#!/bin/bash
# Desc: Deduplicates files within a CBZ file
# Usage: cbz_dedup.sh [CBZ file]
# Example: cbz_dedup.sh input.cbz
# Version: 0.0.5
# Depends: jdupes 1.27.3, unzip 6.00 by Debian


yell() { echo "$0: $*" >&2; } # print script path and all args to stderr
die() { yell "$*"; exit 111; } # same as yell() but non-zero exit status
must() { "$@" || die "cannot $*"; } # runs args as command, reports args if command fails
showUsage() {
    # Desc: Display script usage information
    # Usage: showUsage
    # Version 0.0.2
    # Input: none
    # Output: stdout
    # Depends: GNU-coreutils 8.30 (cat)
    cat <<'EOF'
    USAGE:
        cbz_dedup.sh [FILE]

    EXAMPLE:
      cbz_dedup.sh input.cbz
EOF
}; # Display information on how to use this script.
main() {
     fout="output.cbz";
    
     # Check args
     if [[ $# -ne 1 ]]; then showUsage; die "FATAL:Invalid arg count (should be 1):$#"; fi;
     re1='\.cbz$';
     if [[ ! "$1" =~ $re1 ]]; then showUsage; die "FATAL:Not a .cbz file:$1"; fi;
     if [[ ! -f "$1" ]]; then die "FATAL:Not a file:$1"; fi;
     fin="$1";
     dir_tmp="$(mktemp -d)";
     if [[ ! -d "$dir_tmp" ]]; then die "FATAL:Could not make temporary directory:${dir_tmp}"; fi;
     trap 'rm -rf "${dir_tmp}"' EXIT;
     pout="${dir_tmp}/${fout}";

     # Check depends
     for _cmd in unzip zip jdupes; do
         if ! command -v "$_cmd" 1>/dev/random 2>&1; then
             die "FATAL:Missing app:${_cmd}";
         fi;
     done;
    
     # Extract CBZ to temp dir
     must unzip "$fin" -x / -d "$dir_tmp";

     # Dedupe with jdupes
     ## Check size before
     tmp_size1="$(du -bd0 "$dir_tmp" | cut -f1; )";
     must jdupes -dN "${dir_tmp}";
     ## Check size after
     tmp_size2="$(du -bd0 "$dir_tmp" | cut -f1; )";

     # Replace CBZ if size changed
     if [[ "$tmp_size1" -eq "$tmp_size2" ]]; then yell "STATUS:No deduplication detected."; return 0; fi;
     
     ## Recreate CBZ
     must zip -j "$pout" "${dir_tmp}"/*;

     ## Preserve original CBZ
     must mv -n "$fin" "${fin%.*}_original.cbz";
     
     ## Move deduped CBZ
     must mv -n "$pout" "$fin";

     return 0;
};

main "$@";