From 77af4c7a5cb3d0b3e813c7f678099014c94ff6aa Mon Sep 17 00:00:00 2001
From: Batuhan Taskaya <isidentical@gmail.com>
Date: Tue, 8 Mar 2022 01:34:04 +0300
Subject: [PATCH] Decouple parser definition from argparse (#1293)

---
 docs/README.md              |  21 ++
 httpie/cli/constants.py     |   8 +-
 httpie/cli/definition.py    | 531 ++++++++++++++++++------------------
 httpie/cli/options.py       | 189 +++++++++++++
 httpie/core.py              |  29 +-
 httpie/manager/cli.py       |   8 +
 httpie/manager/tasks.py     |  25 ++
 httpie/output/models.py     |  44 +++
 httpie/output/streams.py    |   4 +-
 httpie/output/writer.py     |  70 +++--
 tests/test_httpie_cli.py    |  13 +
 tests/test_parser_schema.py |  60 ++++
 12 files changed, 708 insertions(+), 294 deletions(-)
 create mode 100644 httpie/cli/options.py
 create mode 100644 httpie/output/models.py
 create mode 100644 tests/test_parser_schema.py

diff --git a/docs/README.md b/docs/README.md
index 81b0aa76..1c171bd8 100644
--- a/docs/README.md
+++ b/docs/README.md
@@ -2402,6 +2402,27 @@ For managing these plugins; starting with 3.0, we are offering a new plugin mana
 
 This command is currently in beta.
 
+### `httpie cli`
+
+#### `httpie cli export-args`
+
+`httpie cli export-args` command can expose the parser specification of `http`/`https` commands
+(like an API definition) to outside tools so that they can use this to build better interactions
+over them (e.g offer auto-complete).
+
+
+Available formats to export in include:
+| format | Description                                                                                                                                       |
+|--------|---------------------------------------------------------------------------------------------------------------------------------------------------|
+| `json` | Export the parser spec in JSON. The schema includes a top-level `version` parameter which should be interpreted in [semver](https://semver.org/). |
+
+You can use any of these formats with `--format` parameter, but the default one is `json`.
+
+```bash
+$ httpie cli export-args | jq '"Program: " + .spec.name + ", Version: " +  .version'
+"Program: http, Version: 0.0.1a0"
+```
+
 ### `httpie plugins`
 
 `plugins` interface is a very simple plugin manager for installing, listing and uninstalling HTTPie plugins.
diff --git a/httpie/cli/constants.py b/httpie/cli/constants.py
index 067aaabd..e8188938 100644
--- a/httpie/cli/constants.py
+++ b/httpie/cli/constants.py
@@ -90,13 +90,19 @@ OUTPUT_OPTIONS = frozenset({
 })
 
 # Pretty
+
+
+class PrettyOptions(enum.Enum):
+    STDOUT_TTY_ONLY = enum.auto()
+
+
 PRETTY_MAP = {
     'all': ['format', 'colors'],
     'colors': ['colors'],
     'format': ['format'],
     'none': []
 }
-PRETTY_STDOUT_TTY_ONLY = object()
+PRETTY_STDOUT_TTY_ONLY = PrettyOptions.STDOUT_TTY_ONLY
 
 
 DEFAULT_FORMAT_OPTIONS = [
diff --git a/httpie/cli/definition.py b/httpie/cli/definition.py
index 806b04bc..5db5b390 100644
--- a/httpie/cli/definition.py
+++ b/httpie/cli/definition.py
@@ -1,67 +1,58 @@
-"""
-CLI arguments definition.
+from __future__ import annotations
 
-"""
-from argparse import (FileType, OPTIONAL, SUPPRESS, ZERO_OR_MORE)
-from textwrap import dedent, wrap
+import textwrap
+from argparse import FileType
 
-from .. import __doc__, __version__
-from .argparser import HTTPieArgumentParser
-from .argtypes import (
-    KeyValueArgType, SessionNameValidator, SSLCredentials,
-    readable_file_arg, response_charset_type, response_mime_type,
-)
-from .constants import (
-    DEFAULT_FORMAT_OPTIONS, BASE_OUTPUT_OPTIONS, OUTPUT_OPTIONS,
-    OUTPUT_OPTIONS_DEFAULT, OUT_REQ_BODY, OUT_REQ_HEAD,
-    OUT_RESP_BODY, OUT_RESP_HEAD, OUT_RESP_META, PRETTY_MAP, PRETTY_STDOUT_TTY_ONLY,
-    RequestType, SEPARATOR_GROUP_ALL_ITEMS, SEPARATOR_PROXY,
-    SORTED_FORMAT_OPTIONS_STRING,
-    UNSORTED_FORMAT_OPTIONS_STRING,
-)
-from .utils import LazyChoices
-from ..output.formatters.colors import (
-    AUTO_STYLE, DEFAULT_STYLE, get_available_styles
-)
-from ..plugins.builtin import BuiltinAuthPlugin
-from ..plugins.registry import plugin_manager
-from ..sessions import DEFAULT_SESSIONS_DIR
-from ..ssl_ import AVAILABLE_SSL_VERSION_ARG_MAPPING, DEFAULT_SSL_CIPHERS
+from httpie import __doc__, __version__
+from httpie.cli.argtypes import (KeyValueArgType, SessionNameValidator,
+                                 SSLCredentials, readable_file_arg,
+                                 response_charset_type, response_mime_type)
+from httpie.cli.constants import (BASE_OUTPUT_OPTIONS, DEFAULT_FORMAT_OPTIONS,
+                                  OUT_REQ_BODY, OUT_REQ_HEAD, OUT_RESP_BODY,
+                                  OUT_RESP_HEAD, OUT_RESP_META, OUTPUT_OPTIONS,
+                                  OUTPUT_OPTIONS_DEFAULT, PRETTY_MAP,
+                                  PRETTY_STDOUT_TTY_ONLY,
+                                  SEPARATOR_GROUP_ALL_ITEMS, SEPARATOR_PROXY,
+                                  SORTED_FORMAT_OPTIONS_STRING,
+                                  UNSORTED_FORMAT_OPTIONS_STRING, RequestType)
+from httpie.cli.options import ParserSpec, Qualifiers, to_argparse
+from httpie.output.formatters.colors import (AUTO_STYLE, DEFAULT_STYLE,
+                                             get_available_styles)
+from httpie.plugins.builtin import BuiltinAuthPlugin
+from httpie.plugins.registry import plugin_manager
+from httpie.sessions import DEFAULT_SESSIONS_DIR
+from httpie.ssl_ import AVAILABLE_SSL_VERSION_ARG_MAPPING, DEFAULT_SSL_CIPHERS
 
-
-parser = HTTPieArgumentParser(
-    prog='http',
+options = ParserSpec(
+    'http',
     description=f'{__doc__.strip()} <https://httpie.io>',
-    epilog=dedent('''
+    epilog="""
     For every --OPTION there is also a --no-OPTION that reverts OPTION
     to its default value.
-
     Suggestions and bug reports are greatly appreciated:
-
         https://github.com/httpie/httpie/issues
-
-    '''),
+    """,
 )
-parser.register('action', 'lazy_choices', LazyChoices)
+
 
 #######################################################################
 # Positional arguments.
 #######################################################################
 
-positional = parser.add_argument_group(
-    title='Positional Arguments',
-    description=dedent('''
+positional_arguments = options.add_group(
+    'Positional Arguments',
+    description="""
     These arguments come after any flags and in the order they are listed here.
     Only URL is required.
-
-    ''')
+    """,
 )
-positional.add_argument(
+
+positional_arguments.add_argument(
     dest='method',
     metavar='METHOD',
-    nargs=OPTIONAL,
+    nargs=Qualifiers.OPTIONAL,
     default=None,
-    help='''
+    help="""
     The HTTP method to be used for the request (GET, POST, PUT, DELETE, ...).
 
     This argument can be omitted in which case HTTPie will use POST if there
@@ -70,12 +61,12 @@ positional.add_argument(
         $ http example.org               # => GET
         $ http example.org hello=world   # => POST
 
-    '''
+    """,
 )
-positional.add_argument(
+positional_arguments.add_argument(
     dest='url',
     metavar='URL',
-    help='''
+    help="""
     The scheme defaults to 'http://' if the URL does not include one.
     (You can override this with: --default-scheme=https)
 
@@ -84,15 +75,15 @@ positional.add_argument(
         $ http :3000                    # => http://localhost:3000
         $ http :/foo                    # => http://localhost/foo
 
-    '''
+    """,
 )
-positional.add_argument(
+positional_arguments.add_argument(
     dest='request_items',
     metavar='REQUEST_ITEM',
-    nargs=ZERO_OR_MORE,
+    nargs=Qualifiers.ZERO_OR_MORE,
     default=None,
     type=KeyValueArgType(*SEPARATOR_GROUP_ALL_ITEMS),
-    help=r'''
+    help=r"""
     Optional key-value pairs to be included in the request. The separator used
     determines the type:
 
@@ -130,66 +121,65 @@ positional.add_argument(
 
         field-name-with\:colon=value
 
-    '''
+    """,
 )
 
 #######################################################################
 # Content type.
 #######################################################################
 
-content_type = parser.add_argument_group(
-    title='Predefined Content Types',
-    description=None
-)
+content_types = options.add_group('Predefined Content Types')
 
-content_type.add_argument(
-    '--json', '-j',
+content_types.add_argument(
+    '--json',
+    '-j',
     action='store_const',
     const=RequestType.JSON,
     dest='request_type',
-    help='''
+    help="""
     (default) Data items from the command line are serialized as a JSON object.
     The Content-Type and Accept headers are set to application/json
     (if not specified).
 
-    '''
+    """,
 )
-content_type.add_argument(
-    '--form', '-f',
+content_types.add_argument(
+    '--form',
+    '-f',
     action='store_const',
     const=RequestType.FORM,
     dest='request_type',
-    help='''
+    help="""
     Data items from the command line are serialized as form fields.
 
     The Content-Type is set to application/x-www-form-urlencoded (if not
     specified). The presence of any file fields results in a
     multipart/form-data request.
 
-    '''
+    """,
 )
-content_type.add_argument(
+content_types.add_argument(
     '--multipart',
     action='store_const',
     const=RequestType.MULTIPART,
     dest='request_type',
-    help='''
+    help="""
     Similar to --form, but always sends a multipart/form-data
     request (i.e., even without files).
 
-    '''
+    """,
 )
-content_type.add_argument(
+content_types.add_argument(
     '--boundary',
-    help='''
+    help="""
     Specify a custom boundary string for multipart/form-data requests.
     Only has effect only together with --form.
 
-    '''
+    """,
 )
-content_type.add_argument(
+content_types.add_argument(
     '--raw',
-    help='''
+    help="""
     This option allows you to pass raw request data without extra processing
     (as opposed to the structured request items syntax):
 
@@ -204,55 +194,37 @@ content_type.add_argument(
         $ http pie.dev/post @data.txt
 
 
-    '''
+    """,
 )
 
-
 #######################################################################
 # Content processing.
 #######################################################################
 
-content_processing = parser.add_argument_group(
-    title='Content Processing Options',
-    description=None
-)
+processing_options = options.add_group('Content Processing Options')
 
-content_processing.add_argument(
-    '--compress', '-x',
+processing_options.add_argument(
+    '--compress',
+    '-x',
     action='count',
     default=0,
-    help='''
+    help="""
     Content compressed (encoded) with Deflate algorithm.
     The Content-Encoding header is set to deflate.
 
     Compression is skipped if it appears that compression ratio is
     negative. Compression can be forced by repeating the argument.
 
-    '''
+    """,
 )
 
 #######################################################################
 # Output processing
 #######################################################################
 
-output_processing = parser.add_argument_group(title='Output Processing')
-
-output_processing.add_argument(
-    '--pretty',
-    dest='prettify',
-    default=PRETTY_STDOUT_TTY_ONLY,
-    choices=sorted(PRETTY_MAP.keys()),
-    help='''
-    Controls output processing. The value can be "none" to not prettify
-    the output (default for redirected output), "all" to apply both colors
-    and formatting (default for terminal output), "colors", or "format".
-
-    '''
-)
-
 
 def format_style_help(available_styles):
-    return '''
+    return """
     Output coloring style (default is "{default}"). It can be one of:
 
         {available_styles}
@@ -261,92 +233,109 @@ def format_style_help(available_styles):
     For non-{auto_style} styles to work properly, please make sure that the
     $TERM environment variable is set to "xterm-256color" or similar
     (e.g., via `export TERM=xterm-256color' in your ~/.bashrc).
-    '''.format(
+    """.format(
         default=DEFAULT_STYLE,
         available_styles='\n'.join(
             f'        {line.strip()}'
-            for line in wrap(', '.join(available_styles), 60)
+            for line in textwrap.wrap(', '.join(available_styles), 60)
         ).strip(),
         auto_style=AUTO_STYLE,
     )
 
 
+_sorted_kwargs = {
+    'action': 'append_const',
+    'const': SORTED_FORMAT_OPTIONS_STRING,
+    'dest': 'format_options',
+}
+_unsorted_kwargs = {
+    'action': 'append_const',
+    'const': UNSORTED_FORMAT_OPTIONS_STRING,
+    'dest': 'format_options',
+}
+
+output_processing = options.add_group('Output Processing')
+
 output_processing.add_argument(
-    '--style', '-s',
+    '--pretty',
+    dest='prettify',
+    default=PRETTY_STDOUT_TTY_ONLY,
+    choices=sorted(PRETTY_MAP.keys()),
+    help="""
+    Controls output processing. The value can be "none" to not prettify
+    the output (default for redirected output), "all" to apply both colors
+    and formatting (default for terminal output), "colors", or "format".
+
+    """,
+)
+output_processing.add_argument(
+    '--style',
+    '-s',
     dest='style',
     metavar='STYLE',
     default=DEFAULT_STYLE,
     action='lazy_choices',
     getter=get_available_styles,
-    help_formatter=format_style_help
+    help_formatter=format_style_help,
 )
 
-_sorted_kwargs = {
-    'action': 'append_const',
-    'const': SORTED_FORMAT_OPTIONS_STRING,
-    'dest': 'format_options'
-}
-_unsorted_kwargs = {
-    'action': 'append_const',
-    'const': UNSORTED_FORMAT_OPTIONS_STRING,
-    'dest': 'format_options'
-}
 # The closest approx. of the documented resetting to default via --no-<option>.
 # We hide them from the doc because they act only as low-level aliases here.
-output_processing.add_argument('--no-unsorted', **_sorted_kwargs, help=SUPPRESS)
-output_processing.add_argument('--no-sorted', **_unsorted_kwargs, help=SUPPRESS)
+output_processing.add_argument(
+    '--no-unsorted', **_sorted_kwargs, help=Qualifiers.SUPPRESS
+)
+output_processing.add_argument(
+    '--no-sorted', **_unsorted_kwargs, help=Qualifiers.SUPPRESS
+)
 
 output_processing.add_argument(
     '--unsorted',
     **_unsorted_kwargs,
-    help=f'''
+    help=f"""
     Disables all sorting while formatting output. It is a shortcut for:
 
         --format-options={UNSORTED_FORMAT_OPTIONS_STRING}
 
-    '''
+    """,
 )
 output_processing.add_argument(
     '--sorted',
     **_sorted_kwargs,
-    help=f'''
+    help=f"""
     Re-enables all sorting options while formatting output. It is a shortcut for:
 
         --format-options={SORTED_FORMAT_OPTIONS_STRING}
 
-    '''
+    """,
 )
-
 output_processing.add_argument(
     '--response-charset',
     metavar='ENCODING',
     type=response_charset_type,
-    help='''
+    help="""
     Override the response encoding for terminal display purposes, e.g.:
 
         --response-charset=utf8
         --response-charset=big5
 
-    '''
+    """,
 )
-
 output_processing.add_argument(
     '--response-mime',
     metavar='MIME_TYPE',
     type=response_mime_type,
-    help='''
+    help="""
     Override the response mime type for coloring and formatting for the terminal, e.g.:
 
         --response-mime=application/json
         --response-mime=text/xml
 
-    '''
+    """,
 )
-
 output_processing.add_argument(
     '--format-options',
     action='append',
-    help='''
+    help="""
     Controls output formatting. Only relevant when formatting is enabled
     through (explicit or implied) --pretty=all or --pretty=format.
     The following are the default options:
@@ -361,22 +350,25 @@ output_processing.add_argument(
 
     This is something you will typically put into your config file.
 
-    '''.format(
+    """.format(
         option_list='\n'.join(
-            f'        {option}' for option in DEFAULT_FORMAT_OPTIONS).strip()
-    )
+            f'        {option}' for option in DEFAULT_FORMAT_OPTIONS
+        ).strip()
+    ),
 )
 
 #######################################################################
 # Output options
 #######################################################################
-output_options = parser.add_argument_group(title='Output Options')
+
+output_options = options.add_group('Output Options')
 
 output_options.add_argument(
-    '--print', '-p',
+    '--print',
+    '-p',
     dest='output_options',
     metavar='WHAT',
-    help=f'''
+    help=f"""
     String specifying what the output should contain:
 
         '{OUT_REQ_HEAD}' request headers
@@ -390,45 +382,49 @@ output_options.add_argument(
     If the output is piped to another program or to a file, then only the
     response body is printed by default.
 
-    '''
+    """,
 )
 output_options.add_argument(
-    '--headers', '-h',
+    '--headers',
+    '-h',
     dest='output_options',
     action='store_const',
     const=OUT_RESP_HEAD,
-    help=f'''
+    help=f"""
     Print only the response headers. Shortcut for --print={OUT_RESP_HEAD}.
 
-    '''
+    """,
 )
 output_options.add_argument(
-    '--meta', '-m',
+    '--meta',
+    '-m',
     dest='output_options',
     action='store_const',
     const=OUT_RESP_META,
-    help=f'''
+    help=f"""
     Print only the response metadata. Shortcut for --print={OUT_RESP_META}.
 
-    '''
+    """,
 )
 output_options.add_argument(
-    '--body', '-b',
+    '--body',
+    '-b',
     dest='output_options',
     action='store_const',
     const=OUT_RESP_BODY,
-    help=f'''
+    help=f"""
     Print only the response body. Shortcut for --print={OUT_RESP_BODY}.
 
-    '''
+    """,
 )
 
 output_options.add_argument(
-    '--verbose', '-v',
+    '--verbose',
+    '-v',
     dest='verbose',
     action='count',
     default=0,
-    help=f'''
+    help=f"""
     Verbose output. For the level one (with single `-v`/`--verbose`), print
     the whole request as well as the response. Also print any intermediary
     requests/responses (such as redirects). For the second level and higher,
@@ -436,37 +432,39 @@ output_options.add_argument(
 
     Level one is a shortcut for: --all --print={''.join(BASE_OUTPUT_OPTIONS)}
     Level two is a shortcut for: --all --print={''.join(OUTPUT_OPTIONS)}
-    '''
+    """,
 )
 output_options.add_argument(
     '--all',
     default=False,
     action='store_true',
-    help='''
+    help="""
     By default, only the final request/response is shown. Use this flag to show
     any intermediary requests/responses as well. Intermediary requests include
     followed redirects (with --follow), the first unauthorized request when
     Digest auth is used (--auth=digest), etc.
 
-    '''
+    """,
 )
 output_options.add_argument(
-    '--history-print', '-P',
+    '--history-print',
+    '-P',
     dest='output_options_history',
     metavar='WHAT',
-    help='''
+    help="""
     The same as --print, -p but applies only to intermediary requests/responses
     (such as redirects) when their inclusion is enabled with --all. If this
     options is not specified, then they are formatted the same way as the final
     response.
 
-    '''
+    """,
 )
 output_options.add_argument(
-    '--stream', '-S',
+    '--stream',
+    '-S',
     action='store_true',
     default=False,
-    help='''
+    help="""
     Always stream the response body by line, i.e., behave like `tail -f'.
 
     Without --stream and with --pretty (either set or implied),
@@ -478,75 +476,75 @@ output_options.add_argument(
     It is useful also without --pretty: It ensures that the output is flushed
     more often and in smaller chunks.
 
-    '''
+    """,
 )
 output_options.add_argument(
-    '--output', '-o',
+    '--output',
+    '-o',
     type=FileType('a+b'),
     dest='output_file',
     metavar='FILE',
-    help='''
+    help="""
     Save output to FILE instead of stdout. If --download is also set, then only
     the response body is saved to FILE. Other parts of the HTTP exchange are
     printed to stderr.
 
-    '''
-
+    """,
 )
 
 output_options.add_argument(
-    '--download', '-d',
+    '--download',
+    '-d',
     action='store_true',
     default=False,
-    help='''
+    help="""
     Do not print the response body to stdout. Rather, download it and store it
     in a file. The filename is guessed unless specified with --output
     [filename]. This action is similar to the default behaviour of wget.
 
-    '''
+    """,
 )
-
 output_options.add_argument(
-    '--continue', '-c',
+    '--continue',
+    '-c',
     dest='download_resume',
     action='store_true',
     default=False,
-    help='''
+    help="""
     Resume an interrupted download. Note that the --output option needs to be
     specified as well.
 
-    '''
+    """,
 )
-
 output_options.add_argument(
-    '--quiet', '-q',
+    '--quiet',
+    '-q',
     action='count',
     default=0,
-    help='''
+    help="""
     Do not print to stdout or stderr, except for errors and warnings when provided once.
     Provide twice to suppress warnings as well.
     stdout is still redirected if --output is specified.
     Flag doesn't affect behaviour of download beyond not printing to terminal.
 
-    '''
+    """,
 )
 
 #######################################################################
 # Sessions
 #######################################################################
 
-sessions = parser.add_argument_group(title='Sessions') \
-    .add_mutually_exclusive_group(required=False)
-
 session_name_validator = SessionNameValidator(
     'Session name contains invalid characters.'
 )
 
+sessions = options.add_group('Sessions', is_mutually_exclusive=True)
+
 sessions.add_argument(
     '--session',
     metavar='SESSION_NAME_OR_PATH',
     type=session_name_validator,
-    help=f'''
+    help=f"""
     Create, or reuse and update a session. Within a session, custom headers,
     auth credential, as well as any cookies sent by the server persist between
     requests.
@@ -555,64 +553,71 @@ sessions.add_argument(
 
         {DEFAULT_SESSIONS_DIR}/<HOST>/<SESSION_NAME>.json.
 
-    '''
+    """,
 )
 sessions.add_argument(
     '--session-read-only',
     metavar='SESSION_NAME_OR_PATH',
     type=session_name_validator,
-    help='''
+    help="""
     Create or read a session without updating it form the request/response
     exchange.
 
-    '''
+    """,
 )
 
 #######################################################################
 # Authentication
 #######################################################################
 
-# ``requests.request`` keyword arguments.
-auth = parser.add_argument_group(title='Authentication')
-auth.add_argument(
-    '--auth', '-a',
-    default=None,
-    metavar='USER[:PASS] | TOKEN',
-    help='''
-    For username/password based authentication mechanisms (e.g
-    basic auth or digest auth) if only the username is provided
-    (-a username), HTTPie will prompt for the password.
-
-    ''',
-)
-
 
 def format_auth_help(auth_plugins_mapping):
     auth_plugins = list(auth_plugins_mapping.values())
-    return '''
+    return """
     The authentication mechanism to be used. Defaults to "{default}".
 
     {types}
 
-    '''.format(default=auth_plugins[0].auth_type, types='\n    '.join(
-        '"{type}": {name}{package}{description}'.format(
-            type=plugin.auth_type,
-            name=plugin.name,
-            package=(
-                '' if issubclass(plugin, BuiltinAuthPlugin)
-                else f' (provided by {plugin.package_name})'
-            ),
-            description=(
-                '' if not plugin.description else
-                '\n      ' + ('\n      '.join(wrap(plugin.description)))
+    """.format(
+        default=auth_plugins[0].auth_type,
+        types='\n    '.join(
+            '"{type}": {name}{package}{description}'.format(
+                type=plugin.auth_type,
+                name=plugin.name,
+                package=(
+                    ''
+                    if issubclass(plugin, BuiltinAuthPlugin)
+                    else f' (provided by {plugin.package_name})'
+                ),
+                description=(
+                    ''
+                    if not plugin.description
+                    else '\n      '
+                    + ('\n      '.join(textwrap.wrap(plugin.description)))
+                ),
             )
-        )
-        for plugin in auth_plugins
-    ))
+            for plugin in auth_plugins
+        ),
+    )
 
 
-auth.add_argument(
-    '--auth-type', '-A',
+authentication = options.add_group('Authentication')
+
+authentication.add_argument(
+    '--auth',
+    '-a',
+    default=None,
+    metavar='USER[:PASS] | TOKEN',
+    help="""
+    For username/password based authentication mechanisms (e.g
+    basic auth or digest auth) if only the username is provided
+    (-a username), HTTPie will prompt for the password.
+
+    """,
+)
+authentication.add_argument(
+    '--auth-type',
+    '-A',
     action='lazy_choices',
     default=None,
     getter=plugin_manager.get_auth_plugin_mapping,
@@ -620,29 +625,29 @@ auth.add_argument(
     cache=False,
     help_formatter=format_auth_help,
 )
-auth.add_argument(
+authentication.add_argument(
     '--ignore-netrc',
     default=False,
     action='store_true',
-    help='''
+    help="""
     Ignore credentials from .netrc.
 
-    ''',
+    """,
 )
 
 #######################################################################
 # Network
 #######################################################################
 
-network = parser.add_argument_group(title='Network')
+network = options.add_group('Network')
 
 network.add_argument(
     '--offline',
     default=False,
     action='store_true',
-    help='''
+    help="""
     Build the request and print it but don’t actually send it.
-    '''
+    """,
 )
 network.add_argument(
     '--proxy',
@@ -650,43 +655,43 @@ network.add_argument(
     action='append',
     metavar='PROTOCOL:PROXY_URL',
     type=KeyValueArgType(SEPARATOR_PROXY),
-    help='''
+    help="""
     String mapping protocol to the URL of the proxy
     (e.g. http:http://foo.bar:3128). You can specify multiple proxies with
     different protocols. The environment variables $ALL_PROXY, $HTTP_PROXY,
     and $HTTPS_proxy are supported as well.
 
-    '''
+    """,
 )
 network.add_argument(
-    '--follow', '-F',
+    '--follow',
+    '-F',
     default=False,
     action='store_true',
-    help='''
+    help="""
     Follow 30x Location redirects.
 
-    '''
+    """,
 )
 
 network.add_argument(
     '--max-redirects',
     type=int,
     default=30,
-    help='''
+    help="""
     By default, requests have a limit of 30 redirects (works with --follow).
 
-    '''
+    """,
 )
-
 network.add_argument(
     '--max-headers',
     type=int,
     default=0,
-    help='''
+    help="""
     The maximum number of response headers to be read before giving up
     (default 0, i.e., no limit).
 
-    '''
+    """,
 )
 
 network.add_argument(
@@ -694,7 +699,7 @@ network.add_argument(
     type=float,
     default=0,
     metavar='SECONDS',
-    help='''
+    help="""
     The connection timeout of the request in seconds.
     The default value is 0, i.e., there is no timeout limit.
     This is not a time limit on the entire response download;
@@ -702,13 +707,13 @@ network.add_argument(
     timeout seconds (more precisely, if no bytes have been received on
     the underlying socket for timeout seconds).
 
-    '''
+    """,
 )
 network.add_argument(
     '--check-status',
     default=False,
     action='store_true',
-    help='''
+    help="""
     By default, HTTPie exits with 0 when no network or other fatal errors
     occur. This flag instructs HTTPie to also check the HTTP status code and
     exit with an error if the status indicates one.
@@ -718,89 +723,88 @@ network.add_argument(
     3xx (Redirect) and --follow hasn't been set, then the exit status is 3.
     Also an error message is written to stderr if stdout is redirected.
 
-    '''
+    """,
 )
 network.add_argument(
     '--path-as-is',
     default=False,
     action='store_true',
-    help='''
+    help="""
     Bypass dot segment (/../ or /./) URL squashing.
 
-    '''
+    """,
 )
-
 network.add_argument(
     '--chunked',
     default=False,
     action='store_true',
-    help='''
+    help="""
     Enable streaming via chunked transfer encoding.
     The Transfer-Encoding header is set to chunked.
 
-    '''
+    """,
 )
 
 #######################################################################
 # SSL
 #######################################################################
 
-ssl = parser.add_argument_group(title='SSL')
+ssl = options.add_group('SSL')
+
 ssl.add_argument(
     '--verify',
     default='yes',
-    help='''
+    help="""
     Set to "no" (or "false") to skip checking the host's SSL certificate.
     Defaults to "yes" ("true"). You can also pass the path to a CA_BUNDLE file
     for private certs. (Or you can set the REQUESTS_CA_BUNDLE environment
     variable instead.)
-    '''
+    """,
 )
 ssl.add_argument(
     '--ssl',
     dest='ssl_version',
     choices=sorted(AVAILABLE_SSL_VERSION_ARG_MAPPING.keys()),
-    help='''
+    help="""
     The desired protocol version to use. This will default to
     SSL v2.3 which will negotiate the highest protocol that both
     the server and your installation of OpenSSL support. Available protocols
     may vary depending on OpenSSL installation (only the supported ones
     are shown here).
 
-    '''
+    """,
 )
 ssl.add_argument(
     '--ciphers',
-    help=f'''
+    help=f"""
 
     A string in the OpenSSL cipher list format. By default, the following
     is used:
 
     {DEFAULT_SSL_CIPHERS}
 
-    '''
+    """,
 )
 ssl.add_argument(
     '--cert',
     default=None,
     type=readable_file_arg,
-    help='''
+    help="""
     You can specify a local cert to use as client side SSL certificate.
     This file may either contain both private key and certificate or you may
     specify --cert-key separately.
 
-    '''
+    """,
 )
-
 ssl.add_argument(
     '--cert-key',
     default=None,
     type=readable_file_arg,
-    help='''
+    help="""
     The private key to use with SSL. Only needed if --cert is given and the
     certificate file does not contain the private key.
 
-    '''
+    """,
 )
 
 ssl.add_argument(
@@ -818,59 +822,66 @@ ssl.add_argument(
 # Troubleshooting
 #######################################################################
 
-troubleshooting = parser.add_argument_group(title='Troubleshooting')
-
+troubleshooting = options.add_group('Troubleshooting')
 troubleshooting.add_argument(
-    '--ignore-stdin', '-I',
+    '--ignore-stdin',
+    '-I',
     action='store_true',
     default=False,
-    help='''
+    help="""
     Do not attempt to read stdin.
 
-    '''
+    """,
 )
 troubleshooting.add_argument(
     '--help',
     action='help',
-    default=SUPPRESS,
-    help='''
+    default=Qualifiers.SUPPRESS,
+    help="""
     Show this help message and exit.
 
-    '''
+    """,
 )
 troubleshooting.add_argument(
     '--version',
     action='version',
     version=__version__,
-    help='''
+    help="""
     Show version and exit.
 
-    '''
+    """,
 )
 troubleshooting.add_argument(
     '--traceback',
     action='store_true',
     default=False,
-    help='''
+    help="""
     Prints the exception traceback should one occur.
 
-    '''
+    """,
 )
 troubleshooting.add_argument(
     '--default-scheme',
-    default="http",
-    help='''
+    default='http',
+    help="""
     The default scheme to use if not specified in the URL.
 
-    '''
+    """,
 )
 troubleshooting.add_argument(
     '--debug',
     action='store_true',
     default=False,
-    help='''
+    help="""
     Prints the exception traceback should one occur, as well as other
     information useful for debugging HTTPie itself and for reporting bugs.
 
-    '''
+    """,
 )
+
+#######################################################################
+# Finalization
+#######################################################################
+
+options.finalize()
+parser = to_argparse(options)
diff --git a/httpie/cli/options.py b/httpie/cli/options.py
new file mode 100644
index 00000000..45f66934
--- /dev/null
+++ b/httpie/cli/options.py
@@ -0,0 +1,189 @@
+import argparse
+import textwrap
+import typing
+from dataclasses import dataclass, field
+from enum import Enum, auto
+from typing import Any, Optional, Dict, List, Type, TypeVar
+
+from httpie.cli.argparser import HTTPieArgumentParser
+from httpie.cli.utils import LazyChoices
+
+
+class Qualifiers(Enum):
+    OPTIONAL = auto()
+    ZERO_OR_MORE = auto()
+    SUPPRESS = auto()
+
+
+def map_qualifiers(
+    configuration: Dict[str, Any], qualifier_map: Dict[Qualifiers, Any]
+) -> Dict[str, Any]:
+    return {
+        key: qualifier_map[value] if isinstance(value, Qualifiers) else value
+        for key, value in configuration.items()
+    }
+
+
+PARSER_SPEC_VERSION = '0.0.1a0'
+
+
+@dataclass
+class ParserSpec:
+    program: str
+    description: Optional[str] = None
+    epilog: Optional[str] = None
+    groups: List['Group'] = field(default_factory=list)
+
+    def finalize(self) -> 'ParserSpec':
+        if self.description:
+            self.description = textwrap.dedent(self.description)
+        if self.epilog:
+            self.epilog = textwrap.dedent(self.epilog)
+        for group in self.groups:
+            group.finalize()
+        return self
+
+    def add_group(self, name: str, **kwargs) -> 'Group':
+        group = Group(name, **kwargs)
+        self.groups.append(group)
+        return group
+
+    def serialize(self) -> Dict[str, Any]:
+        return {
+            'name': self.program,
+            'description': self.description,
+            'groups': [group.serialize() for group in self.groups],
+        }
+
+
+@dataclass
+class Group:
+    name: str
+    description: str = ''
+    is_mutually_exclusive: bool = False
+    arguments: List['Argument'] = field(default_factory=list)
+
+    def finalize(self) -> None:
+        if self.description:
+            self.description = textwrap.dedent(self.description)
+
+    def add_argument(self, *args, **kwargs):
+        argument = Argument(list(args), kwargs.copy())
+        self.arguments.append(argument)
+        return argument
+
+    def serialize(self) -> Dict[str, Any]:
+        return {
+            'name': self.name,
+            'description': self.description or None,
+            'is_mutually_exclusive': self.is_mutually_exclusive,
+            'args': [argument.serialize() for argument in self.arguments],
+        }
+
+
+class Argument(typing.NamedTuple):
+    aliases: List[str]
+    configuration: Dict[str, Any]
+
+    def serialize(self) -> Dict[str, Any]:
+        configuration = self.configuration.copy()
+
+        # Unpack the dynamically computed choices, since we
+        # will need to store the actual values somewhere.
+        action = configuration.pop('action', None)
+        if action == 'lazy_choices':
+            choices = LazyChoices(self.aliases, **{'dest': None, **configuration})
+            configuration['choices'] = list(choices.load())
+            configuration['help'] = choices.help
+
+        result = {}
+        if self.aliases:
+            result['options'] = self.aliases.copy()
+        else:
+            result['options'] = [configuration['metavar']]
+            result['is_positional'] = True
+
+        qualifiers = JSON_QUALIFIER_TO_OPTIONS[configuration.get('nargs', Qualifiers.SUPPRESS)]
+        result.update(qualifiers)
+
+        help_msg = configuration.get('help')
+        if help_msg and help_msg is not Qualifiers.SUPPRESS:
+            result['description'] = help_msg.strip()
+
+        python_type = configuration.get('type')
+        if python_type is not None:
+            if hasattr(python_type, '__name__'):
+                type_name = python_type.__name__
+            else:
+                type_name = type(python_type).__name__
+
+            result['python_type_name'] = type_name
+
+        result.update({
+            key: value
+            for key, value in configuration.items()
+            if key in JSON_DIRECT_MIRROR_OPTIONS
+        })
+
+        return result
+
+    def __getattr__(self, attribute_name):
+        if attribute_name in self.configuration:
+            return self.configuration[attribute_name]
+        else:
+            raise AttributeError(attribute_name)
+
+
+ParserType = TypeVar('ParserType', bound=Type[argparse.ArgumentParser])
+
+ARGPARSE_QUALIFIER_MAP = {
+    Qualifiers.OPTIONAL: argparse.OPTIONAL,
+    Qualifiers.SUPPRESS: argparse.SUPPRESS,
+    Qualifiers.ZERO_OR_MORE: argparse.ZERO_OR_MORE,
+}
+
+
+def to_argparse(
+    abstract_options: ParserSpec,
+    parser_type: ParserType = HTTPieArgumentParser,
+) -> ParserType:
+    concrete_parser = parser_type(
+        prog=abstract_options.program,
+        description=abstract_options.description,
+        epilog=abstract_options.epilog,
+    )
+    concrete_parser.register('action', 'lazy_choices', LazyChoices)
+
+    for abstract_group in abstract_options.groups:
+        concrete_group = concrete_parser.add_argument_group(
+            title=abstract_group.name, description=abstract_group.description
+        )
+        if abstract_group.is_mutually_exclusive:
+            concrete_group = concrete_group.add_mutually_exclusive_group(required=False)
+
+        for abstract_argument in abstract_group.arguments:
+            concrete_group.add_argument(
+                *abstract_argument.aliases,
+                **map_qualifiers(
+                    abstract_argument.configuration, ARGPARSE_QUALIFIER_MAP
+                )
+            )
+
+    return concrete_parser
+
+
+JSON_DIRECT_MIRROR_OPTIONS = (
+    'choices',
+    'metavar'
+)
+
+
+JSON_QUALIFIER_TO_OPTIONS = {
+    Qualifiers.OPTIONAL: {'is_optional': True},
+    Qualifiers.ZERO_OR_MORE: {'is_optional': True, 'is_variadic': True},
+    Qualifiers.SUPPRESS: {}
+}
+
+
+def to_data(abstract_options: ParserSpec) -> Dict[str, Any]:
+    return {'version': PARSER_SPEC_VERSION, 'spec': abstract_options.serialize()}
diff --git a/httpie/core.py b/httpie/core.py
index 3dbed195..98f47f34 100644
--- a/httpie/core.py
+++ b/httpie/core.py
@@ -17,9 +17,10 @@ from .context import Environment, Levels
 from .downloads import Downloader
 from .models import (
     RequestsMessageKind,
-    OutputOptions,
+    OutputOptions
 )
-from .output.writer import write_message, write_stream, MESSAGE_SEPARATOR_BYTES
+from .output.models import ProcessingOptions
+from .output.writer import write_message, write_stream, write_raw_data, MESSAGE_SEPARATOR_BYTES
 from .plugins.registry import plugin_manager
 from .status import ExitStatus, http_status_to_exit_status
 from .utils import unwrap_context
@@ -169,6 +170,7 @@ def program(args: argparse.Namespace, env: Environment) -> ExitStatus:
     downloader = None
     initial_request: Optional[requests.PreparedRequest] = None
     final_response: Optional[requests.Response] = None
+    processing_options = ProcessingOptions.from_raw_args(args)
 
     def separate():
         getattr(env.stdout, 'buffer', env.stdout).write(MESSAGE_SEPARATOR_BYTES)
@@ -183,12 +185,12 @@ def program(args: argparse.Namespace, env: Environment) -> ExitStatus:
             and chunk
         )
         if should_pipe_to_stdout:
-            msg = requests.PreparedRequest()
-            msg.is_body_upload_chunk = True
-            msg.body = chunk
-            msg.headers = initial_request.headers
-            msg_output_options = OutputOptions.from_message(msg, body=True, headers=False)
-            write_message(requests_message=msg, env=env, args=args, output_options=msg_output_options)
+            return write_raw_data(
+                env,
+                chunk,
+                processing_options=processing_options,
+                headers=initial_request.headers
+            )
 
     try:
         if args.download:
@@ -222,9 +224,14 @@ def program(args: argparse.Namespace, env: Environment) -> ExitStatus:
                     exit_status = http_status_to_exit_status(http_status=message.status_code, follow=args.follow)
                     if exit_status != ExitStatus.SUCCESS and (not env.stdout_isatty or args.quiet == 1):
                         env.log_error(f'HTTP {message.raw.status} {message.raw.reason}', level=Levels.WARNING)
-            write_message(requests_message=message, env=env, args=args, output_options=output_options._replace(
-                body=do_write_body
-            ))
+            write_message(
+                requests_message=message,
+                env=env,
+                output_options=output_options._replace(
+                    body=do_write_body
+                ),
+                processing_options=processing_options
+            )
             prev_with_body = output_options.body
 
         # Cleanup
diff --git a/httpie/manager/cli.py b/httpie/manager/cli.py
index 1473ccf9..313f1450 100644
--- a/httpie/manager/cli.py
+++ b/httpie/manager/cli.py
@@ -45,6 +45,14 @@ COMMANDS = {
     },
     'cli': {
         'help': 'Manage HTTPie for Terminal',
+        'export-args': [
+            'Export available options for the CLI',
+            {
+                'flags': ['-f', '--format'],
+                'choices': ['json'],
+                'default': 'json'
+            }
+        ],
         'sessions': {
             'help': 'Manage HTTPie sessions',
             'upgrade': [
diff --git a/httpie/manager/tasks.py b/httpie/manager/tasks.py
index f039a142..5b726a9b 100644
--- a/httpie/manager/tasks.py
+++ b/httpie/manager/tasks.py
@@ -114,3 +114,28 @@ def cli_upgrade_all_sessions(env: Environment, args: argparse.Namespace) -> Exit
                 session_name=session_name
             )
     return status
+
+
+FORMAT_TO_CONTENT_TYPE = {
+    'json': 'application/json'
+}
+
+
+@task('export-args')
+def cli_export(env: Environment, args: argparse.Namespace) -> ExitStatus:
+    import json
+    from httpie.cli.definition import options
+    from httpie.cli.options import to_data
+    from httpie.output.writer import write_raw_data
+
+    if args.format == 'json':
+        data = json.dumps(to_data(options))
+    else:
+        raise NotImplementedError(f'Unexpected format value: {args.format}')
+
+    write_raw_data(
+        env,
+        data,
+        stream_kwargs={'mime_overwrite': FORMAT_TO_CONTENT_TYPE[args.format]},
+    )
+    return ExitStatus.SUCCESS
diff --git a/httpie/output/models.py b/httpie/output/models.py
new file mode 100644
index 00000000..e65199b0
--- /dev/null
+++ b/httpie/output/models.py
@@ -0,0 +1,44 @@
+import argparse
+from typing import Any, Dict, Union, List, NamedTuple, Optional
+
+from httpie.context import Environment
+from httpie.cli.constants import PrettyOptions, PRETTY_MAP, PRETTY_STDOUT_TTY_ONLY
+from httpie.cli.argtypes import PARSED_DEFAULT_FORMAT_OPTIONS
+from httpie.output.formatters.colors import AUTO_STYLE
+
+
+class ProcessingOptions(NamedTuple):
+    """Represents a set of stylistic options
+    that are used when deciding which stream
+    should be used."""
+
+    debug: bool = False
+    traceback: bool = False
+
+    stream: bool = False
+    style: str = AUTO_STYLE
+    prettify: Union[List[str], PrettyOptions] = PRETTY_STDOUT_TTY_ONLY
+
+    response_mime: Optional[str] = None
+    response_charset: Optional[str] = None
+
+    json: bool = False
+    format_options: Dict[str, Any] = PARSED_DEFAULT_FORMAT_OPTIONS
+
+    def get_prettify(self, env: Environment) -> List[str]:
+        if self.prettify is PRETTY_STDOUT_TTY_ONLY:
+            return PRETTY_MAP['all' if env.stdout_isatty else 'none']
+        else:
+            return self.prettify
+
+    @classmethod
+    def from_raw_args(cls, options: argparse.Namespace) -> 'ProcessingOptions':
+        fetched_options = {
+            option: getattr(options, option)
+            for option in cls._fields
+        }
+        return cls(**fetched_options)
+
+    @property
+    def show_traceback(self):
+        return self.debug or self.traceback
diff --git a/httpie/output/streams.py b/httpie/output/streams.py
index ec275faa..81109380 100644
--- a/httpie/output/streams.py
+++ b/httpie/output/streams.py
@@ -34,7 +34,8 @@ class BaseStream(metaclass=ABCMeta):
         self,
         msg: HTTPMessage,
         output_options: OutputOptions,
-        on_body_chunk_downloaded: Callable[[bytes], None] = None
+        on_body_chunk_downloaded: Callable[[bytes], None] = None,
+        **kwargs
     ):
         """
         :param msg: a :class:`models.HTTPMessage` subclass
@@ -45,6 +46,7 @@ class BaseStream(metaclass=ABCMeta):
         self.msg = msg
         self.output_options = output_options
         self.on_body_chunk_downloaded = on_body_chunk_downloaded
+        self.extra_options = kwargs
 
     def get_headers(self) -> bytes:
         """Return the headers' bytes."""
diff --git a/httpie/output/writer.py b/httpie/output/writer.py
index cbd06e92..c580e22c 100644
--- a/httpie/output/writer.py
+++ b/httpie/output/writer.py
@@ -1,6 +1,6 @@
-import argparse
 import errno
-from typing import IO, TextIO, Tuple, Type, Union
+import requests
+from typing import Any, Dict, IO, Optional, TextIO, Tuple, Type, Union
 
 from ..cli.dicts import HTTPHeadersDict
 from ..context import Environment
@@ -10,8 +10,9 @@ from ..models import (
     HTTPMessage,
     RequestsMessage,
     RequestsMessageKind,
-    OutputOptions
+    OutputOptions,
 )
+from .models import ProcessingOptions
 from .processing import Conversion, Formatting
 from .streams import (
     BaseStream, BufferedPrettyStream, EncodedStream, PrettyStream, RawStream,
@@ -25,30 +26,31 @@ MESSAGE_SEPARATOR_BYTES = MESSAGE_SEPARATOR.encode()
 def write_message(
     requests_message: RequestsMessage,
     env: Environment,
-    args: argparse.Namespace,
     output_options: OutputOptions,
+    processing_options: ProcessingOptions,
+    extra_stream_kwargs: Optional[Dict[str, Any]] = None
 ):
     if not output_options.any():
         return
     write_stream_kwargs = {
         'stream': build_output_stream_for_message(
-            args=args,
             env=env,
             requests_message=requests_message,
             output_options=output_options,
+            processing_options=processing_options,
+            extra_stream_kwargs=extra_stream_kwargs
         ),
         # NOTE: `env.stdout` will in fact be `stderr` with `--download`
         'outfile': env.stdout,
-        'flush': env.stdout_isatty or args.stream
+        'flush': env.stdout_isatty or processing_options.stream
     }
     try:
-        if env.is_windows and 'colors' in args.prettify:
+        if env.is_windows and 'colors' in processing_options.get_prettify(env):
             write_stream_with_colors_win(**write_stream_kwargs)
         else:
             write_stream(**write_stream_kwargs)
     except OSError as e:
-        show_traceback = args.debug or args.traceback
-        if not show_traceback and e.errno == errno.EPIPE:
+        if processing_options.show_traceback and e.errno == errno.EPIPE:
             # Ignore broken pipes unless --traceback.
             env.stderr.write('\n')
         else:
@@ -94,11 +96,34 @@ def write_stream_with_colors_win(
             outfile.flush()
 
 
+def write_raw_data(
+    env: Environment,
+    data: Any,
+    *,
+    processing_options: Optional[ProcessingOptions] = None,
+    headers: Optional[HTTPHeadersDict] = None,
+    stream_kwargs: Optional[Dict[str, Any]] = None
+):
+    msg = requests.PreparedRequest()
+    msg.is_body_upload_chunk = True
+    msg.body = data
+    msg.headers = headers or HTTPHeadersDict()
+    msg_output_options = OutputOptions.from_message(msg, body=True, headers=False)
+    return write_message(
+        requests_message=msg,
+        env=env,
+        output_options=msg_output_options,
+        processing_options=processing_options or ProcessingOptions(),
+        extra_stream_kwargs=stream_kwargs
+    )
+
+
 def build_output_stream_for_message(
-    args: argparse.Namespace,
     env: Environment,
     requests_message: RequestsMessage,
     output_options: OutputOptions,
+    processing_options: ProcessingOptions,
+    extra_stream_kwargs: Optional[Dict[str, Any]] = None
 ):
     message_type = {
         RequestsMessageKind.REQUEST: HTTPRequest,
@@ -106,10 +131,12 @@ def build_output_stream_for_message(
     }[output_options.kind]
     stream_class, stream_kwargs = get_stream_type_and_kwargs(
         env=env,
-        args=args,
+        processing_options=processing_options,
         message_type=message_type,
         headers=requests_message.headers
     )
+    if extra_stream_kwargs:
+        stream_kwargs.update(extra_stream_kwargs)
     yield from stream_class(
         msg=message_type(requests_message),
         output_options=output_options,
@@ -124,20 +151,21 @@ def build_output_stream_for_message(
 
 def get_stream_type_and_kwargs(
     env: Environment,
-    args: argparse.Namespace,
+    processing_options: ProcessingOptions,
     message_type: Type[HTTPMessage],
     headers: HTTPHeadersDict,
 ) -> Tuple[Type['BaseStream'], dict]:
     """Pick the right stream type and kwargs for it based on `env` and `args`.
 
     """
-    is_stream = args.stream
+    is_stream = processing_options.stream
+    prettify_groups = processing_options.get_prettify(env)
     if not is_stream and message_type is HTTPResponse:
         # If this is a response, then check the headers for determining
         # auto-streaming.
         is_stream = headers.get('Content-Type') == 'text/event-stream'
 
-    if not env.stdout_isatty and not args.prettify:
+    if not env.stdout_isatty and not prettify_groups:
         stream_class = RawStream
         stream_kwargs = {
             'chunk_size': (
@@ -153,19 +181,19 @@ def get_stream_type_and_kwargs(
         }
         if message_type is HTTPResponse:
             stream_kwargs.update({
-                'mime_overwrite': args.response_mime,
-                'encoding_overwrite': args.response_charset,
+                'mime_overwrite': processing_options.response_mime,
+                'encoding_overwrite': processing_options.response_charset,
             })
-        if args.prettify:
+        if prettify_groups:
             stream_class = PrettyStream if is_stream else BufferedPrettyStream
             stream_kwargs.update({
                 'conversion': Conversion(),
                 'formatting': Formatting(
                     env=env,
-                    groups=args.prettify,
-                    color_scheme=args.style,
-                    explicit_json=args.json,
-                    format_options=args.format_options,
+                    groups=prettify_groups,
+                    color_scheme=processing_options.style,
+                    explicit_json=processing_options.json,
+                    format_options=processing_options.format_options,
                 )
             })
 
diff --git a/tests/test_httpie_cli.py b/tests/test_httpie_cli.py
index 31c44d7f..9da71639 100644
--- a/tests/test_httpie_cli.py
+++ b/tests/test_httpie_cli.py
@@ -3,6 +3,7 @@ import shutil
 import json
 from httpie.sessions import SESSIONS_DIR_NAME
 from httpie.status import ExitStatus
+from httpie.cli.options import PARSER_SPEC_VERSION
 from tests.utils import DUMMY_HOST, httpie
 from tests.fixtures import SESSION_FILES_PATH, SESSION_FILES_NEW, SESSION_FILES_OLD, read_session_file
 
@@ -123,3 +124,15 @@ def test_httpie_sessions_upgrade_all(tmp_path, mock_env, extra_args, extra_varia
         assert read_session_file(refactored_session_file) == read_session_file(
             expected_session_file, extra_variables=extra_variables
         )
+
+
+@pytest.mark.parametrize(
+    'load_func, extra_options', [
+        (json.loads, []),
+        (json.loads, ['--format=json'])
+    ]
+)
+def test_cli_export(load_func, extra_options):
+    response = httpie('cli', 'export-args', *extra_options)
+    assert response.exit_status == ExitStatus.SUCCESS
+    assert load_func(response)['version'] == PARSER_SPEC_VERSION
diff --git a/tests/test_parser_schema.py b/tests/test_parser_schema.py
new file mode 100644
index 00000000..3dc7d7b0
--- /dev/null
+++ b/tests/test_parser_schema.py
@@ -0,0 +1,60 @@
+from httpie.cli.options import ParserSpec, Qualifiers
+
+
+def test_parser_serialization():
+    small_parser = ParserSpec("test_parser")
+
+    group_1 = small_parser.add_group("group_1")
+    group_1.add_argument("regular_arg", help="regular arg")
+    group_1.add_argument(
+        "variadic_arg",
+        metavar="META",
+        help=Qualifiers.SUPPRESS,
+        nargs=Qualifiers.ZERO_OR_MORE,
+    )
+    group_1.add_argument(
+        "-O",
+        "--opt-arg",
+        action="lazy_choices",
+        getter=lambda: ["opt_1", "opt_2"],
+        help_formatter=lambda state: ", ".join(state),
+    )
+
+    group_2 = small_parser.add_group("group_2")
+    group_2.add_argument("--typed", action="store_true", type=int)
+
+    definition = small_parser.finalize()
+    assert definition.serialize() == {
+        "name": "test_parser",
+        "description": None,
+        "groups": [
+            {
+                "name": "group_1",
+                "description": None,
+                "is_mutually_exclusive": False,
+                "args": [
+                    {
+                        "options": ["regular_arg"],
+                        "description": "regular arg",
+                    },
+                    {
+                        "options": ["variadic_arg"],
+                        "is_optional": True,
+                        "is_variadic": True,
+                        "metavar": "META",
+                    },
+                    {
+                        "options": ["-O", "--opt-arg"],
+                        "description": "opt_1, opt_2",
+                        "choices": ["opt_1", "opt_2"],
+                    },
+                ],
+            },
+            {
+                "name": "group_2",
+                "description": None,
+                "is_mutually_exclusive": False,
+                "args": [{"options": ["--typed"], "python_type_name": "int"}],
+            },
+        ],
+    }