"""Adjust some old Python 2 idioms to their modern counterparts.

* Change some type comparisons to isinstance() calls:

    type(x) == T -> isinstance(x, T)

    type(x) is T -> isinstance(x, T)

    type(x) != T -> not isinstance(x, T)

    type(x) is not T -> not isinstance(x, T)

* Change "while 1:" into "while True:".

* Change both

    v = list(EXPR)

    v.sort()

    foo(v)

and the more general

    v = EXPR

    v.sort()

    foo(v)

into

    v = sorted(EXPR)

    foo(v)

"""

# Author: Jacques Frechet, Collin Winter

# Local imports

from .. import fixer_base

from ..fixer_util import Call, Comma, Name, Node, syms

CMP = "(n='!=' | '==' | 'is' | n=comp_op< 'is' 'not' >)"

TYPE = "power< 'type' trailer< '(' x=any ')' > >"

class FixIdioms(fixer_base.BaseFix):

    explicit = True # The user must ask for this fixer

    PATTERN = r"""

        isinstance=comparison< %s %s T=any >

        |

        isinstance=comparison< T=any %s %s >

        |

        while_stmt< 'while' while='1' ':' any+ >

        |

        sorted=any<

            any*

            simple_stmt<

              expr_stmt< id1=any '='

                         power< list='list' trailer< '(' (not arglist<any+>) any ')' > >

              >

              '\n'

            >

            sort=

            simple_stmt<

              power< id2=any

                     trailer< '.' 'sort' > trailer< '(' ')' >

              >

              '\n'

            >

            next=any*

        >

        |

        sorted=any<

            any*

            simple_stmt< expr_stmt< id1=any '=' expr=any > '\n' >

            sort=

            simple_stmt<

              power< id2=any

                     trailer< '.' 'sort' > trailer< '(' ')' >

              >

              '\n'

            >

            next=any*

        >

    """ % (TYPE, CMP, CMP, TYPE)

    def match(self, node):

        r = super(FixIdioms, self).match(node)

        # If we've matched one of the sort/sorted subpatterns above, we

        # want to reject matches where the initial assignment and the

        # subsequent .sort() call involve different identifiers.

        if r and "sorted" in r:

            if r["id1"] == r["id2"]:

                return r

            return None

        return r

    def transform(self, node, results):

        if "isinstance" in results:

            return self.transform_isinstance(node, results)

        elif "while" in results:

            return self.transform_while(node, results)

        elif "sorted" in results:

            return self.transform_sort(node, results)

        else:

            raise RuntimeError("Invalid match")

    def transform_isinstance(self, node, results):

        x = results["x"].clone() # The thing inside of type()

        T = results["T"].clone() # The type being compared against

        x.set_prefix("")

        T.set_prefix(" ")

        test = Call(Name("isinstance"), [x, Comma(), T])

        if "n" in results:

            test.set_prefix(" ")

            test = Node(syms.not_test, [Name("not"), test])

        test.set_prefix(node.get_prefix())

        return test

    def transform_while(self, node, results):

        one = results["while"]

        one.replace(Name("True", prefix=one.get_prefix()))

    def transform_sort(self, node, results):

        sort_stmt = results["sort"]

        next_stmt = results["next"]

        list_call = results.get("list")

        simple_expr = results.get("expr")

        if list_call:

            list_call.replace(Name("sorted", prefix=list_call.get_prefix()))

        elif simple_expr:

            new = simple_expr.clone()

            new.set_prefix("")

            simple_expr.replace(Call(Name("sorted"), [new],

                                     prefix=simple_expr.get_prefix()))

        else:

            raise RuntimeError("should not have reached here")

        sort_stmt.remove()

        if next_stmt:

            next_stmt[0].set_prefix(sort_stmt.get_prefix())