Fixes some off by one issues as well as printing invisible characters

main.go

@@ -35,6 +35,7 @@ type Buffer struct {
 	cursor int
 	maxWidth int
 	offset int
+	cursorStart int
 }
 
 func (lb Buffer) String() string {
@@ -53,7 +54,13 @@ func (lb *Buffer) deleteChar() {
 	}
 }
 
+// TODO rework this so that the changes are made but all drawing to the screen comes
+// from one source and always draws the whole input area. This will make dealing with
+// offsets much easier.
 func (lb *Buffer) addChar(c rune, echo bool) {
+	if c < 9 || (c > 10 && c < 13) || (c > 13 && c < 32) {
+		return
+	}
 	if lb.cursor == len(lb.buf) {
 		lb.buf = append(lb.buf, c)
 		lb.cursor++
@@ -76,9 +83,11 @@ func (lb *Buffer) controlInput(c rune) {
 	case Delete:
 		lb.deleteChar()
 	case BackSpace:
-		lb.cursor--
-		fmt.Print("\033[1D")
-		lb.deleteChar()
+		if lb.cursor > 0 {
+			lb.cursor--
+			fmt.Print("\033[1D")
+			lb.deleteChar()
+		}
 	case LeftArrow:
 		if lb.cursor > 0 {
 			lb.cursor--
@@ -90,11 +99,15 @@ func (lb *Buffer) controlInput(c rune) {
 			fmt.Print("\033[1C")
 		}
 	case Home:
-		fmt.Printf("\033[%dD", lb.cursor)
-		lb.cursor = 0
+		if lb.cursor > 0 {
+			fmt.Printf("\033[%dD", lb.cursor)
+			lb.cursor = 0
+		}
 	case End:
-		fmt.Printf("\033[%dC", len(lb.buf)-lb.cursor)
-		lb.cursor = len(lb.buf)
+		if lb.cursor < len(lb.buf) {
+			fmt.Printf("\033[%dC", len(lb.buf)-lb.cursor)
+			lb.cursor = len(lb.buf)
+		}
 	}
 }
 
@@ -104,12 +117,20 @@ func (lb *Buffer) seedContent(s string) {
 	}
 }
 
+func parseCursorPosition(esc string) (int, int, error) {
+	var row, col int
+	r := strings.NewReader(esc)
+	_, err := fmt.Fscanf(r, "\033[%d;%dR", &row, &col)
+	return row, col, err
+}
+
 func GetText(prompt string, content string) string {
 	cols, _ := termios.GetWindowSize()
-	b := Buffer{make([]rune, 0, (len(content)+1)*2), 0, cols-len(prompt), 0}
+	b := Buffer{make([]rune, 0, (len(content)+1)*2), 0, cols-len(prompt), 0, 0}
 	b.seedContent(content)
 
 	fmt.Print(prompt)
+	fmt.Print("\033[6n")
 	fmt.Print(b.String())
 
 	var ch rune
@@ -118,7 +139,10 @@ func GetText(prompt string, content string) string {
 
 	for {
 		ch, err = readKey(reader)
-		if err != nil {
+		if err != nil && err.Error() == "response" {
+			b.cursorStart = int(ch)
+			b.maxWidth = cols - b.cursorStart
+		} else if err != nil {
 			continue
 		}
 		if ch == CarriageReturn || ch == NewLine {
@@ -172,6 +196,12 @@ func readKey(reader *bufio.Reader) (rune, error) {
 			char = End
 		case isDeleteKey(escSeq):
 			char = Delete
+		case escSeq[len(escSeq)-1] == 'R':
+			_, cols, err := parseCursorPosition(escSeq)
+			if err == nil {
+				err = fmt.Errorf("response")
+			}
+			return rune(cols), err
 		default:
 			fmt.Printf("Odd sequence: %s\n", escSeq[1:])
 		}

qline.swim

@@ -0,0 +1 @@
+{"BoardTitle":"","Lanes":[{"LaneTitle":"Backlog","Stories":[{"StoryTitle":"Figure out a way to solve the linewidth issue","StoryBody":"Right now, line editing is working, but without knowing where the cursor starts out we cant know where the end of the line is.","StoryUsers":["sloum"],"StoryTag":-1,"StoryTasks":[{"TaskBody":"Try the escape code method.","TaskComplete":false}],"StoryComments":[],"StoryCreated":"2021-04-01T21:57:43.386761058-07:00","StoryUpdated":"2021-04-01T21:59:21.689817136-07:00","StoryPoints":3},{"StoryTitle":"Build out line offsetting for display","StoryBody":"Once widths are figured out there needs to be horizontal scrolling of input for display soas to not jump down a line.","StoryUsers":["sloum"],"StoryTag":-1,"StoryTasks":[],"StoryComments":[],"StoryCreated":"2021-04-01T21:59:09.929902095-07:00","StoryUpdated":"2021-04-01T22:00:00.004446556-07:00","StoryPoints":2}],"CurrentStory":1},{"LaneTitle":"Active","Stories":[],"CurrentStory":-1},{"LaneTitle":"Complete","Stories":[],"CurrentStory":-1}],"CurrentLane":0,"Zoom":3,"StoryOpen":true}