Batch create thumbnails with ImageMagick in zsh

make_thumbs.sh

#!/bin/zsh
# ^ Changed shebang to /bin/zsh

# Output directory for thumbnails
OUTPUT_DIR=".thumbs"
FORCE=0
DRY_RUN=0
THUMBNAIL_DIMENSIONS="200x150" # Default size for landscape/portrait images

# ANSI colors
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
CYAN='\033[1;36m'
RED='\033[0;31m'
NC='\033[0m' # No color

# --- Argument Parsing ---
while [[ $# -gt 0 ]]; do
  case "$1" in
    --force)
      FORCE=1
      shift
      ;;
    --dry-run)
      DRY_RUN=1
      shift
      ;;
    *)
      echo -e "${RED}Unknown option: $1${NC}" >&2
      echo "Usage: $(basename "$0") [--force] [--dry-run]" >&2
      exit 1
      ;;
  esac
done

# --- Helper Function for Image Processing (THIS FUNCTION WILL BE RE-DEFINED FOR XARGS) ---
# We keep this for clarity/testing in a non-xargs context, but it won't be directly called by xargs.
# The version used by xargs is injected into the 'bash -c' string.
# (Leaving this 'local' definition commented out as it's not strictly necessary for the xargs path)
# process_image() { ... }

# Export variables needed by process_image
export OUTPUT_DIR FORCE DRY_RUN THUMBNAIL_DIMENSIONS
export GREEN YELLOW CYAN RED NC

# --- Main Logic ---

# Collect image list first using Zsh's array assignment with null splitting
echo -e "${CYAN}Searching for images...${NC}"
local -a image_list # Declare as array
image_list=( "${(@0)$(find . -type f \( -iname '*.png' -o -iname '*.jpg' -o -iname '*.jpeg' \) -print0)}" )


# Check if any images were found
if (( ${#image_list[@]} == 0 )); then
  echo -e "${RED}No images found.${NC}"
  exit 0
fi

# Track if any thumbnails were actually created by ImageMagick (not just dry-run/skipped)
local actual_thumbs_created=0

echo -e "${CYAN}Processing images...${NC}"

# Define the function as a string to be passed to bash -c
# We need to escape any single quotes within the function if the outer string uses single quotes.
# Here-doc (<<<) makes this easier.
read -r -d '' PROCESS_IMAGE_FUNC_DEF << 'EOF'
process_image() {
  local img="$1"
  local thumb_full_path=""

  local rel_path="${img#./}"
  thumb_full_path="$OUTPUT_DIR/$rel_path"
  local thumb_dir=$(dirname "$thumb_full_path")

  if [[ $FORCE -eq 0 && -f "$thumb_full_path" ]]; then
    echo -e "${YELLOW}Skipping (exists): $thumb_full_path${NC}"
    echo "SKIPPED"
    return 0
  fi

  if [[ $DRY_RUN -eq 1 ]]; then
    if [[ $FORCE -eq 1 && -f "$thumb_full_path" ]]; then
      echo -e "${CYAN}Would recreate: $thumb_full_path${NC}"
    else
      echo -e "${CYAN}Would create: $thumb_full_path${NC}"
    fi
    echo "DRY_RUN"
    return 0
  fi

  if ! mkdir -p "$thumb_dir"; then
    echo -e "${RED}Error: Failed to create directory: $thumb_dir${NC}" >&2
    echo "ERROR"
    return 1
  fi

  local dimensions=$(magick identify -format "%w %h" "$img" 2>/dev/null)
  if [ -z "$dimensions" ]; then
    echo -e "${RED}Error: Unable to read image: $img${NC}" >&2
    echo "ERROR"
    return 1
  fi

  # Use bash array indexing (0-based) inside the bash -c subshell
  # We are in a bash subshell, so `read -A` (zsh) won't work, stick to bash's `read -a`
  local -a dims_array
  read -r -a dims_array <<< "$dimensions"

  local width="${dims_array[0]}" # Bash arrays are 0-indexed
  local height="${dims_array[1]}"

  local size="$THUMBNAIL_DIMENSIONS"

  if (( width > height )); then
    size="200x150"
  else
    size="150x200"
  fi

  if magick "$img" -thumbnail "$size^" -gravity center -extent "$size" "$thumb_full_path"; then
    echo -e "${GREEN}Created: $thumb_full_path${NC}"
    echo "CREATED"
    return 0
  else
    echo -e "${RED}Error: Failed to convert image: $img${NC}" >&2
    echo "ERROR"
    return 1
  fi
}
EOF

# The xargs command now passes the function definition and then calls it
results=$(printf '%s\0' "${image_list[@]}" | xargs -0 -n 1 -P 12 bash -c "${PROCESS_IMAGE_FUNC_DEF}; process_image \"\$0\"")


# Process results to determine if any actual thumbnails were created
while IFS= read -r line; do
  if [[ "$line" == "CREATED" ]]; then
    ((actual_thumbs_created++))
  fi
done <<< "$results"

# --- Cleanup and Final Messages ---
if [[ $DRY_RUN -eq 0 ]]; then
  if [[ $actual_thumbs_created -eq 0 ]]; then
    if [[ -d "$OUTPUT_DIR" && -z "$(find "$OUTPUT_DIR" -maxdepth 0 -empty -print -quit 2>/dev/null)" ]]; then
      true
    elif [[ -d "$OUTPUT_DIR" ]]; then
      echo -e "${YELLOW}No new thumbnails created. Removing empty directory: $OUTPUT_DIR${NC}"
      rmdir "$OUTPUT_DIR" 2>/dev/null
    fi
  else
    echo -e "${GREEN}Successfully created $actual_thumbs_created new thumbnails in $OUTPUT_DIR.${NC}"
  fi
else
  echo -e "${CYAN}Dry run complete. No files were modified.${NC}"
fi

exit 0

This is ABSOLUTELY not my code. Generated originally with ChatGPT and then error checked and modified with Gemini.