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

    Implements the template parser.

    :copyright: (c) 2017 by the Jinja Team.
    :license: BSD, see LICENSE for more details.
"""
from jinja2 import nodes
from jinja2.exceptions import TemplateSyntaxError, TemplateAssertionError
from jinja2.lexer import describe_token, describe_token_expr
from jinja2._compat import imap


_statement_keywords = frozenset(['for', 'if', 'block', 'extends', 'print',
                                 'macro', 'include', 'from', 'import',
                                 'set', 'with', 'autoescape'])
_compare_operators = frozenset(['eq', 'ne', 'lt', 'lteq', 'gt', 'gteq'])

_math_nodes = {
    'add': nodes.Add,
    'sub': nodes.Sub,
    'mul': nodes.Mul,
    'div': nodes.Div,
    'floordiv': nodes.FloorDiv,
    'mod': nodes.Mod,
}


class Parser(object):
    """This is the central parsing class Jinja2 uses.  It's passed to
    extensions and can be used to parse expressions or statements.
    """

    def __init__(self, environment, source, name=None, filename=None,
                 state=None):
        self.environment = environment
        self.stream = environment._tokenize(source, name, filename, state)
        self.name = name
        self.filename = filename
        self.closed = False
        self.extensions = {}
        for extension in environment.iter_extensions():
            for tag in extension.tags:
                self.extensions[tag] = extension.parse
        self._last_identifier = 0
        self._tag_stack = []
        self._end_token_stack = []

    def fail(self, msg, lineno=None, exc=TemplateSyntaxError):
        """Convenience method that raises `exc` with the message, passed
        line number or last line number as well as the current name and
        filename.
        """
        if lineno is None:
            lineno = self.stream.current.lineno
        raise exc(msg, lineno, self.name, self.filename)

    def _fail_ut_eof(self, name, end_token_stack, lineno):
        expected = []
        for exprs in end_token_stack:
            expected.extend(imap(describe_token_expr, exprs))
        if end_token_stack:
            currently_looking = ' or '.join(
                "'%s'" % describe_token_expr(expr)
                for expr in end_token_stack[-1])
        else:
            currently_looking = None

        if name is None:
            message = ['Unexpected end of template.']
        else:
            message = ['Encountered unknown tag \'%s\'.' % name]

        if currently_looking:
            if name is not None and name in expected:
                message.append('You probably made a nesting mistake. Jinja '
                               'is expecting this tag, but currently looking '
                               'for %s.' % currently_looking)
            else:
                message.append('Jinja was looking for the following tags: '
                               '%s.' % currently_looking)

        if self._tag_stack:
            message.append('The innermost block that needs to be '
                           'closed is \'%s\'.' % self._tag_stack[-1])

        self.fail(' '.join(message), lineno)

    def fail_unknown_tag(self, name, lineno=None):
        """Called if the parser encounters an unknown tag.  Tries to fail
        with a human readable error message that could help to identify
        the problem.
        """
        return self._fail_ut_eof(name, self._end_token_stack, lineno)

    def fail_eof(self, end_tokens=None, lineno=None):
        """Like fail_unknown_tag but for end of template situations."""
        stack = list(self._end_token_stack)
        if end_tokens is not None:
            stack.append(end_tokens)
        return self._fail_ut_eof(None, stack, lineno)

    def is_tuple_end(self, extra_end_rules=None):
        """Are we at the end of a tuple?"""
        if self.stream.current.type in ('variable_end', 'block_end', 'rparen'):
            return True
        elif extra_end_rules is not None:
            return self.stream.current.test_any(extra_end_rules)
        return False

    def free_identifier(self, lineno=None):
        """Return a new free identifier as :class:`~jinja2.nodes.InternalName`."""
        self._last_identifier += 1
        rv = object.__new__(nodes.InternalName)
        nodes.Node.__init__(rv, 'fi%d' % self._last_identifier, lineno=lineno)
        return rv

    def parse_statement(self):
        """Parse a single statement."""
        token = self.stream.current
        if token.type != 'name':
            self.fail('tag name expected', token.lineno)
        self._tag_stack.append(token.value)
        pop_tag = True
        try:
            if token.value in _statement_keywords:
                return getattr(self, 'parse_' + self.stream.current.value)()
            if token.value == 'call':
                return self.parse_call_block()
            if token.value == 'filter':
                return self.parse_filter_block()
            ext = self.extensions.get(token.value)
            if ext is not None:
                return ext(self)

            # did not work out, remove the token we pushed by accident
            # from the stack so that the unknown tag fail function can
            # produce a proper error message.
            self._tag_stack.pop()
            pop_tag = False
            self.fail_unknown_tag(token.value, token.lineno)
        finally:
            if pop_tag:
                self._tag_stack.pop()

    def parse_statements(self, end_tokens, drop_needle=False):
        """Parse multiple statements into a list until one of the end tokens
        is reached.  This is used to parse the body of statements as it also
        parses template data if appropriate.  The parser checks first if the
        current token is a colon and skips it if there is one.  Then it checks
        for the block end and parses until if one of the `end_tokens` is
        reached.  Per default the active token in the stream at the end of
        the call is the matched end token.  If this is not wanted `drop_needle`
        can be set to `True` and the end token is removed.
        """
        # the first token may be a colon for python compatibility
        self.stream.skip_if('colon')

        # in the future it would be possible to add whole code sections
        # by adding some sort of end of statement token and parsing those here.
        self.stream.expect('block_end')
        result = self.subparse(end_tokens)

        # we reached the end of the template too early, the subparser
        # does not check for this, so we do that now
        if self.stream.current.type == 'eof':
            self.fail_eof(end_tokens)

        if drop_needle:
            next(self.stream)
        return result

    def parse_set(self):
        """Parse an assign statement."""
        lineno = next(self.stream).lineno
        target = self.parse_assign_target(with_namespace=True)
        if self.stream.skip_if('assign'):
            expr = self.parse_tuple()
            return nodes.Assign(target, expr, lineno=lineno)
        filter_node = self.parse_filter(None)
        body = self.parse_statements(('name:endset',),
                                     drop_needle=True)
        return nodes.AssignBlock(target, filter_node, body, lineno=lineno)

    def parse_for(self):
        """Parse a for loop."""
        lineno = self.stream.expect('name:for').lineno
        target = self.parse_assign_target(extra_end_rules=('name:in',))
        self.stream.expect('name:in')
        iter = self.parse_tuple(with_condexpr=False,
                                extra_end_rules=('name:recursive',))
        test = None
        if self.stream.skip_if('name:if'):
            test = self.parse_expression()
        recursive = self.stream.skip_if('name:recursive')
        body = self.parse_statements(('name:endfor', 'name:else'))
        if next(self.stream).value == 'endfor':
            else_ = []
        else:
            else_ = self.parse_statements(('name:endfor',), drop_needle=True)
        return nodes.For(target, iter, body, else_, test,
                         recursive, lineno=lineno)

    def parse_if(self):
        """Parse an if construct."""
        node = result = nodes.If(lineno=self.stream.expect('name:if').lineno)
        while 1:
            node.test = self.parse_tuple(with_condexpr=False)
            node.body = self.parse_statements(('name:elif', 'name:else',
                                               'name:endif'))
            node.elif_ = []
            node.else_ = []
            token = next(self.stream)
            if token.test('name:elif'):
                node = nodes.If(lineno=self.stream.current.lineno)
                result.elif_.append(node)
                continue
            elif token.test('name:else'):
                result.else_ = self.parse_statements(('name:endif',),
                                                     drop_needle=True)
            break
        return result

    def parse_with(self):
        node = nodes.With(lineno=next(self.stream).lineno)
        targets = []
        values = []
        while self.stream.current.type != 'block_end':
            lineno = self.stream.current.lineno
            if targets:
                self.stream.expect('comma')
            target = self.parse_assign_target()
            target.set_ctx('param')
            targets.append(target)
            self.stream.expect('assign')
            values.append(self.parse_expression())
        node.targets = targets
        node.values = values
        node.body = self.parse_statements(('name:endwith',),
                                          drop_needle=True)
        return node

    def parse_autoescape(self):
        node = nodes.ScopedEvalContextModifier(lineno=next(self.stream).lineno)
        node.options = [
            nodes.Keyword('autoescape', self.parse_expression())
        ]
        node.body = self.parse_statements(('name:endautoescape',),
                                            drop_needle=True)
        return nodes.Scope([node])

    def parse_block(self):
        node = nodes.Block(lineno=next(self.stream).lineno)
        node.name = self.stream.expect('name').value
        node.scoped = self.stream.skip_if('name:scoped')

        # common problem people encounter when switching from django
        # to jinja.  we do not support hyphens in block names, so let's
        # raise a nicer error message in that case.
        if self.stream.current.type == 'sub':
            self.fail('Block names in Jinja have to be valid Python '
                      'identifiers and may not contain hyphens, use an '
                      'underscore instead.')

        node.body = self.parse_statements(('name:endblock',), drop_needle=True)
        self.stream.skip_if('name:' + node.name)
        return node

    def parse_extends(self):
        node = nodes.Extends(lineno=next(self.stream).lineno)
        node.template = self.parse_expression()
        return node

    def parse_import_context(self, node, default):
        if self.stream.current.test_any('name:with', 'name:without') and \
           self.stream.look().test('name:context'):
            node.with_context = next(self.stream).value == 'with'
            self.stream.skip()
        else:
            node.with_context = default
        return node

    def parse_include(self):
        node = nodes.Include(lineno=next(self.stream).lineno)
        node.template = self.parse_expression()
        if self.stream.current.test('name:ignore') and \
           self.stream.look().test('name:missing'):
            node.ignore_missing = True
            self.stream.skip(2)
        else:
            node.ignore_missing = False
        return self.parse_import_context(node, True)

    def parse_import(self):
        node = nodes.Import(lineno=next(self.stream).lineno)
        node.template = self.parse_expression()
        self.stream.expect('name:as')
        node.target = self.parse_assign_target(name_only=True).name
        return self.parse_import_context(node, False)

    def parse_from(self):
        node = nodes.FromImport(lineno=next(self.stream).lineno)
        node.template = self.parse_expression()
        self.stream.expect('name:import')
        node.names = []

        def parse_context():
            if self.stream.current.value in ('with', 'without') and \
               self.stream.look().test('name:context'):
                node.with_context = next(self.stream).value == 'with'
                self.stream.skip()
                return True
            return False

        while 1:
            if node.names:
                self.stream.expect('comma')
            if self.stream.current.type == 'name':
                if parse_context():
                    break
                target = self.parse_assign_target(name_only=True)
                if target.name.startswith('_'):
                    self.fail('names starting with an underline can not '
                              'be imported', target.lineno,
                              exc=TemplateAssertionError)
                if self.stream.skip_if('name:as'):
                    alias = self.parse_assign_target(name_only=True)
                    node.names.append((target.name, alias.name))
                else:
                    node.names.append(target.name)
                if parse_context() or self.stream.current.type != 'comma':
                    break
            else:
                self.stream.expect('name')
        if not hasattr(node, 'with_context'):
            node.with_context = False
        return node

    def parse_signature(self, node):
        node.args = args = []
        node.defaults = defaults = []
        self.stream.expect('lparen')