From 0b9962c6c63aab4bbf546b4d594960ecdbfdd733 Mon Sep 17 00:00:00 2001
From: John McLear <john@mclear.co.uk>
Date: Mon, 28 Dec 2020 14:12:24 +0000
Subject: [PATCH] working going to end of the line and beginning of first

---
 src/static/js/ace2_inner.js | 36 +++++++++++++++++++++++-------------
 src/static/js/scroll.js     |  3 ++-
 2 files changed, 25 insertions(+), 14 deletions(-)

diff --git a/src/static/js/ace2_inner.js b/src/static/js/ace2_inner.js
index a2fd165a8..453b64c89 100644
--- a/src/static/js/ace2_inner.js
+++ b/src/static/js/ace2_inner.js
@@ -1,3 +1,4 @@
+'use strict';
 /**
  * This code is mostly from the old Etherpad. Please help us to comment this code.
  * This helps other people to understand this code better and helps them to improve it.
@@ -3059,32 +3060,41 @@ function Ace2Inner() {
           const linesLength = rep.lines.length();
 
           if (isPageUp) {
-            top.console.log('page up');
             // go to the top of the visible content
-            rep.selStart[0] -= visibleLineRange[1] - visibleLineRange[0] + 1;
-            rep.selEnd[0] -= visibleLineRange[1] - visibleLineRange[0] + 1;
-            // if the new rep is beyond the viewport, put the caret on the last line
-            if (rep.selStart[0] < 0) {
+            rep.selStart[0] -= visibleLineRange[1] - visibleLineRange[0];
+            rep.selEnd[0] -= visibleLineRange[1] - visibleLineRange[0];
+            // if the new rep is beyond the viewport or first line,
+            if (rep.selStart[0] <= 0) {
+              // put the caret on the first line in the first position
               rep.selStart = [0, 0];
               rep.selEnd = [0, 0];
             }
           }
 
           if (isPageDown) {
-            top.console.log('pag edown');
             // go to the bottom of the last visible content
             if (rep.selStart[0] === 0) {
               rep.selStart[0] += visibleLineRange[1] - visibleLineRange[0] - 1;
               rep.selEnd[0] += visibleLineRange[1] - visibleLineRange[0] - 1;
             } else {
-              rep.selStart[0] += visibleLineRange[1] - visibleLineRange[0];
-              rep.selEnd[0] += visibleLineRange[1] - visibleLineRange[0];
+              rep.selStart[0] = visibleLineRange[1] - visibleLineRange[0];
+              rep.selEnd[0] = visibleLineRange[1] - visibleLineRange[0];
             }
-            // if the new rep is beyond the viewport, put the caret on the last line
-            if (rep.selStart[0] > linesLength) {
-              top.console.log('beyond scope');
-              rep.selStart = [linesLength - 1, 0];
-              rep.selEnd = [linesLength - 1, 0];
+            if (rep.selStart[0] === -1) rep.selStart[0] = 0;
+            if (rep.selEnd[0] === -1) rep.selEnd[0] = 0;
+            // if the new rep is beyond the viewport
+            // put the caret on the last line at the end of the line
+            if (rep.selStart[0] >= (linesLength - 1)) {
+              // need current character length of line
+              const line = rep.lines.atIndex(rep.selEnd[0]);
+              let lineLength;
+              if (line) { // need to test if this is needed or not.
+                lineLength = line.width;
+              } else {
+                lineLength = 0;
+              }
+              rep.selStart = [linesLength - 1, lineLength];
+              rep.selEnd = [linesLength - 1, lineLength];
             }
             // TODO: Handle if character is X offset from content
           }
diff --git a/src/static/js/scroll.js b/src/static/js/scroll.js
index 1fd77cdfc..e69111912 100644
--- a/src/static/js/scroll.js
+++ b/src/static/js/scroll.js
@@ -365,7 +365,8 @@ Scroll.prototype.getVisibleLineRange = function (rep) {
 
 Scroll.prototype.getVisibleCharRange = function (rep) {
   const lineRange = this.getVisibleLineRange(rep);
-  // top.console.log(rep.lines);
+  // top.console.log('char range', 0, rep.lines.offsetOfIndex(lineRange[0]));
+  // top.console.log('char range', 1, rep.lines.offsetOfIndex(lineRange[1]));
   return [rep.lines.offsetOfIndex(lineRange[0]), rep.lines.offsetOfIndex(lineRange[1])];
 };