MovieNight/common/colors.go

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package common
import (
"errors"
"fmt"
"math/rand"
"regexp"
"strconv"
"strings"
"time"
)
func init() {
rand.Seed(int64(time.Now().Nanosecond()))
}
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// Colors holds all the valid html color names for MovieNight
// the values in colors must be lowercase so it matches with the color input
// this saves from having to call strings.ToLower(color) every time to check
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var Colors = []string{
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"aliceblue",
"antiquewhite",
"aqua",
"aquamarine",
"azure",
"beige",
"bisque",
"blanchedalmond",
"burlywood",
"cadetblue",
"chartreuse",
"chocolate",
"coral",
"cornflowerblue",
"cornsilk",
"cyan",
"darkcyan",
"darkgoldenrod",
"darkgray",
"darkkhaki",
"darkorange",
"darksalmon",
"darkseagreen",
"darkturquoise",
"deeppink",
"deepskyblue",
"dodgerblue",
"floralwhite",
"fuchsia",
"gainsboro",
"ghostwhite",
"gold",
"goldenrod",
"gray",
"greenyellow",
"honeydew",
"hotpink",
"ivory",
"khaki",
"lavender",
"lavenderblush",
"lawngreen",
"lemonchiffon",
"lightblue",
"lightcoral",
"lightcyan",
"lightgoldenrodyellow",
"lightgreen",
"lightgrey",
"lightpink",
"lightsalmon",
"lightseagreen",
"lightskyblue",
"lightslategray",
"lightsteelblue",
"lightyellow",
"lime",
"limegreen",
"linen",
"magenta",
"mediumaquamarine",
"mediumorchid",
"mediumpurple",
"mediumseagreen",
"mediumslateblue",
"mediumspringgreen",
"mediumturquoise",
"mintcream",
"mistyrose",
"moccasin",
"navajowhite",
"oldlace",
"olive",
"olivedrab",
"orange",
"orangered",
"orchid",
"palegoldenrod",
"palegreen",
"paleturquoise",
"palevioletred",
"papayawhip",
"peachpuff",
"peru",
"pink",
"plum",
"powderblue",
"red",
"rosybrown",
"salmon",
"sandybrown",
"seagreen",
"seashell",
"silver",
"skyblue",
"slategray",
"snow",
"springgreen",
"steelblue",
"tan",
"thistle",
"tomato",
"turquoise",
"violet",
"wheat",
"white",
"whitesmoke",
"yellow",
"yellowgreen",
}
var (
regexColor = regexp.MustCompile(`^([0-9A-Fa-f]{3}){1,2}$`)
)
// IsValidColor takes a string s and compares it against a list of css color names.
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// It also accepts hex codes in the form of #RGB and #RRGGBB
func IsValidColor(s string) bool {
s = strings.TrimLeft(strings.ToLower(s), "#")
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for _, c := range Colors {
if s == c {
return true
}
}
if regexColor.MatchString(s) {
r, g, b, err := hex(s)
if err != nil {
return false
}
total := float32(r + g + b)
return total > 0.7 && float32(b)/total < 0.7
}
return false
}
// RandomColor returns a hex color code
func RandomColor() string {
var color string
for !IsValidColor(color) {
color = ""
for i := 0; i < 3; i++ {
s := strconv.FormatInt(rand.Int63n(255), 16)
if len(s) == 1 {
s = "0" + s
}
color += s
}
}
return "#" + color
}
// hex returns R, G, B as values
func hex(s string) (int, int, int, error) {
// Make the string just the base16 numbers
s = strings.TrimLeft(s, "#")
if len(s) == 3 {
var err error
s, err = hexThreeToSix(s)
if err != nil {
return 0, 0, 0, err
}
}
if len(s) == 6 {
R64, err := strconv.ParseInt(s[0:2], 16, 32)
if err != nil {
return 0, 0, 0, err
}
G64, err := strconv.ParseInt(s[2:4], 16, 32)
if err != nil {
return 0, 0, 0, err
}
B64, err := strconv.ParseInt(s[4:6], 16, 32)
if err != nil {
return 0, 0, 0, err
}
return int(R64), int(G64), int(B64), nil
}
return 0, 0, 0, errors.New("incorrect format")
}
func hexThreeToSix(s string) (string, error) {
if len(s) != 3 {
return "", fmt.Errorf("%d is the incorrect length of string for convertsion", len(s))
}
h := ""
for i := 0; i < 3; i++ {
h += string(s[i])
h += string(s[i])
}
return h, nil
}