Cornelia Archive Embedding Program

#!/bin/bash

FUNCTIONS=0
increment() { FUNCTIONS=$((FUNCTIONS+1)); }
die() { echo "$*" >&2;  exit 2; } # Call a usage function from here as well.

while getopts abcdhw:i:z:o: opt
do
    case $opt in
        a) CASE_A=1; increment;;
        b) CASE_B=1; increment;;
        c) CASE_C=1; increment;;
        d) CASE_D=1; increment;;
        h) CASE_H=1;;
        w) WIDTH="$OPTARG";; # Width of image (for -b)
        i) IMAGE="$OPTARG";; # Image file path (for -a and -c)
        z) ARCHIVE="$OPTARG";; # Archive/PNG file path i.e. input
        o) OUTPUT="$OPTARG";; # Output PNG/Archive file path
        ?) die "Error: incorrect flag was given";;
    esac
done

# Note: I will use -eq and -gt to replace = and > for integers
# Note: Integers in formulas does not require doiuble quotes
# Note: -z is for checking if a variable is zero or not
# Note: -r is for checking if a file or directory exists

if [ ${CASE_H} -eq 1 ]; then
    echo "This is the Cornelia Archive Embedding Program (CAEP)"
    echo "It takes an archive (bzip2/gzip/xzip/lzip/lzop/lzma/7zip/zip/rar)"
    echo "and an image if using -a or -c (tif/tiff/jpe/jpg/jpeg/gif/bmp/png)"
    echo "or the width of the photo as specified for -b to create a PNG file"
    echo "Or you can use -d to convert PNG file to a usable BMP format"
    echo "To use this, enter in either of these commands"
    echo "A. Append Space Format (Archive data under iamge)"
    echo "Cornelia -a -i IMAGE -z ARCHIVE -o PNG_OUT"
    echo "B. Blank canvas Format (Archive directly as image)"
    echo "Cornelia -b -w WIDTH -z ARCHIVE -o PNG_OUT"
    echo "C. Cornlia Old Format (Archive overwrite image bottom)"
    echo "Cornelia -c -i IMAGE -z ARCHIVE -o PNG_OUT"
    echo "D. Decompressing PNG (Decompress PNG image to BMP)"
    echo "Cornelia -d -z PNG -o ARCHIVE_OUT"
    echo "H. Help Manual for Cornelia (explaining what this program does)"
    echo "Cornelia -h"
    exit
elif [ ${FUNCTIONS} -eq 0 ]; then
    die "Error: need a function flag"
elif [ ${FUNCTIONS} -gt 1 ]; then
    die "Error: Multiple function flags were given"
elif [ ${CASE_B} -eq 1 ] != ; then
    if [ -z "${WIDTH}" ]; then
        die "Error: Width not given for -b mode"
    elif [ "${WIDTH}" -gt 0 ]; then
        die "Error: Width is not a positive integer"
    fi
elif [ $((CASE_A+CASE_C)) -eq 1 ]; then
    shopt -s extglob
    if [ -z "${IMAGE}" ]; then
        die "Error: Image file path not given for -a or -c mode"
    elif [ ! -r "${IMAGE}" ]; then
        die "Error: Image file path '${IMAGE}' is not readable"
    elif [[ ${IMAGE} != *.@(tif?f|jp([eg]|eg)|gif|bmp|png) ]]; then
        die "Error: Image file path '${IMAGE}' is not a valid input"
    fi
elif [ ${CASE_D} -eq 1 ]; then # Decompression
    if [ -z "${ARCHIVE}" ]; then
        die "Error: PNG file path not given for -d mode"
    elif [ ! -r "${ARCHIVE}" ]; then
        die "Error: PNG file path '${ARCHIVE}' is not readable"
    elif [[ ${ARCHIVE} != *.png ]]; then # does not function
        die "Error: PNG file path '${OUTPUT}' does not end in .png"
    elif [ -z "${OUTPUT}" ]; then
        die "Error: Output BMP file path not given for -d mode"
    elif [ ! -r "$(dirname "${OUTPUT}")" ]; then
        die "Error: Output BMP file path '${OUTPUT}' does not exist"
    elif [[ ${OUTPUT} != *.bmp ]]; then # does not function
        die "Error: Output BMP file path '${OUTPUT}' does not end in .bmp"
    fi
else # Compression
    shopt -s extglob
    if [ -z "${ARCHIVE}" ]; then
        die "Error: Archive file path not given for -a, -b or -c mode"
    elif [ ! -r "${ARCHIVE}" ]; then
        die "Error: Archive file path '${ARCHIVE}' is not readable"
    elif [[ ${ARCHIVE} != *.@(t?(bz2|[gl]z)|[7x]z|lzma|rar|[lt]zo|zip) ]]; then # does not function
        die "Error: Archive file path '${ARCHIVE}' is not a valid input"
    elif [ -z "${OUTPUT}" ]; then
        die "Error: Output PNG file path not given for -a, -b or -c mode"
    elif [ ! -r "$(dirname "$OUTPUT")" ]; then
        die "Error: Output PNG file path '${OUTPUT}' does not exist"
    elif [[ ${OUTPUT} != *.png ]]; then # does not function
        die "Error: Output PNG file path '${OUTPUT}' does not end in .png"
    fi
fi

# width_check checks the width of the image
# height_check checks the height needed for the image
# image_gen1 generates a blank image based on width and height
# image_gen2 converts image to BMP
# Note: I will not use identify, magick or mogrify from Imagemagick
# Note: I will always add a space between last colon and curly brackets

width_check() { WIDTH=$(convert -print "%w" "${IMAGE}" /dev/null); }
height_check() { HEIGHT=$(((SIZE+4*WIDTH-1)/(4*WIDTH))); }
image_gen1() { convert -size "${WIDTH}"x"${HEIGHT}" xc:transparent cornelia_gen/blank.bmp; }
image_gen2() { convert "${IMAGE}" -type truecolormatte cornelia_gen/tmp1.bmp; }
append_format() { width_check; height_check; image_gen1; image_gen2;
    convert -append cornelia_gen/tmp1.bmp cornelia_gen/blank.bmp cornelia_gen/tmp1.bmp; }
blank_format() { height_check; image_gen1; mv cornelia_gen/blank.bmp cornelia_gen/tmp1.bmp; }
cornelia_format() { width_check; height_check;
    if [ "$(convert -print "%h" "${IMAGE}" /dev/null)" -gt "${HEIGHT}" ]; then image_gen2
    else echo "Error: Image is too small for archive"; exit 1
    fi; }
convert_image() {
    head -c 138 cornelia_gen/tmp1.bmp > cornelia_gen/tmp2 # takes the header
    cat "${ARCHIVE}" >> cornelia_gen/tmp2 # concatenate archive to image
    dd if=cornelia_gen/tmp2 of=cornelia_gen/tmp1.bmp conv=notrunc # overwrite bmp
    convert cornelia_gen/tmp1.bmp "${OUTPUT}"; } # output image as png

if [ ${CASE_D} -eq 1 ]; then convert "${ARCHIVE}" -type truecolormatte "${OUTPUT}" # decompress png
else # creates png file
    mkdir cornelia_gen; SIZE=$(stat -c %s "${ARCHIVE}")
    if [ ${CASE_A} -eq 1 ]; then append_format
    elif [ ${CASE_B} -eq 1 ]; then blank_format
    elif [ ${CASE_C} -eq 1 ]; then cornelia_format
    fi; convert_image; rm -r cornelia_gen # deletes temporary file
fi; exit