#!/bin/bash
#
# The concept is simple
# 
# 1. For a given file we split in 1MB files inside a temporary directory
#
# 2. We then create a map file, containing the resulted files and their sha512sum
#
# 3. We move the files to our $CHKDIR named after their checksums
#
# We ultimately want to be seeding the file so
#
# 4. We append the checksum of the original file with its name into the map file
#
# 5. We rename the map file after its checksum and move it to maps directory
#
# 6. We are done!
#

# Uncomment next line if you want to debug 
# set -xe
PROGRAM="$(basename $0)"

if [ ! -f "$1" ]
then
    echo "[ERROR] File not found"
    exit 1
else
    base64 $1 > file
    FILE="file"
fi

# The directory where the chunked data will be living at
CHKDIR="$AK_WORKDIR/ftr/"
# The directory for the map files so we can reconstruct the file
FILEMAPSDIR="$AK_WORKDIR/fmp/"
# Merkle tree file/references
MERKLEDIR="$AK_WORKDIR/fmrk/"
# A temporary root dir to work on
TEMPORARYDIR="$(ak-tempassin)"
# A subdir to split the files there
TECHDIR="$TEMPORARYDIR/chks/"
# A pin point to return from where we came from 
CURRENTDIR="$(pwd)/"

# Our snippet for logging debug info
logit(){
    ak-logthis "<$PROGRAM>" "$1" "$2"
}

# Checking directories and create them if necessary
rm -rf $TEMPORARYDIR
 
# TECHDIR
if [ ! -d "$TECHDIR" ]
then
    mkdir -p "$TECHDIR"
    if [ "$?" == 0 ]
    then
        logit "[INFO]" "Folder $TECHDIR created!"
    else
        logit "[ERROR]" "Problem occured while creating $TECHDIR"
        echo "[ERROR] Can't create $TECHDIR"
        exit 1
    fi
else
    logit "[INFO]" "Temp dir found"
fi

# FILEMAPSDIR
if [ ! -d "$FILEMAPSDIR" ]
then
    mkdir -p "$FILEMAPSDIR"
    if [ "$?" == 0 ]
    then
        logit "[INFO]" "Folder $FILEMAPSDIR created!"
    else
        logit "[ERROR]" "Problem occured while creating $FILEMAPSDIR"
        echo "[ERROR] Can't create $FILEMAPSDIR"
        exit 1
    fi
else
    logit "[INFO]" "Mapsdir found"
fi

# CHKDIR
if [ ! -d "$CHKDIR" ]
then
    mkdir -p "$CHKDIR"
    if [ "$?" == 0 ]
    then
        logit "[INFO]" "Folder $CHKDIR created!"
    else
        logit "[ERROR]" "Problem occured while creating $CHKDIR"
        echo "[ERROR] Can't create $CHKDIR"
        exit 1
    fi
else
    logit "[INFO]" "Workdir found"
fi

# MERKLEDIR
if [ ! -d "$MERKLEDIR" ]
then
    mkdir -p "$MERKLEDIR"
    if [ "$?" == 0 ]
    then
        logit "[INFO]" "Folder $MERKLEDIR created!"
    else
        logit "[ERROR]" "Problem occured while creating $MERKLEDIR"
        echo "[ERROR] Can't create $MERKLEDIR"
        exit 1
    fi
else
    logit "[INFO]" "Workdir found"
fi
# Uncomment next line in case you want to debug the resulting script as well
# echo 'set -xe' > $TEMPORARYDIR/cmd_queue.sh

# We get the SHA512 hash for the $FILE given
CHECKSUM=$(sha512sum "$FILE"|awk '{print $1}')

# We split the file into 4*1024 bytes and output the chunks into TECHDIR
split -a 50 -b 4096 --additional-suffix ".chk" -d "$FILE" "$TECHDIR$(basename "$FILE")-"

# We go over there...
cd $TECHDIR
#set -xe
# We get every chunks' SHA512 and we craft a script to rename the chunks and 
# move them to CHKDIR
for file in $TEMPORARYDIR/chks/* 
do
    sha512sum $file >> $TEMPORARYDIR/map
done
# Append last chk if not even number
appendLastIfNotEven(){
    if [ "$(expr $(wc -l "$1" | awk '{ print $1 }') % 2)" != 0 ]
    then
        tail -n 1 "$1" >> "$1"
    fi
}
appendLastIfNotEven "$TEMPORARYDIR/map"
# Figure out how many times we need to pack
totalChunks=`grep 'chk' $TEMPORARYDIR/map | wc -l`
temp="$totalChunks"
timesRan=0
while [ $temp != 1 ]
do
    temp=`expr $temp / 2`
    timesRan=`expr $timesRan + 1`
done
printf "Ran %s times \n" "$timesRan"
printf "Total chunks %s \n" "$totalChunks"

workingIndex="$TEMPORARYDIR/map"
c=$timesRan
while [ "$c" != 0 ]
do
    a=1
    printf "Level: %s, will work on %s chunks\n" "$c" "$totalChunks"
    while [[ "$a" -lt "$totalChunks" ]]
    do
        b=`expr "$a" + 1`
        sed -n "$a"p "$workingIndex" | awk '{ print $1 }' >> level.$c.pair.$a-$b
        sed -n "$b"p "$workingIndex" | awk '{ print $1 }' >> level.$c.pair.$a-$b
        shaSum="$(sha512sum level.$c.pair.$a-$b | awk '{ print $1 }')"
        cp level.$c.pair.$a-$b $MERKLEDIR/$shaSum
        sha512sum level.$c.pair.$a-$b | awk '{ print $1 }' >> level.$c.map
        a=`expr "$a" + 2`
    done
    workingIndex="level.$c.map"
    shaSum=`sha512sum $workingIndex | awk '{ print $1 }'`
    cp $workingIndex $MERKLEDIR/$shaSum
    appendLastIfNotEven "$workingIndex"
    totalChunks=`cat $workingIndex | wc -l`
    c=`expr $c - 1`
done

if [ -f level.1.map ]
then
    sha512sum level.1.map
else
    echo error
    exit 1
fi

# Reset file with uniq
cat $TEMPORARYDIR/map | uniq > $TEMPORARYDIR/map2
cat $TEMPORARYDIR/map2 > $TEMPORARYDIR/map
rm $TEMPORARYDIR/map2 

counter=0
while IFS="" read -r p || [ -n "$p" ]
do
    printf "mv %s %s%s\n" "$(echo $p | awk '{ print $2 }')" "$CHKDIR" "$(echo $p | awk '{ print $1 }')" >> $TEMPORARYDIR/cmd_queue.sh
    counter=`expr "$counter" + 1`
done < $TEMPORARYDIR/map

# We run the crafted script
sh $TEMPORARYDIR/cmd_queue.sh

# and we delete it
rm $TEMPORARYDIR/cmd_queue.sh

# We inform the map about the original $FILE name and SHA512
echo "$CHECKSUM  $(basename "$FILE")" >> $TEMPORARYDIR/map

# We get the SHA512 hash of the resulted map file
MAPFILEHASH="$(sha512sum $TEMPORARYDIR/map | awk '{ print $1 }')"

# and we rename it with it and move it to FILEMAPSDIR
`sha512sum $TEMPORARYDIR/map | awk '{print "mv " $2 " '$FILEMAPSDIR'" $1}'`

# We remove the TEMPORARYDIR
rm -rf $TEMPORARYDIR

# and print the MAPFILEHASH
echo "$MAPFILEHASH"