# based on http://protips.readthedocs.io/link-roles.html

from __future__ import print_function
from __future__ import unicode_literals
import re
import os
import subprocess
from docutils import nodes


def get_github_rev():
    path = subprocess.check_output(['git', 'rev-parse', '--short', 'HEAD']).strip().decode('utf-8')
    try:
        tag = subprocess.check_output(['git', 'describe', '--exact-match']).strip().decode('utf-8')
    except subprocess.CalledProcessError:
        tag = None
    print('Git commit ID: ', path)
    if tag:
        print('Git tag: ', tag)
        return tag
    return path


def setup(app):
    rev = get_github_rev()

    # links to files or folders on the GitHub
    baseurl = 'https://github.com/espressif/esp-idf'
    app.add_role('idf', autolink('{}/tree/{}/%s'.format(baseurl, rev)))
    app.add_role('idf_file', autolink('{}/blob/{}/%s'.format(baseurl, rev)))
    app.add_role('idf_raw', autolink('{}/raw/{}/%s'.format(baseurl, rev)))
    app.add_role('component', autolink('{}/tree/{}/components/%s'.format(baseurl, rev)))
    app.add_role('component_file', autolink('{}/blob/{}/components/%s'.format(baseurl, rev)))
    app.add_role('component_raw', autolink('{}/raw/{}/components/%s'.format(baseurl, rev)))
    app.add_role('example', autolink('{}/tree/{}/examples/%s'.format(baseurl, rev)))
    app.add_role('example_file', autolink('{}/blob/{}/examples/%s'.format(baseurl, rev)))
    app.add_role('example_raw', autolink('{}/raw/{}/examples/%s'.format(baseurl, rev)))

    # link to the current documentation file in specific language version
    on_rtd = os.environ.get('READTHEDOCS', None) == 'True'
    if on_rtd:
        # provide RTD specific commit identification to be included in the link
        tag_rev = 'latest'
        if (subprocess.check_output(['git','rev-parse', '--short', 'HEAD']).decode('utf-8').strip() != rev):
            tag_rev = rev
    else:
        # if not on the RTD then provide generic identification
        tag_rev = subprocess.check_output(['git', 'describe', '--always']).decode('utf-8').strip()

    app.add_role('link_to_translation', crosslink('%s../../%s/{}/%s.html'.format(tag_rev)))

    return {'parallel_read_safe': True, 'parallel_write_safe': True, 'version': '0.1'}


def autolink(pattern):
    def role(name, rawtext, text, lineno, inliner, options={}, content=[]):
        m = re.search('(.*)\s*<(.*)>', text)  # noqa: W605 - regular expression
        if m:
            link_text = m.group(1)
            link = m.group(2)
        else:
            link_text = text
            link = text
        url = pattern % (link,)
        node = nodes.reference(rawtext, link_text, refuri=url, **options)
        return [node], []
    return role


def crosslink(pattern):
    def role(name, rawtext, text, lineno, inliner, options={}, content=[]):
        (language, link_text) = text.split(':')
        docname = inliner.document.settings.env.docname
        doc_path = inliner.document.settings.env.doc2path(docname, None, None)
        return_path = '../' * doc_path.count('/')
        url = pattern % (return_path, language, docname)
        node = nodes.reference(rawtext, link_text, refuri=url, **options)
        return [node], []
    return role