Use PATH variable to find where frotz binary exists

frotz.py

@@ -50,6 +50,10 @@
 from sugar3.graphics import style
 from sugar3.graphics.alert import ConfirmationAlert
 
+# gets the PATH environment variable
+PATH = os.getenv('PATH').split(os.pathsep)
+
+
 class FrotzActivity(activity.Activity):
 
     def __init__(self, handle):
@@ -129,7 +133,27 @@ def __init__(self, handle):
     def _quit_cb(self, vte, foo=None):
         logging.debug("Quitting...")
         self.close()
-
+
+    def get_executable_path(self, executable, raise_error=True):
+        """
+        Returns the absolute path of the executable
+        if it is found on the PATH,
+        if it is not found raises a FileNotFoundError
+        :param executable:
+        :return:
+        """
+
+        for i in PATH:
+            if os.path.exists(os.path.join(i, executable)):
+                return os.path.join(i, executable)
+        if raise_error:
+            raise FileNotFoundError(
+                "Could not find {p} on PATH. "
+                "Make sure {p} is added to path and try again".format(
+                    p=executable))
+        else:
+            return False
+
     def start_game(self, game_file):
         if not self.game_started:
             # cd to a persistent directory
@@ -138,25 +162,23 @@ def start_game(self, game_file):
             # print a welcome banner and pause for a moment
             # that way the end user will have a chance to see which version of frotz we are using
             # and which file we are loading
-            if platform.version().find("Ubuntu") > -1 or platform.version().find("Debian") > -1:
-                cmd = '/usr/games/frotz'
-            else:
-                cmd = '/usr/bin/frotz'
-            if os.path.isfile(cmd) and os.access(cmd, os.X_OK):
-                logging.debug('Using frotz installed in the system')
-                self._vte.feed_child(
-                    (
-                        "cd '%s'; "
-                        "clear; "
-                        "frotz|head -3 ; "
-                        "echo '\nLoading %s...'; "
-                        "sleep 2; frotz '%s'; "
-                        "exit\n" % (
-                            save_dir,
-                            os.path.basename(game_file),
-                            game_file)
-                    ).encode('utf-8')
-                )
+            if self.get_executable_path("frotz", raise_error=False):
+                cmd = self.get_executable_path("frotz", raise_error=False)
+                if os.path.isfile(cmd) and os.access(cmd, os.X_OK):
+                    logging.debug('Using frotz installed in the system')
+                    self._vte.feed_child(
+                        (
+                            "cd '%s'; "
+                            "clear; "
+                            "frotz|head -3 ; "
+                            "echo '\nLoading %s...'; "
+                            "sleep 2; frotz '%s'; "
+                            "exit\n" % (
+                                save_dir,
+                                os.path.basename(game_file),
+                                game_file)
+                        ).encode('utf-8')
+                    )
             else:
                 alert = ConfirmationAlert()
                 alert.props.title = "No module named frotz"
@@ -178,7 +200,7 @@ def _alert_response_cb(self, alert, response_id):
             logging.debug("Installing frotz")
             if platform.version().find("Ubuntu") > -1 or platform.version().find("Debian") > -1:
                 self._vte.feed_child("sudo apt install frotz\n".encode('utf-8'))
-            if platform.platform().find("fedora") > -1:
+            else:
                 self._vte.feed_child("sudo dnf install frotz\n".encode('utf-8'))
 
     def _game_start_cb(self, alert, response_id):