fancy shortening for authors list

issue #67

2 files changed, 93 insertions, 6 deletions

diff --git a/alot/helper.py b/alot/helper.py
index 91da0811..606e4f4a 100644
--- a/alot/helper.py
+++ b/alot/helper.py
@@ -18,7 +18,8 @@ Copyright (C) 2011 Patrick Totzke <patricktotzke@gmail.com>
 """
 from datetime import date
 from datetime import timedelta
-
+from collections import deque
+from string import strip
 import shlex
 import subprocess
 import email
@@ -32,9 +33,95 @@ from email.mime.multipart import MIMEMultipart
 
 
 def shorten(string, maxlen):
-    if len(string) > maxlen - 3:
-        string = string[:maxlen - 3] + u'\u2026'
-    return string
+    if maxlen > 1 and len(string) > maxlen:
+        string = string[:maxlen - 1] + u'\u2026'
+    return string[:maxlen]
+
+
+def shorten_author_string(authors_string, maxlength):
+    """
+    Parse a list of authors concatenated as a text string (comma
+    separated) and smartly adjust them to maxlength.
+
+    1) If the complete list of sender names does not fit in maxlength, it
+    tries to shorten names by using only the first part of each.
+
+    2) If the list is still too long, hide authors according to the
+    following priority:
+
+      - First author is always shown (if too long is shorten with ellipsis)
+
+      - If possible, last author is also shown (if too long, uses
+        ellipsis)
+
+      - If there are more than 2 authors in the thread, show the
+        maximum of them. More recent senders have more priority (Is
+        the list of authors already sorted by the date of msgs????)
+
+      - If it is finally necessary to hide any author, an ellipsis
+        between first and next authors is added.
+
+
+    EXAMPLE (authors string with different length constrains):
+         'King Kong, Mucho Muchacho, Jaime Huerta, Flash Gordon'
+         'King, Mucho, Jaime, Flash'
+         'King, ., Jaime, Flash'
+         'King, ., J., Flash'
+         'King, ., Flash'
+         'King, ., Fl.'
+         'King, .'
+         'K., .'
+         'K.'
+         """
+
+    # I will create a list of authors by parsing author_string. I use
+    # deque to do popleft without performance penalties
+    authors = deque()
+
+    # If author list is too long, it uses only the first part of each
+    # name (gmail style)
+    short_names = len(authors_string) > maxlength
+    for au in authors_string.split(", "):
+        if short_names:
+            authors.append(strip(au.split()[0]))
+        else:
+            authors.append(au)
+
+    # Author chain will contain the list of author strings to be
+    # concatenated using commas for the final formatted author_string.
+    authors_chain = deque()
+
+    # reserve space for first author
+    first_au = shorten(authors.popleft(), maxlength)
+    remaining_length = maxlength - len(first_au)
+
+    # Tries to add an ellipsis if no space to show more than 1 author
+    if authors and maxlength > 3 and remaining_length < 3:
+        first_au = shorten(first_au, maxlength - 3)
+        remaining_length += 3
+
+    # Tries to add as more authors as possible. It takes into account
+    # that if any author will be hidden, and ellipsis should be added
+    while authors and remaining_length >= 3:
+        au = authors.pop()
+        if len(au) > 1 and (remaining_length == 3 or
+                          (authors and remaining_length < 7)):
+            authors_chain.appendleft(u'\u2026')
+            break
+        else:
+            if authors:
+                # 5= ellipsis + 2 x comma and space used as separators
+                au_string = shorten(au, remaining_length - 5)
+            else:
+                # 2 = comma and space used as separator
+                au_string = shorten(au, remaining_length - 2)
+            remaining_length -= len(au_string) + 2
+            authors_chain.appendleft(au_string)
+
+    # Add the first author to the list and concatenate list
+    authors_chain.appendleft(first_au)
+    authorsstring = ', '.join(authors_chain)
+    return authorsstring
 
 
 def pretty_datetime(d):
diff --git a/alot/widgets.py b/alot/widgets.py
index 1645aff5..badc4fa5 100644
--- a/alot/widgets.py
+++ b/alot/widgets.py
@@ -22,7 +22,7 @@ from urwid.command_map import command_map
 import logging
 
 from settings import config
-from helper import shorten
+from helper import shorten_author_string
 from helper import pretty_datetime
 import message
 
@@ -63,7 +63,7 @@ class ThreadlineWidget(urwid.AttrMap):
 
         authors = self.thread.get_authors() or '(None)'
         maxlength = config.getint('general', 'authors_maxlength')
-        authorsstring = shorten(authors, maxlength)
+        authorsstring = shorten_author_string(authors, maxlength)
         self.authors_w = urwid.AttrMap(urwid.Text(authorsstring),
                                        'threadline_authors')
         cols.append(('fixed', len(authorsstring), self.authors_w))