#   Copyright (c) 2018 PaddlePaddle Authors. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""DocstringChecker is used to check python doc string's style."""

import astroid

from pylint.checkers import BaseChecker, utils
from pylint.interfaces import IAstroidChecker

from collections import defaultdict
import re


def register(linter):
    """Register checkers."""
    linter.register_checker(DocstringChecker(linter))


class Docstring(object):
    """Docstring class holds the parsed doc string elements.
    """

    def __init__(self):
        self.d = defaultdict(list)  #name->[]
        self.clear()

    def clear(self):
        self.d['Args'] = []
        self.d['Examples'] = []
        self.d['Returns'] = []
        self.d['Raises'] = []
        self.args = {}  #arg_name->arg_type

    def get_level(self, string, indent='    '):
        level = 0
        unit_size = len(indent)
        while string[:unit_size] == indent:
            string = string[unit_size:]
            level += 1

        return level

    def parse(self, doc):
        """parse gets sections from doc
        Such as Args, Returns, Raises, Examples s
        Args:
            doc (string): is the astroid node doc string.
        Returns:
            True if doc is parsed successfully.
        """
        self.clear()

        lines = doc.splitlines()
        state = ("others", -1)
        for l in lines:
            c = l.strip()
            if len(c) <= 0:
                continue

            level = self.get_level(l)
            if c.startswith("Args:"):
                state = ("Args", level)
            elif c.startswith("Returns:"):
                state = ("Returns", level)
            elif c.startswith("Raises:"):
                state = ("Raises", level)
            elif c.startswith("Examples:"):
                state = ("Examples", level)
            else:
                if level > state[1]:
                    self.d[state[0]].append(c)
                    continue

                state = ("others", -1)
                self.d[state[0]].append(c)

        self._arg_with_type()
        return True

    def get_returns(self):
        return self.d['Returns']

    def get_raises(self):
        return self.d['Raises']

    def get_examples(self):
        return self.d['Examples']

    def _arg_with_type(self):

        for t in self.d['Args']:
            m = re.search(r'([A-Za-z0-9_-]+)\s{0,4}(\(.+\))\s{0,4}:', t)
            if m:
                self.args[m.group(1)] = m.group(2)

        return self.args


class DocstringChecker(BaseChecker):
    """DosstringChecker is pylint checker to
    check docstring style.
    """
    __implements__ = (IAstroidChecker, )

    POSITIONAL_MESSAGE_ID = 'str-used-on-positional-format-argument'
    KEYWORD_MESSAGE_ID = 'str-used-on-keyword-format-argument'

    name = 'doc-string-checker'
    symbol = "doc-string"
    priority = -1
    msgs = {
        'W9001': ('One line doc string on > 1 lines', symbol + "-one-line",
                  'Used when a short doc string is on multiple lines'),
        'W9002':
        ('Doc string does not end with "." period', symbol + "-end-with",
         'Used when a doc string does not end with a period'),
        'W9003':
        ('All args with their types must be mentioned in doc string %s',
         symbol + "-with-all-args",
         'Used when not all arguments are in the doc string '),
        'W9005': ('Missing docstring or docstring is too short',
                  symbol + "-missing", 'Add docstring longer >=10'),
        'W9006': ('Docstring indent error, use 4 space for indent',
                  symbol + "-indent-error", 'Use 4 space for indent'),
        'W9007': ('You should add `Returns` in comments',
                  symbol + "-with-returns",
                  'There should be a `Returns` section in comments'),
        'W9008': ('You should add `Raises` section in comments',
                  symbol + "-with-raises",
                  'There should be a `Raises` section in comments'),
    }
    options = ()

    def visit_functiondef(self, node):
        """visit_functiondef checks Function node docstring style.
        Args:
            node (astroid.node): The visiting node.
        Returns:
            True if successful other wise False.
        """

        self.check_doc_string(node)

        if node.tolineno - node.fromlineno <= 10:
            return True

        if not node.doc:
            return True

        doc = Docstring()
        doc.parse(node.doc)

        self.all_args_in_doc(node, doc)
        self.with_returns(node, doc)
        self.with_raises(node, doc)

    def visit_module(self, node):
        self.check_doc_string(node)

    def visit_classdef(self, node):
        self.check_doc_string(node)

    def check_doc_string(self, node):
        self.missing_doc_string(node)
        self.one_line(node)
        self.has_period(node)
        self.indent_style(node)

    def missing_doc_string(self, node):
        if node.name.startswith("__") or node.name.startswith("_"):
            return True
        if node.tolineno - node.fromlineno <= 10:
            return True

        if node.doc is None or len(node.doc) < 10:
            self.add_message('W9005', node=node, line=node.fromlineno)
        return False

    # FIXME(gongwb): give the docstring line-no
    def indent_style(self, node, indent=4):
        """indent_style checks docstring's indent style
        Args:
            node (astroid.node): The visiting node.
            indent (int): The default indent of style
        Returns:
            True if successful other wise False.
        """
        if node.doc is None:
            return True

        doc = node.doc
        lines = doc.splitlines()
        line_num = 0

        for l in lines:
            if line_num == 0:
                continue
            cur_indent = len(l) - len(l.lstrip())
            if cur_indent % indent != 0:
                self.add_message('W9006', node=node, line=node.fromlineno)
                return False
            line_num += 1

        return True

    def one_line(self, node):
        """one_line checks if docstring (len < 40) is on one line.
        Args:
            node (astroid.node): The node visiting.
        Returns:
            True if successful otherwise False.
        """

        doc = node.doc
        if doc is None:
            return True

        if len(doc) > 40:
            return True
        elif sum(doc.find(nl) for nl in ('\n', '\r', '\n\r')) == -3:
            return True
        else:
            self.add_message('W9001', node=node, line=node.fromlineno)
            return False

        return True

    def has_period(self, node):
        """has_period checks if one line doc end-with '.' .
        Args:
            node (astroid.node): the node is visiting.
        Returns:
            True if successful otherwise False.
        """
        if node.doc is None:
            return True

        if len(node.doc.splitlines()) > 1:
            return True

        if not node.doc.strip().endswith('.'):
            self.add_message('W9002', node=node, line=node.fromlineno)
            return False

        return True

    def with_raises(self, node, doc):
        """with_raises checks if one line doc end-with '.' .
        Args:
            node (astroid.node): the node is visiting.
            doc (Docstring): Docstring object.
        Returns:
            True if successful otherwise False.
        """

        find = False
        for t in node.body:
            if not isinstance(t, astroid.Raise):
                continue

            find = True
            break

        if not find:
            return True

        if len(doc.get_raises()) == 0:
            self.add_message('W9008', node=node, line=node.fromlineno)
            return False

        return True

    def with_returns(self, node, doc):
        """with_returns checks if docstring comments what are returned .
        Args:
            node (astroid.node): the node is visiting.
            doc (Docstring): Docstring object.
        Returns:
            True if successful otherwise False.
        """

        if node.name.startswith("__") or node.name.startswith("_"):
            return True
        find = False
        for t in node.body:
            if not isinstance(t, astroid.Return):
                continue

            find = True
            break

        if not find:
            return True

        if len(doc.get_returns()) == 0:
            self.add_message('W9007', node=node, line=node.fromlineno)
            return False

        return True

    def all_args_in_doc(self, node, doc):
        """all_args_in_doc checks if arguments are mentioned in doc
        Args:
            node (astroid.node): the node is visiting.
            doc (Docstring): Docstring object
        Returns:
            True if successful otherwise False.
        """
        if node.name.startswith("__") or node.name.startswith("_"):
            return True
        args = []
        for arg in node.args.get_children():
            if (not isinstance(arg, astroid.AssignName)) \
                or arg.name == "self":
                continue
            args.append(arg.name)

        if len(args) <= 0:
            return True

        parsed_args = doc.args
        args_not_documented = set(args) - set(parsed_args)
        if len(args) > 0 and len(parsed_args) <= 0:
            self.add_message(
                'W9003',
                node=node,
                line=node.fromlineno,
                args=list(args_not_documented))
            return False

        for t in args:
            if t not in parsed_args:
                self.add_message(
                    'W9003', node=node, line=node.fromlineno, args=[t, ])
                return False

        return True
