"""
Substantially copied from NumpyDoc 1.0pre.
"""
import copy
import inspect
import re
import textwrap
from collections import namedtuple
from collections.abc import Mapping


def dedent_lines(lines):
    """Deindent a list of lines maximally"""
    return textwrap.dedent("\n".join(lines)).split("\n")


def strip_blank_lines(l):
    """Remove leading and trailing blank lines from a list of lines"""
    while l and not l[0].strip():
        del l[0]
    while l and not l[-1].strip():
        del l[-1]
    return l


class Reader(object):
    """
    A line-based string reader.
    """

    def __init__(self, data):
        """
        Parameters
        ----------
        data : str
           String with lines separated by '\n'.
        """
        if isinstance(data, list):
            self._str = data
        else:
            self._str = data.split('\n')  # store string as list of lines

        self.reset()

    def __getitem__(self, n):
        return self._str[n]

    def reset(self):
        self._l = 0  # current line nr

    def read(self):
        if not self.eof():
            out = self[self._l]
            self._l += 1
            return out
        else:
            return ''

    def seek_next_non_empty_line(self):
        for l in self[self._l:]:
            if l.strip():
                break
            else:
                self._l += 1

    def eof(self):
        return self._l >= len(self._str)

    def read_to_condition(self, condition_func):
        start = self._l
        for line in self[start:]:
            if condition_func(line):
                return self[start:self._l]
            self._l += 1
            if self.eof():
                return self[start:self._l + 1]
        return []

    def read_to_next_empty_line(self):
        self.seek_next_non_empty_line()

        def is_empty(line):
            return not line.strip()

        return self.read_to_condition(is_empty)

    def read_to_next_unindented_line(self):
        def is_unindented(line):
            return (line.strip() and (len(line.lstrip()) == len(line)))

        return self.read_to_condition(is_unindented)

    def peek(self, n=0):
        if self._l + n < len(self._str):
            return self[self._l + n]
        else:
            return ''

    def is_empty(self):
        return not ''.join(self._str).strip()


class ParseError(Exception):
    def __str__(self):
        message = self.args[0]
        if hasattr(self, 'docstring'):
            message = "%s in %r" % (message, self.docstring)
        return message


Parameter = namedtuple('Parameter', ['name', 'type', 'desc'])


class NumpyDocString(Mapping):
    """Parses a numpydoc string to an abstract representation

    Instances define a mapping from section title to structured data.
    """

    sections = {
        'Signature': '',
        'Summary': [''],
        'Extended Summary': [],
        'Parameters': [],
        'Returns': [],
        'Yields': [],
        'Receives': [],
        'Raises': [],
        'Warns': [],
        'Other Parameters': [],
        'Attributes': [],
        'Methods': [],
        'See Also': [],
        'Notes': [],
        'Warnings': [],
        'References': '',
        'Examples': '',
        'index': {}
    }

    def __init__(self, docstring):
        orig_docstring = docstring
        docstring = textwrap.dedent(docstring).split('\n')

        self._doc = Reader(docstring)
        self._parsed_data = copy.deepcopy(self.sections)

        try:
            self._parse()
        except ParseError as e:
            e.docstring = orig_docstring
            raise

    def __getitem__(self, key):
        return self._parsed_data[key]

    def __setitem__(self, key, val):
        if key not in self._parsed_data:
            self._error_location("Unknown section %s" % key)
        else:
            self._parsed_data[key] = val

    def __iter__(self):
        return iter(self._parsed_data)

    def __len__(self):
        return len(self._parsed_data)

    def _is_at_section(self):
        self._doc.seek_next_non_empty_line()

        if self._doc.eof():
            return False

        l1 = self._doc.peek().strip()  # e.g. Parameters

        if l1.startswith('.. index::'):
            return True

        l2 = self._doc.peek(1).strip()  # ---------- or ==========
        return l2.startswith('-' * len(l1)) or l2.startswith('=' * len(l1))

    def _strip(self, doc):
        i = 0
        j = 0
        for i, line in enumerate(doc):
            if line.strip():
                break

        for j, line in enumerate(doc[::-1]):
            if line.strip():
                break

        return doc[i:len(doc) - j]

    def _read_to_next_section(self):
        section = self._doc.read_to_next_empty_line()

        while not self._is_at_section() and not self._doc.eof():
            if not self._doc.peek(-1).strip():  # previous line was empty
                section += ['']

            section += self._doc.read_to_next_empty_line()

        return section

    def _read_sections(self):
        while not self._doc.eof():
            data = self._read_to_next_section()
            name = data[0].strip()

            if name.startswith('..'):  # index section
                yield name, data[1:]
            elif len(data) < 2:
                yield StopIteration
            else:
                yield name, self._strip(data[2:])

    def _parse_param_list(self, content, single_element_is_type=False):
        r = Reader(content)
        params = []
        while not r.eof():
            header = r.read().strip()
            if ' : ' in header:
                arg_name, arg_type = header.split(' : ')[:2]
            else:
                if single_element_is_type:
                    arg_name, arg_type = '', header
                else:
                    arg_name, arg_type = header, ''

            desc = r.read_to_next_unindented_line()
            desc = dedent_lines(desc)
            desc = strip_blank_lines(desc)

            params.append(Parameter(arg_name, arg_type, desc))

        return params

    # See also supports the following formats.
    #
    # <FUNCNAME>
    # <FUNCNAME> SPACE* COLON SPACE+ <DESC> SPACE*
    # <FUNCNAME> ( COMMA SPACE+ <FUNCNAME>)+ (COMMA | PERIOD)? SPACE*
    # <FUNCNAME> ( COMMA SPACE+ <FUNCNAME>)* SPACE* COLON SPACE+ <DESC> SPACE*

    # <FUNCNAME> is one of
    #   <PLAIN_FUNCNAME>
    #   COLON <ROLE> COLON BACKTICK <PLAIN_FUNCNAME> BACKTICK
    # where
    #   <PLAIN_FUNCNAME> is a legal function name, and
    #   <ROLE> is any nonempty sequence of word characters.
    # Examples: func_f1  :meth:`func_h1` :obj:`~baz.obj_r` :class:`class_j`
    # <DESC> is a string describing the function.

    _role = r":(?P<role>\w+):"
    _funcbacktick = r"`(?P<name>(?:~\w+\.)?[a-zA-Z0-9_\.-]+)`"
    _funcplain = r"(?P<name2>[a-zA-Z0-9_\.-]+)"
    _funcname = r"(" + _role + _funcbacktick + r"|" + _funcplain + r")"
    _funcnamenext = _funcname.replace('role', 'rolenext')
    _funcnamenext = _funcnamenext.replace('name', 'namenext')
    _description = r"(?P<description>\s*:(\s+(?P<desc>\S+.*))?)?\s*$"
    _func_rgx = re.compile(r"^\s*" + _funcname + r"\s*")
    _line_rgx = re.compile(
        r"^\s*" +
        r"(?P<allfuncs>" +  # group for all function names
        _funcname +
        r"(?P<morefuncs>([,]\s+" + _funcnamenext + r")*)" +
        r")" +  # end of "allfuncs"
        # Some function lists have a trailing comma (or period)
        r"(?P<trailing>[,\.])?" +
        _description)

    # Empty <DESC> elements are replaced with '..'
    empty_description = '..'

    def _parse_see_also(self, content):
        """
        func_name : Descriptive text
            continued text
        another_func_name : Descriptive text
        func_name1, func_name2, :meth:`func_name`, func_name3
        """

        items = []

        def parse_item_name(text):
            """Match ':role:`name`' or 'name'."""
            m = self._func_rgx.match(text)
            if not m:
                raise ParseError("%s is not a item name" % text)
            role = m.group('role')
            name = m.group('name') if role else m.group('name2')
            return name, role, m.end()

        rest = []
        for line in content:
            if not line.strip():
                continue

            line_match = self._line_rgx.match(line)
            description = None
            if line_match:
                description = line_match.group('desc')
                if line_match.group('trailing') and description:
                    self._error_location(
                        'Unexpected comma or period after function list at '
                        'index %d of line '
                        '"%s"' % (line_match.end('trailing'), line))
            if not description and line.startswith(' '):
                rest.append(line.strip())
            elif line_match:
                funcs = []
                text = line_match.group('allfuncs')
                while True:
                    if not text.strip():
                        break
                    name, role, match_end = parse_item_name(text)
                    funcs.append((name, role))
                    text = text[match_end:].strip()
                    if text and text[0] == ',':
                        text = text[1:].strip()
                rest = list(filter(None, [description]))
                items.append((funcs, rest))
            else:
                raise ParseError("%s is not a item name" % line)
        return items

    def _parse_index(self, section, content):
        """
        .. index: default
           :refguide: something, else, and more
        """

        def strip_each_in(lst):
            return [s.strip() for s in lst]

        out = {}
        section = section.split('::')
        if len(section) > 1:
            out['default'] = strip_each_in(section[1].split(','))[0]
        for line in content:
            line = line.split(':')
            if len(line) > 2:
                out[line[1]] = strip_each_in(line[2].split(','))