[YADM] Make the YADM banner more colorful

This adds some helper functions to pick four random ANSI color codes and
use one for each letter in the YADM banner that gets printed out each
time the bootstrap script is run.

Author: dirn

.config/yadm/bootstrap

@@ -1,22 +1,52 @@
-#!/bin/sh
+#!/bin/bash
 
 RED='\033[0;31m'
 NC='\033[0m'
 
 # Generated using
 # https://textkool.com/en/ascii-art-generator?hl=default&vl=default&font=DOS%20Rebel&text=YADM%20bootstrap
-cat <<EOF
-
- █████ █████   █████████   ██████████   ██████   ██████
-░░███ ░░███   ███░░░░░███ ░░███░░░░███ ░░██████ ██████
- ░░███ ███   ░███    ░███  ░███   ░░███ ░███░█████░███
-  ░░█████    ░███████████  ░███    ░███ ░███░░███ ░███
-   ░░███     ░███░░░░░███  ░███    ░███ ░███ ░░░  ░███
-    ░███     ░███    ░███  ░███    ███  ░███      ░███
-    █████    █████   █████ ██████████   █████     █████
-   ░░░░░    ░░░░░   ░░░░░ ░░░░░░░░░░   ░░░░░     ░░░░░
-
-EOF
+
+# Select 4 unique random colors for the banner letters (Y, A, D, M)
+COLORS=(31 32 33 34 35 36 37 91 92 93 94 95 96 97)
+for i in 0 1 2 3; do
+    j=$((i + RANDOM % (${#COLORS[@]} - i)))
+    tmp=${COLORS[i]}
+    COLORS[i]=${COLORS[j]}
+    COLORS[j]=$tmp
+done
+ESC=$'\033'
+C_Y="${ESC}[${COLORS[0]}m"; C_A="${ESC}[${COLORS[1]}m"
+C_D="${ESC}[${COLORS[2]}m"; C_M="${ESC}[${COLORS[3]}m"
+RST="${ESC}[0m"
+
+# Colorize only the █ characters in the string.
+color_blocks() {
+    printf '%s' "$1" | sed "s/█/$2█$RST/g"
+}
+
+print_banner_line() {
+    local line="$1"
+    local y_part="${line:0:12}"
+    local a_part="${line:12:14}"
+    local d_part="${line:26:13}"
+    local m_part="${line:39}"
+    printf '%s%s%s%s\n' \
+        "$(color_blocks "$y_part" "$C_Y")" \
+        "$(color_blocks "$a_part" "$C_A")" \
+        "$(color_blocks "$d_part" "$C_D")" \
+        "$(color_blocks "$m_part" "$C_M")"
+}
+
+echo ""
+print_banner_line " █████ █████   █████████   ██████████   ██████   ██████"
+print_banner_line "░░███ ░░███   ███░░░░░███ ░░███░░░░███ ░░██████ ██████ "
+print_banner_line " ░░███ ███   ░███    ░███  ░███   ░░███ ░███░█████░███ "
+print_banner_line "  ░░█████    ░███████████  ░███    ░███ ░███░░███ ░███ "
+print_banner_line "   ░░███     ░███░░░░░███  ░███    ░███ ░███ ░░░  ░███ "
+print_banner_line "    ░███     ░███    ░███  ░███    ███  ░███      ░███ "
+print_banner_line "    █████    █████   █████ ██████████   █████     █████"
+print_banner_line "   ░░░░░    ░░░░░   ░░░░░ ░░░░░░░░░░   ░░░░░     ░░░░░ "
+echo ""
 
 if ! command -v brew >/dev/null 2>&1; then
     echo "Installing Homebrew. If it appears stuck, press Enter."