From 0511526d97cb6a74282c5f4dd334be1f5f355ea0 Mon Sep 17 00:00:00 2001
From: Dylan Baker <dylan@pnwbakers.com>
Date: Wed, 25 Jan 2017 15:52:58 -0800
Subject: Implement a hook that runs periodically

This creates a deferred that runs on a user configurable timer and is
provided the ui. This deferred will re-fire after the number of seconds
specified by the timer are eclipsed. By default this is 300 seconds.

Fixes #522
---
 NEWS                                   |  1 +
 alot/defaults/alot.rc.spec             |  3 +++
 alot/ui.py                             | 11 ++++++++++-
 docs/source/configuration/alotrc_table | 10 ++++++++++
 docs/source/configuration/hooks.rst    |  7 +++++++
 5 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/NEWS b/NEWS
index b5774584..ae67e361 100644
--- a/NEWS
+++ b/NEWS
@@ -5,6 +5,7 @@ next release:
 * enable variable interpolation in config file
 * Add encryption to CC addresses
 * Add bufferlist, tablist and pyshell subcommands to the command line interface
+* Add hook that runs periodically.
 
 0.4:
 * signal: refresh current buffer on SIGUSR1
diff --git a/alot/defaults/alot.rc.spec b/alot/defaults/alot.rc.spec
index d2ee450f..cd72b39c 100644
--- a/alot/defaults/alot.rc.spec
+++ b/alot/defaults/alot.rc.spec
@@ -248,6 +248,9 @@ reply_account_header_priority = force_list(default=list(From,To,Cc,Envelope-To,X
 #           history file might get *very* long.
 history_size = integer(default=50)
 
+# The number of seconds to wait between calls to the loop_hook
+periodic_hook_frequency = integer(default=300)
+
 # Key bindings
 [bindings]
     __many__ = string(default=None)
diff --git a/alot/ui.py b/alot/ui.py
index 0208288c..ba708804 100644
--- a/alot/ui.py
+++ b/alot/ui.py
@@ -7,7 +7,7 @@ import logging
 import os
 import signal
 
-from twisted.internet import reactor, defer
+from twisted.internet import reactor, defer, task
 import urwid
 
 from .settings import settings
@@ -103,6 +103,15 @@ class UI(object):
                                        unhandled_input=self._unhandled_input,
                                        input_filter=self._input_filter)
 
+        # Create a defered that calls the loop_hook
+        loop_hook = settings.get_hook('loop_hook')
+        if loop_hook:
+            loop = task.LoopingCall(loop_hook, ui=self)
+            loop_defered = loop.start(settings.get('periodic_hook_frequency'))
+            loop_defered.addErrback(
+                lambda e: logging.error('error in loop hook %s',
+                                        e.getErrorMessage()))
+
         # set up colours
         colourmode = int(settings.get('colourmode'))
         logging.info('setup gui in %d colours', colourmode)
diff --git a/docs/source/configuration/alotrc_table b/docs/source/configuration/alotrc_table
index 9e27b206..6929a665 100644
--- a/docs/source/configuration/alotrc_table
+++ b/docs/source/configuration/alotrc_table
@@ -385,6 +385,16 @@
     :default: 2
 
 
+.. _periodic-hook-frequency:
+
+.. describe:: periodic_hook_frequency
+
+     The number of seconds to wait between calls to the loop_hook
+
+    :type: integer
+    :default: 300
+
+
 .. _prefer-plaintext:
 
 .. describe:: prefer_plaintext
diff --git a/docs/source/configuration/hooks.rst b/docs/source/configuration/hooks.rst
index 6e7162e8..352701c3 100644
--- a/docs/source/configuration/hooks.rst
+++ b/docs/source/configuration/hooks.rst
@@ -205,3 +205,10 @@ Apart from command pre- and posthooks, the following hooks will be interpreted:
     :type suffix: str
     :returns: tuple of `prefix` and `suffix`
     :rtype: (str, str)
+
+.. py:function:: loop_hook(ui=None)
+
+    Run on a period controlled by :ref:`_periodic_hook_frequency <periodic-hook-frequency>`
+
+    :param ui: the main user interface
+    :type ui: :class:`alot.ui.UI`
-- 
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