use UTF-8 box characters in ui

1 files changed, 60 insertions, 12 deletions

diff --git a/ui.go b/ui.go
index 03286ec..2768c43 100644
--- a/ui.go
+++ b/ui.go
@@ -6,15 +6,24 @@ import (
 	"github.com/charmbracelet/bubbletea"
 )
 
-// Types
+// UTF-8 box drawing characters.
+const (
+	boxHorizontal  = '─'
+	boxVertical    = '│'
+	boxTopLeft     = '┌'
+	boxTopRight    = '┐'
+	boxBottomLeft  = '└'
+	boxBottomRight = '┘'
+)
+
+// sigDigs is the number of significant digits when printing a number.
+const sigDigs = 64
 
 type UI struct {
 	calc        Calculator
 	windowWidth int // Width of the window measured in characters.
 }
 
-// Interface Implementations
-
 func (ui UI) Init() tea.Cmd {
 	return nil
 }
@@ -25,8 +34,14 @@ func (ui UI) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 		ui.windowWidth = msg.Width
 	case tea.KeyMsg:
 		switch msg.String() {
-		case "ctrl+c", "q":
+		case "ctrl+c", "Q":
 			return ui, tea.Quit
+		case "backspace":
+			if len(ui.calc.buffer) > 0 {
+				ui.calc.buffer = ui.calc.buffer[:len(ui.calc.buffer)-1]
+			}
+		default:
+			ui.calc.buffer += msg.String()
 		}
 	}
 	return ui, nil
@@ -35,14 +50,47 @@ func (ui UI) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 func (ui UI) View() string {
 	var s string
 	for _, f := range ui.calc.stack {
-		s += fmt.Sprintf("%f\n", f)
-	}
-	horizBar := make([]byte, ui.windowWidth)
-	for i := range horizBar {
-		horizBar[i] = '-'
+		s += fmt.Sprintf("%.*g\n", sigDigs, f)
 	}
-	s += string(horizBar) + "\n"
-	s += fmt.Sprintf("| %*s |\n", ui.windowWidth-4, ui.calc.buffer)
-	s += string(horizBar)
+	s += boxTop(ui.windowWidth) + "\n"
+	s += fmt.Sprintf("%[1]c%-*s%[1]c\n", boxVertical, ui.windowWidth-2, ui.calc.buffer)
+	s += boxBottom(ui.windowWidth)
 	return s
 }
+
+// boxTop returns the top of a UTF-8 box, 'width' characters wide (including
+// corners).
+func boxTop(width int) string {
+	if width < 1 {
+		return ""
+	}
+	row := make([]rune, width)
+	row[0] = boxTopLeft
+	row[width-1] = boxTopRight
+	if width > 1 {
+		fill(row[1:width-1], boxHorizontal)
+	}
+	return string(row)
+}
+
+// boxBottom returns the botom of a UTF-8 box, 'width' characters wide
+// (including corners).
+func boxBottom(width int) string {
+	if width < 1 {
+		return ""
+	}
+	row := make([]rune, width)
+	row[0] = boxBottomLeft
+	row[width-1] = boxBottomRight
+	if width > 1 {
+		fill(row[1:width-1], boxHorizontal)
+	}
+	return string(row)
+}
+
+// fill fills s with c.
+func fill(s []rune, c rune) {
+	for i := range s {
+		s[i] = c
+	}
+}