1 files changed, 74 insertions, 0 deletions
diff --git a/src/lib/random.source.sh b/src/lib/random.source.sh
new file mode 100644
index 0000000..5a1ef59
--- /dev/null
+++ b/src/lib/random.source.sh
@@ -0,0 +1,74 @@
+random_seed_is_set() {
+    [ -n "$RANDOM_SEED" ]
+}
+
+deterministic_index() {
+    local -r namespace="$1"; shift
+    local -r count="$1"; shift
+    local checksum
+
+    checksum=$(printf '%s' "${RANDOM_SEED}:$namespace" | cksum)
+    checksum=${checksum%% *}
+
+    printf '%s\n' $(( checksum % count ))
+}
+
+random_index() {
+    local -r namespace="$1"; shift
+    local -r count="$1"; shift
+
+    if random_seed_is_set; then
+        deterministic_index "$namespace" "$count"
+    else
+        printf '%s\n' $(( RANDOM % count ))
+    fi
+}
+
+random_animation_css_class() {
+    local -r speed="$1"; shift
+    local -r context="${1:-$speed}"
+    local -i index
+    local -a classes=(
+        "animate-opacity-$speed"
+        "animate-top-$speed"
+        "animate-left-$speed"
+        "animate-right-$speed"
+        "animate-bottom-$speed"
+        "animate-zoom-$speed"
+        "animate-snap-rotate-$speed"
+        "animate-hard-zoom-$speed"
+        "animate-slam-left-$speed"
+        "animate-slam-right-$speed"
+        "animate-flash-in-$speed"
+        "animate-invert-pop-$speed"
+        "animate-posterize-pop-$speed"
+        "animate-skew-snap-$speed"
+        "animate-glitch-step-$speed"
+    )
+
+    index=$(random_index "animation:$speed:$context" "${#classes[@]}")
+    printf '%s\n' "${classes[index]}"
+}
+
+deterministic_shuffle() {
+    local checksum
+    local line
+
+    while IFS= read -r line; do
+        checksum=$(printf '%s' "${RANDOM_SEED}:shuffle:$line" | cksum)
+        checksum=${checksum%% *}
+        printf '%010u\t%s\n' "$checksum" "$line"
+    done | sort -n -k1,1 -k2,2 | cut -f2-
+}
+
+maybe_shuffle() {
+    if [ "$SHUFFLE" = yes ]; then
+        if random_seed_is_set; then
+            deterministic_shuffle
+        else
+            sort -R
+        fi
+    else
+        sort
+    fi
+}