Add argument parsing to `Application` class and integrate setup in entry point

src/metar_navigate/application.py

@@ -1,7 +1,35 @@
+import argparse
+import sys
 
 
 class Application:
     def __init__(self):
-        pass
+        self.parser = None
+        self.args = None
+
+    def setup(self):
+        self._validate_args()
+
+    def _validate_args(self):
+        self.parser = argparse.ArgumentParser()
+        self.parser.add_argument("--no-tui", action="store_true", help="disables the TUI")
+        self.parser.add_argument("--detailed", action="store_true", help="displays more detailed METAR Breakdown "
+                                                                    "(Only available with --no-tui flag)")
+        self.parser.add_argument("-t", "--type", choices=["TAF", "METAR"], default="METAR", help="Select the Type "
+                                                                                            "of message (Only Available with"
+                                                                                            " --no-tui flag)")
+        self.parser.add_argument("ICAO", nargs='?', type=str.upper,help="ICAO code of airport (required with --no-tui flag)")
+
+        self.args = self.parser.parse_args()
+
+        if self.args.no_tui and not self.args.ICAO:
+            self.parser.error("--no-tui requires an ICAO code")
+        if self.args.ICAO and not self.args.no_tui:
+            self.parser.error("ICAO code only required with --no-tui flag")
+        if not self.args.no_tui and self.args.detailed:
+            self.parser.error("--detailed flag only available with --no-tui flag")
+        if not self.args.no_tui and ('--type' in sys.argv or '-t' in sys.argv):
+            self.parser.error("--type  or -t flag only available with --no-tui flag")
+
     def run(self):
         pass

src/metar_navigate/command.py

@@ -2,4 +2,5 @@ from metar_navigate import Application
 
 def main():
     app = Application()
-    print("Hello World")
+    app.setup()
+    app.run()