from pypy.tool.pairtype import pairtype
from pypy.rlib.rarithmetic import ovfcheck
from pypy.rpython.error import TyperError
from pypy.rpython.rstr import AbstractStringRepr,AbstractCharRepr,\
     AbstractUniCharRepr, AbstractStringIteratorRepr,\
     AbstractLLHelpers, AbstractUnicodeRepr
from pypy.rpython.rmodel import IntegerRepr
from pypy.rpython.lltypesystem.lltype import Ptr, Char, UniChar, typeOf,\
     cast_primitive
from pypy.rpython.ootypesystem import ootype
from pypy.rpython.rmodel import Repr

# TODO: investigate if it's possible and it's worth to concatenate a
# String and a Char directly without passing to Char-->String
# conversion

class BaseOOStringRepr(Repr):

    def __init__(self, *args):
        AbstractStringRepr.__init__(self, *args)
        self.ll = LLHelpers

    def convert_const(self, value):
        if value is None:
            return self.lowleveltype._null
        if not isinstance(value, self.basetype):
            raise TyperError("not a str: %r" % (value,))
        return self.make_string(value)

    def make_string(self, value):
        raise NotImplementedError

    def make_iterator_repr(self):
        return self.string_iterator_repr

    def _list_length_items(self, hop, v_lst, LIST):
        # ootypesystem list has a different interface that
        # lltypesystem list, so we don't need to calculate the lenght
        # here and to pass the 'items' array. Let's pass the list
        # itself and let LLHelpers.join to manipulate it directly.
        c_length = hop.inputconst(ootype.Void, None)
        return c_length, v_lst


class StringRepr(BaseOOStringRepr, AbstractStringRepr):
    lowleveltype = ootype.String
    basetype = str

    def make_string(self, value):
        return ootype.make_string(value)

    def ll_decode_latin1(self, value):
        sb = ootype.new(ootype.UnicodeBuilder)
        length = value.ll_strlen()
        sb.ll_allocate(length)
        for i in range(length):
            c = value.ll_stritem_nonneg(i)
            sb.ll_append_char(cast_primitive(UniChar, c))
        return sb.ll_build()


class UnicodeRepr(BaseOOStringRepr, AbstractUnicodeRepr):
    lowleveltype = ootype.Unicode
    basetype = basestring

    def make_string(self, value):
        return ootype.make_unicode(value)

    def ll_str(self, value):
        if not value:
            return self.ll.ll_constant('None')
        sb = ootype.new(ootype.StringBuilder)
        lgt = value.ll_strlen()
        sb.ll_allocate(lgt)
        for i in range(lgt):
            c = value.ll_stritem_nonneg(i)
            if ord(c) > 127:
                raise UnicodeEncodeError("%d > 127, not ascii" % ord(c))
            sb.ll_append_char(cast_primitive(Char, c))
        return sb.ll_build()

    def ll_encode_latin1(self, value):
        sb = ootype.new(ootype.StringBuilder)
        length = value.ll_strlen()
        sb.ll_allocate(length)
        for i in range(length):
            c = value.ll_stritem_nonneg(i)
            if ord(c) > 255:
                raise UnicodeEncodeError("%d > 255, not latin-1" % ord(c))
            sb.ll_append_char(cast_primitive(Char, c))
        return sb.ll_build()

class CharRepr(AbstractCharRepr, StringRepr):
    lowleveltype = Char

class UniCharRepr(AbstractUniCharRepr, UnicodeRepr):
    lowleveltype = UniChar


class __extend__(pairtype(UniCharRepr, UnicodeRepr)):
    def convert_from_to((r_from, r_to), v, llops):
        rstr = llops.rtyper.type_system.rstr
        if r_from == unichar_repr and r_to == unicode_repr:
            return llops.gendirectcall(r_from.ll.ll_unichr2unicode, v)
        return NotImplemented

class LLHelpers(AbstractLLHelpers):

    def ll_chr2str(ch):
        return ootype.oostring(ch, -1)

    def ll_str2unicode(s):
        return ootype.oounicode(s, -1)

    def ll_unichr2unicode(ch):
        return ootype.oounicode(ch, -1)

    def ll_strhash(s):
        if not s:
            return 0
        return s.ll_hash()

    def ll_strfasthash(s):
        return s.ll_hash()

    def ll_char_mul(ch, times):
        if times < 0:
            times = 0
        if typeOf(ch) == Char:
            buf = ootype.new(ootype.StringBuilder)
        else:
            buf = ootype.new(ootype.UnicodeBuilder)
        buf.ll_allocate(times)
        i = 0
        while i<times:
            buf.ll_append_char(ch)
            i+= 1
        return buf.ll_build()

    def ll_str_mul(s, times):
        if times < 0:
            times = 0
        try:
            size = ovfcheck(s.ll_strlen() * times)
        except OverflowError:
            raise MemoryError
        buf = ootype.new(typeOf(s).builder)
        buf.ll_allocate(size)
        for i in xrange(times):
            buf.ll_append(s)
        return buf.ll_build()

    def ll_streq(s1, s2):
        if s1 is None:
            return s2 is None
        return s1.ll_streq(s2)

    def ll_strcmp(s1, s2):
        if not s1 and not s2:
            return True
        if not s1 or not s2:
            return False
        return s1.ll_strcmp(s2)

    def ll_join(s, length_dummy, lst):
        length = lst.ll_length()
        buf = ootype.new(typeOf(s).builder)

        # TODO: check if it's worth of preallocating the buffer with
        # the exact length
##        itemslen = 0
##        i = 0
##        while i < length:
##            itemslen += lst.ll_getitem_fast(i).ll_strlen()
##            i += 1
##        resultlen = itemslen + s.ll_strlen()*(length-1)
##        buf.ll_allocate(resultlen)

        i = 0
        while i < length-1:
            item = lst.ll_getitem_fast(i)
            buf.ll_append(item)
            buf.ll_append(s)
            i += 1
        if length > 0:
            lastitem = lst.ll_getitem_fast(i)
            buf.ll_append(lastitem)
        return buf.ll_build()

    def ll_join_chars(length_dummy, lst, RES):
        if RES is ootype.String:
            target = Char
            buf = ootype.new(ootype.StringBuilder)
        else:
            target = UniChar
            buf = ootype.new(ootype.UnicodeBuilder)
        length = lst.ll_length()
        buf.ll_allocate(length)
        i = 0
        while i < length:
            buf.ll_append_char(cast_primitive(target, lst.ll_getitem_fast(i)))
            i += 1
        return buf.ll_build()

    def ll_join_strs(length_dummy, lst):
        if typeOf(lst).ITEM == ootype.String:
            buf = ootype.new(ootype.StringBuilder)
        else:
            buf = ootype.new(ootype.UnicodeBuilder)
        length = lst.ll_length()
        #buf.ll_allocate(length)
        i = 0
        while i < length:
            buf.ll_append(lst.ll_getitem_fast(i))
            i += 1
        return buf.ll_build()

    def ll_stringslice_startonly(s, start):
        return s.ll_substring(start, s.ll_strlen() - start)

    def ll_stringslice_startstop(s, start, stop):
        length = s.ll_strlen()
        if stop > length:
            stop = length
        # If start > stop, return a empty string. This can happen if the start
        # is greater than the length of the string.
        if start > stop:
            start = stop
        return s.ll_substring(start, stop-start)

    def ll_stringslice_minusone(s):
        return s.ll_substring(0, s.ll_strlen()-1)

    def ll_split_chr(RESULT, s, c, max):
        return RESULT.ll_convert_from_array(s.ll_split_chr(c, max))

    def ll_rsplit_chr(RESULT, s, c, max):
        return RESULT.ll_convert_from_array(s.ll_rsplit_chr(c, max))

    def ll_int(s, base):
        if not 2 <= base <= 36:
            raise ValueError
        strlen = s.ll_strlen()
        i = 0
        #XXX: only space is allowed as white space for now
        while i < strlen and s.ll_stritem_nonneg(i) == ' ':
            i += 1
        if not i < strlen:
            raise ValueError
        #check sign
        sign = 1
        if s.ll_stritem_nonneg(i) == '-':
            sign = -1
            i += 1
        elif s.ll_stritem_nonneg(i) == '+':
            i += 1;
        # skip whitespaces between sign and digits
        while i < strlen and s.ll_stritem_nonneg(i) == ' ':
            i += 1
        #now get digits
        val = 0
        oldpos = i
        while i < strlen:
            c = ord(s.ll_stritem_nonneg(i))
            if ord('a') <= c <= ord('z'):
                digit = c - ord('a') + 10
            elif ord('A') <= c <= ord('Z'):
                digit = c - ord('A') + 10
            elif ord('0') <= c <= ord('9'):
                digit = c - ord('0')
            else:
                break
            if digit >= base:
                break
            val = val * base + digit
            i += 1
        if i == oldpos:
            raise ValueError # catch strings like '+' and '+  '
        #skip trailing whitespace
        while i < strlen and s.ll_stritem_nonneg(i) == ' ':
            i += 1
        if not i == strlen:
            raise ValueError
        return sign * val

    def ll_float(ll_str):
        return ootype.ooparse_float(ll_str)

    # interface to build strings:
    #   x = ll_build_start(n)
    #   ll_build_push(x, next_string, 0)
    #   ll_build_push(x, next_string, 1)
    #   ...
    #   ll_build_push(x, next_string, n-1)
    #   s = ll_build_finish(x)

    def ll_build_start(parts_count):
        return ootype.new(ootype.StringBuilder)

    def ll_build_push(buf, next_string, index):
        buf.ll_append(next_string)

    def ll_build_finish(buf):
        return buf.ll_build()

    def ll_constant(s):
        return ootype.make_string(s)
    ll_constant._annspecialcase_ = 'specialize:memo'

    def do_stringformat(cls, hop, sourcevarsrepr):
        InstanceRepr = hop.rtyper.type_system.rclass.InstanceRepr
        string_repr = hop.rtyper.type_system.rstr.string_repr
        s_str = hop.args_s[0]
        assert s_str.is_constant()
        s = s_str.const

        c_append = hop.inputconst(ootype.Void, 'll_append')
        c_build = hop.inputconst(ootype.Void, 'll_build')
        cm1 = hop.inputconst(ootype.Signed, -1)
        c8 = hop.inputconst(ootype.Signed, 8)
        c10 = hop.inputconst(ootype.Signed, 10)
        c16 = hop.inputconst(ootype.Signed, 16)
        c_StringBuilder = hop.inputconst(ootype.Void, ootype.StringBuilder)
        v_buf = hop.genop("new", [c_StringBuilder], resulttype=ootype.StringBuilder)

        things = cls.parse_fmt_string(s)
        argsiter = iter(sourcevarsrepr)
        for thing in things:
            if isinstance(thing, tuple):
                code = thing[0]
                vitem, r_arg = argsiter.next()
                if not hasattr(r_arg, 'll_str'):
                    raise TyperError("ll_str unsupported for: %r" % r_arg)
                if code == 's' or (code == 'r' and isinstance(r_arg, InstanceRepr)):
                    vchunk = hop.gendirectcall(r_arg.ll_str, vitem)
                elif code == 'd':
                    assert isinstance(r_arg, IntegerRepr)
                    vchunk = hop.genop('oostring', [vitem, c10], resulttype=ootype.String)
                elif code == 'f':
                    #assert isinstance(r_arg, FloatRepr)
                    vchunk = hop.gendirectcall(r_arg.ll_str, vitem)
                elif code == 'x':
                    assert isinstance(r_arg, IntegerRepr)
                    vchunk = hop.genop('oostring', [vitem, c16], resulttype=ootype.String)
                elif code == 'o':
                    assert isinstance(r_arg, IntegerRepr)
                    vchunk = hop.genop('oostring', [vitem, c8], resulttype=ootype.String)
                else:
                    raise TyperError, "%%%s is not RPython" % (code, )
            else:
                vchunk = hop.inputconst(string_repr, thing)
            #i = inputconst(Signed, i)
            #hop.genop('setarrayitem', [vtemp, i, vchunk])
            hop.genop('oosend', [c_append, v_buf, vchunk], resulttype=ootype.Void)

        hop.exception_cannot_occur()   # to ignore the ZeroDivisionError of '%'
        return hop.genop('oosend', [c_build, v_buf], resulttype=ootype.String)
    do_stringformat = classmethod(do_stringformat)


def add_helpers():
    dic = {}
    for name, meth in ootype.String._GENERIC_METHODS.iteritems():
        if name in LLHelpers.__dict__:
            continue
        n_args = len(meth.ARGS)
        args = ', '.join(['arg%d' % i for i in range(n_args)])
        code = """
def %s(obj, %s):
    return obj.%s(%s)
""" % (name, args, name, args)
        exec code in dic
        setattr(LLHelpers, name, staticmethod(dic[name]))

add_helpers()
del add_helpers

do_stringformat = LLHelpers.do_stringformat
char_repr = CharRepr()
unichar_repr = UniCharRepr()
char_repr.ll = LLHelpers
unichar_repr.ll = LLHelpers

string_repr = StringRepr()
StringRepr.repr = string_repr
StringRepr.char_repr = char_repr
emptystr = string_repr.convert_const("")
unicode_repr = UnicodeRepr()
UnicodeRepr.repr = unicode_repr
UnicodeRepr.char_repr = unichar_repr


class StringIteratorRepr(AbstractStringIteratorRepr):
    lowleveltype = ootype.Record({'string': string_repr.lowleveltype,
                                  'index': ootype.Signed})

    def __init__(self):
        self.ll_striter = ll_striter
        self.ll_strnext = ll_strnext

class UnicodeIteratorRepr(AbstractStringIteratorRepr):
    lowleveltype = ootype.Record({'string': unicode_repr.lowleveltype,
                                  'index': ootype.Signed})

    def __init__(self):
        self.ll_striter = ll_unicodeiter
        self.ll_strnext = ll_strnext

def ll_striter(string):
    iter = ootype.new(string_repr.string_iterator_repr.lowleveltype)
    iter.string = string
    iter.index = 0
    return iter

def ll_unicodeiter(string):
    iter = ootype.new(unicode_repr.string_iterator_repr.lowleveltype)
    iter.string = string
    iter.index = 0
    return iter

def ll_strnext(iter):
    string = iter.string
    index = iter.index
    if index >= string.ll_strlen():
        raise StopIteration
    iter.index = index + 1
    return string.ll_stritem_nonneg(index)


StringRepr.string_iterator_repr = StringIteratorRepr()
UnicodeRepr.string_iterator_repr = UnicodeIteratorRepr()

# these should be in rclass, but circular imports prevent (also it's
# not that insane that a string constant is built in this file).

instance_str_prefix = string_repr.convert_const("<")
instance_str_suffix = string_repr.convert_const(" object>")

unboxed_instance_str_prefix = string_repr.convert_const("<unboxed ")
unboxed_instance_str_suffix = string_repr.convert_const(">")

list_str_open_bracket = string_repr.convert_const("[")
list_str_close_bracket = string_repr.convert_const("]")
list_str_sep = string_repr.convert_const(", ")
