From 62ac9a887b78c3b5f724c8ea66cb3c0377ca2cb3 Mon Sep 17 00:00:00 2001
From: Daniel Borchmann <daniel@algebra20.de>
Date: Wed, 28 Nov 2018 16:50:18 +0100
Subject: [PATCH] [Timeline] Extract gap-filling into separate function

---
 site-lisp/timeline-tools.el | 67 +++++++++++++++++++++----------------
 1 file changed, 38 insertions(+), 29 deletions(-)

diff --git a/site-lisp/timeline-tools.el b/site-lisp/timeline-tools.el
index 83bbf91..5b1ed2f 100644
--- a/site-lisp/timeline-tools.el
+++ b/site-lisp/timeline-tools.el
@@ -44,7 +44,7 @@
   :group 'applications)
 
 (defcustom timeline-tools-filter-functions
-  (list #'timeline-tools-remove-short-entries
+  (list #'timeline-tools-fill-gaps
         #'timeline-tools-cluster-same-entries)
   "List of functions to apply when formatting timelines.
 Filter are applied in the order they are given in this list."
@@ -332,39 +332,48 @@ function will throw an error."
 A slot is short if it is not longer than THRESHOLD seconds.
 Resulting gaps are distributed evenly among adjacent slots.
 THRESHOLD defaults to the value of
-`timeline-tools-short-task-threshold’ if not supplied."
+`timeline-tools-short-task-threshold’ if not supplied.
+
+This function destructively modifies its first argument."
   (unless (null timeline)
-   (let ((start (timeline-tools-entry-start-time (-first-item timeline)))
-         (end   (timeline-tools-entry-end-time (-last-item timeline)))
-         (threshold (or threshold timeline-tools-short-task-threshold))
-         new-timeline)
+    (let ((start (timeline-tools-entry-start-time (-first-item timeline)))
+          (end   (timeline-tools-entry-end-time (-last-item timeline)))
+          (threshold (or threshold timeline-tools-short-task-threshold))
+          new-timeline)
 
-     ;; remove all slots that are too short
-     (setq new-timeline
-           (cl-remove-if (lambda (entry)
-                           (<= (- (timeline-tools-entry-end-time entry)
-                                  (timeline-tools-entry-start-time entry))
-                               threshold))
-                         timeline))
+      ;; remove all slots that are too short
+      (setq new-timeline
+            (cl-remove-if (lambda (entry)
+                            (<= (- (timeline-tools-entry-end-time entry)
+                                   (timeline-tools-entry-start-time entry))
+                                threshold))
+                          timeline))
 
-     ;; reset start and end times
-     (setf (timeline-tools-entry-start-time (-first-item new-timeline)) start)
-     (setf (timeline-tools-entry-end-time (-last-item new-timeline)) end)
+      ;; reset start and end times
+      (setf (timeline-tools-entry-start-time (-first-item new-timeline)) start)
+      (setf (timeline-tools-entry-end-time (-last-item new-timeline)) end)
 
-     ;; distribute gaps evenly among adjacent slots
-     (cl-do
-         ((sub-timeline new-timeline (cdr sub-timeline)))
-         ((null (cdr sub-timeline)))
-       (let* ((entry-1 (-first-item sub-timeline))
-              (entry-2 (-second-item sub-timeline))
-              (end-1   (timeline-tools-entry-end-time entry-1))
-              (start-2 (timeline-tools-entry-start-time entry-2)))
-         (when (not (= end-1 start-2))
-           (let ((middle (/ (+ end-1 start-2) 2)))
-             (setf (timeline-tools-entry-end-time entry-1) middle)
-             (setf (timeline-tools-entry-start-time entry-2) middle)))))
+      ;; distribute gaps evenly among adjacent slots
+      (timeline-tools-fill-gaps new-timeline))))
 
-     new-timeline)))
+(defun timeline-tools-fill-gaps (timeline)
+  "Fill gaps in TIMELINE evenly.
+
+This is achieved by extending the start time and the end time of
+the surrounding entries equally.
+
+This function destructively modifies its first argument."
+  (cl-do
+      ((sub-timeline timeline (cdr sub-timeline)))
+      ((null (cdr sub-timeline)) timeline)
+    (let* ((entry-1 (-first-item sub-timeline))
+           (entry-2 (-second-item sub-timeline))
+           (end-1   (timeline-tools-entry-end-time entry-1))
+           (start-2 (timeline-tools-entry-start-time entry-2)))
+      (when (not (= end-1 start-2))
+        (let ((middle (/ (+ end-1 start-2) 2)))
+          (setf (timeline-tools-entry-end-time entry-1) middle)
+          (setf (timeline-tools-entry-start-time entry-2) middle))))))
 
 (defun timeline-tools-transform-timeline (timeline)
   "Return timeline from files, after application of