viewport: accept and insert spacing lines below header

This allows the presence of empty lines between the task list and the
header in a viewport, which is especially desirable to abide by standard
Markdown conventions.

The header spacing of existing viewports is preserved. For new Markdown
task lists, the spacing now follows the one configured in vimwiki with
`g:vimwiki_markdown_header_style`.

GitHub: closes tools-life#298

taskwiki/viewport.py

@@ -331,6 +331,9 @@ def load_tasks(self):
         # Load all tasks below the viewport
         for i in range(self.line_number + 1, len(self.cache.buffer)):
             line = self.cache.buffer[i]
+            if not line:
+                continue
+
             match = re.search(regexp.GENERIC_TASK, line)
 
             if match:
@@ -373,15 +376,28 @@ def sync_with_taskwarrior(self):
                 self.cache.remove_line(vimwikitask['line_number'])
 
         # Add the tasks that match the filter and are not listed
-        added_tasks = 0
         existing_tasks = len(self.tasks)
 
         sorted_to_add = list(to_add)
         sorted_to_add.sort(key=lambda x: x['entry'])
 
-        for task in sorted_to_add:
-            added_tasks += 1
-            added_at = self.line_number + existing_tasks + added_tasks
+        # Insert below headers (with separating lines), or below existing tasks
+        if existing_tasks == 0:
+            if to_add and self.cache.markup_syntax == 'markdown':
+                md_h_style = util.get_var('vimwiki_markdown_header_style', 1)
+                newlines = int(md_h_style)
+            else:
+                newlines = 0
+
+            for _ in range(newlines):
+                self.cache.insert_line('', self.line_number + 1)
+
+            insert_start_line = self.line_number + newlines + 1
+        else:
+            insert_start_line = max(t['line_number'] for t in self.tasks) + 1
+
+        for i, task in enumerate(sorted_to_add):
+            added_at = insert_start_line + i
 
             # Add the task object to cache
             self.cache.task[short.ShortUUID(task['uuid'], self.tw)] = task
@@ -399,9 +415,8 @@ def sync_with_taskwarrior(self):
 
         sort.TaskSorter(self.cache, self.tasks, self.sort).execute()
 
+        # Remove excess task lines beyond limit count
         if self.count is not None:
-            for i in range(
-                self.line_number + self.count,
-                self.line_number + existing_tasks + added_tasks,
-            ):
-                self.cache.remove_line(self.line_number + self.count + 1)
+            task_lines = sorted(t['line_number'] for t in self.tasks)
+            for excess_line in reversed(task_lines[self.count:]):
+                self.cache.remove_line(excess_line)

tests/conftest.py

@@ -14,9 +14,9 @@
         'HEADER3': "=== %s ===",
     },
     'markdown': {
-        'HEADER1': "# %s",
-        'HEADER2': "## %s",
-        'HEADER3': "### %s",
+        'HEADER1': "# %s\n",
+        'HEADER2': "## %s\n",
+        'HEADER3': "### %s\n",
     }
 }
 

tests/test_viewport.py

@@ -667,3 +667,28 @@ def execute(self):
         # testfile3 only has header, so refresh on open makes changes
         self.client.edit(testfile3)
         assert self.client.eval('&modified') == '1'
+
+
+class TestViewportsNoChangePreserving(MultiSyntaxIntegrationTest):
+
+    viminput = """
+    HEADER2(Work tasks | +work)
+
+    * [ ] tag work task  #{uuid}
+
+
+    HEADER2(Home tasks | +home)
+
+
+    * [ ] tag home task  #{uuid}
+    """
+
+    vimoutput = viminput
+
+    tasks = [
+        dict(description="tag work task", tags=['work']),
+        dict(description="tag home task", tags=['home']),
+    ]
+
+    def execute(self):
+        self.command("w", regex="written$", lines=1)