From 1cf13b0ec9656b101d30cbc21521de2e69f4429b Mon Sep 17 00:00:00 2001
From: Sander Schobers <sander@schobers.eu>
Date: Sun, 10 May 2020 10:57:13 +0200
Subject: [PATCH] Added color parsing (hex to sdl.Color).

---
 color.go      | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++
 color_test.go | 33 +++++++++++++++++++++++++++++++
 2 files changed, 88 insertions(+)
 create mode 100644 color.go
 create mode 100644 color_test.go

diff --git a/color.go b/color.go
new file mode 100644
index 0000000..4ef740b
--- /dev/null
+++ b/color.go
@@ -0,0 +1,55 @@
+package tins2020
+
+import (
+	"errors"
+	"regexp"
+
+	"github.com/veandco/go-sdl2/sdl"
+)
+
+var hexColorRE = regexp.MustCompile(`^#?([0-9A-Fa-f]{2})-?([0-9A-Fa-f]{2})-?([0-9A-Fa-f]{2})-?([0-9A-Fa-f]{2})?$`)
+
+func HexColor(s string) (sdl.Color, error) {
+	match := hexColorRE.FindStringSubmatch(s)
+	if match == nil {
+		return sdl.Color{}, errors.New("invalid color format")
+	}
+	values, err := HexToInts(match[1:]...)
+	if err != nil {
+		return sdl.Color{}, err
+	}
+	a := 255
+	if len(match[4]) > 0 {
+		a = values[3]
+	}
+	return sdl.Color{R: uint8(values[0]), G: uint8(values[1]), B: uint8(values[2]), A: uint8(a)}, nil
+}
+
+func HexToInt(s string) (int, error) {
+	var i int
+	for _, c := range s {
+		i *= 16
+		if c >= '0' && c <= '9' {
+			i += int(c - '0')
+		} else if c >= 'A' && c <= 'F' {
+			i += int(c - 'A' + 10)
+		} else if c >= 'a' && c <= 'f' {
+			i += int(c - 'a' + 10)
+		} else {
+			return 0, errors.New("hex digit not supported")
+		}
+	}
+	return i, nil
+}
+
+func HexToInts(s ...string) ([]int, error) {
+	ints := make([]int, len(s))
+	for i, s := range s {
+		value, err := HexToInt(s)
+		if err != nil {
+			return nil, err
+		}
+		ints[i] = value
+	}
+	return ints, nil
+}
diff --git a/color_test.go b/color_test.go
new file mode 100644
index 0000000..0b6f08e
--- /dev/null
+++ b/color_test.go
@@ -0,0 +1,33 @@
+package tins2020
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/veandco/go-sdl2/sdl"
+)
+
+func TestHexColor(t *testing.T) {
+	type test struct {
+		Hex      string
+		Success  bool
+		Expected sdl.Color
+	}
+	tests := []test{
+		test{Hex: "#AA3939", Success: true, Expected: sdl.Color{R: 170, G: 57, B: 57, A: 255}},
+		test{Hex: "AA3939", Success: true, Expected: sdl.Color{R: 170, G: 57, B: 57, A: 255}},
+		test{Hex: "#AA3939BB", Success: true, Expected: sdl.Color{R: 170, G: 57, B: 57, A: 187}},
+		test{Hex: "AG3939", Success: false, Expected: sdl.Color{}},
+		test{Hex: "AA3939A", Success: false, Expected: sdl.Color{}},
+		test{Hex: "AA39A", Success: false, Expected: sdl.Color{}},
+	}
+	for _, test := range tests {
+		color, err := HexColor(test.Hex)
+		if test.Success {
+			assert.Nil(t, err)
+			assert.Equal(t, color, test.Expected)
+		} else {
+			assert.NotNil(t, err)
+		}
+	}
+}