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

    Compiles nodes into python code.

    :copyright: (c) 2017 by the Jinja Team.
    :license: BSD, see LICENSE for more details.
"""
from itertools import chain
from copy import deepcopy
from keyword import iskeyword as is_python_keyword
from functools import update_wrapper
from jinja2 import nodes
from jinja2.nodes import EvalContext
from jinja2.visitor import NodeVisitor
from jinja2.optimizer import Optimizer
from jinja2.exceptions import TemplateAssertionError
from jinja2.utils import Markup, concat, escape
from jinja2._compat import range_type, text_type, string_types, \
     iteritems, NativeStringIO, imap, izip
from jinja2.idtracking import Symbols, VAR_LOAD_PARAMETER, \
     VAR_LOAD_RESOLVE, VAR_LOAD_ALIAS, VAR_LOAD_UNDEFINED


operators = {
    'eq':       '==',
    'ne':       '!=',
    'gt':       '>',
    'gteq':     '>=',
    'lt':       '<',
    'lteq':     '<=',
    'in':       'in',
    'notin':    'not in'
}

# what method to iterate over items do we want to use for dict iteration
# in generated code?  on 2.x let's go with iteritems, on 3.x with items
if hasattr(dict, 'iteritems'):
    dict_item_iter = 'iteritems'
else:
    dict_item_iter = 'items'

code_features = ['division']

# does this python version support generator stops? (PEP 0479)
try:
    exec('from __future__ import generator_stop')
    code_features.append('generator_stop')
except SyntaxError:
    pass

# does this python version support yield from?
try:
    exec('def f(): yield from x()')
except SyntaxError:
    supports_yield_from = False
else:
    supports_yield_from = True


def optimizeconst(f):
    def new_func(self, node, frame, **kwargs):
        # Only optimize if the frame is not volatile
        if self.optimized and not frame.eval_ctx.volatile:
            new_node = self.optimizer.visit(node, frame.eval_ctx)
            if new_node != node:
                return self.visit(new_node, frame)
        return f(self, node, frame, **kwargs)
    return update_wrapper(new_func, f)


def generate(node, environment, name, filename, stream=None,
             defer_init=False, optimized=True):
    """Generate the python source for a node tree."""
    if not isinstance(node, nodes.Template):
        raise TypeError('Can\'t compile non template nodes')
    generator = environment.code_generator_class(environment, name, filename,
                                                 stream, defer_init,
                                                 optimized)
    generator.visit(node)
    if stream is None:
        return generator.stream.getvalue()


def has_safe_repr(value):
    """Does the node have a safe representation?"""
    if value is None or value is NotImplemented or value is Ellipsis:
        return True
    if type(value) in (bool, int, float, complex, range_type, Markup) + string_types:
        return True
    if type(value) in (tuple, list, set, frozenset):
        for item in value:
            if not has_safe_repr(item):
                return False
        return True
    elif type(value) is dict:
        for key, value in iteritems(value):
            if not has_safe_repr(key):
                return False
            if not has_safe_repr(value):
                return False
        return True
    return False


def find_undeclared(nodes, names):
    """Check if the names passed are accessed undeclared.  The return value
    is a set of all the undeclared names from the sequence of names found.
    """
    visitor = UndeclaredNameVisitor(names)
    try:
        for node in nodes:
            visitor.visit(node)
    except VisitorExit:
        pass
    return visitor.undeclared


class MacroRef(object):

    def __init__(self, node):
        self.node = node
        self.accesses_caller = False
        self.accesses_kwargs = False
        self.accesses_varargs = False


class Frame(object):
    """Holds compile time information for us."""

    def __init__(self, eval_ctx, parent=None, level=None):
        self.eval_ctx = eval_ctx
        self.symbols = Symbols(parent and parent.symbols or None,
                               level=level)

        # a toplevel frame is the root + soft frames such as if conditions.
        self.toplevel = False

        # the root frame is basically just the outermost frame, so no if
        # conditions.  This information is used to optimize inheritance
        # situations.
        self.rootlevel = False

        # in some dynamic inheritance situations the compiler needs to add
        # write tests around output statements.
        self.require_output_check = parent and parent.require_output_check

        # inside some tags we are using a buffer rather than yield statements.
        # this for example affects {% filter %} or {% macro %}.  If a frame
        # is buffered this variable points to the name of the list used as
        # buffer.
        self.buffer = None

        # the name of the block we're in, otherwise None.
        self.block = parent and parent.block or None

        # the parent of this frame
        self.parent = parent

        if parent is not None:
            self.buffer = parent.buffer

    def copy(self):
        """Create a copy of the current one."""
        rv = object.__new__(self.__class__)
        rv.__dict__.update(self.__dict__)
        rv.symbols = self.symbols.copy()
        return rv

    def inner(self, isolated=False):
        """Return an inner frame."""
        if isolated:
            return Frame(self.eval_ctx, level=self.symbols.level + 1)
        return Frame(self.eval_ctx, self)

    def soft(self):
        """Return a soft frame.  A soft frame may not be modified as
        standalone thing as it shares the resources with the frame it
        was created of, but it's not a rootlevel frame any longer.

        This is only used to implement if-statements.
        """
        rv = self.copy()
        rv.rootlevel = False
        return rv

    __copy__ = copy


class VisitorExit(RuntimeError):
    """Exception used by the `UndeclaredNameVisitor` to signal a stop."""


class DependencyFinderVisitor(NodeVisitor):
    """A visitor that collects filter and test calls."""

    def __init__(self):
        self.filters = set()
        self.tests = set()

    def visit_Filter(self, node):
        self.generic_visit(node)
        self.filters.add(node.name)

    def visit_Test(self, node):
        self.generic_visit(node)
        self.tests.add(node.name)

    def visit_Block(self, node):
        """Stop visiting at blocks."""


class UndeclaredNameVisitor(NodeVisitor):
    """A visitor that checks if a name is accessed without being
    declared.  This is different from the frame visitor as it will
    not stop at closure frames.
    """

    def __init__(self, names):
        self.names = set(names)
        self.undeclared = set()

    def visit_Name(self, node):
        if node.ctx == 'load' and node.name in self.names:
            self.undeclared.add(node.name)
            if self.undeclared == self.names:
                raise VisitorExit()
        else:
            self.names.discard(node.name)

    def visit_Block(self, node):
        """Stop visiting a blocks."""


class CompilerExit(Exception):
    """Raised if the compiler encountered a situation where it just
    doesn't make sense to further process the code.  Any block that
    raises such an exception is not further processed.
    """


class CodeGenerator(NodeVisitor):

    def __init__(self, environment, name, filename, stream=None,
                 defer_init=False, optimized=True):
        if stream is None:
            stream = NativeStringIO()
        self.environment = environment
        self.name = name
        self.filename = filename
        self.stream = stream
        self.created_block_context = False
        self.defer_init = defer_init
        self.optimized = optimized
        if optimized:
            self.optimizer = Optimizer(environment)

        # aliases for imports
        self.import_aliases = {}

        # a registry for all blocks.  Because blocks are moved out
        # into the global python scope they are registered here
        self.blocks = {}

        # the number of extends statements so far
        self.extends_so_far = 0

        # some templates have a rootlevel extends.  In this case we
        # can safely assume that we're a child template and do some
        # more optimizations.
        self.has_known_extends = False

        # the current line number
        self.code_lineno = 1

        # registry of all filters and tests (global, not block local)
        self.tests = {}
        self.filters = {}

        # the debug information
        self.debug_info = []
        self._write_debug_info = None

        # the number of new lines before the next write()
        self._new_lines = 0

        # the line number of the last written statement
        self._last_line = 0

        # true if nothing was written so far.
        self._first_write = True

        # used by the `temporary_identifier` method to get new
        # unique, temporary identifier
        self._last_identifier = 0

        # the current indentation
        self._indentation = 0

        # Tracks toplevel assignments
        self._assign_stack = []

        # Tracks parameter definition blocks
        self._param_def_block = []

        # Tracks the current context.
        self._context_reference_stack = ['context']

    # -- Various compilation helpers

    def fail(self, msg, lineno):
        """Fail with a :exc:`TemplateAssertionError`."""
        raise TemplateAssertionError(msg, lineno, self.name, self.filename)

    def temporary_identifier(self):
        """Get a new unique identifier."""
        self._last_identifier += 1
        return 't_%d' % self._last_identifier

    def buffer(self, frame):
        """Enable buffering for the frame from that point onwards."""
        frame.buffer = self.temporary_identifier()
        self.writeline('%s = []' % frame.buffer)

    def return_buffer_contents(self, frame, force_unescaped=False):
        """Return the buffer contents of the frame."""
        if not force_unescaped:
            if frame.eval_ctx.volatile:
                self.writeline('if context.eval_ctx.autoescape:')
                self.indent()
                self.writeline('return Markup(concat(%s))' % frame.buffer)
                self.outdent()
                self.writeline('else:')
                self.indent()
                self.writeline('return concat(%s)' % frame.buffer)
                self.outdent()
                return
            elif frame.eval_ctx.autoescape:
                self.writeline('return Markup(concat(%s))' % frame.buffer)
                return
        self.writeline('return concat(%s)' % frame.buffer)

    def indent(self):