From f4a252a29474a5c5f75f34d4f44db3454981b30e Mon Sep 17 00:00:00 2001
From: Timothy Warren <twarren@nabancard.com>
Date: Fri, 2 Apr 2021 10:48:51 -0400
Subject: [PATCH] Basic character deletion

---
 editor/constants.go |  4 ++--
 editor/editor.go    | 30 ++++++++++++++++++++++++------
 editor/row.go       | 19 +++++++++++++++++++
 3 files changed, 45 insertions(+), 8 deletions(-)

diff --git a/editor/constants.go b/editor/constants.go
index 0027ff3..73edecf 100644
--- a/editor/constants.go
+++ b/editor/constants.go
@@ -5,7 +5,7 @@ package editor
 // ----------------------------------------------------------------------------
 
 const (
-	KiloVersion = "0.0.1"
-	KiloTabStop = 4
+	KiloVersion   = "0.0.1"
+	KiloTabStop   = 4
 	KiloQuitTimes = 3
 )
diff --git a/editor/editor.go b/editor/editor.go
index 20cedc2..cb31ef5 100644
--- a/editor/editor.go
+++ b/editor/editor.go
@@ -22,13 +22,13 @@ type statusMsg struct {
 }
 
 type editor struct {
-	screen   *terminal.Screen
-	cursor   *point
-	offset   *point
-	document *document
-	status   *statusMsg
+	screen    *terminal.Screen
+	cursor    *point
+	offset    *point
+	document  *document
+	status    *statusMsg
 	quitTimes uint8
-	renderX  int
+	renderX   int
 }
 
 func New() *editor {
@@ -100,6 +100,7 @@ func (e *editor) ProcessKeypress() bool {
 	case key.Enter:
 
 	case key.Backspace, key.Ctrl('h'):
+		e.delChar()
 
 	case key.Esc, key.Ctrl('l'):
 		// Modifier keys that return ANSI escape sequences
@@ -116,6 +117,10 @@ func (e *editor) ProcessKeypress() bool {
 			keyEnd:
 
 			e.moveCursor(str)
+
+		case keyDelete:
+			e.moveCursor(keyRight)
+			e.delChar()
 		}
 
 	default:
@@ -209,6 +214,19 @@ func (e *editor) insertChar(ch rune) {
 	e.document.dirty = true
 }
 
+func (e *editor) delChar() {
+	if e.cursor.y == e.document.rowCount() {
+		return
+	}
+
+	if e.cursor.x > 0 {
+		e.document.rows[e.cursor.y].deleteRune(e.cursor.x - 1)
+		e.cursor.x -= 1
+	}
+
+	e.document.dirty = true
+}
+
 // Convert the raw ANSI escape sequences to the type of key input
 func parseEscapeSequence() string {
 	var runes []rune
diff --git a/editor/row.go b/editor/row.go
index 5a51964..04c99d5 100644
--- a/editor/row.go
+++ b/editor/row.go
@@ -54,6 +54,25 @@ func (r *row) insertRune(ch rune, at int) {
 	r.update()
 }
 
+func (r *row) deleteRune(at int) {
+	if at < 0 || at >= r.size() {
+		return
+	}
+
+	var newSlice []rune
+
+	// Split the character array at the insertion point
+	start := r.chars[0:at]
+	end := r.chars[at+1 : r.size()] // Skip the index in question
+
+	// Splice it back together
+	newSlice = append(newSlice, start...)
+	newSlice = append(newSlice, end...)
+
+	r.chars = newSlice
+	r.update()
+}
+
 func (r *row) update() {
 	r.render = r.render[:0]
 	replacement := strings.Repeat(" ", KiloTabStop)