#!/bin/sh
###########################################################################
##  Copyright (C) Wizardry and Steamworks 2018 - License: GNU GPLv3      ##
##  Please see: http://www.gnu.org/licenses/gpl.html for legal details,  ##
##  rights of fair usage, the disclaimer and warranty conditions.        ##
###########################################################################
 
# Load system defaults.
SCRIPT_NAME=`basename $0`
[ -f "/etc/default/$SCRIPT_NAME" ] && . /etc/default/"$SCRIPT_NAME"
 
# Check that the paths exist.
for DIRECTORY in $DOWNLOADS_FOLDER $TORRENTS_FOLDER $DROPBOX_FOLDER; do
    if [ ! -d $DIRECTORY ]; then
        logger -p daemon.err "$0: Could not find $DIRECTORY."
        exit 1
    fi
done
 
# Acquire a lock.
LOCK_FILE="/var/lock/$SCRIPT_NAME"
if mkdir $LOCK_FILE 2>&1 >/dev/null; then
    trap '{ rm -rf $LOCK_FILE; }' KILL QUIT TERM EXIT INT HUP
else
    exit 0
fi
 
IFS=","; for CREATE_FOLDER in `find $DROPBOX_FOLDER -maxdepth 1 -mindepth 1 -not -path '\.*' -type d -printf '%P\n'`; do
    logger -p daemon.info "$SCRIPT_NAME: Creating torrent for directory $CREATE_FOLDER"
    # Create the .torrent metafile.
    mkdir -p /tmp/$SCRIPT_NAME
    mktorrent -a $HTTP_TRACKER -a $UDP_TRACKER "$DROPBOX_FOLDER/$CREATE_FOLDER" -o "/tmp/$SCRIPT_NAME/$CREATE_FOLDER.torrent" 2>/dev/null >/dev/null
    if [ ! -f "/tmp/$SCRIPT_NAME/$CREATE_FOLDER.torrent" ]; then
        logger -p daemon.err "$SCRIPT_NAME: Something went wrong whilst generating the \"$CREATE_FOLDER.torrent\" file."
        exit 1
    fi
    # If the .torrent metafile already exists, compare it to the temporary metafile already generated.
    if [ -f "$TORRENTS_FOLDER/$CREATE_FOLDER.torrent" ]; then
        SUM_NEW=`sha1sum "/tmp/$SCRIPT_NAME/$CREATE_FOLDER.torrent" | awk '{ print $1 }'`
        SUM_OLD=`sha1sum "$TORRENTS_FOLDER/$CREATE_FOLDER.torrent" | awk '{ print $1 }'`
        if [ x$SUM_NEW = x$SUM_OLD ]; then
            # The files are identical so just terminate.
            exit 0
        fi
    fi
    # Check if the download folder already exists and delete it.
    if [ -d "$DOWNLOADS_FOLDER/$CREATE_FOLDER" ]; then
        rm -rf "$DOWNLOADS_FOLDER/$CREATE_FOLDER"
    fi
    # Copy the new folder into the downloads folder.
    mv "$DROPBOX_FOLDER/$CREATE_FOLDER" "$DOWNLOADS_FOLDER"
 
    # Copy the temporary .torrent metafile into the torrents folder.
    mv "/tmp/$SCRIPT_NAME/$CREATE_FOLDER.torrent" "$TORRENTS_FOLDER"
 
    logger -p daemon.info "$SCRIPT_NAME: Created torrent for directory \"$CREATE_FOLDER\"!"
done