"""A module for inferring objects

For more information see the documentation in `rope.base.oi`
package.

"""
import rope.base.builtins
import rope.base.pynames
import rope.base.pyobjects
from rope.base import evaluate, utils, arguments


_ignore_inferred = utils.ignore_exception(
    rope.base.pyobjects.IsBeingInferredError)


@_ignore_inferred
def infer_returned_object(pyfunction, args):
    """Infer the `PyObject` this `PyFunction` returns after calling"""
    object_info = pyfunction.pycore.object_info
    result = object_info.get_exact_returned(pyfunction, args)
    if result is not None:
        return result
    result = _infer_returned(pyfunction, args)
    if result is not None:
        if args and pyfunction.get_module().get_resource() is not None:
            params = args.get_arguments(
                pyfunction.get_param_names(special_args=False))
            object_info.function_called(pyfunction, params, result)
        return result
    return object_info.get_returned(pyfunction, args)

@_ignore_inferred
def infer_parameter_objects(pyfunction):
    """Infer the `PyObject`\s of parameters of this `PyFunction`"""
    object_info = pyfunction.pycore.object_info
    result = object_info.get_parameter_objects(pyfunction)
    if result is None:
        result = _parameter_objects(pyfunction)
    _handle_first_parameter(pyfunction, result)
    return result

def _handle_first_parameter(pyobject, parameters):
    kind = pyobject.get_kind()
    if parameters is None or kind not in ['method', 'classmethod']:
        pass
    if not parameters:
        if not pyobject.get_param_names(special_args=False):
            return
        parameters.append(rope.base.pyobjects.get_unknown())
    if kind == 'method':
        parameters[0] = rope.base.pyobjects.PyObject(pyobject.parent)
    if kind == 'classmethod':
        parameters[0] = pyobject.parent

@_ignore_inferred
def infer_assigned_object(pyname):
    if not pyname.assignments:
        return
    for assignment in reversed(pyname.assignments):
        result = _infer_assignment(assignment, pyname.module)
        if result is not None:
            return result

def get_passed_objects(pyfunction, parameter_index):
    object_info = pyfunction.pycore.object_info
    result = object_info.get_passed_objects(pyfunction,
                                            parameter_index)
    if not result:
        statically_inferred = _parameter_objects(pyfunction)
        if len(statically_inferred) > parameter_index:
            result.append(statically_inferred[parameter_index])
    return result

def _infer_returned(pyobject, args):
    if args:
        # HACK: Setting parameter objects manually
        # This is not thread safe and might cause problems if `args`
        # does not come from a good call site
        pyobject.get_scope().invalidate_data()
        pyobject._set_parameter_pyobjects(
            args.get_arguments(pyobject.get_param_names(special_args=False)))
    scope = pyobject.get_scope()
    if not scope._get_returned_asts():
        return
    maxtries = 3
    for returned_node in reversed(scope._get_returned_asts()[-maxtries:]):
        try:
            resulting_pyname = evaluate.eval_node(scope, returned_node)
            if resulting_pyname is None:
                continue
            pyobject = resulting_pyname.get_object()
            if pyobject == rope.base.pyobjects.get_unknown():
                continue
            if not scope._is_generator():
                return pyobject
            else:
                return rope.base.builtins.get_generator(pyobject)
        except rope.base.pyobjects.IsBeingInferredError:
            pass

def _parameter_objects(pyobject):
    params = pyobject.get_param_names(special_args=False)
    return [rope.base.pyobjects.get_unknown()] * len(params)

# handling `rope.base.pynames.AssignmentValue`

@_ignore_inferred
def _infer_assignment(assignment, pymodule):
    result = _follow_pyname(assignment, pymodule)
    if result is None:
        return None
    pyname, pyobject = result
    pyobject = _follow_evaluations(assignment, pyname, pyobject)
    if pyobject is None:
        return None
    return _follow_levels(assignment, pyobject)

def _follow_levels(assignment, pyobject):
    for index in assignment.levels:
        if isinstance(pyobject.get_type(), rope.base.builtins.Tuple):
            holdings = pyobject.get_type().get_holding_objects()
            if holdings:
                pyobject = holdings[min(len(holdings) - 1, index)]
            else:
                pyobject = None
        elif isinstance(pyobject.get_type(), rope.base.builtins.List):
            pyobject = pyobject.get_type().holding
        else:
            pyobject = None
        if pyobject is None:
            break
    return pyobject

@_ignore_inferred
def _follow_pyname(assignment, pymodule, lineno=None):
    assign_node = assignment.ast_node
    if lineno is None:
        lineno = _get_lineno_for_node(assign_node)
    holding_scope = pymodule.get_scope().get_inner_scope_for_line(lineno)
    pyname = evaluate.eval_node(holding_scope, assign_node)
    if pyname is not None:
        result = pyname.get_object()
        if isinstance(result.get_type(), rope.base.builtins.Property) and \
           holding_scope.get_kind() == 'Class':
            arg = rope.base.pynames.UnboundName(
                rope.base.pyobjects.PyObject(holding_scope.pyobject))
            return pyname, result.get_type().get_property_object(
                arguments.ObjectArguments([arg]))
        return pyname, result

@_ignore_inferred
def _follow_evaluations(assignment, pyname, pyobject):
    new_pyname = pyname
    tokens = assignment.evaluation.split('.')
    for token in tokens:
        call = token.endswith('()')
        if call:
            token = token[:-2]
        if token:
            pyname = new_pyname
            new_pyname = _get_attribute(pyobject, token)
            if new_pyname is not None:
                pyobject = new_pyname.get_object()
        if pyobject is not None and call:
            if isinstance(pyobject, rope.base.pyobjects.AbstractFunction):
                args = arguments.ObjectArguments([pyname])
                pyobject = pyobject.get_returned_object(args)
            else:
                pyobject = None
        if pyobject is None:
            break
    if pyobject is not None and assignment.assign_type:
        return rope.base.pyobjects.PyObject(pyobject)
    return pyobject


def _get_lineno_for_node(assign_node):
    if hasattr(assign_node, 'lineno') and \
       assign_node.lineno is not None:
        return assign_node.lineno
    return 1

def _get_attribute(pyobject, name):
    if pyobject is not None and name in pyobject:
        return pyobject[name]
