Add shiny console script

requirements.txt

@@ -6,3 +6,4 @@ websockets==10.0
 typing_extensions==4.0.1
 python-multipart
 htmltools
+click==8.0.3

setup.cfg

@@ -17,3 +17,7 @@ universal = 1
 [flake8]
 ignore = E203, E302, E402, E501, F403, F405, W503
 exclude = docs
+
+[options.entry_points]
+console_scripts =
+    shiny = shiny.main:main

shiny/__main__.py

@@ -0,0 +1,4 @@
+from .main import main
+
+if __name__ == "__main__":
+    main()

shiny/main.py

@@ -0,0 +1,172 @@
+import importlib
+import importlib.util
+import os
+import sys
+import types
+import click
+import typing
+
+import uvicorn
+import uvicorn.config
+
+import shiny
+
+__all__ = ["main", "run"]
+
+
+@click.group()
+def main() -> None:
+    pass
+
+
+@main.command()
+@click.argument("app", default="app:app")
+@click.option(
+    "--host",
+    type=str,
+    default="127.0.0.1",
+    help="Bind socket to this host.",
+    show_default=True,
+)
+@click.option(
+    "--port",
+    type=int,
+    default=8000,
+    help="Bind socket to this port.",
+    show_default=True,
+)
+@click.option(
+    "--debug", is_flag=True, default=False, help="Enable debug mode.", hidden=True
+)
+@click.option("--reload", is_flag=True, default=False, help="Enable auto-reload.")
+@click.option(
+    "--ws-max-size",
+    type=int,
+    default=16777216,
+    help="WebSocket max size message in bytes",
+    show_default=True,
+)
+@click.option(
+    "--log-level",
+    type=click.Choice(list(uvicorn.config.LOG_LEVELS.keys())),
+    default=None,
+    help="Log level. [default: info]",
+    show_default=True,
+)
+@click.option(
+    "--app-dir",
+    default=".",
+    show_default=True,
+    help="Look for APP in the specified directory, by adding this to the PYTHONPATH."
+    " Defaults to the current working directory.",
+)
+def run(
+    app: typing.Union[str, shiny.App],
+    host: str,
+    port: int,
+    debug: bool,
+    reload: bool,
+    ws_max_size: int,
+    log_level: str,
+    app_dir: str,
+) -> None:
+    """Starts a Shiny app. Press Ctrl+C (or Ctrl+Break on Windows) to stop.
+
+    The APP argument indicates where the Shiny app should be loaded from. You have
+    several options for specifying this:
+
+    \b
+    - No APP argument; `shiny run` will look for app.py in the current directory.
+    - A module name to load. It should have an `app` attribute.
+    - A "<module>:<attribute>" string. Useful when you named your Shiny app
+      something other than `app`, or if there are multiple apps in a single
+      module.
+    - A relative path to a Python file.
+    - A relative path to a Python directory (it must contain an app.py file).
+    - A "<path-to-file-or-dir>:<attribute>" string.
+
+    \b
+    Examples
+    ========
+    shiny run
+    shiny run mypackage.mymodule
+    shiny run mypackage.mymodule:app
+    shiny run mydir
+    shiny run mydir/myapp.py
+    shiny run mydir/myapp.py:app
+    """
+
+    if isinstance(app, str):
+        app = resolve_app(app, app_dir)
+
+    uvicorn.run(
+        app,  # type: ignore
+        host=host,
+        port=port,
+        debug=debug,
+        reload=reload,
+        ws_max_size=ws_max_size,
+        log_level=log_level,
+        # DON'T pass app_dir, we've already handled it ourselves
+        # app_dir=app_dir,
+    )
+
+
+def resolve_app(app: str, app_dir: typing.Optional[str]) -> str:
+    # The `app` parameter can be:
+    #
+    # - A module:attribute name
+    # - An absolute or relative path to a:
+    #   - .py file (look for app inside of it)
+    #   - directory (look for app:app inside of it)
+    # - A module name (look for :app) inside of it
+
+    module, _, attr = app.partition(":")
+    if not module:
+        raise ImportError("The APP parameter cannot start with ':'.")
+    if not attr:
+        attr = "app"
+
+    if app_dir is not None:
+        sys.path.insert(0, app_dir)
+
+    instance = try_import_module(module)
+    if not instance:
+        # It must be a path
+        path = os.path.normpath(module)
+        if path.startswith("../") or path.startswith("..\\"):
+            raise ImportError(
+                "The APP parameter cannot refer to a parent directory ('..'). "
+                "Either change the working directory to a parent of the app, "
+                "or use the --app-dir option to specify a different starting "
+                "directory to search from."
+            )
+        fullpath = os.path.normpath(os.path.join(app_dir or ".", module))
+        if not os.path.exists(fullpath):
+            raise ImportError(f"Could not find the module or path '{module}'")
+        if os.path.isdir(fullpath):
+            path = os.path.join(path, "app.py")
+            fullpath = os.path.join(fullpath, "app.py")
+            if not os.path.exists(fullpath):
+                raise ImportError(
+                    f"The directory '{fullpath}' did not include an app.py file"
+                )
+        module = path.removesuffix(".py").replace("/", ".").replace("\\", ".")
+        instance = try_import_module(module)
+        if not instance:
+            raise ImportError(f"Could not find the module '{module}'")
+
+    return f"{module}:{attr}"
+
+
+def try_import_module(module: str) -> typing.Optional[types.ModuleType]:
+    try:
+        if importlib.util.find_spec(module):
+            return importlib.import_module(module)
+        return None
+    except ModuleNotFoundError:
+        # find_spec throws this when the module contains both '/' and '.' characters
+        return None
+    except ImportError:
+        # find_spec throws this when the module starts with "."
+        return None