1 files changed, 124 insertions, 0 deletions
diff --git a/pkg/jp/barchart.go b/pkg/jp/barchart.go
new file mode 100644
index 0000000..c561f98
--- /dev/null
+++ b/pkg/jp/barchart.go
@@ -0,0 +1,124 @@
+package jp
+
+import (
+	"math"
+	"strings"
+
+	"github.com/sgreben/jp/pkg/jp/primitives"
+)
+
+// BarChart is a bar chart
+type BarChart struct {
+	Buffer []string
+
+	data *DataTable
+
+	Width       int
+	Height      int
+	Symbol      string
+	BarPaddingX int
+
+	chartHeight int
+	chartWidth  int
+
+	paddingX int
+	paddingY int
+}
+
+// NewBarChart returns a new bar chart
+func NewBarChart(width, height int) *BarChart {
+	chart := new(BarChart)
+	chart.Width = width
+	chart.Height = height
+	chart.Buffer = primitives.Buffer(width * height)
+	chart.Symbol = primitives.FullBlock4
+	chart.paddingY = 3
+	chart.BarPaddingX = 1
+	return chart
+}
+
+func (c *BarChart) writeText(text string, x, y int) {
+	coord := y*c.Width + x
+
+	for idx, char := range strings.Split(text, "") {
+		if coord+idx >= 0 && coord+idx < len(c.Buffer) {
+			c.Buffer[coord+idx] = char
+		}
+	}
+}
+
+// Draw implements Chart
+func (c *BarChart) Draw(data *DataTable) (out string) {
+
+	c.data = data
+
+	minY := math.Inf(1)
+	maxY := math.Inf(-1)
+	for _, row := range data.Rows {
+		for _, y := range row {
+			if y < minY {
+				minY = y
+			}
+			if y > maxY {
+				maxY = y
+			}
+		}
+	}
+
+	c.paddingX = 1
+	c.chartHeight = c.Height - c.paddingY
+	c.chartWidth = c.Width - c.paddingX - 1
+	scaleY := float64(c.chartHeight) / maxY
+	barPaddedWidth := c.chartWidth / len(data.Columns)
+	barWidth := barPaddedWidth - c.BarPaddingX
+	if barPaddedWidth < 1 {
+		barPaddedWidth = 1
+	}
+	if barWidth < 1 {
+		barWidth = 1
+	}
+
+	scaleY = float64(c.chartHeight) / maxY
+
+	for i, group := range data.Columns {
+		barLeft := c.paddingX + barPaddedWidth*i
+		barRight := barLeft + barWidth
+		y := data.Rows[0][i]
+		barHeight := y * scaleY
+		barTop := c.paddingY - 1 + int(barHeight)
+		for x := barLeft; x < barRight; x++ {
+			for y := c.paddingY - 1; y < barTop; y++ {
+				c.set(x, y, c.Symbol)
+			}
+			if barHeight < 1 && y > 0 {
+				for x := barLeft; x < barRight; x++ {
+					c.set(x, barTop, "▁")
+				}
+			}
+		}
+
+		// Group label
+		barMiddle := (barLeft + barRight) / 2
+		c.writeText(group, barMiddle-(len(group)/2), 0)
+
+		// Count label
+		countLabelY := barTop
+		if barHeight < 1 {
+			countLabelY = barTop + 1
+		}
+		c.writeText(primitives.Ff(y), barMiddle-(len(primitives.Ff(y))/2), countLabelY)
+	}
+
+	for row := c.Height - 1; row >= 0; row-- {
+		out += strings.Join(c.Buffer[row*c.Width:(row+1)*c.Width], "") + "\n"
+	}
+
+	return
+}
+
+func (c *BarChart) set(x, y int, s string) {
+	coord := y*c.Width + x
+	if coord > 0 && coord < len(c.Buffer) {
+		c.Buffer[coord] = s
+	}
+}