    def __eq__(self, other):
        return type(self) == type(other) and self.ds == other.ds and self.ignore_border == other.ignore_border

    def __hash__(self):
        return hash(type(self)) ^ hash(self.ds) ^ hash(self.ignore_border)

    def __str__(self):
        return '%s{%s,%s}' % (self.__class__.__name__, self.ds, self.ignore_border)

    def make_node(self, x):
        if x.type.ndim != 4:
            raise TypeError()
        # TODO: consider restrucing the dtype?
        return gof.Apply(self, [x], [x.type()])

    def perform(self, node, (x,), (z,)):
        """
        """
        if len(x.shape)!=4:
            raise NotImplementedError('DownsampleFactorMax requires 4D input for now')
        if z[0] is None:
            z[0] = numpy.zeros(self.out_shape(x.shape, self.ds, self.ignore_border)) -float('inf')
            z[0] = theano._asarray(z[0], dtype=x.dtype)
        zz=z[0]
        ds0, ds1 = self.ds
        if self.ignore_border:
            x_usable2 = (x.shape[2] / ds0 * ds0)
        else: x_usable2 = x.shape[2]
        if self.ignore_border:
            x_usable3 = (x.shape[3] / ds1 * ds1)
        else: x_usable3 = x.shape[3]
        for n in xrange(x.shape[0]):
            for k in xrange(x.shape[1]):
                for i in xrange(x_usable2):
                    zi = i / ds0
                    for j in xrange(x_usable3):
                        zj = j / ds1
                        zz[n,k,zi,zj] = __builtin__.max(zz[n,k,zi,zj], x[n,k,i,j])

    def grad(self,(x,), (gz,)):
        maxout = self(x)
        return [DownsampleFactorMaxGrad(self.ds, ignore_border=self.ignore_border)(x, maxout, gz)]

    def c_code(self, node, name, (x,), (z, ), sub):
        fail=sub['fail']
        ignore_border = int(self.ignore_border)
        ds0, ds1 = self.ds
        return """
        int typenum = PyArray_ObjectType((PyObject*)%(x)s, 0);
        int x_shp0_usable;
        int x_shp1_usable;
        int z_shp0, z_shp1;
        if(%(x)s->nd!=4) 
        {
            PyErr_SetString(PyExc_ValueError, "x must be a 4d ndarray");
            %(fail)s;
        }
        z_shp0 = %(x)s->dimensions[2] / %(ds0)s;
        z_shp1 = %(x)s->dimensions[3] / %(ds1)s;
        if (%(ignore_border)s)
        {
            x_shp0_usable = z_shp0 * %(ds0)s;
            x_shp1_usable = z_shp1 * %(ds1)s;
        }
        else
        {
            z_shp0 += (%(x)s->dimensions[2] %% %(ds0)s) ? 1 : 0;
            z_shp1 += (%(x)s->dimensions[3] %% %(ds1)s) ? 1 : 0;
            x_shp0_usable = %(x)s->dimensions[2];
            x_shp1_usable = %(x)s->dimensions[3];
        }
        if ((!%(z)s)
          || *PyArray_DIMS(%(z)s)!=4
          ||(%(z)s->dimensions[0] != %(x)s->dimensions[0])
          ||(%(z)s->dimensions[1] != %(x)s->dimensions[1])
          ||(%(z)s->dimensions[2] != z_shp0)
          ||(%(z)s->dimensions[3] != z_shp1)
          )
        {
          if (%(z)s) Py_XDECREF(%(z)s);
          npy_intp dims[4] = {0,0,0,0};
          dims[0]=%(x)s->dimensions[0];
          dims[1]=%(x)s->dimensions[1];
          dims[2]=z_shp0;
          dims[3]=z_shp1;
          %(z)s = (PyArrayObject*) PyArray_ZEROS(4, dims, typenum,0); //TODO: zeros not necessary
        }

        if (z_shp0 && z_shp1)
        {
            for(int b=0;b<%(x)s->dimensions[0];b++){
              for(int k=0;k<%(x)s->dimensions[1];k++){
                int mini_i = 0;
                int zi = 0;
                for(int i=0;i< x_shp0_usable; i++){
                  int mini_j = 0;
                  int zj = 0;
                  for(int j=0; j<x_shp1_usable; j++){
                    dtype_%(x)s a = ((dtype_%(x)s*)(PyArray_GETPTR4(%(x)s,b,k,i,j)))[0];
                    dtype_%(z)s * __restrict__ z = ((dtype_%(z)s*)(PyArray_GETPTR4(%(z)s,b,k,zi,zj)));
                    z[0] = (((mini_j|mini_i) == 0) || z[0] < a) ? a : z[0];
                    mini_j = ((mini_j + 1) == %(ds1)s) ? 0 : mini_j+1;
                    zj += (mini_j == 0);
                  }
                  mini_i = ((mini_i + 1) == %(ds0)s) ? 0 : mini_i+1;
                  zi += (mini_i == 0);
                }
              }
            }
        }
        """ % locals()

    def c_code_cache_version(self):
        return (0,1)


class DownsampleFactorMaxGrad(Op):

    def __init__(self, ds, ignore_border):
        self.ds = tuple(ds)
        self.ignore_border = ignore_border

    def __eq__(self, other):
        return type(self) == type(other) and self.ds == other.ds and self.ignore_border == other.ignore_border

    def __hash__(self):
        return hash(type(self)) ^ hash(self.ds) ^ hash(self.ignore_border)

    def __str__(self):
        return '%s{%s,%s}' % (self.__class__.__name__, self.ds, self.ignore_border)

    def make_node(self, x, maxout, gz):
        # make_node should only be called by the grad function of DownsampleFactorMax,
        # so these asserts should not fail.
        assert isinstance(x, Variable) and x.ndim==4
        assert isinstance(maxout, Variable) and maxout.ndim==4
        assert isinstance(gz, Variable) and gz.ndim==4

        return Apply(self, [x, maxout, gz], [x.type()])

    def perform(self, node, (x, maxout, gz), (gx_stg,)):
        gx = numpy.zeros_like(x)

        ds0, ds1 = self.ds
        shape2 = (x.shape[2] / ds0 * ds0)
        if not self.ignore_border: shape2 = x.shape[2]
        shape3 = (x.shape[3] / ds1 * ds1)
        if not self.ignore_border: shape3 = x.shape[3]
        for n in xrange(x.shape[0]):
            for k in xrange(x.shape[1]):
                for i in xrange(shape2):
                    zi = i / ds0
                    for j in xrange(shape3):
                        zj = j / ds1
                        if (maxout[n,k,zi,zj] == x[n,k,i,j]):
                            gx[n,k,i,j] = gz[n,k,zi,zj]
                        else: gx[n,k,i,j] = 0
        gx_stg[0] = gx

    def c_code(self, node, name, (x, z, gz), (gx,), sub):
        fail = sub['fail']
        ignore_border = int(self.ignore_border)
        ds0, ds1 = self.ds
        return """
        int x_typenum = PyArray_ObjectType((PyObject*)%(x)s, 0);
        int z_typenum = PyArray_ObjectType((PyObject*)%(z)s, 0);
        int gz_typenum = PyArray_ObjectType((PyObject*)%(gz)s, 0);
        int x_shp0_usable;
        int x_shp1_usable;
        int z_shp0, z_shp1;
        if ((x_typenum != z_typenum) || (x_typenum != gz_typenum))
        {
            PyErr_SetString(PyExc_ValueError, "input types must all match");
            %(fail)s;
        }
        if(%(x)s->nd!=4) 
        {
            PyErr_SetString(PyExc_ValueError, "x must be a 4d ndarray");
            %(fail)s;
        }
        if(%(z)s->nd!=4) 
        {
            PyErr_SetString(PyExc_ValueError, "z must be a 4d ndarray");
            %(fail)s;
        }
        if(%(gz)s->nd!=4) 
        {
            PyErr_SetString(PyExc_ValueError, "gz must be a 4d ndarray");
            %(fail)s;
        }
        z_shp0 = %(z)s->dimensions[2];
        z_shp1 = %(z)s->dimensions[3];
        if (%(ignore_border)s)
        {
            x_shp0_usable = z_shp0 * %(ds0)s;
            x_shp1_usable = z_shp1 * %(ds1)s;
        }
        else
        {
            x_shp0_usable = %(x)s->dimensions[2];
            x_shp1_usable = %(x)s->dimensions[3];
        }
        if ((!%(gx)s)
          || *PyArray_DIMS(%(gx)s)!=4
          ||(%(gx)s->dimensions[0] != %(x)s->dimensions[0])
          ||(%(gx)s->dimensions[1] != %(x)s->dimensions[1])
          ||(%(gx)s->dimensions[2] != %(x)s->dimensions[2])
          ||(%(gx)s->dimensions[3] != %(x)s->dimensions[3])
          )
        {
          Py_XDECREF(%(gx)s);
          %(gx)s = (PyArrayObject*) PyArray_ZEROS(4, %(x)s->dimensions, x_typenum,0);
        }

        for(int b=0;b<%(x)s->dimensions[0];b++){
          for(int k=0;k<%(x)s->dimensions[1];k++){
            int mini_i = 0;
            int zi = 0;
            for(int i=0;i< x_shp0_usable; i++){
               int mini_j = 0;
               int zj = 0;
               for(int j=0; j< x_shp1_usable; j++){
                 dtype_%(x)s * __restrict__ xp = ((dtype_%(x)s*)(PyArray_GETPTR4(%(x)s,b,k,i,j)));
                 dtype_%(gx)s * __restrict__ gxp = ((dtype_%(gx)s*)(PyArray_GETPTR4(%(gx)s,b,k,i,j)));
                 dtype_%(z)s * __restrict__ zp = ((dtype_%(z)s*)(PyArray_GETPTR4(%(z)s,b,k,zi,zj)));
                 dtype_%(gz)s * __restrict__ gzp = ((dtype_%(gz)s*)(PyArray_GETPTR4(%(gz)s,b,k,zi,zj)));
                 gxp[0] = (zp[0] == xp[0]) ? gzp[0] : 0;
                 mini_j = (mini_j + 1 == %(ds1)s) ? 0 : mini_j+1;
                 zj += (mini_j == 0);
              }//for j
              mini_i = (mini_i + 1 == %(ds0)s) ? 0 : mini_i+1;
              zi += (mini_i == 0);

              for (int j = x_shp1_usable; j < %(x)s->dimensions[3]; ++j) {
                dtype_%(gx)s * gxp = ((dtype_%(gx)s*)(PyArray_GETPTR4(%(gx)s,b,k,i,j)));
                gxp[0] = 0;
              }
            }//for i

            for(int i = x_shp0_usable; i < %(x)s->dimensions[2]; i++){
                for (int j = 0; j < %(x)s->dimensions[3]; ++j) {
                    dtype_%(gx)s * gxp = ((dtype_%(gx)s*)(PyArray_GETPTR4(%(gx)s,b,k,i,j)));
                    gxp[0] = 0;
                }
            }
          }//for k
        }//for b
        """ %locals()

    def c_code_cache_version(self):
        return (0,1)
