From ebf6b38a97a4d2396de0c73bd0bbb6b1831167fe Mon Sep 17 00:00:00 2001
From: Timothy J Warren <tim@timshomepage.net>
Date: Thu, 25 Mar 2021 12:46:53 -0400
Subject: [PATCH] Move cursor with wasd keys

---
 editor/editor.go | 22 +++++++++++++++++++++-
 terminal/ansi.go | 11 +++++++++++
 2 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/editor/editor.go b/editor/editor.go
index 3289f67..4d229c7 100644
--- a/editor/editor.go
+++ b/editor/editor.go
@@ -36,8 +36,8 @@ func (e *editor) RefreshScreen() {
 	ab.append(terminal.ResetCursor)
 
 	e.drawRows(ab)
+	ab.append(terminal.MoveCursor(e.cursor.x, e.cursor.y))
 
-	ab.append(terminal.ResetCursor)
 	ab.append(terminal.ShowCursor)
 
 	terminal.Write(ab.toString())
@@ -53,6 +53,13 @@ func (e *editor) ProcessKeypress() bool {
 		return false
 	}
 
+	switch ch {
+	case 'w', 'a', 's', 'd':
+		e.moveCursor(ch)
+	default:
+		// Do nothing!
+	}
+
 	return true
 }
 
@@ -86,4 +93,17 @@ func (e *editor) drawRows(ab *buffer) {
 			ab.append("\r\n")
 		}
 	}
+}
+
+func (e *editor) moveCursor (key rune) {
+	switch key {
+	case 'a':
+		e.cursor.x -= 1
+	case 'd':
+		e.cursor.x += 1
+	case 'w':
+		e.cursor.y -= 1
+	case 's':
+		e.cursor.y += 1
+	}
 }
\ No newline at end of file
diff --git a/terminal/ansi.go b/terminal/ansi.go
index 0a87565..17c76eb 100644
--- a/terminal/ansi.go
+++ b/terminal/ansi.go
@@ -1,3 +1,4 @@
+// ANSI Terminal Escape Codes and helpers
 package terminal
 
 import "fmt"
@@ -11,4 +12,14 @@ const ResetCursor = "\x1b[H"
 
 func Code (s string) string {
 	return fmt.Sprintf("\x1b[%s", s)
+}
+
+
+// Move the terminal cursor to the 0-based coordinate
+func MoveCursor(x int, y int) string {
+	// Allow 0-based indexing, the terminal code is 1-based
+	x += 1
+	y += 1
+
+	return Code(fmt.Sprintf("%d;%dH", y, x))
 }
\ No newline at end of file