"""
Copyright 2013 Steven Diamond

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.
"""

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

"""

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

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 not self._parsed_data.has_key(key):
            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.iteritems():
            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.getargspec(func)
                argspec = inspect.formatargspec(*argspec)
                argspec = argspec.replace('*','\*')
                signature = '%s%s' % (func_name, argspec)
            except TypeError, 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 not roles.has_key(self._role):
                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 callable(func))]

    @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]
