#!/usr/bin/env bash
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# |  __|  _  |    |__ --|  __|   _||  ||  _  ||   _|
# |____|_____|    |_____|____|__|  |__||   __||____|
#                                      |__|                  
#
#    script to make cd jewel case inserts easily    
#    by sun                  https://sx7n8.tech/    
#                                                   
#    dependencies are:    imagemagick, bash, awk    

# TODO:
# - !!! Add support for back insert !!!            
# - Remove bugs                                    
# - Add more paper types                           DONE
# - Make DPI a command line option                 DONE
# - Add different folding points for inserts       
# - Clean up code and add more comments            
# - Improve input and output further               DONE


# usage message
USAGE="Usage: $0 -p <paper> -c <cover> -b <back> [-i <back_image>] [-m <border>] -o <output>"


# help message
HELP="Script to create printable CD jewel case inserts

Usage:
  $0 -p <paper> -c <cover> -b <back> [-i <back_image>] [-m <border>] [-d  DPI] -o <output>

Required options:
  -p  Paper format            a4 | letter | legal
  -c  Album cover path        Path to cover image 
  -b  Back type               no | image
  -o  Output file             Path to save the resulting insert (NO PNG)


Optional options:
  -i  Back image path         Required if back type is 'image'
  -m  Border width (px)       Adds a border around the cover/back
  -d  DPI                     Desired DPI of the output

DO NOT USE PNG FOR OUTPUT
"


# default DPI
DPI="300"


# error function
error() {
    echo -e "Error: $1" >&2
    echo -e "$USAGE" >&2
    exit 1
}


# file existance check
check_file_exists() {
    if [ ! -f "$1" ]; then
        error "File '$1' does not exist."
    fi
}


# file existance check but opposite
check_output_file() {
    if [ -f "$1" ]; then
        error "Output file '$1' already exists."
    fi
}


# number check
check_dpi() {
    if ! [[ "$var" =~ ^[1-9][0-9]*$ ]]; then
        error "DPI is not a valid number"
    fi
}


# getops argument handling
while getopts "hp:c:b:i:m:o:d:" o; do
    case "${o}" in
        h)
            echo -e "$HELP"
            exit
        ;;
        p)
            if [[ "$OPTARG" != "a4" && "$OPTARG" != "letter" ]]; then
                error "Invalid paper type '$OPTARG'. Must be 'a4' or 'letter'."
            fi
            PAPER="$OPTARG"
        ;;
        c)
            check_file_exists "$OPTARG"
            COVER="$OPTARG"
            COVERSIZE="$(identify -format "%w" "$COVER")"
        ;;
        b)
            if [[ "$OPTARG" != "no" && "$OPTARG" != "image" ]]; then
                error "Invalid back type '$OPTARG'. Must be 'no' or 'image'."
            fi
            BACKTYPE="$OPTARG"
        ;;
        i)
            if [[ "$BACKTYPE" != "image" ]]; then
                error "-i option requires back type to be 'image'."
            fi
            check_file_exists "$OPTARG"
            BACKIMG="$OPTARG"
        ;;
        m)
            BORDER="TRUE"
            BORDER_WIDTH="$OPTARG"
        ;;
        o)
            check_output_file "$OPTARG"
            OUTPUT="$OPTARG"
        ;;

        d)
            check_dpi "$OPTARG"
            DPI="$OPTARG"
        ;;
        *)
            echo -e "$USAGE"
            exit 1
        ;;
    esac
done


# check if something is missing
[[ -z "$PAPER" ]] && error "Missing paper format (-p)."
[[ -z "$COVER" ]] && error "Missing cover image (-c)."
[[ -z "$BACKTYPE" ]] && error "Missing back type (-b)."
[[ -z "$OUTPUT" ]] && error "Missing output file (-o)."
[[ "$BACKTYPE" == "image" && -z "$BACKIMG" ]] && error "Missing back image (-i) for back type 'image'."


# function to convert mm to px with dpi
CONVERT() { awk -v mm="$1" -v dpi="$2" 'BEGIN{printf("%d", mm/25.4*dpi + 0.5)}'; }


# cover art size (mm)
CO_MM="120"
CO_PX="$(CONVERT "$CO_MM" "$DPI")"


# Width and Height of paper in mm
A4MM_W="210"
A4MM_H="297"

LTMM_W="216"
LTMM_H="279"

LGMM_W="216"
LGMM_H="279"


# same values in pixels
A4PX="$(CONVERT "$A4MM_W" "$DPI")x$(CONVERT "$A4MM_H" "$DPI")"
LTPX="$(CONVERT "$LTMM_W" "$DPI")x$(CONVERT "$LTMM_H" "$DPI")"
LGPX="$(CONVERT "$LGMM_W" "$DPI")x$(CONVERT "$LGMM_H" "$DPI")"


# assign to the 'size' variable the right value
if [ "$PAPER" = "a4" ]; then
    SIZE=$A4PX
elif [ "$PAPER" = "letter" ]; then  
    SIZE=$LTPX
elif [ "$PAPER" = "legal" ]; then  
    SIZE=$LGPX
fi


# create a blank file with the specified paper type
magick -colorspace sRGB -type TrueColor -depth 8 -size $SIZE canvas:white "$OUTPUT" > /dev/null


# draws border (rectangle)
if [ "$BORDER" = "TRUE" ]; then
INSET=$((BORDER_WIDTH / 2))
magick ""$OUTPUT"" \( -size $((CO_PX + 2 * BORDER_WIDTH))x$((CO_PX * 2 + 2 * BORDER_WIDTH)) xc:none -colorspace sRGB -type TrueColor -depth 8 -fill none -stroke black -strokewidth $BORDER_WIDTH -draw "rectangle $INSET,$INSET $((CO_PX + BORDER_WIDTH - 1)),$((CO_PX * 2 + BORDER_WIDTH - 1))" \) -gravity center -composite ""$OUTPUT""

fi


# adds the cover
magick \
 -colorspace sRGB\
 -type TrueColor \
 -depth 8 \
 "$OUTPUT" \
 \( "$COVER" \
  -resize ${CO_PX}x${CO_PX} \
  -rotate 270 \) \
 -gravity center \
 -geometry +0-$((CO_PX/2)) \
 -composite \
 "$OUTPUT" \
> /dev/null


# adds back 
if [ "$BACKTYPE" = "image" ]; then # if the back is an image 

# adds image
magick \
 -colorspace sRGB \
 -type TrueColor \
 -depth 8 \
 "$OUTPUT" \
 \( "$BACKIMG" \ 
  -resize ${CO_PX}x${CO_PX} \ 
  -rotate 270 \) \
 -gravity center \
 -geometry +0+$((CO_PX/2)) \
 -composite \
 "$OUTPUT" \
> /dev/null

else  # if the back is not an image

# adds white square
magick \
 -colorspace sRGB \
 -type TrueColor \
 -depth 8 \
 "$OUTPUT" \
 \( -size ${CO_PX}x${CO_PX} \
  xc:'#FFFFFF' \) \
 -gravity center \
 -geometry +0+$((CO_PX/2)) \
 -composite "$OUTPUT"\
> /dev/null

fi