From bb6f7764a1a83576804005b9a9697c8999eed233 Mon Sep 17 00:00:00 2001
From: Timothy Warren <twarren@nabancard.com>
Date: Wed, 24 Mar 2021 15:09:28 -0400
Subject: [PATCH] Use buffer for creating output

---
 internal/ansi/ansi.go         | 10 +++++
 internal/editor/editor.go     | 85 +++++++++++++++++++++++++----------
 internal/terminal/terminal.go | 37 +++++----------
 3 files changed, 83 insertions(+), 49 deletions(-)
 create mode 100644 internal/ansi/ansi.go

diff --git a/internal/ansi/ansi.go b/internal/ansi/ansi.go
new file mode 100644
index 0000000..37b66e9
--- /dev/null
+++ b/internal/ansi/ansi.go
@@ -0,0 +1,10 @@
+package ansi
+
+import "fmt"
+
+const ClearScreen = "\x1b[2J"
+const ResetCursor = "\x1b[H"
+
+func Code (s string) string {
+	return fmt.Sprintf("\x1b[%s", s)
+}
\ No newline at end of file
diff --git a/internal/editor/editor.go b/internal/editor/editor.go
index a7b63f8..65d0b11 100644
--- a/internal/editor/editor.go
+++ b/internal/editor/editor.go
@@ -1,32 +1,39 @@
 package editor
 
 import (
+	"fmt"
+	"strings"
+	"timshome.page/gilo/internal/ansi"
 	"timshome.page/gilo/internal/char"
 	"timshome.page/gilo/internal/terminal"
 )
 
+// ----------------------------------------------------------------------------
+// !Editor
+// ----------------------------------------------------------------------------
+
 type editor struct {
 	rows int
 	cols int
 }
 
 func New() *editor {
-	cols, rows := terminal.Size()
+	rows, cols := terminal.Size()
 
-	e := new(editor)
-	e.cols = cols
-	e.rows = rows
-
-	return e
+	return &editor{rows, cols}
 }
 
 func (e *editor) RefreshScreen() {
-	terminal.ANSICode(terminal.ClearScreen)
-	terminal.ANSICode(terminal.ResetCursor)
+	ab := newBuffer()
 
-	e.drawRows()
+	ab.append(ansi.ClearScreen)
+	ab.append(ansi.ResetCursor)
 
-	terminal.ANSICode(terminal.ResetCursor)
+	e.drawRows(ab)
+
+	ab.append(ansi.ResetCursor)
+
+	terminal.Write(ab.toString())
 }
 
 func (e *editor) ProcessKeypress() bool {
@@ -34,29 +41,61 @@ func (e *editor) ProcessKeypress() bool {
 
 	// Clean up on exit
 	if ch == char.Ctrl('q') {
-		terminal.ANSICode(terminal.ClearScreen)
-		terminal.ANSICode(terminal.ResetCursor)
+		terminal.Write(ansi.ClearScreen)
+		terminal.Write(ansi.ResetCursor)
 
 		return false
 	}
 
-	// Ugliest syntax structure ever?
-	switch {
-	case char.IsCtrl(ch):
-		terminal.WriteLn("%d", ch)
-	default:
-		terminal.WriteLn("%d ('%c')", ch, ch)
-	}
-
 	return true
 }
 
-func (e *editor) drawRows() {
+func (e *editor) drawRows(ab *buffer) {
 	for y :=0; y < e.rows; y += 1 {
-		terminal.Write("~")
+		ab.appendRune('~')
 
 		if y < (e.rows - 1) {
-			terminal.Write("\r\n")
+			ab.append("\r\n")
 		}
 	}
 }
+
+// ----------------------------------------------------------------------------
+// !buffer
+// ----------------------------------------------------------------------------
+
+type buffer struct {
+	buf *strings.Builder
+}
+
+func newBuffer() *buffer {
+	var buf strings.Builder
+
+	b := new(buffer)
+	b.buf = &buf
+
+	return b
+}
+
+func (b *buffer) appendRune(r rune) int {
+	size, _ := b.buf.WriteRune(r)
+
+	return size
+}
+
+func (b *buffer) append(s string) int {
+	size, _ := b.buf.WriteString(s)
+
+	return size
+}
+
+func (b *buffer) appendLn(s string) int {
+	str := fmt.Sprintf("%s\r\n", s)
+	size, _ := b.buf.WriteString(str)
+
+	return size
+}
+
+func (b *buffer) toString() string {
+	return b.buf.String()
+}
diff --git a/internal/terminal/terminal.go b/internal/terminal/terminal.go
index c0638cc..dafe9c5 100644
--- a/internal/terminal/terminal.go
+++ b/internal/terminal/terminal.go
@@ -8,9 +8,6 @@ import (
 	"golang.org/x/term"
 )
 
-const ClearScreen = "2J"
-const ResetCursor = "H"
-
 var reader = bufio.NewReader(os.Stdin)
 
 func ReadKey() (rune, int) {
@@ -49,10 +46,6 @@ func RawOff(oldState *term.State) {
 	}
 }
 
-func ANSICode (code string) {
-	fmt.Printf("\x1b[%s", code)
-}
-
 func sizeTrick () (rows int, cols int) {
 	// Move cursor to location further than likely screen size
 	// The cursor will move to maximum available position
@@ -84,32 +77,24 @@ func sizeTrick () (rows int, cols int) {
 	return rows, cols
 }
 
-func Size () (width int, height int) {
-	width = 80
-	height = 24
+// Get the size of the terminal in rows and columns
+func Size () (rows int, cols int) {
+	cols = 80
+	rows = 24
 
 	// Try the syscall first
-	width, height, err := term.GetSize(int(os.Stdin.Fd()))
+	cols, rows, err := term.GetSize(int(os.Stdin.Fd()))
 	if err == nil {
-		return width, height
+		return rows, cols
 	}
 
 	// Figure out the size the hard way
-	height, width = sizeTrick()
+	rows, cols = sizeTrick()
 
-	WriteLn("%d Rows, %d Cols", height, width)
-
-	return width, height
+	return rows, cols
 }
 
-
-// Print a formatted string to stdout, with CRLF line endings for proper terminal formatting
-func WriteLn(format string, a ...interface{}) {
-	formatted := fmt.Sprintf(format, a...)
-
-	fmt.Printf("%s\r\n", formatted)
-}
-
-func Write(format string, a ...interface{}) {
-	fmt.Printf(format, a...)
+// Print string to stdout
+func Write(s string) {
+	fmt.Print(s)
 }