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

"""

import inspect
import textwrap
import re
import pydoc
from io import StringIO
from warnings import warn
import collections


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 NumpyDocString(object):

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

        self._doc = Reader(docstring)
        self._parsed_data = {
            'Signature': '',
            'Summary': [''],
            'Extended Summary': [],
            'Parameters': [],
            'Returns': [],
            'Raises': [],
            'Warns': [],
            'Other Parameters': [],
            'Attributes': [],
            'Methods': [],
            'See Also': [],
            'Notes': [],
            'Warnings': [],
            'References': '',
            'Examples': '',
            'index': {}
        }

        self._parse()

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

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

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

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

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

        return params

    _name_rgx = re.compile(r"^\s*(:(?P<role>\w+):`(?P<name>[a-zA-Z0-9_.-]+)`|"
                           r" (?P<name2>[a-zA-Z0-9_.-]+))\s*", re.X)

    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._name_rgx.match(text)
            if m:
                g = m.groups()
                if g[1] is None:
                    return g[3], None
                else:
                    return g[2], g[1]
            raise ValueError("%s is not a item name" % text)

        def push_item(name, rest):
            if not name:
                return
            name, role = parse_item_name(name)
            items.append((name, list(rest), role))
            del rest[:]

        current_func = None
        rest = []

        for line in content:
            if not line.strip():
                continue

            m = self._name_rgx.match(line)
            if m and line[m.end():].strip().startswith(':'):
                push_item(current_func, rest)
                current_func, line = line[:m.end()], line[m.end():]
                rest = [line.split(':', 1)[1].strip()]
                if not rest[0]:
                    rest = []
            elif not line.startswith(' '):
                push_item(current_func, rest)
                current_func = None
                if ',' in line:
                    for func in line.split(','):
                        if func.strip():
                            push_item(func, [])
                elif line.strip():
                    current_func = line
            elif current_func is not None:
                rest.append(line.strip())
        push_item(current_func, rest)
        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

        summary = self._doc.read_to_next_empty_line()
        summary_str = " ".join([s.strip() for s in summary]).strip()
        if re.compile('^([\w., ]+=)?\s*[\w\.]+\(.*\)$').match(summary_str):
            self['Signature'] = summary_str
            if not self._is_at_section():
                self['Summary'] = self._doc.read_to_next_empty_line()
        else:
            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()

        for (section, content) in self._read_sections():
            if not section.startswith('..'):
                section = ' '.join([s.capitalize()
                                    for s in section.split(' ')])
            if section in ('Parameters', 'Returns', 'Raises', 'Warns',
                           'Other Parameters', 'Attributes', 'Methods'):
                self[section] = self._parse_param_list(content)
            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

    # 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('*', '\*')] + ['']
        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, param_type, desc in self[name]:
                out += ['%s : %s' % (param, param_type)]
                out += self._str_indent(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")
        last_had_desc = True
        for func, desc, role in self['See Also']:
            if role:
                link = ':%s:`%s`' % (role, func)
            elif func_role:
                link = ':%s:`%s`' % (func_role, func)
            else:
                link = "`%s`_" % func
            if desc or last_had_desc:
                out += ['']
                out += [link]
            else:
                out[-1] += ", %s" % link
            if desc:
                out += self._str_indent([' '.join(desc)])
                last_had_desc = True
            else:
                last_had_desc = False
        out += ['']
        return out

    def _str_index(self):
        idx = self['index']
        out = []
        out += ['.. index:: %s' % idx.get('default', '')]
        for section, references in idx.items():
            if section == 'default':
                continue
            out += ['   :%s: %s' % (section, ', '.join(references))]
        return out

    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', '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)

        if not self['Signature'] and func is not None:
            func, func_name = self.get_func()
            try:
                # try to read signature
                argspec = inspect.signature(func)
                argspec = inspect.formatargspec(*argspec)
                argspec = argspec.replace('*', '\*')
                signature = '%s%s' % (func_name, argspec)
            except TypeError as e:
                signature = '%s()' % func_name
            self['Signature'] = signature

    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()
        signature = self['Signature'].replace('*', '\*')

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

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

        out += super(FunctionDoc, self).__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 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)

        if config.get('show_class_members', True):
            if not self['Methods']:
                self['Methods'] = [(name, '', '')
                                   for name in sorted(self.methods)]
            if not self['Attributes']:
                self['Attributes'] = [(name, '', '')
                                      for name in sorted(self.properties)]

    @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, collections.Callable))]

    @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]
