tool: add wcag test script

1 files changed, 57 insertions, 0 deletions

diff --git a/colors/wcag.sh b/colors/wcag.sh
new file mode 100644
index 0000000..4b8d313
--- /dev/null
+++ b/colors/wcag.sh
@@ -0,0 +1,57 @@
+#!/bin/sh
+. ./ansi.sh
+. ./colors.sh
+
+# this uses the webaim.org contrast checker api to check all colors against
+# background.
+# depends on jo, jq, and xh
+
+[ $# -lt 0 ] || set -- \
+	red   green   yellow   blue   magenta   cyan   white \
+	brred brgreen bryellow brblue brmagenta brcyan brwhite
+
+# lower: error if below this
+lower=4.5
+# higher: warn if below this
+higher=7
+
+# reset after printing
+reprint() {
+	printf '%s%s' "$@" "$(reset)"
+}
+
+prefix() {
+	reprint "$(acol $1)$2"
+}
+
+demo() {
+	reprint "$(fgc $color)$(bgc $background)demo text"
+}
+
+# $1 should be "fail" or "warn"
+fmt() {
+	case "$1" in
+		fail) printf '"%s: #%s at \(.ratio)\t%s (%s)\n"' \
+				"$(prefix 31 fail)" "$color" "$(demo)" "$colnm";;
+		warn) printf '"%s: #%s at \(.ratio)\t%s (%s)\n"' \
+				"$(prefix 33 warn)" "$color" "$(demo)" "$colnm";;
+		*) printf '""' ;;
+	esac
+}
+
+# reads stdin (json) and prints information about color if it fails
+check() {
+	jq -j "
+		if (.ratio | tonumber) < $lower then    $(fmt fail)
+		elif (.ratio | tonumber) < $higher then $(fmt warn)
+		else                                    $(fmt none)
+		end"
+}
+
+for i; do
+	color=$(eval echo '$'$i)
+	colnm=$i
+	xh https://webaim.org/resources/contrastchecker/ api== \
+		bcolor==$background fcolor==$color | \
+		jo -f- color=$color | check
+	done