#
# This file is part of Glances.
#
# SPDX-FileCopyrightText: 2024 Nicolas Hennion <nicolas@nicolargo.com>
#
# SPDX-License-Identifier: LGPL-3.0-only
#

"""Generate Glances Restful API documentation."""

import json
import time
from pprint import pformat

from glances import __apiversion__
from glances.logger import logger

API_URL = f"http://localhost:61208/api/{__apiversion__}"

APIDOC_HEADER = f"""\
.. _api_restful:

Restful/JSON API documentation
==============================

This documentation describes the Glances API version {__apiversion__} (Restful/JSON) interface.

An OpenAPI specification file is available at:
``https://raw.githubusercontent.com/nicolargo/glances/refs/heads/develop/docs/api/openapi.json``

Run the Glances API server
--------------------------

The Glances Restful/API server could be ran using the following command line:

.. code-block:: bash

    # glances -w --disable-webui

It is also ran automatically when Glances is started in Web server mode (-w).

If you want to enable the Glances Central Browser, use:

.. code-block:: bash

    # glances -w --browser --disable-webui

API URL
-------

The default root API URL is ``http://localhost:61208/api/{__apiversion__}``.

The bind address and port could be changed using the ``--bind`` and ``--port`` command line options.

It is also possible to define an URL prefix using the ``url_prefix`` option from the [outputs] section
of the Glances configuration file.

Note: The url_prefix should always end with a slash (``/``).

For example:

.. code-block:: ini

    [outputs]
    url_prefix = /glances/

will change the root API URL to ``http://localhost:61208/glances/api/{__apiversion__}`` and the Web UI URL to
``http://localhost:61208/glances/``

API documentation URL
---------------------

The API documentation is embeded in the server and available at the following URL:
``http://localhost:61208/docs#/``.

Authentication
--------------

Glances API supports both HTTP Basic authentication and JWT (JSON Web Token) Bearer authentication.

To enable authentication, start Glances with the ``--password`` option.

To generate a new login/password pair, use the following command:

.. code-block:: bash

    glances -w --username
    > Enter new username: foo
    > Enter new password: ********
    > Confirm new password: ********
    > User 'username' created/updated successfully.

To reuse an existing login/password pair, start Glances with the ``-u <user>`` option:

.. code-block:: bash

    glances -w -u foo

JWT Token Authentication
~~~~~~~~~~~~~~~~~~~~~~~~

JWT authentication requires the ``python-jose`` library to be installed.

**Step 1: Get a JWT Token**

Request a token by sending your credentials to the token endpoint:

.. code-block:: bash

    curl -X POST http://localhost:61208/api/{__apiversion__}/token \\
      -H "Content-Type: application/json" \\
      -d '{{"username": "your_username", "password": "your_password"}}'

This will return a response like:

.. code-block:: json

    {{
      "access_token": "...",
      "token_type": "bearer",
      "expires_in": 3600
    }}

**Step 2: Use the Token**

Use the token in the Authorization header with Bearer authentication:

.. code-block:: bash

    # Store the token in a variable
    TOKEN="your_access_token_here"

    # Access a protected endpoint
    curl -H "Authorization: Bearer $TOKEN" \\
      http://localhost:61208/api/{__apiversion__}/cpu

**Complete Example:**

.. code-block:: bash

    # Get token and extract access_token
    TOKEN=$(curl -s -X POST http://localhost:61208/api/{__apiversion__}/token \\
      -H "Content-Type: application/json" \\
      -d '{{"username": "glances", "password": "mypassword"}}' \\
      | grep -o '"access_token":"[^"]*"' \\
      | cut -d'"' -f4)

    # Use the token to get CPU stats
    curl -H "Authorization: Bearer $TOKEN" \\
      http://localhost:61208/api/{__apiversion__}/cpu

**Configuration:**

You can configure JWT settings in the Glances configuration file:

.. code-block:: ini

    [outputs]
    # JWT secret key (if not set, a random key will be generated)
    jwt_secret_key = your-secret-key-here
    # JWT token expiration in minutes (default: 60)
    jwt_expire_minutes = 60

**Note:** The token endpoint (``/api/{__apiversion__}/token``) does not require authentication.
Protected endpoints support both Bearer token and Basic Auth authentication methods.

.. _security:

Security
--------

By default, Glances web server runs **without authentication** and binds to
**all network interfaces** (``0.0.0.0``). This means any client that can reach
the server on the network can access the full REST API, including sensitive
system information such as process command-lines, which may contain credentials
(passwords, API keys, tokens passed as arguments).

This default is intentional for ease of use on private, trusted networks (home
labs, local machines, internal infrastructure). However, if your Glances
instance is reachable from untrusted networks, you should take the following
precautions:

**Enable authentication** by starting Glances with the ``--password`` option:

.. code-block:: bash

    glances -w --password

**Bind to localhost only** if remote access is not needed:

.. code-block:: bash

    glances -w --bind 127.0.0.1

**Enable DNS rebinding protection** by setting ``webui_allowed_hosts`` in
``glances.conf``. This restricts the HTTP ``Host`` header values accepted by the
web server. Without this setting, a DNS rebinding attack could allow an
untrusted web page to read the REST API from a victim's browser on the same
network, even without direct network access to the Glances instance.

.. code-block:: ini

    [outputs]
    # Comma-separated list of allowed hostnames/IPs.
    # Wildcards are supported (e.g. *.example.com).
    webui_allowed_hosts=localhost,127.0.0.1,myserver.example.com

When ``webui_allowed_hosts`` is set, requests with a ``Host`` header not in the
list are rejected with ``400 Bad Request``. When absent or commented out
(the default), no host filtering is applied.

**Use a reverse proxy** (nginx, Caddy, Apache) with TLS and authentication for
any public-facing or semi-public deployment. This is the recommended approach
for production environments.

.. code-block:: ini

    # Example: restrict bind to localhost, access via reverse proxy
    # In glances.conf:
    [outputs]
    # Bind to localhost, let the reverse proxy handle external access
    # then configure your reverse proxy to forward to 127.0.0.1:61208
    webui_allowed_hosts=localhost,127.0.0.1

.. note::

    The bind address (``0.0.0.0`` by default) controls which network interfaces
    the server listens on, but it is **not a security boundary**. For
    deployments on non-loopback interfaces, always set ``webui_allowed_hosts``
    and consider enabling authentication.

**CORS (Cross-Origin Resource Sharing)** controls which external websites can
make requests to the Glances API from a browser. By default, Glances allows
requests from any origin (``cors_origins=*``) but does **not** allow credentials
(``cors_credentials=False``). This means cross-origin requests work for
unauthenticated API access, but browsers will not send stored credentials
(e.g. Basic Auth) to the API from a third-party page.

If you need credentialed cross-origin access (e.g. a separate dashboard
application that authenticates to Glances), you **must** configure explicit
origins — the wildcard ``*`` combined with credentials is insecure and will be
automatically rejected:

.. code-block:: ini

    [outputs]
    cors_origins=https://my-dashboard.internal.example.com
    cors_credentials=True

.. warning::

    Setting ``cors_credentials=True`` with ``cors_origins=*`` is not allowed.
    Glances will automatically disable credentials and log a warning if this
    combination is detected. This prevents a class of cross-site data theft
    attacks where any website could read your monitoring data.

When Glances is started without authentication or without host filtering,
warning messages are displayed at startup to remind you of the risks.

WebUI refresh
-------------

It is possible to change the Web UI refresh rate (default is 2 seconds) using the following option in the URL:
``http://localhost:61208/?refresh=5``

"""


def indent_stat(stat, indent='    '):
    # Indent stats to pretty print it
    if isinstance(stat, list) and len(stat) > 1 and isinstance(stat[0], dict):
        # Only display two first items
        return indent + pformat(stat[0:2]).replace('\n', '\n' + indent).replace("'", '"')
    return indent + pformat(stat).replace('\n', '\n' + indent).replace("'", '"')


def print_api_status():
    sub_title = 'GET API status'
    print(sub_title)
    print('-' * len(sub_title))
    print('')
    print('This entry point should be used to check the API status.')
    print('It will the Glances version and a 200 return code if everything is OK.')
    print('')
    print('Get the Rest API status::')
    print('')
    print(f'    # curl -I {API_URL}/status')
    print(indent_stat('HTTP/1.0 200 OK'))
    print('')


def print_plugins_list(stat):
    sub_title = 'GET plugins list'
    print(sub_title)
    print('-' * len(sub_title))
    print('')
    print('Get the plugins list::')
    print('')
    print(f'    # curl {API_URL}/pluginslist')
    print(indent_stat(stat))
    print('')


def print_plugin_stats(plugin, stat):
    sub_title = f'GET {plugin}'
    print(sub_title)
    print('-' * len(sub_title))
    print('')

    print('Get plugin stats::')
    print('')
    print(f'    # curl {API_URL}/{plugin}')
    print(indent_stat(json.loads(stat.get_stats())))
    print('')


def print_plugin_description(plugin, stat):
    if stat.fields_description:
        # For each plugins with a description
        print('Fields descriptions:')
        print('')
        time_since_update = False
        for field, description in stat.fields_description.items():
            print(
                '* **{}**: {} (unit is *{}*)'.format(
                    field,
                    (
                        description['description'][:-1]
                        if description['description'].endswith('.')
                        else description['description']
                    ),
                    description['unit'] if 'unit' in description else 'None',
                )
            )
            if 'rate' in description and description['rate']:
                time_since_update = True
                print(
                    '* **{}**: {} (unit is *{}* per second)'.format(
                        field + '_rate_per_sec',
                        (
                            description['description'][:-1]
                            if description['description'].endswith('.')
                            else description['description']
                        )
                        + ' per second',
                        description['unit'] if 'unit' in description else 'None',
                    )
                )
                print(
                    '* **{}**: {} (unit is *{}*)'.format(
                        field + '_gauge',
                        (
                            description['description'][:-1]
                            if description['description'].endswith('.')
                            else description['description']
                        )
                        + ' (cumulative)',
                        description['unit'] if 'unit' in description else 'None',
                    )
                )

        if time_since_update:
            print(
                '* **{}**: {} (unit is *{}*)'.format(
                    'time_since_update', 'Number of seconds since last update', 'seconds'
                )
            )

        print('')
    else:
        logger.error(f'No fields_description variable defined for plugin {plugin}')


def print_plugin_item_value(plugin, stat, stat_export):
    item = None
    value = None
    if isinstance(stat_export, dict):
        item = list(stat_export.keys())[0]
        value = None
    elif isinstance(stat_export, list) and len(stat_export) > 0 and isinstance(stat_export[0], dict):
        if 'key' in stat_export[0]:
            item = stat_export[0]['key']
        else:
            item = list(stat_export[0].keys())[0]
    if item and stat.get_stats_item(item):
        stat_item = json.loads(stat.get_stats_item(item))
        if isinstance(stat_item[item], list):
            value = stat_item[item][0]
        else:
            value = stat_item[item]
        print('Get a specific field::')
        print('')
        print(f'    # curl {API_URL}/{plugin}/{item}')
        print(indent_stat(stat_item))
        print('')
    if item and value and stat.get_stats_value(item, value):
        print('Get a specific item when field matches the given value::')
        print('')
        print(f'    # curl {API_URL}/{plugin}/{item}/value/{value}')
        print(indent_stat(json.loads(stat.get_stats_value(item, value))))
        print('')


def print_all():
    sub_title = 'GET all stats'
    print(sub_title)
    print('-' * len(sub_title))
    print('')
    print('Get all Glances stats::')
    print('')
    print(f'    # curl {API_URL}/all')
    print('    Return a very big dictionary with all stats')
    print('')
    print('Note: Update is done automatically every time /all or /<plugin> is called.')
    print('')


def print_processes():
    sub_title = 'GET stats of a specific process'
    print(sub_title)
    print('-' * len(sub_title))
    print('')
    print('Get stats for process with PID == 777::')
    print('')
    print(f'    # curl {API_URL}/processes/777')
    print('    Return stats for process (dict)')
    print('')
    print('Enable extended stats for process with PID == 777 (only one process at a time can be enabled)::')
    print('')
    print(f'    # curl -X POST {API_URL}/processes/extended/777')
    print(f'    # curl {API_URL}/all')
    print(f'    # curl {API_URL}/processes/777')
    print('    Return stats for process (dict)')
    print('')
    print('Note: Update *is not* done automatically when you call /processes/<pid>.')
    print('')


def print_top(stats):
    time.sleep(1)
    stats.update()
    sub_title = 'GET top n items of a specific plugin'
    print(sub_title)
    print('-' * len(sub_title))
    print('')
    print('Get top 2 processes of the processlist plugin::')
    print('')
    print(f'    # curl {API_URL}/processlist/top/2')
    print(indent_stat(stats.get_plugin('processlist').get_export()[:2]))
    print('')
    print('Note: Only work for plugin with a list of items')
    print('')


def print_fields_info(stats):
    sub_title = 'GET item description'
    print(sub_title)
    print('-' * len(sub_title))
    print('Get item description (human readable) for a specific plugin/item::')
    print('')
    print(f'    # curl {API_URL}/diskio/read_bytes/description')
    print(indent_stat(stats.get_plugin('diskio').get_item_info('read_bytes', 'description')))
    print('')
    print('Note: the description is defined in the fields_description variable of the plugin.')
    print('')
    sub_title = 'GET item unit'
    print(sub_title)
    print('-' * len(sub_title))
    print('Get item unit for a specific plugin/item::')
    print('')
    print(f'    # curl {API_URL}/diskio/read_bytes/unit')
    print(indent_stat(stats.get_plugin('diskio').get_item_info('read_bytes', 'unit')))
    print('')
    print('Note: the description is defined in the fields_description variable of the plugin.')
    print('')


def print_history(stats):
    time.sleep(1)
    stats.update()
    time.sleep(1)
    stats.update()
    sub_title = 'GET stats history'
    print(sub_title)
    print('-' * len(sub_title))
    print('')
    print('History of a plugin::')
    print('')
    print(f'    # curl {API_URL}/cpu/history')
    print(indent_stat(json.loads(stats.get_plugin('cpu').get_stats_history(nb=3))))
    print('')
    print('Limit history to last 2 values::')
    print('')
    print(f'    # curl {API_URL}/cpu/history/2')
    print(indent_stat(json.loads(stats.get_plugin('cpu').get_stats_history(nb=2))))
    print('')
    print('History for a specific field::')
    print('')
    print(f'    # curl {API_URL}/cpu/system/history')
    print(indent_stat(json.loads(stats.get_plugin('cpu').get_stats_history('system'))))
    print('')
    print('Limit history for a specific field to last 2 values::')
    print('')
    print(f'    # curl {API_URL}/cpu/system/history')
    print(indent_stat(json.loads(stats.get_plugin('cpu').get_stats_history('system', nb=2))))
    print('')


def print_limits(stats):
    sub_title = 'GET limits (used for thresholds)'
    print(sub_title)
    print('-' * len(sub_title))
    print('')
    print('All limits/thresholds::')
    print('')
    print(f'    # curl {API_URL}/all/limits')
    print(indent_stat(stats.getAllLimitsAsDict()))
    print('')
    print('Limits/thresholds for the cpu plugin::')
    print('')
    print(f'    # curl {API_URL}/cpu/limits')
    print(indent_stat(stats.get_plugin('cpu').limits))
    print('')


def print_plugin_post_events():
    sub_title = 'POST clear events'
    print(sub_title)
    print('-' * len(sub_title))
    print('')
    print('Clear all alarms from the list::')
    print('')
    print(f'    # curl -H "Content-Type: application/json" -X POST {API_URL}/events/clear/all')
    print('')
    print('Clear warning alarms from the list::')
    print('')
    print(f'    # curl -H "Content-Type: application/json" -X POST {API_URL}/events/clear/warning')
    print('')


class GlancesStdoutApiRestfulDoc:
    """This class manages the fields description display."""

    def __init__(self, config=None, args=None):
        # Init
        self.config = config
        self.args = args

    def end(self):
        pass

    def update(self, stats, duration=1):
        """Display issue"""

        # Display header
        print(APIDOC_HEADER)

        # Display API status
        print_api_status()

        # Display plugins list
        print_plugins_list(sorted(stats._plugins))

        # Loop over plugins
        for plugin in sorted(stats._plugins):
            stat = stats.get_plugin(plugin)
            print_plugin_stats(plugin, stat)
            print_plugin_description(plugin, stat)
            if plugin == 'alert':
                print_plugin_post_events()

            stat_export = stat.get_export()
            if stat_export is None or stat_export == [] or stat_export == {}:
                continue
            print_plugin_item_value(plugin, stat, stat_export)

        # Get all stats
        print_all()

        # Get process stats
        print_processes()

        # Get top stats (only for plugins with a list of items)
        # Example for processlist plugin: get top 2 processes
        print_top(stats)

        # Fields description
        print_fields_info(stats)

        # History
        print_history(stats)

        # Limits
        print_limits(stats)

        # Return True to exit directly (no refresh)
        return True
