thread: allow switching between multipart/alternative parts

3 files changed, 61 insertions, 18 deletions

diff --git a/alot/commands/thread.py b/alot/commands/thread.py
index 9d67456b..178264c0 100644
--- a/alot/commands/thread.py
+++ b/alot/commands/thread.py
@@ -523,6 +523,9 @@ class EditNewCommand(Command):
     arguments=[(['fold'], {'action': cargparse.ValidatedStoreAction,
                              'validator': cargparse.is_int_or_pm})])
 @registerCommand(
+    MODE, 'cycle_alt', help='cycle among MIME alternative parts',
+    forced = {'cycle_alt' : True },)
+@registerCommand(
     MODE, 'weight', help='change weight of the thread tree',
     arguments=[(['weight'], {'action': cargparse.ValidatedStoreAction,
                              'validator': cargparse.is_int_or_pm})])
@@ -531,7 +534,8 @@ class ChangeDisplaymodeCommand(Command):
     repeatable = True
 
     def __init__(self, query=None, raw=None, all_headers=None,
-                 indent=None, fold = None, weight = None, **kwargs):
+                 indent=None, fold = None, weight = None, cycle_alt = None,
+                 **kwargs):
         """
         :param query: notmuch query string used to filter messages to affect
         :type query: str
@@ -552,6 +556,7 @@ class ChangeDisplaymodeCommand(Command):
         self.indent = indent
         self.fold   = fold
         self.weight = weight
+        self.cycle_alt = cycle_alt
         Command.__init__(self, **kwargs)
 
     def apply(self, ui):
@@ -619,6 +624,9 @@ class ChangeDisplaymodeCommand(Command):
                 else:
                     m.foldlevel = int(self.fold)
 
+            if self.cycle_alt:
+                m.cycle_alt()
+
 
 @registerCommand(MODE, 'pipeto', arguments=[
     (['cmd'], {'help': 'shellcommand to pipe to', 'nargs': '+'}),
diff --git a/alot/defaults/default.bindings b/alot/defaults/default.bindings
index cf64fc51..e28253ed 100644
--- a/alot/defaults/default.bindings
+++ b/alot/defaults/default.bindings
@@ -79,6 +79,7 @@ q = exit
     s = save
     r = reply
     | = prompt 'pipeto '
+    @ = cycle_alt
 
     'g j' = move next sibling
     'g k' = move previous sibling
diff --git a/alot/widgets/thread.py b/alot/widgets/thread.py
index 3be17976..3da660a5 100644
--- a/alot/widgets/thread.py
+++ b/alot/widgets/thread.py
@@ -82,6 +82,13 @@ class _MIMEPartWidget(urwid.WidgetWrap):
 
         self._fold_level = val_out
 
+    def cycle_alt(self):
+        if self._children is None:
+            return
+
+        for c in self._children:
+            c.cycle_alt()
+
 class _CryptPartWidget(_MIMEPartWidget):
     def __init__(self, mime_tree, alternative_pref):
         children = None
@@ -136,6 +143,43 @@ class _MultiMixedWidget(_MIMEPartWidget):
     def __init__(self, children):
         super().__init__(urwid.Pile(children), children)
 
+class _MultiAltWidget(_MIMEPartWidget):
+    _cur_idx         = None
+    _child_parts     = None
+    _sel_placeholder = None
+
+    def __init__(self, child_widgets, child_parts, alternative_pref):
+        self._child_parts = child_parts
+
+        child_idx = None
+        for idx, ch in enumerate(child_parts):
+            if ch.content_type == alternative_pref:
+                child_idx = idx
+                break
+        if child_idx is None:
+            child_idx = 0
+
+        self._sel_placeholder = urwid.WidgetPlaceholder(urwid.Text(''))
+
+        body_wgt = urwid.LineBox(self._sel_placeholder)
+
+        super().__init__(body_wgt, child_widgets)
+
+        self._select_alt(child_idx)
+
+    def _select_alt(self, idx):
+        child_part = self._child_parts[idx]
+        child_wgt  = self._children[idx]
+
+        self._w.set_title('Alternative MIME part %d/%d: %s' %
+                          (idx + 1, len(self._children), child_part.content_type))
+        self._sel_placeholder.original_widget = child_wgt
+
+        self._cur_idx = idx
+
+    def cycle_alt(self):
+        self._select_alt((self._cur_idx + 1) % len(self._children))
+
 class _Fold:
     level    = None
     start    = None
@@ -320,7 +364,7 @@ class _EmptyMessageWidget(_MIMEPartWidget):
         body_wgt = urwid.Text('<<< No displayable content >>>', align = 'center')
         super().__init__(body_wgt)
 
-def _handle_mixed(mime_tree, alternative_pref):
+def _handle_multipart(mime_tree, alternative_pref):
     children = []
     for child in mime_tree.children:
         ch = _render_mime_tree(child, alternative_pref)
@@ -328,20 +372,10 @@ def _handle_mixed(mime_tree, alternative_pref):
             children.append(ch)
 
     if len(children) > 0:
+        if mime_tree.is_alternative:
+            return _MultiAltWidget(children, mime_tree.children, alternative_pref)
         return _MultiMixedWidget(children)
 
-def _handle_alternative(mime_tree, alternative_pref):
-    # TODO: switching between alternatives
-    child = None
-    for ch in mime_tree.children:
-        if ch.content_type == alternative_pref:
-            child = ch
-            break
-    if child is None:
-        child = mime_tree.children[0]
-
-    return _render_mime_tree(child, alternative_pref)
-
 def _render_mime_tree(mime_tree, alternative_pref):
     # handle encrypted/signed parts
     if mime_tree.is_signed or mime_tree.is_encrypted:
@@ -349,10 +383,7 @@ def _render_mime_tree(mime_tree, alternative_pref):
 
     if mime_tree.children is not None:
         # multipart MIME parts
-        if mime_tree.is_alternative:
-            return _handle_alternative(mime_tree, alternative_pref)
-
-        return _handle_mixed(mime_tree, alternative_pref)
+        return _handle_multipart(mime_tree, alternative_pref)
 
     # no children - this is a leaf node
     # skip attachment parts
@@ -580,6 +611,9 @@ class MessageWidget(urwid.WidgetWrap):
     def foldlevel(self, val):
         self._body_wgt.foldlevel = val
 
+    def cycle_alt(self):
+        self._body_wgt.cycle_alt()
+
     def get_selected_attachment(self):
         """
         If an AttachmentWidget is currently focused, return it. Otherwise return