#A place for code to be called from C-code
#  that implements more complicated stuff.

import re
from multiarray import _flagdict, dtypedescr, ndarray

_defflags = _flagdict.keys()

_setable = ['WRITEABLE','UPDATEIFCOPY', 'ALIGNED',
            'W','U','A']
_setable2 = ['write','uic','align']*2
_firstltr = {'W':'WRITEABLE',
             'A':'ALIGNED',
             'C':'CONTIGUOUS',
             'F':'FORTRAN',
             'O':'OWNDATA',
             'U':'UPDATEIFCOPY'}

_anum = _flagdict['ALIGNED']
_wnum = _flagdict['WRITEABLE']
_cnum = _flagdict['CONTIGUOUS']
_fnum = _flagdict['FORTRAN']
_unum = _flagdict['UPDATEIFCOPY']
_onum = _flagdict['OWNDATA']

class flagsobj(dict):
    def __init__(self, arr, flags, scalar):
        self._arr = arr
        self._flagnum = flags
        for k in _defflags:
            num = _flagdict[k]
            dict.__setitem__(self, k, flags & num == num)
        self.scalar = scalar

    def __getitem__(self, key):
        if not isinstance(key, str):
            raise KeyError, "Unknown flag %s" % key
        if len(key) == 1:
            try:
                return dict.__getitem__(self, _firstltr[key])
            except:
                if (key == 'B'):
                    num = _anum + _wnum
                    return self._flagnum & num == num
        else:
            try:
                return dict.__getitem__(self, key)
            except: # special cases
                if (key == 'FNC'):
                    return (self._flagnum & _fnum == _fnum) and not \
                           (self._flagnum & _cnum == _cnum)
	        if (key == 'FORC'):
		    return (self._flagnum & _fnum == _fnum) or \
                           (self._flagnum & _cnum == _cnum)
                if (key == 'BEHAVED'):
                    num = _anum + _wnum
                    return self._flagnum & num == num
                if (key in ['CARRAY','CA']):
                    num = _anum + _wnum + _cnum
                    return self._flagnum & num == num
                if (key in ['FARRAY','FA']):
                    num = _anum + _wnum + _fnum
                    return (self._flagnum & num == num) and not \
                           (self._flagnum & _cnum == _cnum)
        raise KeyError, "Unknown flag: %s" % key
        
    def __setitem__(self, item, val):
        if self.scalar:
            raise ValueError, "Cannot set flags on array scalars."
        val = not not val  # convert to boolean
        if item not in _setable:
            raise KeyError, "Cannot set flag", item
        dict.__setitem__(self, item, val) # Does this matter?

        kwds = {}
        for k, name in enumerate(_setable):
            if item == name:
                kwds[_setable2[k]] = val

        # now actually update array flags
        self._arr.setflags(**kwds)
        

    def get_fnc(self):
        fl = self._flagnum
        return (fl & _fnum == _fnum) and \
               not (fl & _cnum == _cnum)

    def get_forc(self):
        fl = self._flagnum
        return (fl & _cnum == _cnum) or \
               (fl & _fnum == _fnum)

    def get_behaved(self):
        fl = self._flagnum
        return (fl & _anum == _anum) and \
               (fl & _wnum == _wnum)

    def get_carray(self):
        fl = self._flagnum
        return (fl & _anum == _anum) and \
               (fl & _wnum == _wnum) and \
               (fl & _cnum == _cnum)

    def get_farray(self):
        fl = self._flagnum
        return (fl & _anum == _anum) and \
               (fl & _wnum == _wnum) and \
               (fl & _fnum == _fnum) and \
               not (fl & _cnum == _cnum)

    def get_contiguous(self):
        return (self._flagnum & _cnum == _cnum)

    def get_fortran(self):
        return (self._flagnum & _fnum == _fnum)

    def get_updateifcopy(self):
        return (self._flagnum & _unum == _unum)

    def get_owndata(self):
        return (self._flagnum & _onum == _onum)

    def get_aligned(self):
        return (self._flagnum & _anum == _anum)

    def get_writeable(self):
        return (self._flagnum & _wnum == _wnum)

    def set_writeable(self, val):
        val = not not val
        self._arr.setflags(write=val)

    def set_aligned(self, val):
        val = not not val
        self._arr.setflags(align=val)

    def set_updateifcopy(self, val):
        val = not not val
        self._arr.setflags(uic=val)

    contiguous = property(get_contiguous, None, "")
    fortran = property(get_fortran, None, "")
    updateifcopy = property(get_updateifcopy, set_updateifcopy, "")
    owndata = property(get_owndata, None, "")
    aligned = property(get_aligned, set_aligned, "")
    writeable = property(get_writeable, set_writeable, "")

    fnc = property(get_fnc, None, "")
    forc = property(get_forc, None, "")
    behaved = property(get_behaved, None, "")
    carray = property(get_carray, None, "")
    farray = property(get_farray, None, "")
    


# make sure the tuple entries are PyArray_Descr
#	   or convert them
#
# make sure offsets are all interpretable 
#	   as positive integers and
#	   convert them to positive integers if so 
#
#
# return totalsize from last offset and size

# Called in PyArray_DescrConverter function when
#  a dictionary without "names" and "formats"
#  fields is used as a data-type descriptor.
def _usefields(adict, align):
    try:
        names = adict[-1]
    except KeyError:
        names = None
    if names is None:
        allfields = []
        fnames = adict.keys()
        for fname in fnames:
            obj = adict[fname]
            n = len(obj)
            if not isinstance(obj, tuple) or n not in [2,3]:
                raise ValueError, "entry not a 2- or 3- tuple"
            if (n > 2) and (obj[2] == fname):
                continue
            num = int(obj[1])
            if (num < 0):
                raise ValueError, "invalid offset."
            format = dtypedescr(obj[0])
            if (format.itemsize == 0):
                raise ValueError, "all itemsizes must be fixed."
            if (n > 2):
                title = obj[2]
            else:
                title = None
            allfields.append((fname, format, num, title))
        # sort by offsets
        allfields.sort(lambda x,y: cmp(x[2],y[2]))
        names = [x[0] for x in allfields]
        formats = [x[1] for x in allfields]
        offsets = [x[2] for x in allfields]
        titles = [x[3] for x in allfields]
    else:
        formats = []
        offsets = []
        titles = []
        for name in names:
            res = adict[name]
            formats.append(res[0])
            offsets.append(res[1])
            if (len(res) > 2):
                titles.append(res[2])
            else:
                titles.append(None)

    return dtypedescr({"names" : names,
                       "formats" : formats,
                       "offsets" : offsets,
                       "titles" : titles}, align)


# construct an array_protocol descriptor list
#  from the fields attribute of a descriptor
# This calls itself recursively but should eventually hit
#  a descriptor that has no fields and then return
#  a simple typestring 

def _array_descr(descriptor):
    fields = descriptor.fields
    if fields is None:
        return descriptor.dtypestr

    #get ordered list of fields with names
    ordered_fields = fields.items()
    # remove duplicates
    new = {}
    for item in ordered_fields:
        # We don't want to include redundant or non-string
        #  entries
        if not isinstance(item[0],str) or (len(item[1]) > 2 \
                                           and item[0] == item[1][2]):
            continue
        new[item[1]] = item[0]
    ordered_fields = [x[0] + (x[1],) for x in new.items()]
    #sort the list on the offset
    ordered_fields.sort(lambda x,y : cmp(x[1],y[1]))

    result = []
    offset = 0
    for field in ordered_fields:
        if field[1] > offset:
            result.append(('','|V%d' % (field[1]-offset)))
        if len(field) > 3:
            name = (field[2],field[3])
        else:
            name = field[2]
        if field[0].subdescr:
            tup = (name, _array_descr(field[0].subdescr[0]),
                   field[0].subdescr[1])
        else:
            tup = (name, _array_descr(field[0]))
        offset += field[0].itemsize
        result.append(tup)

    return result

def _reconstruct(subtype, shape, dtype):
    return ndarray.__new__(subtype, shape, dtype)


# format_re and _split were taken from numarray by J. Todd Miller
format_re = re.compile(r'(?P<repeat> *[(]?[ ,0-9]*[)]? *)(?P<dtype>[><|A-Za-z0-9.]*)')

def _split(input):
    """Split the input formats string into field formats without splitting 
       the tuple used to specify multi-dimensional arrays."""

    newlist = []
    hold = ''

    for element in input.split(','):
        if hold != '':
            item = hold + ',' + element
        else:
            item = element
        left = item.count('(')
        right = item.count(')')

        # if the parenthesis is not balanced, hold the string
        if left > right :
            hold = item  

        # when balanced, append to the output list and reset the hold
        elif left == right:
            newlist.append(item.strip())
            hold = ''

        # too many close parenthesis is unacceptable
        else:
            raise SyntaxError, item

    # if there is string left over in hold
    if hold != '':
        raise SyntaxError, hold

    return newlist

# str is a string (perhaps comma separated)
def _commastring(astr):
    res = _split(astr)
    if (len(res)) == 1:
        raise ValueError, "no commas present"
    result = []
    for k,item in enumerate(res):
        # convert item
        try:
            (repeats, dtype) = format_re.match(item).groups()
        except (TypeError, AttributeError): 
            raise ValueError('format %s is not recognized' % item)
        
        if (repeats == ''):
            newitem = dtype
        else:
            newitem = (dtype, eval(repeats))
        result.append(newitem)

    return result