Set a maximum of refreshes when wall is empty

The previous behaviour was to try to delete 5000 posts, even if the wall
is empty. The drawback was that if you want to delete only 10 posts,
then you would wait 5000*5 secondes (~7 hours) before the end of the
script.
Now, you can set a number of tries before quitting. If the delete button
is not found consecutively during this number of times, then we break
the loop.

I also added an environment variable parser like argparse to ease the
future use of other env variables.

.gitignore

@@ -1,3 +1,4 @@
 .envrc
 __pycache__
 venv
+.mypy_cache

deletefb/deletefb.py

@@ -6,6 +6,7 @@ from .tools.login import login
 from .tools.wall import delete_posts
 from .tools.conversations import traverse_conversations
 from .tools.comments import delete_comments
+from .tools.env_variables import EnvParser
 
 import argparse
 import getpass
@@ -13,8 +14,18 @@ import sys
 
 LOG = logger("deletefb")
 
+
 def run_delete():
     parser = argparse.ArgumentParser()
+    env_parser = EnvParser()
+
+    parser.add_argument(
+        "--help-env",
+        action="store_true",
+        dest="help_env",
+        default=False,
+        help="Print help about environment variables"
+    )
 
     parser.add_argument(
         "-M",
@@ -30,7 +41,7 @@ def run_delete():
     parser.add_argument(
         "-E",
         "--email",
-        required=True,
+        required='--help-env' not in sys.argv,
         dest="email",
         type=str,
         help="Your email address associated with the account"
@@ -48,7 +59,7 @@ def run_delete():
     parser.add_argument(
         "-U",
         "--profile-url",
-        required=True,
+        required='--help-env' not in sys.argv,
         dest="profile_url",
         type=str,
         help="The link to your Facebook profile, e.g. https://www.facebook.com/your.name"
@@ -99,9 +110,23 @@ def run_delete():
         help="Optional path to the Google Chrome (or Chromium) binary"
     )
 
+    env_parser.add_argument(
+        "DELETEFB_RETRY_THRESHOLD",
+        default=5,
+        dest="retry_threshold",
+        type=int,
+        help="Number of refreshes to ensure your wall is empty before quitting"
+    )
+
     args = parser.parse_args()
+    env = env_parser.parse_args()
+
+    if args.help_env:
+        env_parser.print_help()
+        sys.exit(0)
 
     settings["ARCHIVE"] = not args.archive_off
+    settings["RETRY_THRESHOLD"] = env.retry_threshold
 
     if args.year and args.mode not in ("wall", "conversations"):
         parser.error("The --year option is not supported in this mode")
@@ -133,5 +158,6 @@ def run_delete():
         print("Please enter a valid mode")
         sys.exit(1)
 
+
 if __name__ == "__main__":
     run_delete()

deletefb/tools/config.py

@@ -1,4 +1,5 @@
 settings = {
     "ARCHIVE" : True,
-    "MAX_POSTS" : 5000
+    "MAX_POSTS" : 5000,
+    "RETRY_THRESHOLD": 5
 }

deletefb/tools/env_variables.py

@@ -0,0 +1,50 @@
+#!/usr/bin/env python3
+
+import sys
+import os
+import re
+import typing as ty
+
+from types import SimpleNamespace
+
+
+class EnvVar:
+    def __init__(self,
+                 env_key: str,
+                 dest: ty.Optional[str] = None,
+                 type: ty.Type = str,
+                 default: ty.Optional[str] = None,
+                 help: ty.Optional[str] = None):
+
+        assert re.match('^[a-zA-Z_]+[a-zA-Z0-9_]*$', env_key), "Bad env key {0}".format(env_key)
+        self.key = env_key
+        self.dest = dest or env_key.lower()
+        self.type = type
+        self.help = help
+        self.default = default
+
+
+class EnvParser:
+    def __init__(self):
+        self.env_vars = set()
+
+    def add_argument(self, *args, **kwargs):
+        self.env_vars.add(EnvVar(*args, **kwargs))
+
+    def print_help(self):
+        print("environment variables:")
+        for v in self.env_vars:
+            print("  {0}=<{1}>\t{2}".format(v.key, v.type.__name__, v.help or ''))
+
+    def parse_args(self):
+        args = {}
+        for v in self.env_vars:
+            try:
+                args[v.dest] = v.type(os.environ.get(v.key, v.default))
+            except ValueError:
+                print("{0}: error: environment variable {1} should be of type {2}".format(
+                      sys.argv[0].split('/')[-1],
+                      v.key,
+                      v.type.__name__))
+                sys.exit(1)
+        return SimpleNamespace(**args)

deletefb/tools/wall.py

@@ -26,7 +26,11 @@ def delete_posts(driver,
 
     driver.get(user_profile_url)
 
+    retry_threshold = 0
     for _ in range(MAX_POSTS):
+        if retry_threshold >= settings["RETRY_THRESHOLD"]:
+            break
+
         post_button_sel = "_4xev"
 
         post_content_sel = "userContent"
@@ -36,6 +40,9 @@ def delete_posts(driver,
 
         with archiver("wall") as archive_wall_post:
             while True:
+                if retry_threshold >= settings["RETRY_THRESHOLD"]:
+                    break
+
                 try:
                     timeline_element = driver.find_element_by_class_name(post_button_sel)
 
@@ -67,15 +74,18 @@ def delete_posts(driver,
                             continue
 
                     if not delete_button:
+                        retry_threshold += 1
                         print("Could not find anything to delete")
                         break
+                    else:
+                        retry_threshold = 0
 
                     click_button(driver, delete_button)
                     confirmation_button = driver.find_element_by_class_name("layerConfirm")
 
                     click_button(driver, confirmation_button)
-
                 except SELENIUM_EXCEPTIONS as e:
+                    retry_threshold += 1
                     print(e)
                     continue
                 else: