support for a pre_tweet_hook configuration parameter

README.rst

@@ -125,6 +125,7 @@ Here’s an example ``conf`` file, showing every currently supported option:
     limit_timeline = 20
     timeout = 5.0
     sorting = descending
+    pre_tweet_hook = "scp [email protected]:~/public_html/twtxt.txt {twtfile}"
     post_tweet_hook = "scp {twtfile} [email protected]:~/public_html/twtxt.txt"
 
     [following]
@@ -151,10 +152,12 @@ Here’s an example ``conf`` file, showing every currently supported option:
 +-------------------+-------+------------+---------------------------------------------------+
 | sorting           | TEXT  | descending | sort timeline either descending or ascending      |
 +-------------------+-------+------------+---------------------------------------------------+
+| pre_tweet_hook    | TEXT  |            | command to be executed before tweeting            |
++-------------------+-------+------------+---------------------------------------------------+
 | post_tweet_hook   | TEXT  |            | command to be executed after tweeting             |
 +-------------------+-------+------------+---------------------------------------------------+
 
-``post_tweet_hook`` is very useful if you want to push your twtxt file to a remote (web) server. Check the example above tho see how it’s used with ``scp``.
+``pre_tweet_hook`` and ``post_tweet_hook`` are very useful if you want to push your twtxt file to a remote (web) server. Check the example above tho see how it’s used with ``scp``.
 
 [followings] section:
 =====================

config.example

@@ -6,6 +6,7 @@ use_pager = False
 limit_timeline = 20
 timeout = 5.0
 sorting = descending
+pre_tweet_hook = "scp [email protected]:~/public_html/twtxt.txt {twtfile}"
 post_tweet_hook = "scp {twtfile} [email protected]:~/public_html/twtxt.txt"
 
 [following]

twtxt/cli.py

@@ -18,6 +18,7 @@
 from twtxt.config import Config
 from twtxt.file import get_local_tweets, add_local_tweet
 from twtxt.helper import run_post_tweet_hook
+from twtxt.helper import run_pre_tweet_hook
 from twtxt.helper import style_tweet, style_source, style_source_with_status
 from twtxt.helper import validate_created_at, validate_text
 from twtxt.helper import sort_and_truncate_tweets
@@ -69,12 +70,18 @@ def cli(ctx, config, verbose):
 def tweet(ctx, created_at, twtfile, text):
     """Append a new tweet to your twtxt file."""
     tweet = Tweet(text, created_at) if created_at else Tweet(text)
+
+    pre_tweet_hook = ctx.obj["conf"].pre_tweet_hook
+    if pre_tweet_hook:
+        if not run_pre_tweet_hook(pre_tweet_hook, ctx.obj["conf"].options):
+            raise Exception("✗ pre_tweet_hook returned non-zero")
+
     if not add_local_tweet(tweet, twtfile):
         click.echo("✗ Couldn’t write to file.")
     else:
-        hook = ctx.obj["conf"].post_tweet_hook
-        if hook:
-            run_post_tweet_hook(hook, ctx.obj["conf"].options)
+        post_tweet_hook = ctx.obj["conf"].post_tweet_hook
+        if post_tweet_hook:
+            run_post_tweet_hook(post_tweet_hook, ctx.obj["conf"].options)
 
 
 @cli.command()

twtxt/config.py

@@ -101,6 +101,11 @@ def nick(self):
         cfg = self.open_config()
         return cfg.get("twtxt", "nick", fallback=os.environ.get("USER", ""))
 
+    @property
+    def pre_tweet_hook(self):
+        cfg = self.open_config()
+        return cfg.get("twtxt", "pre_tweet_hook", fallback=None)
+
     @property
     def post_tweet_hook(self):
         cfg = self.open_config()

twtxt/helper.py

@@ -66,6 +66,14 @@ def validate_text(ctx, param, value):
         raise click.BadArgumentUsage("Text can’t be empty.")
 
 
+def run_pre_tweet_hook(hook, options):
+    try:
+        command = shlex.split(hook.format(**options))
+    except KeyError:
+        click.echo("✗ Invalid variables in pre_tweet_hook.")
+        return False
+    return not subprocess.call(command, shell=True, stdout=subprocess.PIPE)
+
 def run_post_tweet_hook(hook, options):
     try:
         command = shlex.split(hook.format(**options))