"""Extract reference documentation from the NumPy source tree.

"""
# copied from numpydoc/docscrape.py
import inspect
import textwrap
import re
import pydoc
from warnings import warn
from collections import namedtuple
from collections.abc import Callable, Mapping
import copy
import sys


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:
    """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 = f"{message} in {self.docstring!r}"
        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, config={}):
        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, error=False)
        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)  '\s*'
        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),
                        error=False)
            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(','))
        return out

    def _parse_summary(self):
        """Grab signature (if given) and summary"""
        if self._is_at_section():
            return

        # If several signatures present, take the last one
        while True:
            summary = self._doc.read_to_next_empty_line()
            summary_str = " ".join([s.strip() for s in summary]).strip()
            compiled = re.compile(r'^([\w., ]+=)?\s*[\w\.]+\(.*\)$')
            if compiled.match(summary_str):
                self['Signature'] = summary_str
                if not self._is_at_section():
                    continue
            break

        if summary is not None:
            self['Summary'] = summary

        if not self._is_at_section():
            self['Extended Summary'] = self._read_to_next_section()

    def _parse(self):
        self._doc.reset()
        self._parse_summary()

        sections = list(self._read_sections())
        section_names = {section for section, content in sections}

        has_returns = 'Returns' in section_names
        has_yields = 'Yields' in section_names
        # We could do more tests, but we are not. Arbitrarily.
        if has_returns and has_yields:
            msg = 'Docstring contains both a Returns and Yields section.'
            raise ValueError(msg)
        if not has_yields and 'Receives' in section_names:
            msg = 'Docstring contains a Receives section but not Yields.'
            raise ValueError(msg)

        for (section, content) in sections:
            if not section.startswith('..'):
                section = (s.capitalize() for s in section.split(' '))
                section = ' '.join(section)
                if self.get(section):
                    self._error_location("The section %s appears twice"
                                         % section)

            if section in ('Parameters', 'Other Parameters', 'Attributes',
                           'Methods'):
                self[section] = self._parse_param_list(content)
            elif section in ('Returns', 'Yields', 'Raises', 'Warns',
                             'Receives'):
                self[section] = self._parse_param_list(
                    content, single_element_is_type=True)
            elif section.startswith('.. index::'):
                self['index'] = self._parse_index(section, content)
            elif section == 'See Also':
                self['See Also'] = self._parse_see_also(content)
            else:
                self[section] = content

    def _error_location(self, msg, error=True):
        if hasattr(self, '_obj'):
            # we know where the docs came from:
            try:
                filename = inspect.getsourcefile(self._obj)
            except TypeError:
                filename = None
            msg = msg + (f" in the docstring of {self._obj} in {filename}.")
        if error:
            raise ValueError(msg)
        else:
            warn(msg, stacklevel=3)

    # string conversion routines

    def _str_header(self, name, symbol='-'):
        return [name, len(name)*symbol]

    def _str_indent(self, doc, indent=4):
        out = []
        for line in doc:
            out += [' '*indent + line]
        return out

    def _str_signature(self):
        if self['Signature']:
            return [self['Signature'].replace('*', r'\*')] + ['']
        else:
            return ['']

    def _str_summary(self):
        if self['Summary']:
            return self['Summary'] + ['']
        else:
            return []

    def _str_extended_summary(self):
        if self['Extended Summary']:
            return self['Extended Summary'] + ['']
        else:
            return []

    def _str_param_list(self, name):
        out = []
        if self[name]:
            out += self._str_header(name)
            for param in self[name]:
                parts = []
                if param.name:
                    parts.append(param.name)
                if param.type:
                    parts.append(param.type)
                out += [' : '.join(parts)]
                if param.desc and ''.join(param.desc).strip():
                    out += self._str_indent(param.desc)
            out += ['']
        return out

    def _str_section(self, name):
        out = []
        if self[name]:
            out += self._str_header(name)
            out += self[name]
            out += ['']
        return out

    def _str_see_also(self, func_role):
        if not self['See Also']:
            return []
        out = []
        out += self._str_header("See Also")
        out += ['']
        last_had_desc = True
        for funcs, desc in self['See Also']:
            assert isinstance(funcs, list)
            links = []
            for func, role in funcs:
                if role:
                    link = f':{role}:`{func}`'
                elif func_role:
                    link = f':{func_role}:`{func}`'
                else:
                    link = "`%s`_" % func
                links.append(link)
            link = ', '.join(links)
            out += [link]
            if desc:
                out += self._str_indent([' '.join(desc)])
                last_had_desc = True
            else:
                last_had_desc = False
                out += self._str_indent([self.empty_description])

        if last_had_desc:
            out += ['']
        out += ['']
        return out

    def _str_index(self):
        idx = self['index']
        out = []
        output_index = False
        default_index = idx.get('default', '')
        if default_index:
            output_index = True
        out += ['.. index:: %s' % default_index]
        for section, references in idx.items():
            if section == 'default':
                continue
            output_index = True
            out += ['   :{}: {}'.format(section, ', '.join(references))]
        if output_index:
            return out
        else:
            return ''

    def __str__(self, func_role=''):
        out = []
        out += self._str_signature()
        out += self._str_summary()
        out += self._str_extended_summary()
        for param_list in ('Parameters', 'Returns', 'Yields', 'Receives',
                           'Other Parameters', 'Raises', 'Warns'):
            out += self._str_param_list(param_list)
        out += self._str_section('Warnings')
        out += self._str_see_also(func_role)
        for s in ('Notes', 'References', 'Examples'):
            out += self._str_section(s)
        for param_list in ('Attributes', 'Methods'):
            out += self._str_param_list(param_list)
        out += self._str_index()
        return '\n'.join(out)


def indent(str, indent=4):
    indent_str = ' '*indent
    if str is None:
        return indent_str
    lines = str.split('\n')
    return '\n'.join(indent_str + l for l in lines)


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


def header(text, style='-'):
    return text + '\n' + style*len(text) + '\n'


class FunctionDoc(NumpyDocString):
    def __init__(self, func, role='func', doc=None, config={}):
        self._f = func
        self._role = role  # e.g. "func" or "meth"

        if doc is None:
            if func is None:
                raise ValueError("No function or docstring given")
            doc = inspect.getdoc(func) or ''
        NumpyDocString.__init__(self, doc, config)

    def get_func(self):
        func_name = getattr(self._f, '__name__', self.__class__.__name__)
        if inspect.isclass(self._f):
            func = getattr(self._f, '__call__', self._f.__init__)
        else:
            func = self._f
        return func, func_name

    def __str__(self):
        out = ''

        func, func_name = self.get_func()

        roles = {'func': 'function',
                 'meth': 'method'}

        if self._role:
            if self._role not in roles:
                print("Warning: invalid role %s" % self._role)
            out += '.. {}:: {}\n    \n\n'.format(roles.get(self._role, ''),
                                             func_name)

        out += super().__str__(func_role=self._role)
        return out


class ClassDoc(NumpyDocString):

    extra_public_methods = ['__call__']

    def __init__(self, cls, doc=None, modulename='', func_doc=FunctionDoc,
                 config={}):
        if not inspect.isclass(cls) and cls is not None:
            raise ValueError("Expected a class or None, but got %r" % cls)
        self._cls = cls

        if 'sphinx' in sys.modules:
            from sphinx.ext.autodoc import ALL
        else:
            ALL = object()

        self.show_inherited_members = config.get(
                    'show_inherited_class_members', True)

        if modulename and not modulename.endswith('.'):
            modulename += '.'
        self._mod = modulename

        if doc is None:
            if cls is None:
                raise ValueError("No class or documentation string given")
            doc = pydoc.getdoc(cls)

        NumpyDocString.__init__(self, doc)

        _members = config.get('members', [])
        if _members is ALL:
            _members = None
        _exclude = config.get('exclude-members', [])

        if config.get('show_class_members', True) and _exclude is not ALL:
            def splitlines_x(s):
                if not s:
                    return []
                else:
                    return s.splitlines()
            for field, items in [('Methods', self.methods),
                                 ('Attributes', self.properties)]:
                if not self[field]:
                    doc_list = []
                    for name in sorted(items):
                        if (name in _exclude or
                                (_members and name not in _members)):
                            continue
                        try:
                            doc_item = pydoc.getdoc(getattr(self._cls, name))
                            doc_list.append(
                                Parameter(name, '', splitlines_x(doc_item)))
                        except AttributeError:
                            pass  # method doesn't exist
                    self[field] = doc_list

    @property
    def methods(self):
        if self._cls is None:
            return []
        return [name for name, func in inspect.getmembers(self._cls)
                if ((not name.startswith('_')
                     or name in self.extra_public_methods)
                    and isinstance(func, Callable)
                    and self._is_show_member(name))]

    @property
    def properties(self):
        if self._cls is None:
            return []
        return [name for name, func in inspect.getmembers(self._cls)
                if (not name.startswith('_') and
                    (func is None or isinstance(func, property) or
                     inspect.isdatadescriptor(func))
                    and self._is_show_member(name))]

    def _is_show_member(self, name):
        if self.show_inherited_members:
            return True  # show all class members
        if name not in self._cls.__dict__:
            return False  # class member is inherited, we do not show it
        return True
