intersphinx.py

"""
    sphinx.ext.intersphinx
    ~~~~~~~~~~~~~~~~~~~~~~

    Insert links to objects documented in remote Sphinx documentation.

    This works as follows:

    * Each Sphinx HTML build creates a file named "objects.inv" that contains a
      mapping from object names to URIs relative to the HTML set's root.

    * Projects using the Intersphinx extension can specify links to such mapping
      files in the `intersphinx_mapping` config value.  The mapping will then be
      used to resolve otherwise missing references to objects into links to the
      other documentation.

    * By default, the mapping file is assumed to be at the same location as the
      rest of the documentation; however, the location of the mapping file can
      also be specified individually, e.g. if the docs should be buildable
      without Internet access.

    :copyright: Copyright 2007-2021 by the Sphinx team, see AUTHORS.
    :license: BSD, see LICENSE for details.
"""

import concurrent.futures
import functools
import posixpath
import sys
import time
from os import path
from typing import IO, Any, Dict, Iterator, List, Optional, Tuple
from urllib.parse import urlsplit, urlunsplit

from docutils import nodes
from docutils.nodes import Element, TextElement, reference
from docutils.utils import relative_path

import sphinx
from sphinx.addnodes import pending_xref
from sphinx.application import Sphinx
from sphinx.builders.html import INVENTORY_FILENAME
from sphinx.config import Config
from sphinx.domains import Domain
from sphinx.environment import BuildEnvironment
from sphinx.locale import _, __
from sphinx.transforms.post_transforms import SphinxPostTransform
from sphinx.util import logging, requests
from sphinx.util.inventory import InventoryFile
from sphinx.util.typing import Inventory, InventoryItem

logger = logging.getLogger(__name__)


class InventoryAdapter:
    """Inventory adapter for environment"""

    def __init__(self, env: BuildEnvironment) -> None:
        self.env = env

        if not hasattr(env, 'intersphinx_cache'):
            self.env.intersphinx_cache = {}  # type: ignore
            self.env.intersphinx_inventory = {}  # type: ignore
            self.env.intersphinx_named_inventory = {}  # type: ignore

    @property
    def cache(self) -> Dict[str, Tuple[str, int, Inventory]]:
        return self.env.intersphinx_cache  # type: ignore

    @property
    def main_inventory(self) -> Inventory:
        return self.env.intersphinx_inventory  # type: ignore

    @property
    def named_inventory(self) -> Dict[str, Inventory]:
        return self.env.intersphinx_named_inventory  # type: ignore

    def clear(self) -> None:
        self.env.intersphinx_inventory.clear()  # type: ignore
        self.env.intersphinx_named_inventory.clear()  # type: ignore


class ExternalLinksChecker(SphinxPostTransform):
    """
    For each external link, check if it can be replaced by a crossreference.

    We treat each ``reference`` node without ``internal`` attribute as an external link.
    """

    default_priority = 100

    def run(self, **kwargs: Any) -> None:
        for refnode in self.document.traverse(reference):
            self.check_uri(refnode)

    def check_uri(self, refnode: reference) -> None:
        """
        If the URI in ``refnode`` has a replacement in an ``intersphinx`` inventory,
        emit a warning with a replacement suggestion.
        """
        if 'internal' in refnode or 'refuri' not in refnode:
            return

        uri = refnode['refuri']
        cache = self.app.env.intersphinx_cache

        for inventory_uri, (inventory_name, size, inventory) in cache.items():
            if uri.startswith(inventory_uri):
                # build a replacement suggestion
                replacements = find_replacements(self.app, uri)
                try:
                    suggestion = f'try using {next(replacements)!r} instead'
                    logger.warning(
                        __(
                            'hardcoded link %r could be replaced by '
                            'a cross-reference to %r inventory (%s)'
                        ),
                        uri,
                        inventory_name,
                        suggestion,
                        location=refnode,
                    )
                except StopIteration:
                    pass


def find_replacements(app: Sphinx, uri: str) -> Iterator[str]:
    """
    Try finding a crossreference to replace hardcoded ``uri``.

    This is straightforward: search the available inventories
    for an entry that points to the given ``uri`` and build
    a ReST markup that should replace ``uri`` with a crossref.
    """
    cache = getattr(app.env, 'intersphinx_cache', dict())

    for inventory_uri, (inventory_name, size, inventory) in cache.items():
        if uri.startswith(inventory_uri):
            for key, entries in inventory.items():
                domain_name, directive_type = key.split(':')
                for target, (
                    project_name,
                    version,
                    target_uri,
                    display_name,
                ) in entries.items():
                    if uri == target_uri:
                        for domain in app.env.domains.values():
                            if domain_name == domain.name:
                                role = domain.role_for_objtype(directive_type) or 'any'
                                yield f':{domain_name}:{role}:`{target}`'


def _strip_basic_auth(url: str) -> str:
    """Returns *url* with basic auth credentials removed. Also returns the
    basic auth username and password if they're present in *url*.

    E.g.: https://user:pass@example.com => https://example.com

    *url* need not include basic auth credentials.

    :param url: url which may or may not contain basic auth credentials
    :type url: ``str``

    :return: *url* with any basic auth creds removed
    :rtype: ``str``
    """
    frags = list(urlsplit(url))
    # swap out "user[:pass]@hostname" for "hostname"
    if '@' in frags[1]:
        frags[1] = frags[1].split('@')[1]
    return urlunsplit(frags)


def _read_from_url(url: str, config: Config = None) -> IO:
    """Reads data from *url* with an HTTP *GET*.

    This function supports fetching from resources which use basic HTTP auth as
    laid out by RFC1738 § 3.1. See § 5 for grammar definitions for URLs.

    .. seealso:

       https://www.ietf.org/rfc/rfc1738.txt

    :param url: URL of an HTTP resource
    :type url: ``str``

    :return: data read from resource described by *url*
    :rtype: ``file``-like object
    """
    r = requests.get(url, stream=True, config=config, timeout=config.intersphinx_timeout)
    r.raise_for_status()
    r.raw.url = r.url
    # decode content-body based on the header.
    # ref: https://github.com/kennethreitz/requests/issues/2155
    r.raw.read = functools.partial(r.raw.read, decode_content=True)
    return r.raw


def _get_safe_url(url: str) -> str:
    """Gets version of *url* with basic auth passwords obscured. This function
    returns results suitable for printing and logging.

    E.g.: https://user:12345@example.com => https://user@example.com

    :param url: a url
    :type url: ``str``

    :return: *url* with password removed
    :rtype: ``str``
    """
    parts = urlsplit(url)
    if parts.username is None:
        return url
    else:
        frags = list(parts)
        if parts.port:
            frags[1] = '{}@{}:{}'.format(parts.username, parts.hostname, parts.port)
        else:
            frags[1] = '{}@{}'.format(parts.username, parts.hostname)

        return urlunsplit(frags)


def fetch_inventory(app: Sphinx, uri: str, inv: Any) -> Any:
    """Fetch, parse and return an intersphinx inventory file."""
    # both *uri* (base URI of the links to generate) and *inv* (actual
    # location of the inventory file) can be local or remote URIs
    localuri = '://' not in uri
    if not localuri:
        # case: inv URI points to remote resource; strip any existing auth
        uri = _strip_basic_auth(uri)
    try:
        if '://' in inv:
            f = _read_from_url(inv, config=app.config)
        else:
            f = open(path.join(app.srcdir, inv), 'rb')
    except Exception as err:
        err.args = ('intersphinx inventory %r not fetchable due to %s: %s',
                    inv, err.__class__, str(err))
        raise
    try:
        if hasattr(f, 'url'):
            newinv = f.url  # type: ignore
            if inv != newinv:
                logger.info(__('intersphinx inventory has moved: %s -> %s'), inv, newinv)

                if uri in (inv, path.dirname(inv), path.dirname(inv) + '/'):
                    uri = path.dirname(newinv)
        with f:
            try:
                join = path.join if localuri else posixpath.join
                invdata = InventoryFile.load(f, uri, join)
            except ValueError as exc:
                raise ValueError('unknown or unsupported inventory version: %r' % exc) from exc
    except Exception as err:
        err.args = ('intersphinx inventory %r not readable due to %s: %s',
                    inv, err.__class__.__name__, str(err))
        raise
    else:
        return invdata


def fetch_inventory_group(
    name: str, uri: str, invs: Any, cache: Any, app: Any, now: float
) -> bool:
    cache_time = now - app.config.intersphinx_cache_limit * 86400
    failures = []
    try:
        for inv in invs:
            if not inv:
                inv = posixpath.join(uri, INVENTORY_FILENAME)
            # decide whether the inventory must be read: always read local
            # files; remote ones only if the cache time is expired
            if '://' not in inv or uri not in cache or cache[uri][1] < cache_time:
                safe_inv_url = _get_safe_url(inv)
                logger.info(__('loading intersphinx inventory from %s...'), safe_inv_url)
                try:
                    invdata = fetch_inventory(app, uri, inv)
                except Exception as err:
                    failures.append(err.args)
                    continue
                if invdata:
                    cache[uri] = (name, now, invdata)
                    return True
        return False
    finally:
        if failures == []:
            pass
        elif len(failures) < len(invs):
            logger.info(__("encountered some issues with some of the inventories,"
                           " but they had working alternatives:"))
            for fail in failures:
                logger.info(*fail)
        else:
            issues = '\n'.join([f[0] % f[1:] for f in failures])
            logger.warning(__("failed to reach any of the inventories "
                           "with the following issues:") + "\n" + issues)


def load_mappings(app: Sphinx) -> None:
    """Load all intersphinx mappings into the environment."""
    now = int(time.time())
    inventories = InventoryAdapter(app.builder.env)

    with concurrent.futures.ThreadPoolExecutor() as pool:
        futures = []
        for name, (uri, invs) in app.config.intersphinx_mapping.values():
            futures.append(pool.submit(
                fetch_inventory_group, name, uri, invs, inventories.cache, app, now
            ))
        updated = [f.result() for f in concurrent.futures.as_completed(futures)]

    if any(updated):
        inventories.clear()

        # Duplicate values in different inventories will shadow each
        # other; which one will override which can vary between builds
        # since they are specified using an unordered dict.  To make
        # it more consistent, we sort the named inventories and then
        # add the unnamed inventories last.  This means that the
        # unnamed inventories will shadow the named ones but the named
        # ones can still be accessed when the name is specified.
        cached_vals = list(inventories.cache.values())
        named_vals = sorted(v for v in cached_vals if v[0])
        unnamed_vals = [v for v in cached_vals if not v[0]]
        for name, _x, invdata in named_vals + unnamed_vals:
            if name:
                inventories.named_inventory[name] = invdata
            for type, objects in invdata.items():
                inventories.main_inventory.setdefault(type, {}).update(objects)


def _create_element_from_result(domain: Domain, inv_name: Optional[str],
                                data: InventoryItem,
                                node: pending_xref, contnode: TextElement) -> Element:
    proj, version, uri, dispname = data
    if '://' not in uri and node.get('refdoc'):
        # get correct path in case of subdirectories
        uri = path.join(relative_path(node['refdoc'], '.'), uri)
    if version:
        reftitle = _('(in %s v%s)') % (proj, version)
    else:
        reftitle = _('(in %s)') % (proj,)
    newnode = nodes.reference('', '', internal=False, refuri=uri, reftitle=reftitle)
    if node.get('refexplicit'):
        # use whatever title was given
        newnode.append(contnode)
    elif dispname == '-' or \
            (domain.name == 'std' and node['reftype'] == 'keyword'):
        # use whatever title was given, but strip prefix
        title = contnode.astext()
        if inv_name is not None and title.startswith(inv_name + ':'):
            newnode.append(contnode.__class__(title[len(inv_name) + 1:],
                                              title[len(inv_name) + 1:]))
        else:
            newnode.append(contnode)
    else:
        # else use the given display name (used for :ref:)
        newnode.append(contnode.__class__(dispname, dispname))
    return newnode


def _resolve_reference_in_domain_by_target(
        inv_name: Optional[str], inventory: Inventory,
        domain: Domain, objtypes: List[str],
        target: str,
        node: pending_xref, contnode: TextElement) -> Optional[Element]:
    for objtype in objtypes:
        if objtype not in inventory:
            # Continue if there's nothing of this kind in the inventory
            continue

        if target in inventory[objtype]:
            # Case sensitive match, use it
            data = inventory[objtype][target]
        elif objtype == 'std:term':
            # Check for potential case insensitive matches for terms only
            target_lower = target.lower()
            insensitive_matches = list(filter(lambda k: k.lower() == target_lower,
                                              inventory[objtype].keys()))
            if insensitive_matches:
                data = inventory[objtype][insensitive_matches[0]]
            else:
                # No case insensitive match either, continue to the next candidate
                continue
        else:
            # Could reach here if we're not a term but have a case insensitive match.
            # This is a fix for terms specifically, but potentially should apply to
            # other types.
            continue
        return _create_element_from_result(domain, inv_name, data, node, contnode)
    return None


def _resolve_reference_in_domain(env: BuildEnvironment,
                                 inv_name: Optional[str], inventory: Inventory,
                                 honor_disabled_refs: bool,
                                 domain: Domain, objtypes: List[str],
                                 node: pending_xref, contnode: TextElement
                                 ) -> Optional[Element]:
    # we adjust the object types for backwards compatibility
    if domain.name == 'std' and 'cmdoption' in objtypes:
        # until Sphinx-1.6, cmdoptions are stored as std:option
        objtypes.append('option')
    if domain.name == 'py' and 'attribute' in objtypes:
        # Since Sphinx-2.1, properties are stored as py:method
        objtypes.append('method')

    # the inventory contains domain:type as objtype
    objtypes = ["{}:{}".format(domain.name, t) for t in objtypes]

    # now that the objtypes list is complete we can remove the disabled ones
    if honor_disabled_refs:
        disabled = env.config.intersphinx_disabled_reftypes
        objtypes = [o for o in objtypes if o not in disabled]

    # without qualification
    res = _resolve_reference_in_domain_by_target(inv_name, inventory, domain, objtypes,
                                                 node['reftarget'], node, contnode)
    if res is not None:
        return res

    # try with qualification of the current scope instead
    full_qualified_name = domain.get_full_qualified_name(node)
    if full_qualified_name is None:
        return None
    return _resolve_reference_in_domain_by_target(inv_name, inventory, domain, objtypes,
                                                  full_qualified_name, node, contnode)


def _resolve_reference(env: BuildEnvironment, inv_name: Optional[str], inventory: Inventory,
                       honor_disabled_refs: bool,
                       node: pending_xref, contnode: TextElement) -> Optional[Element]:
    # disabling should only be done if no inventory is given
    honor_disabled_refs = honor_disabled_refs and inv_name is None

    if honor_disabled_refs and '*' in env.config.intersphinx_disabled_reftypes:
        return None

    typ = node['reftype']
    if typ == 'any':
        for domain_name, domain in env.domains.items():
            if honor_disabled_refs \
                    and (domain_name + ":*") in env.config.intersphinx_disabled_reftypes:
                continue
            objtypes = list(domain.object_types)
            res = _resolve_reference_in_domain(env, inv_name, inventory,
                                               honor_disabled_refs,
                                               domain, objtypes,
                                               node, contnode)
            if res is not None:
                return res
        return None
    else:
        domain_name = node.get('refdomain')
        if not domain_name:
            # only objects in domains are in the inventory
            return None
        if honor_disabled_refs \
                and (domain_name + ":*") in env.config.intersphinx_disabled_reftypes:
            return None
        domain = env.get_domain(domain_name)
        objtypes = domain.objtypes_for_role(typ)
        if not objtypes:
            return None
        return _resolve_reference_in_domain(env, inv_name, inventory,
                                            honor_disabled_refs,
                                            domain, objtypes,
                                            node, contnode)


def inventory_exists(env: BuildEnvironment, inv_name: str) -> bool:
    return inv_name in InventoryAdapter(env).named_inventory


def resolve_reference_in_inventory(env: BuildEnvironment,
                                   inv_name: str,
                                   node: pending_xref, contnode: TextElement
                                   ) -> Optional[Element]:
    """Attempt to resolve a missing reference via intersphinx references.

    Resolution is tried in the given inventory with the target as is.

    Requires ``inventory_exists(env, inv_name)``.
    """
    assert inventory_exists(env, inv_name)
    return _resolve_reference(env, inv_name, InventoryAdapter(env).named_inventory[inv_name],
                              False, node, contnode)


def resolve_reference_any_inventory(env: BuildEnvironment,
                                    honor_disabled_refs: bool,
                                    node: pending_xref, contnode: TextElement
                                    ) -> Optional[Element]:
    """Attempt to resolve a missing reference via intersphinx references.

    Resolution is tried with the target as is in any inventory.
    """
    return _resolve_reference(env, None, InventoryAdapter(env).main_inventory,
                              honor_disabled_refs,
                              node, contnode)


def resolve_reference_detect_inventory(env: BuildEnvironment,
                                       node: pending_xref, contnode: TextElement
                                       ) -> Optional[Element]:
    """Attempt to resolve a missing reference via intersphinx references.

    Resolution is tried first with the target as is in any inventory.
    If this does not succeed, then the target is split by the first ``:``,
    to form ``inv_name:newtarget``. If ``inv_name`` is a named inventory, then resolution
    is tried in that inventory with the new target.
    """

    # ordinary direct lookup, use data as is
    res = resolve_reference_any_inventory(env, True, node, contnode)
    if res is not None:
        return res

    # try splitting the target into 'inv_name:target'
    target = node['reftarget']
    if ':' not in target:
        return None
    inv_name, newtarget = target.split(':', 1)
    if not inventory_exists(env, inv_name):
        return None
    node['reftarget'] = newtarget
    res_inv = resolve_reference_in_inventory(env, inv_name, node, contnode)
    node['reftarget'] = target
    return res_inv


def missing_reference(app: Sphinx, env: BuildEnvironment, node: pending_xref,
                      contnode: TextElement) -> Optional[Element]:
    """Attempt to resolve a missing reference via intersphinx references."""

    return resolve_reference_detect_inventory(env, node, contnode)


def normalize_intersphinx_mapping(app: Sphinx, config: Config) -> None:
    for key, value in config.intersphinx_mapping.copy().items():
        try:
            if isinstance(value, (list, tuple)):
                # new format
                name, (uri, inv) = key, value
                if not isinstance(name, str):
                    logger.warning(__('intersphinx identifier %r is not string. Ignored'),
                                   name)
                    config.intersphinx_mapping.pop(key)
                    continue
            else:
                # old format, no name
                name, uri, inv = None, key, value

            if not isinstance(inv, tuple):
                config.intersphinx_mapping[key] = (name, (uri, (inv,)))
            else:
                config.intersphinx_mapping[key] = (name, (uri, inv))
        except Exception as exc:
            logger.warning(__('Failed to read intersphinx_mapping[%s], ignored: %r'), key, exc)
            config.intersphinx_mapping.pop(key)


def setup(app: Sphinx) -> Dict[str, Any]:
    app.add_config_value('intersphinx_mapping', {}, True)
    app.add_config_value('intersphinx_cache_limit', 5, False)
    app.add_config_value('intersphinx_timeout', None, False)
    app.add_config_value('intersphinx_disabled_reftypes', ['std:doc'], True)
    app.connect('config-inited', normalize_intersphinx_mapping, priority=800)
    app.connect('builder-inited', load_mappings)
    app.connect('missing-reference', missing_reference)
    app.add_post_transform(ExternalLinksChecker)

    return {
        'version': sphinx.__display_version__,
        'env_version': 1,
        'parallel_read_safe': True
    }


def inspect_main(argv: List[str]) -> None:
    """Debug functionality to print out an inventory"""
    if len(argv) < 1:
        print("Print out an inventory file.\n"
              "Error: must specify local path or URL to an inventory file.",
              file=sys.stderr)
        sys.exit(1)

    class MockConfig:
        intersphinx_timeout: int = None
        tls_verify = False
        user_agent = None

    class MockApp:
        srcdir = ''
        config = MockConfig()

        def warn(self, msg: str) -> None:
            print(msg, file=sys.stderr)

    try:
        filename = argv[0]
        invdata = fetch_inventory(MockApp(), '', filename)  # type: ignore
        for key in sorted(invdata or {}):
            print(key)
            for entry, einfo in sorted(invdata[key].items()):
                print('\t%-40s %s%s' % (entry,
                                        '%-40s: ' % einfo[3] if einfo[3] != '-' else '',
                                        einfo[2]))
    except ValueError as exc:
        print(exc.args[0] % exc.args[1:])
    except Exception as exc:
        print('Unknown error: %r' % exc)


if __name__ == '__main__':
    import logging as _logging

    _logging.basicConfig()

    inspect_main(argv=sys.argv[1:])