commands/thread: auto-page copiousoutput mailcap handlers

2 files changed, 17 insertions, 4 deletions

diff --git a/alot/commands/thread.py b/alot/commands/thread.py
index 5b9d527b..fe84695b 100644
--- a/alot/commands/thread.py
+++ b/alot/commands/thread.py
@@ -11,6 +11,7 @@ from   email.utils import getaddresses, parseaddr
 import logging
 import mailcap
 import os
+import shutil
 import subprocess
 import tempfile
 
@@ -945,15 +946,24 @@ class OpenAttachmentCommand(Command):
             ui.notify('No handler for: %s' % mimetype)
             return
 
-        # TODO: page copiousoutput
         # TODO: hook for processing the command
-        if h.needs_terminal:
+        pager = None
+        if h.copious_output:
+            # pipe the command's output to a pager
+            # TODO: allow configuring the pager from the config?
+            pager = os.getenv('PAGER', 'less')
+            if not shutil.which(pager):
+                pager = None
+
+        if h.needs_terminal or pager:
             with ui.paused(), h:
+                cmd = ('( %s ) | %s' % (h.cmd, pager)) if pager else h.cmd
+
                 logging.debug('Displaying part %s on terminal: %s',
-                              mimetype, h.cmd)
+                              mimetype, cmd)
 
                 try:
-                    result = subprocess.run(h.cmd, shell = True, check = True,
+                    result = subprocess.run(cmd, shell = True, check = True,
                                             input = h.stdin, stderr = subprocess.PIPE)
                 except subprocess.CalledProcessError as e:
                     logging.error('Calling mailcap handler "%s" failed with code %d: %s',
diff --git a/alot/utils/mailcap.py b/alot/utils/mailcap.py
index 9dccd7a0..f95a0a71 100644
--- a/alot/utils/mailcap.py
+++ b/alot/utils/mailcap.py
@@ -111,3 +111,6 @@ class MailcapHandler:
     @property
     def needs_terminal(self):
         return self._entry.get('needsterminal') is not None
+    @property
+    def copious_output(self):
+        return self._entry.get('copiousoutput') is not None