from numpy import ones, ndarray, array, asarray, concatenate, zeros, shape, \
         alltrue, equal, divide, arccos, arcsin, arctan, cos, cosh, \
         sin, sinh, exp, ceil, floor, fabs, log, log10, sqrt, argmin, \
         argmax, argsort, around, absolute, sign, negative, float32

import sys

numericTypes = (int, long, float, complex)
def isnumeric(t):
    return isinstance(t, numericTypes)

def time_it():
    import time

    expr = "ex[:,1:,1:] =   ca_x[:,1:,1:] * ex[:,1:,1:]" \
                         "+ cb_y_x[:,1:,1:] * (hz[:,1:,1:] - hz[:,:-1,1:])" \
                         "- cb_z_x[:,1:,1:] * (hy[:,1:,1:] - hy[:,1:,:-1])"
    ex = ones((10,10,10),dtype=float32)
    ca_x = ones((10,10,10),dtype=float32)
    cb_y_x = ones((10,10,10),dtype=float32)
    cb_z_x = ones((10,10,10),dtype=float32)
    hz = ones((10,10,10),dtype=float32)
    hy = ones((10,10,10),dtype=float32)

    N = 1
    t1 = time.time()
    for i in range(N):
        passed = check_expr(expr,locals())
    t2 = time.time()
    print 'time per call:', (t2 - t1)/N
    print 'passed:', passed

def check_expr(expr,local_vars,global_vars={}):
    """ Currently only checks expressions (not suites).
        Doesn't check that lhs = rhs. checked by compiled func though
    """
    values ={}

    #first handle the globals
    for var,val in global_vars.items():
        if isinstance(val, ndarray):
            values[var] = dummy_array(val,name=var)
        elif isnumeric(val):
            values[var] = val
    #now handle the locals
    for var,val in local_vars.items():
        if isinstance(val, ndarray):
            values[var] = dummy_array(val,name=var)
        if isnumeric(val):
            values[var] = val
    exec(expr,values)
    try:
        exec(expr,values)
    except:
        try:
            eval(expr,values)
        except:
            return 0
    return 1

empty = array(())
empty_slice = slice(None)

def make_same_length(x,y):
    try:
        Nx = len(x)
    except:
        Nx = 0
    try:
        Ny = len(y)
    except:
        Ny = 0
    if Nx == Ny == 0:
        return empty,empty
    elif Nx == Ny:
        return asarray(x),asarray(y)
    else:
        diff = abs(Nx - Ny)
        front = ones(diff, int)
        if Nx > Ny:
            return asarray(x), concatenate((front,y))
        elif Ny > Nx:
            return concatenate((front,x)),asarray(y)

def binary_op_size(xx,yy):
    """ This returns the resulting size from operating on xx, and yy
        with a binary operator.  It accounts for broadcasting, and
        throws errors if the array sizes are incompatible.
    """
    x,y = make_same_length(xx,yy)
    res = zeros(len(x))
    for i in range(len(x)):
        if x[i] == y[i]:
            res[i] = x[i]
        elif x[i] == 1:
            res[i] = y[i]
        elif y[i] == 1:
            res[i] = x[i]
        else:
            # offer more information here about which variables.
            raise ValueError("frames are not aligned")
    return res

class dummy_array(object):
    def __init__(self,ary,ary_is_shape = 0,name=None):
        self.name = name
        if ary_is_shape:
            self.shape = ary
            #self.shape = asarray(ary)
        else:
            try:
                self.shape = shape(ary)
            except:
                self.shape = empty
        #self.value = ary
    def binary_op(self,other):
        try:
            x = other.shape
        except AttributeError:
            x = empty
        new_shape = binary_op_size(self.shape,x)
        return dummy_array(new_shape,1)
    def __cmp__(self,other):
        # This isn't an exact compare, but does work for ==
        # cluge for Numeric
        if isnumeric(other):
            return 0
        if len(self.shape) == len(other.shape) == 0:
            return 0
        return not alltrue(equal(self.shape,other.shape),axis=0)

    def __add__(self,other): return self.binary_op(other)
    def __radd__(self,other): return self.binary_op(other)
    def __sub__(self,other): return self.binary_op(other)
    def __rsub__(self,other): return self.binary_op(other)
    def __mul__(self,other): return self.binary_op(other)
    def __rmul__(self,other): return self.binary_op(other)
    def __div__(self,other): return self.binary_op(other)
    def __rdiv__(self,other): return self.binary_op(other)
    def __mod__(self,other): return self.binary_op(other)
    def __rmod__(self,other): return self.binary_op(other)
    def __lshift__(self,other): return self.binary_op(other)
    def __rshift__(self,other): return self.binary_op(other)
    # unary ops
    def __neg__(self,other): return self
    def __pos__(self,other): return self
    def __abs__(self,other): return self
    def __invert__(self,other): return self
    # Not sure what to do with coersion ops.  Ignore for now.
    #
    # not currently supported by compiler.
    # __divmod__
    # __pow__
    # __rpow__
    # __and__
    # __or__
    # __xor__
    # item access and slicing
    def __setitem__(self,indices,val):
        #ignore for now
        pass
    def __len__(self):
        return self.shape[0]
    def __getslice__(self,i,j):
        i = max(i, 0); j = max(j, 0)
        return self.__getitem__((slice(i,j),))
    def __getitem__(self,indices):
        # ayeyaya this is a mess
        #print indices, type(indices), indices.shape
        if not isinstance(indices, tuple):
            indices = (indices,)
        if Ellipsis in indices:
            raise IndexError("Ellipsis not currently supported")
        new_dims = []
        dim = 0
        for index in indices:
            try:
                dim_len = self.shape[dim]
            except IndexError:
                raise IndexError("To many indices specified")

            #if (type(index) is SliceType and index.start == index.stop == index.step):
            if (index is empty_slice):
                slc_len = dim_len
            elif isinstance(index, slice):
                beg,end,step = index.start,index.stop,index.step
                # handle if they are dummy arrays
                #if hasattr(beg,'value') and type(beg.value) != ndarray:
                #    beg = beg.value
                #if hasattr(end,'value') and type(end.value) != ndarray:
                #    end = end.value
                #if hasattr(step,'value') and type(step.value) != ndarray:
                #    step = step.value
                if beg is None: beg = 0
                if end == sys.maxint or  end is None:
                    end = dim_len
                if step is None:
                    step = 1

                if beg < 0: beg += dim_len
                if end < 0: end += dim_len
                # the following is list like behavior,
                # which isn't adhered to by arrays.
                # FIX THIS ANOMOLY IN NUMERIC!
                if beg < 0: beg = 0
                if beg > dim_len: beg = dim_len
                if end < 0: end = 0
                if end > dim_len: end = dim_len
                # This is rubbish.
                if  beg == end:
                    beg,end,step = 0,0,1
                elif  beg >= dim_len and step > 0:
                    beg,end,step = 0,0,1
                #elif index.step > 0 and beg <= end:
                elif step > 0 and beg <= end:
                    pass #slc_len = abs(divide(end-beg-1,step)+1)
                # handle [::-1] and [-1::-1] correctly
                #elif index.step > 0 and beg > end:
                elif step > 0 and beg > end:
                    beg,end,step = 0,0,1
                elif(step < 0 and index.start is None and index.stop is None):
                    beg,end,step = 0,dim_len,-step
                elif(step < 0 and index.start is None):
                    # +1 because negative stepping is inclusive
                    beg,end,step = end+1,dim_len,-step
                elif(step < 0 and index.stop is None):
                    beg,end,step = 0,beg+1,-step
                elif(step < 0 and beg > end):
                    beg,end,step = end,beg,-step
                elif(step < 0 and beg < end):
                    beg,end,step = 0,0,-step
                slc_len = abs(divide(end-beg-1,step)+1)
                new_dims.append(slc_len)
            else:
                if index < 0: index += dim_len
                if index >=0 and index < dim_len:
                    #this reduces the array dimensions by one
                    pass
                else:
                    raise IndexError("Index out of range")
            dim += 1
        new_dims.extend(self.shape[dim:])
        if 0 in new_dims:
            raise IndexError("Zero length slices not currently supported")
        return dummy_array(new_dims,1)
    def __repr__(self):
        val = str((self.name, str(self.shape)))
        return val

def unary(ary):
    return ary

def not_implemented(ary):
    return ary

#all imported from Numeric and need to be reassigned.
unary_op = [arccos, arcsin, arctan, cos, cosh, sin, sinh,
            exp,ceil,floor,fabs,log,log10,sqrt]

unsupported = [argmin,argmax, argsort,around, absolute,sign,negative,floor]

for func in unary_op:
    func = unary

for func in unsupported:
    func = not_implemented

def reduction(ary,axis=0):
    if axis < 0:
        axis += len(ary.shape)
    if axis < 0 or axis >= len(ary.shape):
        raise ValueError("Dimension not in array")
    new_dims = list(ary.shape[:axis]) + list(ary.shape[axis+1:])
    return dummy_array(new_dims,1)

# functions currently not supported by compiler
# reductions are gonna take some array reordering for the general case,
# so this is gonna take some thought (probably some tree manipulation).
def take(ary,axis=0): raise NotImplemented
# and all the rest
