# Copyright The IETF Trust 2015-2020, All Rights Reserved
# -*- coding: utf-8 -*-


import os
import sys
import time
from textwrap import dedent
from typing import List, Tuple      # pyflakes:ignore

import debug                            # pyflakes:ignore
debug.debug = True

from django.conf import settings
from django.core import checks
from django.utils.module_loading import import_string
import ietf.utils.patch as patch

checks_run = []                         # type: List[str]

def already_ran():
    import inspect
    outerframe = inspect.currentframe().f_back
    name = outerframe.f_code.co_name
    if name in checks_run:
        return True
    else:
        checks_run.append(name)
        return False

@checks.register('directories')
def check_cdn_directory_exists(app_configs, **kwargs):
    """This checks that the path from which the CDN will serve static files for
       this version of the datatracker actually exists.  In development and test
       mode STATIC_ROOT will normally be just static/, but in production it will be
       set to a different part of the file system which is served via CDN, and the
       path will contain the datatracker release version.
    """
    if already_ran():
        return []
    #
    errors = []
    if settings.SERVER_MODE == 'production' and not os.path.exists(settings.STATIC_ROOT):
        errors.append(checks.Error(
            "The static files directory has not been set up.",
            hint="Please run 'ietf/manage.py collectstatic'.",
            obj=None,
            id='datatracker.E001',
        ))
    return errors

@checks.register('files')
def check_group_email_aliases_exists(app_configs, **kwargs):
    from ietf.group.views import check_group_email_aliases
    #
    if already_ran():
        return []
    #
    errors = []
    try:
        ok = check_group_email_aliases()
        if not ok:
            errors.append(checks.Error(
                "Found no aliases in the group email aliases file\n'%s'."%settings.GROUP_ALIASES_PATH,
                hint="Please run ietf/bin/generate-wg-aliases to generate them.",
                obj=None,
                id="datatracker.E0002",
            ))
    except IOError as e:
        errors.append(checks.Error(
            "Could not read group email aliases:\n   %s" % e,
            hint="Please run ietf/bin/generate-wg-aliases to generate them.",
            obj=None,
            id="datatracker.E0003",
        ))
        
    return errors

@checks.register('files')
def check_doc_email_aliases_exists(app_configs, **kwargs):
    from ietf.doc.views_doc import check_doc_email_aliases
    #
    if already_ran():
        return []
    #
    errors = []
    try:
        ok = check_doc_email_aliases()
        if not ok:
            errors.append(checks.Error(
                "Found no aliases in the document email aliases file\n'%s'."%settings.DRAFT_VIRTUAL_PATH,
                hint="Please run ietf/bin/generate-draft-aliases to generate them.",
                obj=None,
                id="datatracker.E0004",
            ))
    except IOError as e:
        errors.append(checks.Error(
            "Could not read document email aliases:\n   %s" % e,
            hint="Please run ietf/bin/generate-draft-aliases to generate them.",
            obj=None,
            id="datatracker.E0005",
        ))

    return errors
    
@checks.register('directories')
def check_id_submission_directories(app_configs, **kwargs):
    #
    if already_ran():
        return []
    #
    errors = []
    for s in ("IDSUBMIT_STAGING_PATH", "IDSUBMIT_REPOSITORY_PATH", "INTERNET_DRAFT_ARCHIVE_DIR", ):
        p = getattr(settings, s)
        if not os.path.exists(p):
            errors.append(checks.Critical(
                "A directory used by the ID submission tool does not\n"
                "exist at the path given in the settings file.  The setting is:\n"
                "    %s = %s" % (s, p),
                hint = ("Please either update the local settings to point at the correct\n"
                    "\tdirectory, or if the setting is correct, create the indicated directory.\n"),
                id = "datatracker.E0006",
            ))
    return errors

@checks.register('files')
def check_id_submission_files(app_configs, **kwargs):
    #
    if already_ran():
        return []
    #
    errors = []
    for s in ("IDSUBMIT_IDNITS_BINARY", ):
        p = getattr(settings, s)
        if not os.path.exists(p):
            errors.append(checks.Critical(
                "A file used by the ID submission tool does not exist\n"
                "at the path given in the settings file.  The setting is:\n"
                "    %s = %s" % (s, p),
                hint = ("Please either update the local settings to point at the correct\n"
                    "\tfile, or if the setting is correct, make sure the file is in place and\n"
                    "\thas the right permissions.\n"),
                id = "datatracker.E0007",
            ))
    return errors


@checks.register('directories')
def check_yang_model_directories(app_configs, **kwargs):
    #
    if already_ran():
        return []
    #
    errors = []
    for s in ("SUBMIT_YANG_RFC_MODEL_DIR", "SUBMIT_YANG_DRAFT_MODEL_DIR", "SUBMIT_YANG_IANA_MODEL_DIR", ):
        p = getattr(settings, s)
        if not os.path.exists(p):
            errors.append(checks.Critical(
                "A directory used by the yang validation tools does\n"
                "not exist at the path gvien in the settings file.  The setting is:\n"
                "    %s = %s" % (s, p),
                hint = ("Please either update your local settings to point at the correct\n"
                    "\tdirectory, or if the setting is correct, create the indicated directory.\n"),
                id = "datatracker.E0017",
            ))
    return errors


@checks.register('submission-checkers')
def check_id_submission_checkers(app_configs, **kwargs):
    #
    if already_ran():
        return []
    #
    errors = []
    for checker_path in settings.IDSUBMIT_CHECKER_CLASSES:
        try:
            checker_class = import_string(checker_path)
        except Exception as e:
            errors.append(checks.Critical(
                "An exception was raised when trying to import the\n"
                "draft submission checker class '%s':\n    %s" % (checker_path, e),
                hint = "Please check that the class exists and can be imported.\n",
                id = "datatracker.E0008",
            ))
        try:
            checker = checker_class()
        except Exception as e:
            errors.append(checks.Critical(
                "An exception was raised when trying to instantiate\n"
                "the draft submission checker class '%s':\n    %s" % (checker_path, e),
                hint = "Please check that the class can be instantiated.\n",
                id = "datatracker.E0009",
            ))
            continue
        for attr in ('name',):
            if not hasattr(checker, attr):
                errors.append(checks.Critical(
                    "The draft submission checker\n    '%s'\n"
                    "has no attribute '%s', which is required" % (checker_path, attr),
                    hint = "Please update the class.\n",
                    id = "datatracker.E0010",
                ))
        checker_methods = ("check_file_txt", "check_file_xml", "check_fragment_txt", "check_fragment_xml", )
        for method in checker_methods:
            if hasattr(checker, method):
                break
        else:
            errors.append(checks.Critical(
                "The draft submission checker\n    '%s'\n"
                " has no recognised checker method;  "
                "should be one or more of %s." % (checker_path, checker_methods),
                hint = "Please update the class.\n",
                id = "datatracker.E0011",
            ))
    return errors

@checks.register('directories')
def check_media_directories(app_configs, **kwargs):
    #
    if already_ran():
        return []
    #
    errors = []
    for s in ("PHOTOS_DIR", ):
        p = getattr(settings, s)
        if not os.path.exists(p):
            errors.append(checks.Critical(
                "A directory used for media uploads and serves does\n"
                "not exist at the path given in the settings file.  The setting is:\n"
                "    %s = %s" % (s, p),
                hint = ("Please either update the local settings to point at the correct\n"
                    "\tdirectory, or if the setting is correct, create the indicated directory.\n"),
                id = "datatracker.E0012",
            ))
    return errors

    
@checks.register('directories')
def check_proceedings_directories(app_configs, **kwargs):
    #
    if already_ran():
        return []
    #
    errors = []
    for s in ("AGENDA_PATH", ):
        p = getattr(settings, s)
        if not os.path.exists(p):
            errors.append(checks.Critical(
                "A directory used for meeting materials does not\n"
                "exist at the path given in the settings file.  The setting is:\n"
                "    %s = %s" % (s, p),
                hint = ("Please either update the local settings to point at the correct\n"
                    "\tdirectory, or if the setting is correct, create the indicated directory.\n"),
                id = "datatracker.E0013",
            ))
    return errors

@checks.register('cache')
def check_cache(app_configs, **kwargs):
    #
    if already_ran():
        return []
    #
    errors = []
    if settings.SERVER_MODE == 'production':
        from django.core.cache import cache
        def cache_error(msg, errnum):
            return checks.Warning(
                ( "A cache test failed with the message:\n    '%s'.\n"
                "This indicates that the cache is unavailable or not working as expected.\n"
                "It will impact performance, but isn't fatal.  The default cache is:\n"
                "    CACHES['default']['BACKEND'] = %s") % (
                    msg,
                    settings.CACHES["default"]["BACKEND"],
                ),
                hint = "Please check that the configured cache backend is available.\n",
                id = "datatracker.%s" % errnum,
            )
        cache_key = "checks:check_cache"
        val = os.urandom(32)
        wait = 1
        cache.set(cache_key, val, wait)
        if not cache.get(cache_key) == val:
            errors.append(cache_error("Could not get value from cache", "E0014"))
        time.sleep(wait+1)
        # should have timed out
        if cache.get(cache_key) == val:
            errors.append(cache_error("Cache value didn't time out", "E0015"))
        cache.set(cache_key, val, settings.SESSION_COOKIE_AGE)
        if not cache.get(cache_key) == val:
            errors.append(cache_error("Cache didn't accept session cookie age", "E0016"))
    return errors

    
def maybe_create_svn_symlinks(settings):
    site_packages_dir = None
    errors = []
    for p in sys.path:
        if ('/env/' in p or '/venv/' in p) and '/site-packages' in p:
            site_packages_dir = p
            break
    if site_packages_dir:
        for path in settings.SVN_PACKAGES:
            if os.path.exists(path):
                dir, name = os.path.split(path)
                package_link = os.path.join(site_packages_dir, name)
                if not os.path.lexists(package_link):
                    os.symlink(path, package_link)
            else:
                errors.append(checks.Critical(
                    "The setting SVN_PACKAGES specify a library path which\n"
                    "does not exist:\n"
                    "   %s\n" % path,
                    hint = "Please provide the correct python system site-package paths for\n"
                    "\tsvn and libsvn in SVN_PACKAGES.\n",
                    id = "datatracker.E0018",))
    return errors

@checks.register('cache')
def check_svn_import(app_configs, **kwargs):
    #
    if already_ran():
        return []
    #
    errors = []
    # 
    errors += maybe_create_svn_symlinks(settings)
    #
    if settings.SERVER_MODE == 'production':
        try:
            import svn                  # pyflakes:ignore
        except ImportError as e:
            errors.append(checks.Critical(
                "Could not import the python svn module:\n   %s\n" % e,
                hint = dedent("""
                    You are running in production mode, and the subversion bindings for python
                    are necessary in order to run the Trac wiki glue scripts.

                    However, the subversion bindings seem to be unavailable.  The subversion
                    bindings are not available for install using pip, but must be supplied by
                    the system package manager.  In order to be available within the python
                    virtualenv, ietf.checks.check_svn_import() tries to create a symlink from
                    the configured location of the system-provided svn package to the
                    site-packages directory of the virtualenv. If you get this message, that has
                    failed to provide the svn package.

                    Please install 'python-subversion' (Debian), 'subversion-python' (RedHat,
                    CentOS, Fedora), 'subversion-python27bindings' (BSD); and provide the
                    correct path to the svn package in settings.SVN_PACKAGE.  Further tips are
                    available at https://trac.edgewall.org/wiki/TracSubversion.

                    """).replace('\n', '\n   ').rstrip(),
                id = "datatracker.E0019",
            ))
    return errors

@checks.register('files')
def maybe_patch_library(app_configs, **kwargs):
    errors = []
    # Change path to our copy of django (this assumes we're running in a
    # virtualenv, which we should)
    import os, django
    django_path = os.path.dirname(django.__file__)
    library_path = os.path.dirname(django_path)
    cwd = os.getcwd()
    # All patches in settings.CHECKS_LIBRARY_PATCHES_TO_APPLY must have a
    # relative file path rooted in the django dir, for instance
    # 'django/db/models/fields/__init__.py'
    for patch_file in settings.CHECKS_LIBRARY_PATCHES_TO_APPLY:
        try:
            patch_path = os.path.join(cwd, patch_file)
            patch_set = patch.fromfile(patch_path)
            if patch_set:
                if not patch_set.apply(root=library_path.encode('utf-8')):
                    errors.append(checks.Warning(
                        "Could not apply patch from file '%s'"%patch_file,
                        hint=("Make sure that the patch file contains a unified diff and has valid file paths\n\n"
                            "\tPatch root: %s\n"
                            "\tTarget files: %s\n") % (library_path, ',  '.join(i.target for i in patch_set.items)),
                        id="datatracker.W0002",
                        ))
            else:
                errors.append(checks.Warning(
                    "Could not parse patch file '%s'"%patch_file,
                    hint="Make sure that the patch file contains a unified diff",
                    id="datatracker.W0001",
                    ))
        except IOError as e:
            errors.append(
                checks.Warning("Could not apply patch from %s: %s" % (patch_file, e),
                    hint="Check file permissions and locations",
                    id="datatracker.W0003",
                )
            )
            pass
    return errors

@checks.register('security')
def check_api_key_in_local_settings(app_configs, **kwargs):
    errors = []
    import ietf.settings_local
    if settings.SERVER_MODE == 'production':
        if not (    hasattr(ietf.settings_local, 'API_PUBLIC_KEY_PEM')
                and hasattr(ietf.settings_local, 'API_PRIVATE_KEY_PEM')):
            errors.append(checks.Critical(
                "There are no API key settings in your settings_local.py",
                hint = dedent("""
                    You are running in production mode, and need API key settings that are
                    different than the default settings.  Please add settings for
                    API_PUBLIC_KEY_PEM and API_PRIVATE_KEY_PEM to your settings local.  The
                    content should be matching public and private keys in PEM format.  You
                    can generate a suitable keypair with 'ssh-keygen -f apikey.pem', and then
                    extract the public key with 'openssl rsa -in apikey.pem -pubout > apikey.pub'.
                    
                    """).replace('\n', '\n   ').rstrip(),
                id = "datatracker.E0020",
            ))
        elif not ( ietf.settings_local.API_PUBLIC_KEY_PEM == settings.API_PUBLIC_KEY_PEM
                    and ietf.settings_local.API_PRIVATE_KEY_PEM == settings.API_PRIVATE_KEY_PEM ):
            errors.append(checks.Critical(
                "Your API key settings in your settings_local.py are not picked up in settings.",
                hint = dedent("""
                    You are running in production mode, and need API key settings which are
                    different than the default settings.  You seem to have  API key settings
                    in settings_local.py, but they don't seem to propagate to django.conf.settings.
                    Please check if you have multiple settings_local.py files.

                    """).replace('\n', '\n   ').rstrip(),
                id = "datatracker.E0021",
            ))

    return errors