From 60e6f0c723dcd224f5f14a914823a292bfbab5d7 Mon Sep 17 00:00:00 2001
From: Kevin Ansfield <kevin@lookingsideways.co.uk>
Date: Tue, 31 Jul 2018 13:45:31 +0100
Subject: [PATCH] Add delete to start of line for MacOS

refs https://github.com/bustle/mobiledoc-kit/issues/445
- add `Position.atStartOfLine` method that takes an existing position from which to find the start of it's line
- add `line` unit for use in `editor.performDelete`
- update delete key event handler to pass `line` unit when <kbd>Meta+Backspace</kbd> is pressed
---
 src/js/editor/event-manager.js  |  2 ++
 src/js/editor/post.js           | 11 ++++++-
 src/js/utils/cursor/position.js | 52 +++++++++++++++++++++++++++++++++
 3 files changed, 64 insertions(+), 1 deletion(-)

diff --git a/src/js/editor/event-manager.js b/src/js/editor/event-manager.js
index a744243cc..b73aee934 100644
--- a/src/js/editor/event-manager.js
+++ b/src/js/editor/event-manager.js
@@ -184,6 +184,8 @@ export default class EventManager {
         let unit = 'char';
         if (key.altKey && Browser.isMac()) {
           unit = 'word';
+        } else if (key.metaKey && Browser.isMac()) {
+          unit = 'line';
         } else if (key.ctrlKey && Browser.isWin()) {
           unit = 'word';
         }
diff --git a/src/js/editor/post.js b/src/js/editor/post.js
index 3051078dd..ac9fb5be8 100644
--- a/src/js/editor/post.js
+++ b/src/js/editor/post.js
@@ -401,7 +401,16 @@ class PostEditor {
       this.toggleSection('p', position);
       return this._range.head;
     } else {
-      let prevPosition = unit === 'word' ? position.moveWord(BACKWARD) : position.move(BACKWARD);
+      let prevPosition;
+
+      if (unit === 'word') {
+        prevPosition = position.moveWord(BACKWARD);
+      } else if (unit === 'line') {
+        prevPosition = Position.atStartOfLine(position, this.editor);
+      } else {
+        prevPosition = position.move(BACKWARD);
+      }
+
       let range = prevPosition.toRange(position);
       return this.deleteRange(range);
     }
diff --git a/src/js/utils/cursor/position.js b/src/js/utils/cursor/position.js
index 7e2fac370..97af5d437 100644
--- a/src/js/utils/cursor/position.js
+++ b/src/js/utils/cursor/position.js
@@ -62,6 +62,40 @@ function findOffsetInSection(section, node, offset) {
   }
 }
 
+// TODO: expose as utility function, update cursor._findNodeForPosition
+function findNodeForPosition(position) {
+  let { section } = position;
+  let node, offset;
+  if (section.isCardSection) {
+    offset = 0;
+    if (position.offset === 0) {
+      node = section.renderNode.element.firstChild;
+    } else {
+      node = section.renderNode.element.lastChild;
+    }
+  } else if (section.isBlank) {
+    node = section.renderNode.cursorElement;
+    offset = 0;
+  } else {
+    let { marker, offsetInMarker } = position;
+    if (marker.isAtom) {
+      if (offsetInMarker > 0) {
+        // FIXME -- if there is a next marker, focus on it?
+        offset = 0;
+        node = marker.renderNode.tailTextNode;
+      } else {
+        offset = 0;
+        node = marker.renderNode.headTextNode;
+      }
+    } else {
+      node = marker.renderNode.element;
+      offset = offsetInMarker;
+    }
+  }
+
+  return { node, offset };
+}
+
 let Position, BlankPosition;
 
 Position = class Position {
@@ -101,6 +135,24 @@ Position = class Position {
     return Position.fromNode(_renderTree, node, offset);
   }
 
+  static atStartOfLine(position, editor) {
+    let isPostBoundary = position.isHeadOfPost();
+    if (isPostBoundary) {
+      return position;
+    }
+
+    let { node, offset } = findNodeForPosition(position);
+
+    let range = document.createRange();
+    range.setStart(node, offset);
+    range.setEnd(node, offset);
+
+    let { y, height } = range.getBoundingClientRect();
+    let { left } = position.section.renderNode.element.getBoundingClientRect();
+
+    return Position.atPoint(left, y + height / 2, editor);
+  }
+
   static blankPosition() {
     return new BlankPosition();
   }