"""
Implementations of standard library functions, because it's not possible to
understand them with Jedi.
"""
from jedi._compatibility import unicode
from jedi.evaluate import compiled
from jedi.evaluate import representation as er
from jedi.evaluate import iterable
from jedi.evaluate.helpers import FakeArray, FakeStatement
from jedi.parser import representation as pr
from jedi import debug


class NotInStdLib(LookupError):
    pass


def execute(evaluator, obj, params):
    try:
        obj_name = str(obj.name)
    except AttributeError:
        pass
    else:
        if obj.parent == compiled.builtin:
            module_name = 'builtins'
        elif isinstance(obj.parent, pr.Module):
            module_name = str(obj.parent.name)
        else:
            module_name = ''

        # for now we just support builtin functions.
        try:
            return _implemented[module_name][obj_name](evaluator, obj, params)
        except KeyError:
            pass
    raise NotInStdLib()


def _follow_param(evaluator, params, index):
    try:
        stmt = params[index]
    except IndexError:
        return []
    else:
        if isinstance(stmt, pr.Statement):
            return evaluator.eval_statement(stmt)
        else:
            return [stmt]  # just some arbitrary object


def builtins_getattr(evaluator, obj, params):
    stmts = []
    # follow the first param
    objects = _follow_param(evaluator, params, 0)
    names = _follow_param(evaluator, params, 1)
    for obj in objects:
        if not isinstance(obj, (er.Instance, er.Class, pr.Module, compiled.CompiledObject)):
            debug.warning('getattr called without instance')
            continue

        for name in names:
            s = unicode, str
            if isinstance(name, compiled.CompiledObject) and isinstance(name.obj, s):
                stmts += evaluator.follow_path(iter([name.obj]), [obj], obj)
            else:
                debug.warning('getattr called without str')
                continue
    return stmts


def builtins_type(evaluator, obj, params):
    if len(params) == 1:
        # otherwise it would be a metaclass... maybe someday...
        objects = _follow_param(evaluator, params, 0)
        return [o.base for o in objects if isinstance(o, er.Instance)]
    return []


def builtins_super(evaluator, obj, params):
    # TODO make this able to detect multiple inheritance super
    accept = (pr.Function,)
    func = params.get_parent_until(accept)
    if func.isinstance(*accept):
        cls = func.get_parent_until(accept + (pr.Class,),
                                    include_current=False)
        if isinstance(cls, pr.Class):
            cls = er.Class(evaluator, cls)
            su = cls.get_super_classes()
            if su:
                return evaluator.execute(su[0])
    return []


def builtins_reversed(evaluator, obj, params):
    objects = tuple(_follow_param(evaluator, params, 0))
    if objects:
        # unpack the iterator values
        objects = tuple(iterable.get_iterator_types(objects))
        if objects:
            rev = reversed(objects)
            # Repack iterator values and then run it the normal way. This is
            # necessary, because `reversed` is a function and autocompletion
            # would fail in certain cases like `reversed(x).__iter__` if we
            # just returned the result directly.
            stmts = [FakeStatement([r]) for r in rev]
            objects = (iterable.Array(evaluator, FakeArray(stmts, objects[0].parent)),)
    return [er.Instance(evaluator, obj, objects)]


def _return_first_param(evaluator, obj, params):
    if len(params) == 1:
        return _follow_param(evaluator, params, 0)
    return []


_implemented = {
    'builtins': {
        'getattr': builtins_getattr,
        'type': builtins_type,
        'super': builtins_super,
        'reversed': builtins_reversed,
    },
    'copy': {
        'copy': _return_first_param,
        'deepcopy': _return_first_param,
    },
    'json': {
        'load': lambda *args: [],
        'loads': lambda *args: [],
    },
}