From 8230bf89443781c7662e69dbd52457585ef4e7c2 Mon Sep 17 00:00:00 2001
From: Ariel Don <arieldn@protonmail.com>
Date: Thu, 15 Jul 2021 15:50:03 -0500
Subject: [PATCH] LibGUI: Add Ctrl-H to insert mode

In Vim, Ctrl-H is effectively equivalent to backspace in insert mode, as
it deletes the previous character.

This commit implements method delete_previous_char() to TextEditor.
delete_char() already exists in EditingEngine, but it deletes the
next character rather than the previous. delete_previous_char() is then
called from within VimEditingEngine.
---
 Userland/Libraries/LibGUI/TextEditor.cpp       | 17 +++++++++++++++++
 Userland/Libraries/LibGUI/TextEditor.h         |  1 +
 Userland/Libraries/LibGUI/VimEditingEngine.cpp |  3 +++
 3 files changed, 21 insertions(+)

diff --git a/Userland/Libraries/LibGUI/TextEditor.cpp b/Userland/Libraries/LibGUI/TextEditor.cpp
index 7fcdec582e..a1b2cc7074 100644
--- a/Userland/Libraries/LibGUI/TextEditor.cpp
+++ b/Userland/Libraries/LibGUI/TextEditor.cpp
@@ -911,6 +911,23 @@ void TextEditor::delete_current_line()
     execute<RemoveTextCommand>(document().text_in_range(erased_range), erased_range);
 }
 
+void TextEditor::delete_previous_char()
+{
+    if (!is_editable())
+        return;
+
+    if (has_selection())
+        return delete_selection();
+
+    TextRange to_erase({ m_cursor.line(), m_cursor.column() - 1 }, m_cursor);
+    if (m_cursor.column() == 0 && m_cursor.line() != 0) {
+        size_t prev_line_len = line(m_cursor.line() - 1).length();
+        to_erase.set_start({ m_cursor.line() - 1, prev_line_len });
+    }
+
+    execute<RemoveTextCommand>(document().text_in_range(to_erase), to_erase);
+}
+
 void TextEditor::do_delete()
 {
     if (!is_editable())
diff --git a/Userland/Libraries/LibGUI/TextEditor.h b/Userland/Libraries/LibGUI/TextEditor.h
index 1a7830397a..6e1a1c0e9b 100644
--- a/Userland/Libraries/LibGUI/TextEditor.h
+++ b/Userland/Libraries/LibGUI/TextEditor.h
@@ -136,6 +136,7 @@ public:
     void do_delete();
     void delete_current_line();
     void delete_previous_word();
+    void delete_previous_char();
     void select_all();
     virtual void undo();
     virtual void redo();
diff --git a/Userland/Libraries/LibGUI/VimEditingEngine.cpp b/Userland/Libraries/LibGUI/VimEditingEngine.cpp
index a3530f6d32..1057373539 100644
--- a/Userland/Libraries/LibGUI/VimEditingEngine.cpp
+++ b/Userland/Libraries/LibGUI/VimEditingEngine.cpp
@@ -799,6 +799,9 @@ bool VimEditingEngine::on_key_in_insert_mode(const KeyEvent& event)
         case KeyCode::Key_W:
             m_editor->delete_previous_word();
             return true;
+        case KeyCode::Key_H:
+            m_editor->delete_previous_char();
+            return true;
         default:
             break;
         }