"""
* adds github_link(mode) context variable: provides URL (in relevant mode) of
  current document on github
* if sphinx.ext.linkcode is enabled, automatically generates github linkcode
  links (by setting config.linkcode_resolve)

Settings
========

* ``github_user``, username/organisation under which the project lives
* ``github_project``, name of the project on github
* (optional) ``version``, github branch to link to (default: master)

Notes
=====

* provided ``linkcode_resolve`` only supports Python domain
* generates https github links
* explicitly imports ``odoo``, so useless for anyone else
"""

import importlib
import inspect
import os.path

import werkzeug
import contextlib


def setup(app):
    app.add_config_value('github_user', None, 'env')
    app.add_config_value('github_project', None, 'env')
    app.connect('html-page-context', add_doc_link)

    def linkcode_resolve(domain, info):
        """ Resolves provided object to corresponding github URL """
        # TODO: js?
        if domain != 'py':
            return None

        if not (app.config.github_user and app.config.github_project):
            return None

        module, fullname = info['module'], info['fullname']
        # TODO: attributes/properties don't have modules, maybe try to look
        #       them up based on their cached host object?
        if not module:
            return None

        obj = importlib.import_module(module)
        for item in fullname.split('.'):
            obj = getattr(obj, item, None)

        if obj is None:
            return None

        # get original from decorated methods
        with contextlib.suppress(AttributeError):
            obj = obj._orig

        try:
            obj_source_path = inspect.getsourcefile(obj)
            _, line = inspect.getsourcelines(obj)
        except (TypeError, OSError):
            # obj doesn't have a module, or something
            return None

        # FIXME: make finding project root project-independent
        if module.startswith('odoo.upgrade.util'):
            from odoo.upgrade import util
            project = 'upgrade-util'
            project_root = os.path.join(os.path.dirname(util.__file__), '../..')
        else:
            import odoo
            project = 'odoo'
            project_root = os.path.join(os.path.dirname(odoo.__file__), '..')
        return make_github_link(
            app,
            project=project,
            path=os.path.relpath(obj_source_path, project_root),
            line=line,
        )
    app.config.linkcode_resolve = linkcode_resolve

    return {
        'parallel_read_safe': True,
        'parallel_write_safe': True
    }

def make_github_link(app, project, path, line=None, mode="blob"):
    branch = app.config.version or 'master'
    if project == 'upgrade-util':
        branch = 'master'

    urlpath = f"/{app.config.github_user}/{project}/{mode}/{branch}/{path}"
    return werkzeug.urls.url_unparse((
        'https',
        'git.nextzenos.com',
        urlpath,
        '',
        '' if line is None else 'L%d' % line
    ))


def add_doc_link(app, pagename, templatename, context, doctree):
    """ Add github_link function linking to the current (.rst) page on github """
    if not app.config.github_user and app.config.github_project:
        return

    # FIXME: find other way to recover current document's source suffix
    # in Sphinx 1.3 it's possible to have multiple source suffixes and that
    # may be useful in the future
    source_suffix = app.config.source_suffix
    source_suffix = next(iter(source_suffix))
    context['github_link'] = lambda mode='_edit': make_github_link(
        app, project=app.config.github_project, path=f'content/{pagename}{source_suffix}', mode=mode)