from pypy.tool.pairtype import pairtype, pair
from pypy.annotation import model as annmodel
from pypy.rpython.error import TyperError
from pypy.rpython.rmodel import Repr, IntegerRepr, inputconst
from pypy.rpython.rmodel import externalvsinternal
from pypy.rpython.rlist import AbstractBaseListRepr, AbstractListRepr, \
        AbstractFixedSizeListRepr, AbstractListIteratorRepr, rtype_newlist, \
        rtype_alloc_and_set, ll_setitem_nonneg, ADTIList, ADTIFixedList
from pypy.rpython.rlist import dum_nocheck, dum_checkidx
from pypy.rpython.lltypesystem.lltype import \
     GcForwardReference, Ptr, GcArray, GcStruct, \
     Void, Signed, malloc, typeOf, Primitive, \
     Bool, nullptr, typeMethod
from pypy.rpython.lltypesystem import rstr
from pypy.rpython import robject
from pypy.rlib.debug import ll_assert
from pypy.rlib.rarithmetic import ovfcheck
from pypy.rpython.lltypesystem import rffi
from pypy.rlib.objectmodel import keepalive_until_here
from pypy.rpython.lltypesystem.lloperation import llop
from pypy.rlib import rgc

# ____________________________________________________________
#
#  Concrete implementation of RPython lists:
#
#    struct list {
#        int length;
#        items_array *items;
#    }
#
#    'items' points to a C-like array in memory preceded by a 'length' header,
#    where each item contains a primitive value or pointer to the actual list
#    item.
#
#    or for fixed-size lists an array is directly used:
#
#    item_t list_items[]
#

class BaseListRepr(AbstractBaseListRepr):
    rstr_ll = rstr.LLHelpers

    # known_maxlength is ignored by lltype but used by ootype
    def __init__(self, rtyper, item_repr, listitem=None, known_maxlength=False):
        self.rtyper = rtyper
        self.LIST = GcForwardReference()
        self.lowleveltype = Ptr(self.LIST)
        if not isinstance(item_repr, Repr):  # not computed yet, done by setup()
            assert callable(item_repr)
            self._item_repr_computer = item_repr
        else:
            self.external_item_repr, self.item_repr = externalvsinternal(rtyper, item_repr)
        self.listitem = listitem
        self.list_cache = {}
        # setup() needs to be called to finish this initialization

    def null_const(self):
        return nullptr(self.LIST)

    def get_eqfunc(self):
        return inputconst(Void, self.item_repr.get_ll_eq_function())

    def make_iterator_repr(self):
        return ListIteratorRepr(self)

    def get_itemarray_lowleveltype(self):
        ITEM = self.item_repr.lowleveltype
        ITEMARRAY = GcArray(ITEM,
                            adtmeths = ADTIFixedList({
                                 "ll_newlist": ll_fixed_newlist,
                                 "ll_newemptylist": ll_fixed_newemptylist,
                                 "ll_length": ll_fixed_length,
                                 "ll_items": ll_fixed_items,
                                 "ITEM": ITEM,
                                 "ll_getitem_fast": ll_fixed_getitem_fast,
                                 "ll_setitem_fast": ll_fixed_setitem_fast,
                            }))
        return ITEMARRAY


class __extend__(pairtype(BaseListRepr, BaseListRepr)):
    def rtype_is_((r_lst1, r_lst2), hop):
        if r_lst1.lowleveltype != r_lst2.lowleveltype:
            # obscure logic, the is can be true only if both are None
            v_lst1, v_lst2 = hop.inputargs(r_lst1, r_lst2)
            return hop.gendirectcall(ll_both_none, v_lst1, v_lst2)

        return pairtype(Repr, Repr).rtype_is_(pair(r_lst1, r_lst2), hop)


class ListRepr(AbstractListRepr, BaseListRepr):

    def _setup_repr(self):
        if 'item_repr' not in self.__dict__:
            self.external_item_repr, self.item_repr = externalvsinternal(self.rtyper, self._item_repr_computer())
        if isinstance(self.LIST, GcForwardReference):
            ITEM = self.item_repr.lowleveltype
            ITEMARRAY = self.get_itemarray_lowleveltype()
            # XXX we might think of turning length stuff into Unsigned
            self.LIST.become(GcStruct("list", ("length", Signed),
                                              ("items", Ptr(ITEMARRAY)),
                                      adtmeths = ADTIList({
                                          "ll_newlist": ll_newlist,
                                          "ll_newemptylist": ll_newemptylist,
                                          "ll_length": ll_length,
                                          "ll_items": ll_items,
                                          "ITEM": ITEM,
                                          "ll_getitem_fast": ll_getitem_fast,
                                          "ll_setitem_fast": ll_setitem_fast,
                                          "_ll_resize_ge": _ll_list_resize_ge,
                                          "_ll_resize_le": _ll_list_resize_le,
                                          "_ll_resize": _ll_list_resize,
                                      }),
                                      hints = {'list': True})
                             )

    def compact_repr(self):
        return 'ListR %s' % (self.item_repr.compact_repr(),)

    def prepare_const(self, n):
        result = malloc(self.LIST, immortal=True)
        result.length = n
        result.items = malloc(self.LIST.items.TO, n)
        return result

    def rtype_method_append(self, hop):
        if getattr(self.listitem, 'hint_maxlength', False):
            v_lst, v_value = hop.inputargs(self, self.item_repr)
            hop.exception_cannot_occur()
            hop.gendirectcall(ll_append_noresize, v_lst, v_value)
        else:
            AbstractListRepr.rtype_method_append(self, hop)

    def rtype_hint(self, hop):
        optimized = getattr(self.listitem, 'hint_maxlength', False)
        hints = hop.args_s[-1].const
        if 'maxlength' in hints:
            if optimized:
                v_list = hop.inputarg(self, arg=0)
                v_maxlength = self._get_v_maxlength(hop)
                hop.llops.gendirectcall(ll_set_maxlength, v_list, v_maxlength)
                return v_list
        if 'fence' in hints:
            v_list = hop.inputarg(self, arg=0)
            if isinstance(hop.r_result, FixedSizeListRepr):
                if optimized and 'exactlength' in hints:
                    llfn = ll_list2fixed_exact
                else:
                    llfn = ll_list2fixed
                v_list = hop.llops.gendirectcall(llfn, v_list)
            return v_list
        return AbstractListRepr.rtype_hint(self, hop)


class FixedSizeListRepr(AbstractFixedSizeListRepr, BaseListRepr):

    def _setup_repr(self):
        if 'item_repr' not in self.__dict__:
            self.external_item_repr, self.item_repr = externalvsinternal(self.rtyper, self._item_repr_computer())
        if isinstance(self.LIST, GcForwardReference):
            ITEMARRAY = self.get_itemarray_lowleveltype()
            self.LIST.become(ITEMARRAY)

    def compact_repr(self):
        return 'FixedSizeListR %s' % (self.item_repr.compact_repr(),)

    def prepare_const(self, n):
        result = malloc(self.LIST, n, immortal=True)
        return result


# ____________________________________________________________
#
#  Low-level methods.  These can be run for testing, but are meant to
#  be direct_call'ed from rtyped flow graphs, which means that they will
#  get flowed and annotated, mostly with SomePtr.

# adapted C code

def _ll_list_resize_really(l, newsize):
    """
    Ensure l.items has room for at least newsize elements, and set
    l.length to newsize.  Note that l.items may change, and even if
    newsize is less than l.length on entry.
    """
    # This over-allocates proportional to the list size, making room
    # for additional growth.  The over-allocation is mild, but is
    # enough to give linear-time amortized behavior over a long
    # sequence of appends() in the presence of a poorly-performing
    # system malloc().
    # The growth pattern is:  0, 4, 8, 16, 25, 35, 46, 58, 72, 88, ...
    if newsize <= 0:
        ll_assert(newsize == 0, "negative list length")
        l.length = 0
        l.items = _ll_new_empty_item_array(typeOf(l).TO)
        return
    else:
        if newsize < 9:
            some = 3
        else:
            some = 6
        some += newsize >> 3
        try:
            new_allocated = ovfcheck(newsize + some)
        except OverflowError:
            raise MemoryError
    # new_allocated is a bit more than newsize, enough to ensure an amortized
    # linear complexity for e.g. repeated usage of l.append().
    items = l.items
    newitems = malloc(typeOf(l).TO.items.TO, new_allocated)
    before_len = l.length
    if before_len:   # avoids copying GC flags from the prebuilt_empty_array
        if before_len < newsize:
            p = before_len
        else:
            p = newsize
        rgc.ll_arraycopy(items, newitems, 0, 0, p)
    l.length = newsize
    l.items = newitems
_ll_list_resize_really._annenforceargs_ = (None, int)

# this common case was factored out of _ll_list_resize
# to see if inlining it gives some speed-up.

def _ll_list_resize(l, newsize):
    # Bypass realloc() when a previous overallocation is large enough
    # to accommodate the newsize.  If the newsize falls lower than half
    # the allocated size, then proceed with the realloc() to shrink the list.
    allocated = len(l.items)
    if allocated >= newsize and newsize >= ((allocated >> 1) - 5):
        l.length = newsize
    else:
        _ll_list_resize_really(l, newsize)

def _ll_list_resize_ge(l, newsize):
    if len(l.items) >= newsize:
        l.length = newsize
    else:
        _ll_list_resize_really(l, newsize)

def _ll_list_resize_le(l, newsize):
    if newsize >= (len(l.items) >> 1) - 5:
        l.length = newsize
    else:
        _ll_list_resize_really(l, newsize)


def ll_append_noresize(l, newitem):
    length = l.length
    l.length = length + 1
    l.ll_setitem_fast(length, newitem)
ll_append_noresize.oopspec = 'list.append(l, newitem)'


def ll_both_none(lst1, lst2):
    return not lst1 and not lst2
        

# ____________________________________________________________
#
#  Accessor methods

def ll_newlist(LIST, length):
    ll_assert(length >= 0, "negative list length")
    l = malloc(LIST)
    l.length = length
    l.items = malloc(LIST.items.TO, length)
    return l
ll_newlist = typeMethod(ll_newlist)
ll_newlist.oopspec = 'newlist(length)'

# should empty lists start with no allocated memory, or with a preallocated
# minimal number of entries?  XXX compare memory usage versus speed, and
# check how many always-empty lists there are in a typical pypy-c run...
INITIAL_EMPTY_LIST_ALLOCATION = 0

def _ll_prebuilt_empty_array(LISTITEM):
    return malloc(LISTITEM, 0)
_ll_prebuilt_empty_array._annspecialcase_ = 'specialize:memo'

def _ll_new_empty_item_array(LIST):
    if INITIAL_EMPTY_LIST_ALLOCATION > 0:
        return malloc(LIST.items.TO, INITIAL_EMPTY_LIST_ALLOCATION)
    else:
        return _ll_prebuilt_empty_array(LIST.items.TO)

def ll_newemptylist(LIST):
    l = malloc(LIST)
    l.length = 0
    l.items = _ll_new_empty_item_array(LIST)
    return l
ll_newemptylist = typeMethod(ll_newemptylist)
ll_newemptylist.oopspec = 'newlist(0)'

def ll_length(l):
    return l.length
ll_length.oopspec = 'list.len(l)'

def ll_items(l):
    return l.items

def ll_getitem_fast(l, index):
    ll_assert(index < l.length, "getitem out of bounds")
    return l.ll_items()[index]
ll_getitem_fast.oopspec = 'list.getitem(l, index)'

def ll_setitem_fast(l, index, item):
    ll_assert(index < l.length, "setitem out of bounds")
    l.ll_items()[index] = item
ll_setitem_fast.oopspec = 'list.setitem(l, index, item)'

# fixed size versions

def ll_fixed_newlist(LIST, length):
    ll_assert(length >= 0, "negative fixed list length")
    l = malloc(LIST, length)
    return l
ll_fixed_newlist = typeMethod(ll_fixed_newlist)
ll_fixed_newlist.oopspec = 'newlist(length)'

def ll_fixed_newemptylist(LIST):
    return ll_fixed_newlist(LIST, 0)
ll_fixed_newemptylist = typeMethod(ll_fixed_newemptylist)

def ll_fixed_length(l):
    return len(l)
ll_fixed_length.oopspec = 'list.len(l)'

def ll_fixed_items(l):
    return l

def ll_fixed_getitem_fast(l, index):
    ll_assert(index < len(l), "fixed getitem out of bounds")
    return l[index]
ll_fixed_getitem_fast.oopspec = 'list.getitem(l, index)'

def ll_fixed_setitem_fast(l, index, item):
    ll_assert(index < len(l), "fixed setitem out of bounds")
    l[index] = item
ll_fixed_setitem_fast.oopspec = 'list.setitem(l, index, item)'

def newlist(llops, r_list, items_v):
    LIST = r_list.LIST
    if len(items_v) == 0:
        v_result = llops.gendirectcall(LIST.ll_newemptylist)
    else:
        cno = inputconst(Signed, len(items_v))
        v_result = llops.gendirectcall(LIST.ll_newlist, cno)
    v_func = inputconst(Void, dum_nocheck)
    for i, v_item in enumerate(items_v):
        ci = inputconst(Signed, i)
        llops.gendirectcall(ll_setitem_nonneg, v_func, v_result, ci, v_item)
    return v_result

# special operations for list comprehension optimization
def ll_set_maxlength(l, n):
    LIST = typeOf(l).TO
    l.items = malloc(LIST.items.TO, n)

def ll_list2fixed(l):
    n = l.length
    olditems = l.items
    if n == len(olditems):
        return olditems
    else:
        LIST = typeOf(l).TO
        newitems = malloc(LIST.items.TO, n)
        rgc.ll_arraycopy(olditems, newitems, 0, 0, n)
        return newitems
ll_list2fixed.oopspec = 'list.list2fixed(l)'

def ll_list2fixed_exact(l):
    ll_assert(l.length == len(l.items), "ll_list2fixed_exact: bad length")
    return l.items

# ____________________________________________________________
#
#  Iteration.

class ListIteratorRepr(AbstractListIteratorRepr):

    def __init__(self, r_list):
        self.r_list = r_list
        self.lowleveltype = Ptr(GcStruct('listiter',
                                         ('list', r_list.lowleveltype),
                                         ('index', Signed)))
        self.ll_listiter = ll_listiter
        self.ll_listnext = ll_listnext
        self.ll_getnextindex = ll_getnextindex

def ll_listiter(ITERPTR, lst):
    iter = malloc(ITERPTR.TO)
    iter.list = lst
    iter.index = 0
    return iter

def ll_listnext(iter):
    l = iter.list
    index = iter.index
    if index >= l.ll_length():
        raise StopIteration
    iter.index = index + 1      # cannot overflow because index < l.length
    return l.ll_getitem_fast(index)

def ll_getnextindex(iter):
    return iter.index