+
+config_easteregg() {
+ checkbootparam 'noeasteregg' && return 0
+
+ zmodload zsh/datetime 2>/dev/null || return 0
+ zmodload zsh/mathfunc 2>/dev/null || return 0
+
+ local birthday=1694822400 # := 2023-09-16 -> TZ=UTC date -d "2023-09-16" +%s
+ local one_month=$[24*30*3600]
+ local pi=3.14159265358979323846
+ local magic=$(( one_month/(pi/2) )) # normalization factor, used to map the [birthday;birthday+-one_month] range onto [0;+-pi/2]
+
+ if [[ $(( abs(birthday-EPOCHSECONDS) )) -le $one_month ]] ; then
+ if [[ $(( rand48() )) -le $(( cos((birthday-EPOCHSECONDS)/magic) )) ]] ; then
+ display_easteregg
+ fi
+ fi
+
+ return 0
+}