feat: attempt to check whether packages are installed

main.py

@@ -1,16 +1,39 @@
 #!/usr/bin/env python
+"""
+Wrapper for the champagne CLI.
+Allows running the CLI out-of-the-box without first installing it with pip.
+"""
+import importlib.util
 import os
 import re
 import sys
+import tomllib
 
 # add script directory to the path to allow champagne CLI to work out-of-the-box
 # without the need to install it via pip first
 SCRIPT_DIR = os.path.join(os.path.dirname(os.path.abspath(__file__)), "src")
 sys.path.append(SCRIPT_DIR)
 from src.__main__ import main
 
+
+def check_packages_installed(proj_file="pyproject.toml"):
+    """Check whether required dependencies are installed.
+    WARNING: Does not check for the required version.
+    """
+
+    with open(proj_file, "rb") as file:
+        proj_data = tomllib.load(file)
+    package_deps = {pkg.split()[0] for pkg in proj_data["project"]["dependencies"]}
+    missing_pkgs = {pkg for pkg in package_deps if not importlib.util.find_spec(pkg)}
+    if any(missing_pkgs):
+        raise ImportError(
+            f"Required Python packages are not installed: {', '.join(missing_pkgs)}"
+        )
+
+
 if (
     __name__ == "__main__"
 ):  # this block is adapted from the bin/champagne file created by pip
+    check_packages_installed()
     sys.argv[0] = re.sub(r"(-script\.pyw|\.exe)?$", "", sys.argv[0])
     sys.exit(main())