"""
========
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, nodes
from docutils.parsers.rst import directives, Directive

from sphinx.roles import XRefRole
from sphinx.domains.python import PyXRefRole

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, 'as_file': 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
        if 'as_file' in self.options:
            rawtext = prefs.as_file
            return [nodes.literal_block(text=rawtext)]
        else:
            rawtext = prefs.get_documentation(section,
                                              'nolinks' not in self.options)
            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 = f'{text} <brian-pref-{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 getattr(imported, '__module__', None):
                        text = f"~{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 = (f"{classname}.{attrname}{parentheses} "
                                f"<{imported.__module__}.{classname}.{attrname}>")

            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([f'`{member}`' for
                                    member in exported_members[:25]]))
            if len(exported_members) > 25:
                lines.append(f'... ({int(len(exported_members) - 25)} more members)')

            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 = f"R{int(reference_offset[0] + int(r))}"
                else:
                    new_r = f"{r}{int(reference_offset[0])}"
                lines[i] = lines[i].replace(f'[{r}]_',
                                            f'[{new_r}]_')
                lines[i] = lines[i].replace(f'.. [{r}]',
                                            f'.. [{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 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

