# coding=utf-8
# Copyright 2015 Pants project contributors (see CONTRIBUTORS.md).
# Licensed under the Apache License, Version 2.0 (see LICENSE).

from __future__ import absolute_import, division, print_function, unicode_literals

import ast

from pants.contrib.python.checks.checker.common import CheckstylePlugin


class Newlines(CheckstylePlugin):
    @classmethod
    def name(cls):
        return "newlines"

    def iter_toplevel_defs(self):
        for node in self.python_file.tree.body:
            if isinstance(node, ast.FunctionDef) or isinstance(node, ast.ClassDef):
                yield node

    def previous_blank_lines(self, line_number):
        blanks = 0
        while line_number > 1:
            line_number -= 1
            line_value = self.python_file.lines[line_number].strip()
            if line_value.startswith("#"):
                continue
            if line_value:
                break
            blanks += 1
        return blanks

    def nits(self):
        for node in self.iter_toplevel_defs():
            previous_blank_lines = self.previous_blank_lines(node.lineno)
            if node.lineno > 2 and previous_blank_lines != 2:
                yield self.error(
                    "T302", "Expected 2 blank lines, found {}".format(previous_blank_lines), node
                )
        for node in self.iter_ast_types(ast.ClassDef):
            for subnode in node.body:
                if not isinstance(subnode, ast.FunctionDef):
                    continue
                previous_blank_lines = self.previous_blank_lines(subnode.lineno)
                if subnode.lineno - node.lineno > 1 and previous_blank_lines != 1:
                    yield self.error(
                        "T301",
                        "Expected 1 blank lines, found {}".format(previous_blank_lines),
                        subnode,
                    )