From f2e9cd3075cdf12e7c86f28aad63ee016a039d14 Mon Sep 17 00:00:00 2001
From: Timothy Warren <twarren@nabancard.com>
Date: Fri, 2 Apr 2021 11:57:24 -0400
Subject: [PATCH] Refactor input mapping

---
 editor/editor.go | 174 +++++++++++++++++++++++++++++------------------
 1 file changed, 109 insertions(+), 65 deletions(-)

diff --git a/editor/editor.go b/editor/editor.go
index cb31ef5..f02d3ed 100644
--- a/editor/editor.go
+++ b/editor/editor.go
@@ -80,6 +80,13 @@ func (e *editor) SetStatusMessage(template string, a ...interface{}) {
 func (e *editor) ProcessKeypress() bool {
 	ch, _ := terminal.ReadKey()
 
+	return e.processKeypressChar(ch)
+}
+
+/**
+ * Determine what to do with an individual character of input
+ */
+func (e *editor) processKeypressChar(ch rune) bool {
 	switch ch {
 	case key.Ctrl('q'):
 		if e.document.dirty && e.quitTimes > 0 {
@@ -106,34 +113,51 @@ func (e *editor) ProcessKeypress() bool {
 		// Modifier keys that return ANSI escape sequences
 		str := parseEscapeSequence()
 
-		switch str {
-		case keyUp,
-			keyDown,
-			keyLeft,
-			keyRight,
-			keyPageUp,
-			keyPageDown,
-			keyHome,
-			keyEnd:
-
-			e.moveCursor(str)
-
-		case keyDelete:
-			e.moveCursor(keyRight)
-			e.delChar()
+		// Don't swallow a character after ESC if it doesn't
+		// start an ANSI escape sequence
+		if len(str) == 1 {
+			return e.processKeypressChar(rune(str[0]))
 		}
 
+		e.processKeypressStr(str)
+
 	default:
 		e.insertChar(ch)
 	}
 
+	// Clear the quit message and restart the
+	// confirmation count if confirmation is not
+	// completed
 	if e.quitTimes != KiloQuitTimes {
 		e.quitTimes = KiloQuitTimes
+		e.SetStatusMessage("")
 	}
 
 	return true
 }
 
+/**
+ * Determine what do do with a parsed ANSI escape sequence
+ */
+func (e *editor) processKeypressStr(key string) {
+	switch key {
+	case keyUp,
+		keyDown,
+		keyLeft,
+		keyRight,
+		keyPageUp,
+		keyPageDown,
+		keyHome,
+		keyEnd:
+
+		e.moveCursor(key)
+
+	case keyDelete:
+		e.moveCursor(keyRight)
+		e.delChar()
+	}
+}
+
 func (e *editor) moveCursor(key string) {
 	var row *row
 	if e.cursor.y >= e.document.rowCount() {
@@ -229,64 +253,84 @@ func (e *editor) delChar() {
 
 // Convert the raw ANSI escape sequences to the type of key input
 func parseEscapeSequence() string {
-	var runes []rune
+	// If we aren't starting an escape sequence,
+	// return the character
+	startChar, _ := terminal.ReadKey()
+	if startChar != '[' && startChar != 'O' {
+		return string(startChar)
+	}
 
-	for i := 0; i < 3; i++ {
+	// Read one or two characters after
+	// \e[ or \eO, which is the end of the
+	// handled escape sequences
+	runes := [2]rune{'\000', '\000'}
+	for i := 0; i < 2; i++ {
 		ch, size := terminal.ReadKey()
 		if size == 0 {
-			return "\x1b"
+			return string(rune(key.Esc))
 		}
-		runes = append(runes, ch)
+		runes[i] = ch
 
-		if i == 1 && runes[1] >= 'A' {
-			// \eOH \eOF
-			if runes[0] == 'O' {
-				switch runes[1] {
-				case 'H':
-					return keyHome
-				case 'F':
-					return keyEnd
-				}
-			}
-			// \e[A
-			if runes[0] == '[' {
-				switch runes[1] {
-				case 'A':
-					return keyUp
-				case 'B':
-					return keyDown
-				case 'C':
-					return keyRight
-				case 'D':
-					return keyLeft
-				case 'H':
-					return keyHome
-				case 'F':
-					return keyEnd
-				}
-			}
+		if i == 0 && runes[0] >= 'A' && runes[0] <= 'Z' {
+			return escSeqToKey([]rune{startChar, runes[0]})
 		}
 
-		// \e[1~
-		if i == 2 && runes[0] == '[' && runes[2] == '~' {
-			switch runes[1] {
-			case '1':
-				return keyHome
-			case '3':
-				return keyDelete
-			case '4':
-				return keyEnd
-			case '5':
-				return keyPageUp
-			case '6':
-				return keyPageDown
-			case '7':
-				return keyHome
-			case '8':
-				return keyEnd
-			}
+		// \e[*~
+		if i == 1 && startChar == '[' && runes[1] == '~' {
+			return escSeqToKey([]rune{startChar, runes[0], runes[1]})
 		}
 	}
 
-	return string('\x1b')
+	return string(rune(key.Esc))
+}
+
+func escSeqToKey (seq []rune) string {
+	// \eO*
+	// \e[*
+	if len(seq) == 2 {
+		startChar, cmd := seq[0], seq[1]
+		if startChar == 'O' {
+			switch cmd {
+			case 'H':
+				return keyHome
+			case 'F':
+				return keyEnd
+			}
+		} else if startChar == '[' {
+			switch cmd {
+			case 'A':
+				return keyUp
+			case 'B':
+				return keyDown
+			case 'C':
+				return keyRight
+			case 'D':
+				return keyLeft
+			case 'H':
+				return keyHome
+			case 'F':
+				return keyEnd
+			}
+		}
+	} else if len(seq) == 3 { // \e[*~
+		cmd := seq[1]
+		switch cmd {
+		case '1':
+			return keyHome
+		case '3':
+			return keyDelete
+		case '4':
+			return keyEnd
+		case '5':
+			return keyPageUp
+		case '6':
+			return keyPageDown
+		case '7':
+			return keyHome
+		case '8':
+			return keyEnd
+		}
+	}
+
+	return string(rune(key.Esc))
 }