1 files changed, 143 insertions, 0 deletions
diff --git a/pkg/common/draw.go b/pkg/common/draw.go
new file mode 100644
index 0000000..b5b21fe
--- /dev/null
+++ b/pkg/common/draw.go
@@ -0,0 +1,143 @@
+package common
+
+import (
+	"fmt"
+	"io"
+	"os"
+	"strings"
+)
+
+// Style is a specific style
+type Style int
+
+// Styles
+const (
+	StyleDoubleLine = iota
+	StyleSingleLine
+	StyleDashedLine
+	StyleNoLine
+)
+
+// NewPen creates a new pen
+func NewPen(style Style, color int) *Pen {
+	bgcolor := 49
+	if os.Getenv("CLICOLOR") == "0" {
+		color = 0
+		bgcolor = 0
+	}
+	return &Pen{
+		style:   style,
+		color:   color,
+		bgcolor: bgcolor,
+	}
+}
+
+type styleDef struct {
+	cornerTL string
+	cornerTR string
+	cornerBL string
+	cornerBR string
+	lineH    string
+	lineV    string
+}
+
+var styleDefs = []styleDef{
+	{"\u2554", "\u2557", "\u255a", "\u255d", "\u2550", "\u2551"},
+	{"\u256d", "\u256e", "\u2570", "\u256f", "\u2500", "\u2502"},
+	{"\u250c", "\u2510", "\u2514", "\u2518", "\u254c", "\u254e"},
+	{" ", " ", " ", " ", " ", " "},
+}
+
+// Pen struct
+type Pen struct {
+	style   Style
+	color   int
+	bgcolor int
+}
+
+// Drawing struct
+type Drawing struct {
+	buf   *strings.Builder
+	width int
+}
+
+func (p *Pen) drawTopBars(buf io.Writer, labels ...string) {
+	style := styleDefs[p.style]
+	for _, label := range labels {
+		bar := strings.Repeat(style.lineH, len(label)+2)
+		fmt.Fprintf(buf, " ")
+		fmt.Fprintf(buf, "\x1b[%d;%dm", p.color, p.bgcolor)
+		fmt.Fprintf(buf, "%s%s%s", style.cornerTL, bar, style.cornerTR)
+		fmt.Fprintf(buf, "\x1b[%dm", 0)
+	}
+	fmt.Fprintf(buf, "\n")
+}
+func (p *Pen) drawBottomBars(buf io.Writer, labels ...string) {
+	style := styleDefs[p.style]
+	for _, label := range labels {
+		bar := strings.Repeat(style.lineH, len(label)+2)
+		fmt.Fprintf(buf, " ")
+		fmt.Fprintf(buf, "\x1b[%d;%dm", p.color, p.bgcolor)
+		fmt.Fprintf(buf, "%s%s%s", style.cornerBL, bar, style.cornerBR)
+		fmt.Fprintf(buf, "\x1b[%dm", 0)
+	}
+	fmt.Fprintf(buf, "\n")
+}
+func (p *Pen) drawLabels(buf io.Writer, labels ...string) {
+	style := styleDefs[p.style]
+	for _, label := range labels {
+		fmt.Fprintf(buf, " ")
+		fmt.Fprintf(buf, "\x1b[%d;%dm", p.color, p.bgcolor)
+		fmt.Fprintf(buf, "%s %s %s", style.lineV, label, style.lineV)
+		fmt.Fprintf(buf, "\x1b[%dm", 0)
+	}
+	fmt.Fprintf(buf, "\n")
+}
+
+// DrawArrow between boxes
+func (p *Pen) DrawArrow() *Drawing {
+	drawing := &Drawing{
+		buf:   new(strings.Builder),
+		width: 1,
+	}
+	fmt.Fprintf(drawing.buf, "\x1b[%dm", p.color)
+	fmt.Fprintf(drawing.buf, "\u2b07")
+	fmt.Fprintf(drawing.buf, "\x1b[%dm", 0)
+	return drawing
+}
+
+// DrawBoxes to draw boxes
+func (p *Pen) DrawBoxes(labels ...string) *Drawing {
+	width := 0
+	for _, l := range labels {
+		width += len(l) + 2 + 2 + 1
+	}
+	drawing := &Drawing{
+		buf:   new(strings.Builder),
+		width: width,
+	}
+	p.drawTopBars(drawing.buf, labels...)
+	p.drawLabels(drawing.buf, labels...)
+	p.drawBottomBars(drawing.buf, labels...)
+
+	return drawing
+}
+
+// Draw to writer
+func (d *Drawing) Draw(writer io.Writer, centerOnWidth int) {
+	padSize := (centerOnWidth - d.GetWidth()) / 2
+	if padSize < 0 {
+		padSize = 0
+	}
+	for _, l := range strings.Split(d.buf.String(), "\n") {
+		if len(l) > 0 {
+			padding := strings.Repeat(" ", padSize)
+			fmt.Fprintf(writer, "%s%s\n", padding, l)
+		}
+	}
+}
+
+// GetWidth of drawing
+func (d *Drawing) GetWidth() int {
+	return d.width
+}