#!/bin/bash
#
# rar2zip conversion script
# Based on: https://shkspr.mobi/blog/2016/12/converting-rar-to-zip-in-linux/
#
# Usage: rar2zip.sh file [file ...]

if [ $# -eq 0 ]; then
    echo "Usage: $0 file.rar [file2.rar ...]"
    exit 1
fi

echo "Converting RARs to ZIPs"

# Use RAM disk for temporary files.
WORKDIR="/dev/shm/"

# Cleanup function
cleanup_temp() {
    if [ -n "$TEMPDIR" ] && [ -d "$TEMPDIR" ]; then
        rm -r "$TEMPDIR"
    fi
}

for INFILE in "$@"; do
    # Absolute path to old file
    OLDFILE=$(realpath "${INFILE}")

    # Get the file name without the extension
    BASENAME=$(basename "${OLDFILE%.*}")

    # Path for the file. The ".zip" file will be written there.
    DIRNAME=$(dirname "$OLDFILE")

    # Name of the .zip file
    NEWNAME="${DIRNAME}/$BASENAME.zip"

    if [ ! -e "${NEWNAME}" ]; then
        # Set name for the temp dir. This directory will be created under WORKDIR
        TEMPDIR=$(mktemp -p "$WORKDIR" -d)

        # Set up cleanup trap
        trap cleanup_temp EXIT INT TERM

        # Create a temporary folder for unRARed files
        echo "Extracting $OLDFILE"

        if ! rar x "$OLDFILE" "${TEMPDIR}/"; then
            echo "Error: Failed to extract $OLDFILE"
            cleanup_temp
            continue
        fi

        # Zip the files with maximum compression
        pushd "$TEMPDIR" > /dev/null
        if ! 7z a -tzip -mx=9 "$NEWNAME" ./*; then
            echo "Error: Failed to create ZIP for $BASENAME"
            popd > /dev/null
            cleanup_temp
            continue
        fi
        popd > /dev/null

        # Alternative. MUCH SLOWER, but better compression
        # 7z a -mm=Deflate -mfb=258 -mpass=15 -r "$NEWNAME" *

        # Preserve file modification time
        touch -r "$OLDFILE" "$NEWNAME"

        # Delete the temporary directory
        cleanup_temp
        trap - EXIT INT TERM

        # OPTIONAL. Safe-remove the old file
        #gio trash "$OLDFILE"
    else
        echo "${NEWNAME}: File exists!"
    fi
done

echo "Conversion Done"