From 3195e3e213084f086dec5d81447e0db16d622337 Mon Sep 17 00:00:00 2001
From: Elena ``of Valhalla'' Grandi <valhalla@trueelena.org>
Date: Tue, 22 Feb 2022 17:03:55 +0100
Subject: Main Command

---
 hazwaz/__init__.py    |  2 +-
 hazwaz/command.py     | 65 +++++++++++++++++++++++++++++++++++++++++++++
 tests/test_command.py | 73 +++++++++++++++++++++++++++++++++++++++++++++++++--
 3 files changed, 137 insertions(+), 3 deletions(-)

diff --git a/hazwaz/__init__.py b/hazwaz/__init__.py
index 8b85231..f5f0a6d 100644
--- a/hazwaz/__init__.py
+++ b/hazwaz/__init__.py
@@ -1 +1 @@
-from .command import *
+from .command import MainCommand  # noqa: F401
diff --git a/hazwaz/command.py b/hazwaz/command.py
index eea436a..c99e012 100644
--- a/hazwaz/command.py
+++ b/hazwaz/command.py
@@ -1,3 +1,68 @@
+import argparse
 import logging
 
 logger = logging.getLogger(__name__)
+
+
+def _get_first_docstring_line(obj):
+    try:
+        return obj.__doc__.split('\n')[1].strip()
+    except (AttributeError, IndexError):
+        return None
+
+def _get_remaining_docstring_lines(obj):
+    try:
+        return "\n".join(obj.__doc__.split('\n')[2:]).strip()
+    except (AttributeError, IndexError):
+        return None
+
+
+class MainCommand:
+    commands = ()
+
+    def __init__(self):
+        desc = _get_first_docstring_line(self)
+        epilog = _get_remaining_docstring_lines(self)
+        self.parser = argparse.ArgumentParser(
+            description=desc,
+            epilog=epilog,
+        )
+        self.add_arguments(self.parser)
+        self.parser.set_defaults(func=self._main)
+        self.subparsers = self.parser.add_subparsers()
+        for name, sub in self.commands:
+            sub_help = _get_first_docstring_line(sub)
+            sub_parser = self.subparsers.add_parser(
+                name,
+                help=sub_help,
+                description=sub.__doc__,
+            )
+            for arg in sub.arguments:
+                sub_parser.add_argument(*arg[0], **arg[1])
+            sub_parser.set_defaults(func=sub._main)
+
+    def _main(self, args):
+        self.parser.print_help()
+
+    def add_arguments(self, parser):
+        group = parser.add_mutually_exclusive_group()
+        group.add_argument(
+            '--verbose', '-v',
+            action='store_true',
+            help="Show more details",
+        )
+        group.add_argument(
+            '--debug',
+            action='store_true',
+            help="Show debug messages",
+        )
+
+    def main(self):
+        self.args = self.parser.parse_args()
+
+        if self.args.verbose:
+            logger.setLevel(logging.VERBOSE)
+        if self.args.debug:
+            logger.setLevel(logging.DEBUG)
+
+        self.args.func(self.args)
diff --git a/tests/test_command.py b/tests/test_command.py
index f5b824c..eed6e1f 100644
--- a/tests/test_command.py
+++ b/tests/test_command.py
@@ -1,10 +1,79 @@
+import contextlib
+import io
+import sys
 import unittest
 
-from hazwaz import command
+import hazwaz
+
+
+class MyCommand(hazwaz.MainCommand):
+    """
+    A command that does things.
+
+    This is a command, but honestly it doesn't really do anything.
+    """
+    commands = ()
+
+    def add_arguments(self, parser):
+        super().add_arguments(parser)
+        parser.add_argument(
+            "--foo",
+            help="foobar things"
+        )
 
 
 class testCommand(unittest.TestCase):
-    pass
+    def _run_with_argv(self, cmd, argv):
+        stream = {
+            'stdout': io.StringIO(),
+            'stderr': io.StringIO(),
+        }
+        old_argv = sys.argv
+        sys.argv = argv
+        with contextlib.redirect_stdout(stream['stdout']):
+            with contextlib.redirect_stderr(stream['stderr']):
+                cmd.main()
+        sys.argv = old_argv
+        return stream
+
+    def test_description(self):
+        cmd = MyCommand()
+        self.assertEqual(
+            cmd.parser.description,
+            "A command that does things."
+        )
+        self.assertEqual(
+            cmd.parser.epilog,
+            "This is a command, but honestly it doesn't really do anything."
+        )
+
+    def test_description_none(self):
+        class NoHelpCommand(hazwaz.MainCommand):
+            pass
+
+        cmd = NoHelpCommand()
+        self.assertEqual(cmd.parser.description, None)
+
+    def test_description_empty(self):
+        class NoHelpCommand(hazwaz.MainCommand):
+            """
+            """
+
+        cmd = NoHelpCommand()
+        self.assertEqual(cmd.parser.description, '')
+
+    def test_arguments(self):
+        cmd = MyCommand()
+        cmd_help = cmd.parser.format_help()
+        self.assertIn("--verbose", cmd_help)
+        self.assertIn("--foo", cmd_help)
+
+    def test_run(self):
+        cmd = MyCommand()
+        cmd_help = cmd.parser.format_help()
+        stream = self._run_with_argv(cmd, ["mycommand"])
+        self.assertEqual(stream["stdout"].getvalue(), cmd_help)
+
 
 
 if __name__ == '__main__':
-- 
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