#!/bin/bash

# Default values
INVERT=false

# Help function
usage() {
    echo "Usage: $0 [-i] <tape_width_mm> <input_image.png>"
    echo "Options:"
    echo "  -i    Invert colors (Black -> White, White -> Black)"
    echo "Example: $0 -i 12 sticker.png"
    exit 1
}

# Parse options
while getopts "i" opt; do
  case $opt in
    i) INVERT=true ;;
    *) usage ;;
  esac
done
shift $((OPTIND-1))

# Check for remaining arguments
if [ "$#" -ne 2 ]; then
    usage
fi

TAPE_WIDTH=$1
INPUT_FILE=$2

# Map tape width (mm) to pixel height
case $TAPE_WIDTH in
    3.5) PIXELS=24 ;;
    6)   PIXELS=32 ;;
    9)   PIXELS=48 ;;
    12)  PIXELS=64 ;;
    18)  PIXELS=96 ;;
    24)  PIXELS=128 ;;
    36)  PIXELS=192 ;;
    *)
        echo "Error: Unsupported tape width ($TAPE_WIDTH mm)."
        exit 1
        ;;
esac

if [ ! -f "$INPUT_FILE" ]; then
    echo "Error: File $INPUT_FILE not found."
    exit 1
fi

FILENAME=$(basename -- "$INPUT_FILE")
EXTENSION="${FILENAME##*.}"
BASENAME="${FILENAME%.*}"

# Prepare the magick command parts
INVERT_CMD=""
if [ "$INVERT" = true ]; then
    INVERT_CMD="-negate"
    echo "Color inversion: ENABLED"
fi

echo "Processing $INPUT_FILE for ${TAPE_WIDTH}mm tape (${PIXELS}px slices)..."

# Execute ImageMagick
magick "$INPUT_FILE" \
    $INVERT_CMD \
    -threshold 50% \
    -type Bilevel \
    -crop x${PIXELS} \
    +repage \
    "${BASENAME}_${TAPE_WIDTH}mm_%d.${EXTENSION}"

echo "Done! Slices saved as: ${BASENAME}_${TAPE_WIDTH}mm_*.${EXTENSION}"