Merge pull request #7 from jepler/issue6

add `chap --version`

src/chap/__main__.py

@@ -1,15 +1,41 @@
 # SPDX-FileCopyrightText: 2023 Jeff Epler <[email protected]>
 #
 # SPDX-License-Identifier: MIT
+# pylint: disable=import-outside-toplevel
 
 import importlib
+import pathlib
 import pkgutil
+import subprocess
 
 import click
 
 from . import commands  # pylint: disable=no-name-in-module
 
 
+def version_callback(ctx, param, value) -> None:  # pylint: disable=unused-argument
+    if not value or ctx.resilient_parsing:
+        return
+
+    git_dir = pathlib.Path(__file__).parent.parent.parent / ".git"
+    if git_dir.exists():
+        version = subprocess.check_output(
+            ["git", f"--git-dir={git_dir}", "describe", "--tags", "--dirty"],
+            encoding="utf-8",
+        )
+    else:
+        try:
+            from .__version__ import __version__ as version
+        except ImportError:
+            version = "unknown"
+    prog_name = ctx.find_root().info_name
+    click.utils.echo(
+        f"{prog_name}, version {version}",
+        color=ctx.color,
+    )
+    ctx.exit()
+
+
 class MyCLI(click.MultiCommand):
     def list_commands(self, ctx):
         rv = []
@@ -27,7 +53,18 @@ def get_command(self, ctx, cmd_name):
             raise click.UsageError(f"Invalid subcommand {cmd_name!r}", ctx) from exc
 
 
-main = MyCLI(help="Commandline interface to ChatGPT")
+main = MyCLI(
+    help="Commandline interface to ChatGPT",
+    params=[
+        click.Option(
+            ("--version",),
+            is_flag=True,
+            is_eager=True,
+            help="Show the version and exit",
+            callback=version_callback,
+        )
+    ],
+)
 
 if __name__ == "__main__":
     main()