From 0902d494c5a6de6069b4dcd8aa4e52ae537cfc64 Mon Sep 17 00:00:00 2001
From: Timothy Warren <twarren@nabancard.com>
Date: Wed, 24 Mar 2021 13:24:40 -0400
Subject: [PATCH] Get terminal size two ways

---
 internal/editor/editor.go     | 20 +++---------
 internal/terminal/terminal.go | 61 ++++++++++++++++++++++++++++++++---
 2 files changed, 60 insertions(+), 21 deletions(-)

diff --git a/internal/editor/editor.go b/internal/editor/editor.go
index 8142232..717ecff 100644
--- a/internal/editor/editor.go
+++ b/internal/editor/editor.go
@@ -1,9 +1,6 @@
 package editor
 
 import (
-	"bufio"
-	"os"
-
 	"timshome.page/gilo/internal/char"
 	"timshome.page/gilo/internal/terminal"
 )
@@ -13,19 +10,10 @@ type Editor struct {
 	cols int
 }
 
-var reader = bufio.NewReader(os.Stdin)
-
-func readKey() (rune, int) {
-	ch, size, err := reader.ReadRune()
-	if err != nil {
-		panic(err)
-	}
-
-	return ch, size
-}
-
 func drawRows() {
-	for y :=0; y < 24; y += 1 {
+	_, rows := terminal.Size()
+
+	for y :=0; y < rows; y += 1 {
 		terminal.OutLn("~")
 	}
 }
@@ -40,7 +28,7 @@ func RefreshScreen() {
 }
 
 func ProcessKeypress() bool {
-	ch, _ := readKey()
+	ch, _ := terminal.ReadKey()
 
 	// Clean up on exit
 	if ch == char.Ctrl('q') {
diff --git a/internal/terminal/terminal.go b/internal/terminal/terminal.go
index 4d48483..bce1f20 100644
--- a/internal/terminal/terminal.go
+++ b/internal/terminal/terminal.go
@@ -1,6 +1,7 @@
 package terminal
 
 import (
+	"bufio"
 	"fmt"
 	"os"
 
@@ -10,6 +11,17 @@ import (
 const ClearScreen = "2J"
 const ResetCursor = "H"
 
+var reader = bufio.NewReader(os.Stdin)
+
+func ReadKey() (rune, int) {
+	ch, size, err := reader.ReadRune()
+	if err != nil {
+		panic(err)
+	}
+
+	return ch, size
+}
+
 // Is this a valid interactive terminal?
 func check() {
 	if !term.IsTerminal(int(os.Stdin.Fd())) {
@@ -41,13 +53,52 @@ func ANSICode (code string) {
 	fmt.Printf("\x1b[%s", code)
 }
 
-func Size () (width int, height int) {
-	width, height, err := term.GetSize(int(os.Stdin.Fd()))
-	if err != nil {
-		width = 80
-		height = 24
+func sizeTrick () (rows int, cols int) {
+	// Move cursor to location further than likely screen size
+	// The cursor will move to maximum available position
+	fmt.Print("\x1b[999C\x1b[99B")
+
+	// Ask the terminal where the cursor is
+	fmt.Print("\x1b[6n")
+
+	// Read stdin looking for the reported location
+	buffer := ""
+	for char, _ := ReadKey(); char != 'R'; char, _ = ReadKey() {
+
+		if char == '\x1b' || char == '[' {
+			continue
+		}
+
+		if char == 'R' || char == '\x00'{
+			break
+		}
+
+		buffer += string(char)
 	}
 
+	_, err := fmt.Sscanf(buffer, "%d;%d", &rows, &cols)
+	if err != nil {
+		panic(err)
+	}
+
+	return rows, cols
+}
+
+func Size () (width int, height int) {
+	width = 80
+	height = 24
+
+	// Try the syscall first
+	width, height, err := term.GetSize(int(os.Stdin.Fd()))
+	if err == nil {
+		return width, height
+	}
+
+	// Figure out the size the hard way
+	height, width = sizeTrick()
+
+	OutLn("%d Rows, %d Cols", height, width)
+
 	return width, height
 }