# -*- coding: utf-8 -*-
"""
    jinja2.nodes
    ~~~~~~~~~~~~

    This module implements additional nodes derived from the ast base node.

    It also provides some node tree helper functions like `in_lineno` and
    `get_nodes` used by the parser and translator in order to normalize
    python and jinja nodes.

    :copyright: (c) 2017 by the Jinja Team.
    :license: BSD, see LICENSE for more details.
"""
import types
import operator

from collections import deque
from jinja2.utils import Markup
from jinja2._compat import izip, with_metaclass, text_type, PY2


#: the types we support for context functions
_context_function_types = (types.FunctionType, types.MethodType)


_binop_to_func = {
    '*':        operator.mul,
    '/':        operator.truediv,
    '//':       operator.floordiv,
    '**':       operator.pow,
    '%':        operator.mod,
    '+':        operator.add,
    '-':        operator.sub
}

_uaop_to_func = {
    'not':      operator.not_,
    '+':        operator.pos,
    '-':        operator.neg
}

_cmpop_to_func = {
    'eq':       operator.eq,
    'ne':       operator.ne,
    'gt':       operator.gt,
    'gteq':     operator.ge,
    'lt':       operator.lt,
    'lteq':     operator.le,
    'in':       lambda a, b: a in b,
    'notin':    lambda a, b: a not in b
}


class Impossible(Exception):
    """Raised if the node could not perform a requested action."""


class NodeType(type):
    """A metaclass for nodes that handles the field and attribute
    inheritance.  fields and attributes from the parent class are
    automatically forwarded to the child."""

    def __new__(cls, name, bases, d):
        for attr in 'fields', 'attributes':
            storage = []
            storage.extend(getattr(bases[0], attr, ()))
            storage.extend(d.get(attr, ()))
            assert len(bases) == 1, 'multiple inheritance not allowed'
            assert len(storage) == len(set(storage)), 'layout conflict'
            d[attr] = tuple(storage)
        d.setdefault('abstract', False)
        return type.__new__(cls, name, bases, d)


class EvalContext(object):
    """Holds evaluation time information.  Custom attributes can be attached
    to it in extensions.
    """

    def __init__(self, environment, template_name=None):
        self.environment = environment
        if callable(environment.autoescape):
            self.autoescape = environment.autoescape(template_name)
        else:
            self.autoescape = environment.autoescape
        self.volatile = False

    def save(self):
        return self.__dict__.copy()

    def revert(self, old):
        self.__dict__.clear()
        self.__dict__.update(old)


def get_eval_context(node, ctx):
    if ctx is None:
        if node.environment is None:
            raise RuntimeError('if no eval context is passed, the '
                               'node must have an attached '
                               'environment.')
        return EvalContext(node.environment)
    return ctx


class Node(with_metaclass(NodeType, object)):
    """Baseclass for all Jinja2 nodes.  There are a number of nodes available
    of different types.  There are four major types:

    -   :class:`Stmt`: statements
    -   :class:`Expr`: expressions
    -   :class:`Helper`: helper nodes
    -   :class:`Template`: the outermost wrapper node

    All nodes have fields and attributes.  Fields may be other nodes, lists,
    or arbitrary values.  Fields are passed to the constructor as regular
    positional arguments, attributes as keyword arguments.  Each node has
    two attributes: `lineno` (the line number of the node) and `environment`.
    The `environment` attribute is set at the end of the parsing process for
    all nodes automatically.
    """
    fields = ()
    attributes = ('lineno', 'environment')
    abstract = True

    def __init__(self, *fields, **attributes):
        if self.abstract:
            raise TypeError('abstract nodes are not instanciable')
        if fields:
            if len(fields) != len(self.fields):
                if not self.fields:
                    raise TypeError('%r takes 0 arguments' %
                                    self.__class__.__name__)
                raise TypeError('%r takes 0 or %d argument%s' % (
                    self.__class__.__name__,
                    len(self.fields),
                    len(self.fields) != 1 and 's' or ''
                ))
            for name, arg in izip(self.fields, fields):
                setattr(self, name, arg)
        for attr in self.attributes:
            setattr(self, attr, attributes.pop(attr, None))
        if attributes:
            raise TypeError('unknown attribute %r' %
                            next(iter(attributes)))

    def iter_fields(self, exclude=None, only=None):
        """This method iterates over all fields that are defined and yields
        ``(key, value)`` tuples.  Per default all fields are returned, but
        it's possible to limit that to some fields by providing the `only`
        parameter or to exclude some using the `exclude` parameter.  Both
        should be sets or tuples of field names.
        """
        for name in self.fields:
            if (exclude is only is None) or \
               (exclude is not None and name not in exclude) or \
               (only is not None and name in only):
                try:
                    yield name, getattr(self, name)
                except AttributeError:
                    pass

    def iter_child_nodes(self, exclude=None, only=None):
        """Iterates over all direct child nodes of the node.  This iterates
        over all fields and yields the values of they are nodes.  If the value
        of a field is a list all the nodes in that list are returned.
        """
        for field, item in self.iter_fields(exclude, only):
            if isinstance(item, list):
                for n in item:
                    if isinstance(n, Node):
                        yield n
            elif isinstance(item, Node):
                yield item

    def find(self, node_type):
        """Find the first node of a given type.  If no such node exists the
        return value is `None`.
        """
        for result in self.find_all(node_type):
            return result

    def find_all(self, node_type):
        """Find all the nodes of a given type.  If the type is a tuple,
        the check is performed for any of the tuple items.
        """
        for child in self.iter_child_nodes():
            if isinstance(child, node_type):
                yield child
            for result in child.find_all(node_type):
                yield result

    def set_ctx(self, ctx):
        """Reset the context of a node and all child nodes.  Per default the
        parser will all generate nodes that have a 'load' context as it's the
        most common one.  This method is used in the parser to set assignment
        targets and other nodes to a store context.
        """
        todo = deque([self])
        while todo:
            node = todo.popleft()
            if 'ctx' in node.fields:
                node.ctx = ctx
            todo.extend(node.iter_child_nodes())
        return self

    def set_lineno(self, lineno, override=False):
        """Set the line numbers of the node and children."""
        todo = deque([self])
        while todo:
            node = todo.popleft()
            if 'lineno' in node.attributes:
                if node.lineno is None or override:
                    node.lineno = lineno
            todo.extend(node.iter_child_nodes())
        return self

    def set_environment(self, environment):
        """Set the environment for all nodes."""
        todo = deque([self])
        while todo:
            node = todo.popleft()
            node.environment = environment
            todo.extend(node.iter_child_nodes())
        return self

    def __eq__(self, other):
        return type(self) is type(other) and \
               tuple(self.iter_fields()) == tuple(other.iter_fields())

    def __ne__(self, other):
        return not self.__eq__(other)

    # Restore Python 2 hashing behavior on Python 3
    __hash__ = object.__hash__

    def __repr__(self):
        return '%s(%s)' % (
            self.__class__.__name__,
            ', '.join('%s=%r' % (arg, getattr(self, arg, None)) for
                      arg in self.fields)
        )

    def dump(self):
        def _dump(node):
            if not isinstance(node, Node):
                buf.append(repr(node))
                return

            buf.append('nodes.%s(' % node.__class__.__name__)
            if not node.fields:
                buf.append(')')
                return
            for idx, field in enumerate(node.fields):
                if idx:
                    buf.append(', ')
                value = getattr(node, field)
                if isinstance(value, list):
                    buf.append('[')
                    for idx, item in enumerate(value):
                        if idx:
                            buf.append(', ')
                        _dump(item)
                    buf.append(']')
                else:
                    _dump(value)
            buf.append(')')
        buf = []
        _dump(self)
        return ''.join(buf)



class Stmt(Node):
    """Base node for all statements."""
    abstract = True


class Helper(Node):
    """Nodes that exist in a specific context only."""
    abstract = True


class Template(Node):
    """Node that represents a template.  This must be the outermost node that
    is passed to the compiler.
    """
    fields = ('body',)


class Output(Stmt):
    """A node that holds multiple expressions which are then printed out.
    This is used both for the `print` statement and the regular template data.
    """
    fields = ('nodes',)


class Extends(Stmt):
    """Represents an extends statement."""
    fields = ('template',)


class For(Stmt):
    """The for loop.  `target` is the target for the iteration (usually a
    :class:`Name` or :class:`Tuple`), `iter` the iterable.  `body` is a list
    of nodes that are used as loop-body, and `else_` a list of nodes for the
    `else` block.  If no else node exists it has to be an empty list.

    For filtered nodes an expression can be stored as `test`, otherwise `None`.
    """
    fields = ('target', 'iter', 'body', 'else_', 'test', 'recursive')


class If(Stmt):
    """If `test` is true, `body` is rendered, else `else_`."""
    fields = ('test', 'body', 'elif_', 'else_')


class Macro(Stmt):
    """A macro definition.  `name` is the name of the macro, `args` a list of
    arguments and `defaults` a list of defaults if there are any.  `body` is
    a list of nodes for the macro body.
    """
    fields = ('name', 'args', 'defaults', 'body')


class CallBlock(Stmt):
    """Like a macro without a name but a call instead.  `call` is called with
    the unnamed macro as `caller` argument this node holds.
    """
    fields = ('call', 'args', 'defaults', 'body')


class FilterBlock(Stmt):
    """Node for filter sections."""
    fields = ('body', 'filter')


class With(Stmt):
    """Specific node for with statements.  In older versions of Jinja the
    with statement was implemented on the base of the `Scope` node instead.

    .. versionadded:: 2.9.3
    """