From 42156f1aea5ad69fc14977b343c88acfc8e5d454 Mon Sep 17 00:00:00 2001
From: Lucas dos Santos Abreu <lucas.s.abreu@gmail.com>
Date: Mon, 28 Jun 2021 21:31:27 -0300
Subject: [PATCH] (feat): allow prompt callback on rune input and initial input

---
 terminal/runereader.go | 31 ++++++++++++++++++++++++++-----
 1 file changed, 26 insertions(+), 5 deletions(-)

diff --git a/terminal/runereader.go b/terminal/runereader.go
index a9a43ba3..6ab158a0 100644
--- a/terminal/runereader.go
+++ b/terminal/runereader.go
@@ -31,7 +31,13 @@ func (rr *RuneReader) printChar(char rune, mask rune) {
 	}
 }
 
-func (rr *RuneReader) ReadLine(mask rune, onRunes ...func(rune) bool) ([]rune, error) {
+type OnRuneFn func(rune, []rune) ([]rune, bool, error)
+
+func (rr *RuneReader) ReadLine(mask rune, onRunes ...OnRuneFn) ([]rune, error) {
+	return rr.ReadLineWithDefault(mask, []rune{}, onRunes...)
+}
+
+func (rr *RuneReader) ReadLineWithDefault(mask rune, d []rune, onRunes ...OnRuneFn) ([]rune, error) {
 	line := []rune{}
 	// we only care about horizontal displacements from the origin so start counting at 0
 	index := 0
@@ -41,11 +47,26 @@ func (rr *RuneReader) ReadLine(mask rune, onRunes ...func(rune) bool) ([]rune, e
 		Out: rr.stdio.Out,
 	}
 
+	onRune := func(r rune, line []rune) ([]rune, bool, error) {
+		return line, false, nil
+	}
+
+	// if the user pressed a key the caller was interested in capturing
+	if len(onRunes) > 0 {
+		onRune = onRunes[0]
+	}
+
 	// we get the terminal width and height (if resized after this point the property might become invalid)
 	terminalSize, _ := cursor.Size(rr.Buffer())
 	// we set the current location of the cursor once
 	cursorCurrent, _ := cursor.Location(rr.Buffer())
 
+	if len(d) > 0 {
+		index = len(d)
+		fmt.Fprint(rr.stdio.Out, string(d))
+		line = d
+	}
+
 	for {
 		// wait for some input
 		r, _, err := rr.ReadRune()
@@ -55,10 +76,10 @@ func (rr *RuneReader) ReadLine(mask rune, onRunes ...func(rune) bool) ([]rune, e
 		// increment cursor location
 		cursorCurrent.X++
 
-		// if the user pressed a key the caller was interested in capturing
-		if len(onRunes) > 0 && onRunes[0](r) {
-			return line, nil
-		} 
+		if l, stop, err := onRune(r, line); stop || err != nil {
+			return l, err
+		}
+
 		// if the user pressed enter or some other newline/termination like ctrl+d
 		if r == '\r' || r == '\n' || r == KeyEndTransmission {
 			// delete what's printed out on the console screen (cleanup)