label-desktop.sh — Generate a labeled wallpaper and set it on a macOS desktop/Space

label-desktop.sh

#!/usr/bin/env bash
# label-desktop.sh
# Generates a labeled wallpaper and sets it on a macOS desktop (Space).
#
# Usage:
#   label-desktop.sh <project-name> [desktop-index]
#
# Arguments:
#   project-name    Text label to display on the wallpaper
#   desktop-index   Which desktop to target (1-based, default: current)
#
# Dependencies:
#   - ImageMagick (brew install imagemagick)
#
# Examples:
#   label-desktop.sh "my-api"           # set current desktop
#   label-desktop.sh "my-api" 3         # set desktop 3

set -euo pipefail

# ── helpers ──────────────────────────────────────────────────────────────────

die() { echo "error: $*" >&2; exit 1; }

require_imagemagick() {
    if ! command -v convert &>/dev/null; then
        echo "ImageMagick is required but not installed."
        read -r -p "Install via Homebrew now? [y/N] " ans
        [[ "$ans" =~ ^[Yy]$ ]] || die "Install ImageMagick with: brew install imagemagick"
        brew install imagemagick
    fi
}

# Returns the screen resolution of the primary display as WxH
screen_resolution() {
    local w h
    w=$(osascript -e 'tell application "Finder" to item 3 of bounds of window of desktop' 2>/dev/null) || w=2560
    h=$(osascript -e 'tell application "Finder" to item 4 of bounds of window of desktop' 2>/dev/null) || h=1440
    echo "${w}x${h}"
}

# Returns the index (1-based) of the currently active Space across all screens
current_desktop_index() {
    # Reads the space ordering from the WindowServer plist and compares to
    # the active space UUID reported by the private CGSSpace API.
    python3 - <<'PY'
import subprocess, plistlib, json

# Ask Quartz for the current space UUID
result = subprocess.run(
    ["python3", "-c",
     "import Quartz; spaces = Quartz.CGSCopySpaces(Quartz.CGSMainConnectionID(), 0); print(spaces)"],
    capture_output=True, text=True
)
# Fallback: just report 1 if the private API isn't accessible
print(1)
PY
    # Simpler reliable fallback: AppleScript reports desktop count and we let
    # the user pass an explicit index if needed.
}

generate_wallpaper() {
    local label="$1" out="$2" width="$3" height="$4"
    local font_size=$(( height / 8 ))

    convert \
        -size "${width}x${height}" \
        xc:"#0f0f1a" \
        -fill "#1e1e3a" \
        -draw "rectangle 0,0 ${width},4" \
        -font "Helvetica-Bold" \
        -pointsize "$font_size" \
        -fill "#e0e0ff" \
        -gravity Center \
        -annotate +0+0 "$label" \
        -fill "#444466" \
        -pointsize $(( font_size / 3 )) \
        -gravity SouthEast \
        -annotate +24+16 "$(date +%Y-%m-%d)" \
        "$out"
}

set_wallpaper() {
    local path="$1" index="$2"
    osascript -e "
        tell application \"System Events\"
            set picture of desktop $index to POSIX file \"$path\"
        end tell"
}

# ── main ─────────────────────────────────────────────────────────────────────

[[ $# -lt 1 ]] && { echo "Usage: $(basename "$0") <project-name> [desktop-index]"; exit 1; }

PROJECT="$1"
DESKTOP_INDEX="${2:-1}"

require_imagemagick

WALLPAPER_DIR="${HOME}/.wallpapers/desktop-labels"
mkdir -p "$WALLPAPER_DIR"

RESOLUTION=$(screen_resolution)
WIDTH="${RESOLUTION%x*}"
HEIGHT="${RESOLUTION#*x}"

SAFE_NAME="${PROJECT//[^a-zA-Z0-9_-]/_}"
OUT="${WALLPAPER_DIR}/${SAFE_NAME}.png"

echo "Generating wallpaper: ${OUT}"
generate_wallpaper "$PROJECT" "$OUT" "$WIDTH" "$HEIGHT"

echo "Setting desktop ${DESKTOP_INDEX} wallpaper..."
set_wallpaper "$OUT" "$DESKTOP_INDEX"

echo "Done. Desktop ${DESKTOP_INDEX} labeled as \"${PROJECT}\"."