"""
========
briandoc
========

Sphinx extension that handles docstrings in the Numpy standard format with some
brian-specific tweaks. [1]

It will:

- Convert Parameters etc. sections to field lists.
- Convert See Also section to a See also entry.
- Renumber references.
- Extract the signature from the docstring, if it can't be determined otherwise.

.. [1] https://github.com/numpy/numpy/blob/master/doc/HOWTO_DOCUMENT.rst.txt

"""
import re
import pydoc
import inspect
from docutils import statemachine
from docutils.parsers.rst import directives, Directive

import sphinx
from sphinx.roles import XRefRole
from sphinx.domains.python import PyXRefRole
if sphinx.__version__ < '1.0.1':
    raise RuntimeError("Sphinx 1.0.1 or newer is required")

from brian2.core.preferences import prefs

from .docscrape_sphinx import get_doc_object, SphinxDocString


class BrianPrefsDirective(Directive):
    '''
    A sphinx 'Directive' for automatically generated documentation of Brian preferences.
    
    The directive takes an optional argument, the basename of the preferences
    to document. In addition, you can specify a `nolinks` option which means
    that no target links for the references are added. Do this if you document
    preferences in more then one place.
    
    Examples
    --------
    
    Document one category of preferences and generate links::
    
        .. document_brian_prefs:: core
    
    Document all preferences without generating links::
    
        .. document_brian_prefs::
           :nolinks:
    '''
    required_arguments = 0
    optional_arguments = 1
    final_argument_whitespace = True
    option_spec = {'nolinks': directives.flag}
    has_content = False

    def run(self):
        # The section that should be documented
        if len(self.arguments):
            section = self.arguments[0]
        else:
            section = None
        link_targets = not ('nolinks' in self.options)
        rawtext = prefs.get_documentation(section, link_targets)
        include_lines = statemachine.string2lines(rawtext,
                                                  convert_whitespace=True)
        self.state_machine.insert_input(include_lines, 'Brian preferences')
        return []


def brianobj_role(role, rawtext, text, lineno, inliner, options={}, content=[]):
    '''
    A Sphinx role, used as a wrapper for the default `py:obj` role, allowing
    us to use the simple backtick syntax for brian classes/functions without
    having to qualify the package for classes/functions that are available after
    a `from brian2 import *`, e.g `NeuronGroup`.
    Also allows to directly link to preference names using the same syntax.
    '''
    if text in prefs:
        linktext = text.replace('_', '-').replace('.', '-')
        text = '%s <brian-pref-%s>' % (text, linktext)
        # Use sphinx's cross-reference role
        xref = XRefRole(warn_dangling=True)
        return xref('std:ref', rawtext, text, lineno, inliner, options, content)
    else:
        if text and (not '~' in text):
            try:
                # A simple class or function name
                if not '.' in text:
                    module = __import__('brian2', fromlist=[str(text)])
                    imported = getattr(module, str(text), None)
                    if hasattr(imported, '__module__'):
                        text = '~' + imported.__module__ + '.' + text
                        if inspect.isfunction(imported):
                            text += '()'
                # Possibly a method/classmethod/attribute name
                elif len(text.split('.')) == 2:
                    classname, attrname = text.split('.')
                    # Remove trailing parentheses (will be readded for display)
                    if attrname.endswith('()'):
                        attrname = attrname[:-2]
                    module = __import__('brian2', fromlist=[str(classname)])
                    imported = getattr(module, str(classname), None)
                    if hasattr(imported, '__module__'):
                        # Add trailing parentheses only for methods not for
                        # attributes
                        if inspect.ismethod(getattr(imported,
                                                    str(attrname),
                                                    None)):
                            parentheses = '()'
                        else:
                            parentheses = ''

                        text = ('{classname}.{attrname}{parentheses} '
                                '<{modname}.{classname}.{attrname}>').format(classname=classname,
                                                                             attrname=attrname,
                                                                             modname=imported.__module__,
                                                                             parentheses=parentheses)

            except ImportError:
                pass
        role = 'py:obj'
        py_role = PyXRefRole()
        return py_role(role, rawtext, text, lineno, inliner, options, content)


def mangle_docstrings(app, what, name, obj, options, lines,
                      reference_offset=[0]):
    cfg = dict()
    if what == 'module':
        # Strip top title
        title_re = re.compile(r'^\s*[#*=]{4,}\n[a-z0-9 -]+\n[#*=]{4,}\s*',
                              re.I | re.S)
        lines[:] = title_re.sub('', "\n".join(lines)).split("\n")
        exported_members = getattr(obj, '__all__', None)
        if exported_members:
            lines.append('*Exported members:* ')
            # do not print more than 25 members
            lines.append(', '.join(['`%s`' % member for
                                    member in exported_members[:25]]))
            if len(exported_members) > 25:
                lines.append('... (%d more members)' % (len(exported_members) - 25))

            lines.append('')
    else:
        doc = get_doc_object(obj, what, "\n".join(lines), name=name,
                             config=cfg)
        lines[:] = str(doc).split("\n")

    # replace reference numbers so that there are no duplicates
    references = []
    for line in lines:
        line = line.strip()
        m = re.match(r'^.. \[([a-z0-9_.-])\]', line, re.I)
        if m:
            references.append(m.group(1))

    # start renaming from the longest string, to avoid overwriting parts
    references.sort(key=lambda x:-len(x))
    if references:
        for i, line in enumerate(lines):
            for r in references:
                if re.match(r'^\d+$', r):
                    new_r = "R%d" % (reference_offset[0] + int(r))
                else:
                    new_r = "%s%d" % (r, reference_offset[0])
                lines[i] = lines[i].replace('[%s]_' % r,
                                            '[%s]_' % new_r)
                lines[i] = lines[i].replace('.. [%s]' % r,
                                            '.. [%s]' % new_r)

    reference_offset[0] += len(references)


def mangle_signature(app, what, name, obj, options, sig, retann):
    # Do not try to inspect classes that don't define `__init__`
    if (inspect.isclass(obj) and
        (not hasattr(obj, '__init__') or
        'initializes x; see ' in pydoc.getdoc(obj.__init__))):
        return '', ''

    if not (callable(obj) or hasattr(obj, '__argspec_is_invalid_')):
        return
    if not hasattr(obj, '__doc__'):
        return

    doc = SphinxDocString(pydoc.getdoc(obj))
    if doc['Signature']:
        sig = re.sub("^[^(]*", "", doc['Signature'])
        return sig, ''

def setup(app, get_doc_object_=get_doc_object):
    global get_doc_object
    get_doc_object = get_doc_object_

    app.connect('autodoc-process-docstring', mangle_docstrings)
    app.connect('autodoc-process-signature', mangle_signature)

    # Extra mangling domains
    app.add_domain(NumpyPythonDomain)
    app.add_domain(NumpyCDomain)

    directives.register_directive('document_brian_prefs', BrianPrefsDirective)

    # provide the brianobj role with a link to the Python domain
    app.add_role('brianobj', brianobj_role)

#------------------------------------------------------------------------------
# Docstring-mangling domains
#------------------------------------------------------------------------------

from docutils.statemachine import ViewList
from sphinx.domains.c import CDomain
from sphinx.domains.python import PythonDomain

class ManglingDomainBase(object):
    directive_mangling_map = {}

    def __init__(self, *a, **kw):
        super(ManglingDomainBase, self).__init__(*a, **kw)
        self.wrap_mangling_directives()

    def wrap_mangling_directives(self):
        for name, objtype in list(self.directive_mangling_map.items()):
            self.directives[name] = wrap_mangling_directive(
                self.directives[name], objtype)

class NumpyPythonDomain(ManglingDomainBase, PythonDomain):
    name = 'np'
    directive_mangling_map = {
        'function': 'function',
        'class': 'class',
        'exception': 'class',
        'method': 'function',
        'classmethod': 'function',
        'staticmethod': 'function',
        'attribute': 'attribute',
    }

class NumpyCDomain(ManglingDomainBase, CDomain):
    name = 'np-c'
    directive_mangling_map = {
        'function': 'function',
        'member': 'attribute',
        'macro': 'function',
        'type': 'class',
        'var': 'object',
    }

def wrap_mangling_directive(base_directive, objtype):
    class directive(base_directive):
        def run(self):
            env = self.state.document.settings.env

            name = None
            if self.arguments:
                m = re.match(r'^(.*\s+)?(.*?)(\(.*)?', self.arguments[0])
                name = m.group(2).strip()

            if not name:
                name = self.arguments[0]

            lines = list(self.content)
            mangle_docstrings(env.app, objtype, name, None, None, lines)
            self.content = ViewList(lines, self.content.parent)

            return base_directive.run(self)

    return directive

