from abc import abstractmethod
from contextlib import contextmanager

from parso.tree import search_ancestor
from parso.python.tree import Name

from jedi.inference.filters import ParserTreeFilter, MergedFilter, \
    GlobalNameFilter
from jedi.inference.names import AnonymousParamName, TreeNameDefinition
from jedi.inference.base_value import NO_VALUES, ValueSet
from jedi.parser_utils import get_parent_scope
from jedi import debug
from jedi import parser_utils


class AbstractContext:
    # Must be defined: inference_state and tree_node and parent_context as an attribute/property

    def __init__(self, inference_state):
        self.inference_state = inference_state
        self.predefined_names = {}

    @abstractmethod
    def get_filters(self, until_position=None, origin_scope=None):
        raise NotImplementedError

    def goto(self, name_or_str, position):
        from jedi.inference import finder
        filters = _get_global_filters_for_name(
            self, name_or_str if isinstance(name_or_str, Name) else None, position,
        )
        names = finder.filter_name(filters, name_or_str)
        debug.dbg('context.goto %s in (%s): %s', name_or_str, self, names)
        return names

    def py__getattribute__(self, name_or_str, name_context=None, position=None,
                           analysis_errors=True):
        """
        :param position: Position of the last statement -> tuple of line, column
        """
        if name_context is None:
            name_context = self
        names = self.goto(name_or_str, position)

        string_name = name_or_str.value if isinstance(name_or_str, Name) else name_or_str

        # This paragraph is currently needed for proper branch type inference
        # (static analysis).
        found_predefined_types = None
        if self.predefined_names and isinstance(name_or_str, Name):
            node = name_or_str
            while node is not None and not parser_utils.is_scope(node):
                node = node.parent
                if node.type in ("if_stmt", "for_stmt", "comp_for", 'sync_comp_for'):
                    try:
                        name_dict = self.predefined_names[node]
                        types = name_dict[string_name]
                    except KeyError:
                        continue
                    else:
                        found_predefined_types = types
                        break
        if found_predefined_types is not None and names:
            from jedi.inference import flow_analysis
            check = flow_analysis.reachability_check(
                context=self,
                value_scope=self.tree_node,
                node=name_or_str,
            )
            if check is flow_analysis.UNREACHABLE:
                values = NO_VALUES
            else:
                values = found_predefined_types
        else:
            values = ValueSet.from_sets(name.infer() for name in names)

        if not names and not values and analysis_errors:
            if isinstance(name_or_str, Name):
                from jedi.inference import analysis
                message = ("NameError: name '%s' is not defined." % string_name)
                analysis.add(name_context, 'name-error', name_or_str, message)

        debug.dbg('context.names_to_types: %s -> %s', names, values)
        if values:
            return values
        return self._check_for_additional_knowledge(name_or_str, name_context, position)

    def _check_for_additional_knowledge(self, name_or_str, name_context, position):
        name_context = name_context or self
        # Add isinstance and other if/assert knowledge.
        if isinstance(name_or_str, Name) and not name_context.is_instance():
            flow_scope = name_or_str
            base_nodes = [name_context.tree_node]

            if any(b.type in ('comp_for', 'sync_comp_for') for b in base_nodes):
                return NO_VALUES
            from jedi.inference.finder import check_flow_information
            while True:
                flow_scope = get_parent_scope(flow_scope, include_flows=True)
                n = check_flow_information(name_context, flow_scope,
                                           name_or_str, position)
                if n is not None:
                    return n
                if flow_scope in base_nodes:
                    break
        return NO_VALUES

    def get_root_context(self):
        parent_context = self.parent_context
        if parent_context is None:
            return self
        return parent_context.get_root_context()

    def is_module(self):
        return False

    def is_builtins_module(self):
        return False

    def is_class(self):
        return False

    def is_stub(self):
        return False

    def is_instance(self):
        return False

    def is_compiled(self):
        return False

    def is_bound_method(self):
        return False

    @abstractmethod
    def py__name__(self):
        raise NotImplementedError

    def get_value(self):
        raise NotImplementedError

    @property
    def name(self):
        return None

    def get_qualified_names(self):
        return ()

    def py__doc__(self):
        return ''

    @contextmanager
    def predefine_names(self, flow_scope, dct):
        predefined = self.predefined_names
        predefined[flow_scope] = dct
        try:
            yield
        finally:
            del predefined[flow_scope]


class ValueContext(AbstractContext):
    """
    Should be defined, otherwise the API returns empty types.
    """
    def __init__(self, value):
        super().__init__(value.inference_state)
        self._value = value

    @property
    def tree_node(self):
        return self._value.tree_node

    @property
    def parent_context(self):
        return self._value.parent_context

    def is_module(self):
        return self._value.is_module()

    def is_builtins_module(self):
        return self._value == self.inference_state.builtins_module

    def is_class(self):
        return self._value.is_class()

    def is_stub(self):
        return self._value.is_stub()

    def is_instance(self):
        return self._value.is_instance()

    def is_compiled(self):
        return self._value.is_compiled()

    def is_bound_method(self):
        return self._value.is_bound_method()

    def py__name__(self):
        return self._value.py__name__()

    @property
    def name(self):
        return self._value.name

    def get_qualified_names(self):
        return self._value.get_qualified_names()

    def py__doc__(self):
        return self._value.py__doc__()

    def get_value(self):
        return self._value

    def __repr__(self):
        return '%s(%s)' % (self.__class__.__name__, self._value)


class TreeContextMixin:
    def infer_node(self, node):
        from jedi.inference.syntax_tree import infer_node
        return infer_node(self, node)

    def create_value(self, node):
        from jedi.inference import value

        if node == self.tree_node:
            assert self.is_module()
            return self.get_value()

        parent_context = self.create_context(node)

        if node.type in ('funcdef', 'lambdef'):
            func = value.FunctionValue.from_context(parent_context, node)
            if parent_context.is_class():
                class_value = parent_context.parent_context.create_value(parent_context.tree_node)
                instance = value.AnonymousInstance(
                    self.inference_state, parent_context.parent_context, class_value)
                func = value.BoundMethod(
                    instance=instance,
                    class_context=class_value.as_context(),
                    function=func
                )
            return func
        elif node.type == 'classdef':
            return value.ClassValue(self.inference_state, parent_context, node)
        else:
            raise NotImplementedError("Probably shouldn't happen: %s" % node)

    def create_context(self, node):
        def from_scope_node(scope_node, is_nested=True):
            if scope_node == self.tree_node:
                return self

            if scope_node.type in ('funcdef', 'lambdef', 'classdef'):
                return self.create_value(scope_node).as_context()
            elif scope_node.type in ('comp_for', 'sync_comp_for'):
                parent_scope = parser_utils.get_parent_scope(scope_node)
                parent_context = from_scope_node(parent_scope)
                if node.start_pos >= scope_node.children[-1].start_pos:
                    return parent_context
                return CompForContext(parent_context, scope_node)
            raise Exception("There's a scope that was not managed: %s" % scope_node)

        def parent_scope(node):
            while True:
                node = node.parent

                if parser_utils.is_scope(node):
                    return node
                elif node.type in ('argument', 'testlist_comp'):
                    if node.children[1].type in ('comp_for', 'sync_comp_for'):
                        return node.children[1]
                elif node.type == 'dictorsetmaker':
                    for n in node.children[1:4]:
                        # In dictionaries it can be pretty much anything.
                        if n.type in ('comp_for', 'sync_comp_for'):
                            return n

        scope_node = parent_scope(node)
        if scope_node.type in ('funcdef', 'classdef'):
            colon = scope_node.children[scope_node.children.index(':')]
            if node.start_pos < colon.start_pos:
                parent = node.parent
                if not (parent.type == 'param' and parent.name == node):
                    scope_node = parent_scope(scope_node)
        return from_scope_node(scope_node, is_nested=True)

    def create_name(self, tree_name):
        definition = tree_name.get_definition()
        if definition and definition.type == 'param' and definition.name == tree_name:
            funcdef = search_ancestor(definition, 'funcdef', 'lambdef')
            func = self.create_value(funcdef)
            return AnonymousParamName(func, tree_name)
        else:
            context = self.create_context(tree_name)
            return TreeNameDefinition(context, tree_name)


class FunctionContext(TreeContextMixin, ValueContext):
    def get_filters(self, until_position=None, origin_scope=None):
        yield ParserTreeFilter(
            self.inference_state,
            parent_context=self,
            until_position=until_position,
            origin_scope=origin_scope
        )


class ModuleContext(TreeContextMixin, ValueContext):
    def py__file__(self):
        return self._value.py__file__()

    def get_filters(self, until_position=None, origin_scope=None):
        filters = self._value.get_filters(origin_scope)
        # Skip the first filter and replace it.
        next(filters, None)
        yield MergedFilter(
            ParserTreeFilter(
                parent_context=self,
                until_position=until_position,
                origin_scope=origin_scope
            ),
            self.get_global_filter(),
        )
        yield from filters

    def get_global_filter(self):
        return GlobalNameFilter(self, self.tree_node)

    @property
    def string_names(self):
        return self._value.string_names

    @property
    def code_lines(self):
        return self._value.code_lines

    def get_value(self):
        """
        This is the only function that converts a context back to a value.
        This is necessary for stub -> python conversion and vice versa. However
        this method shouldn't be moved to AbstractContext.
        """
        return self._value


class NamespaceContext(TreeContextMixin, ValueContext):
    def get_filters(self, until_position=None, origin_scope=None):
        return self._value.get_filters()

    def get_value(self):
        return self._value

    @property
    def string_names(self):
        return self._value.string_names

    def py__file__(self):
        return self._value.py__file__()


class ClassContext(TreeContextMixin, ValueContext):
    def get_filters(self, until_position=None, origin_scope=None):
        yield self.get_global_filter(until_position, origin_scope)

    def get_global_filter(self, until_position=None, origin_scope=None):
        return ParserTreeFilter(
            parent_context=self,
            until_position=until_position,
            origin_scope=origin_scope
        )


class CompForContext(TreeContextMixin, AbstractContext):
    def __init__(self, parent_context, comp_for):
        super().__init__(parent_context.inference_state)
        self.tree_node = comp_for
        self.parent_context = parent_context

    def get_filters(self, until_position=None, origin_scope=None):
        yield ParserTreeFilter(self)

    def get_value(self):
        return None

    def py__name__(self):
        return '<comprehension context>'

    def __repr__(self):
        return '%s(%s)' % (self.__class__.__name__, self.tree_node)


class CompiledContext(ValueContext):
    def get_filters(self, until_position=None, origin_scope=None):
        return self._value.get_filters()


class CompiledModuleContext(CompiledContext):
    code_lines = None

    def get_value(self):
        return self._value

    @property
    def string_names(self):
        return self._value.string_names

    def py__file__(self):
        return self._value.py__file__()


def _get_global_filters_for_name(context, name_or_none, position):
    # For functions and classes the defaults don't belong to the
    # function and get inferred in the value before the function. So
    # make sure to exclude the function/class name.
    if name_or_none is not None:
        ancestor = search_ancestor(name_or_none, 'funcdef', 'classdef', 'lambdef')
        lambdef = None
        if ancestor == 'lambdef':
            # For lambdas it's even more complicated since parts will
            # be inferred later.
            lambdef = ancestor
            ancestor = search_ancestor(name_or_none, 'funcdef', 'classdef')
        if ancestor is not None:
            colon = ancestor.children[-2]
            if position is not None and position < colon.start_pos:
                if lambdef is None or position < lambdef.children[-2].start_pos:
                    position = ancestor.start_pos

    return get_global_filters(context, position, name_or_none)


def get_global_filters(context, until_position, origin_scope):
    """
    Returns all filters in order of priority for name resolution.

    For global name lookups. The filters will handle name resolution
    themselves, but here we gather possible filters downwards.

    >>> from jedi import Script
    >>> script = Script('''
    ... x = ['a', 'b', 'c']
    ... def func():
    ...     y = None
    ... ''')
    >>> module_node = script._module_node
    >>> scope = next(module_node.iter_funcdefs())
    >>> scope
    <Function: func@3-5>
    >>> context = script._get_module_context().create_context(scope)
    >>> filters = list(get_global_filters(context, (4, 0), None))

    First we get the names from the function scope.

    >>> print(filters[0])  # doctest: +ELLIPSIS
    MergedFilter(<ParserTreeFilter: ...>, <GlobalNameFilter: ...>)
    >>> sorted(str(n) for n in filters[0].values())  # doctest: +NORMALIZE_WHITESPACE
    ['<TreeNameDefinition: string_name=func start_pos=(3, 4)>',
     '<TreeNameDefinition: string_name=x start_pos=(2, 0)>']
    >>> filters[0]._filters[0]._until_position
    (4, 0)
    >>> filters[0]._filters[1]._until_position

    Then it yields the names from one level "lower". In this example, this is
    the module scope (including globals).
    As a side note, you can see, that the position in the filter is None on the
    globals filter, because there the whole module is searched.

    >>> list(filters[1].values())  # package modules -> Also empty.
    []
    >>> sorted(name.string_name for name in filters[2].values())  # Module attributes
    ['__doc__', '__name__', '__package__']

    Finally, it yields the builtin filter, if `include_builtin` is
    true (default).

    >>> list(filters[3].values())  # doctest: +ELLIPSIS
    [...]
    """
    base_context = context
    from jedi.inference.value.function import BaseFunctionExecutionContext
    while context is not None:
        # Names in methods cannot be resolved within the class.
        yield from context.get_filters(
            until_position=until_position,
            origin_scope=origin_scope
        )
        if isinstance(context, (BaseFunctionExecutionContext, ModuleContext)):
            # The position should be reset if the current scope is a function.
            until_position = None

        context = context.parent_context

    b = next(base_context.inference_state.builtins_module.get_filters(), None)
    assert b is not None
    # Add builtins to the global scope.
    yield b
