#!/bin/bash

FILE="$1"
TYPE="$2"
SPLITSIZE="100M"
INFO="info.cfg"

# Check if 2 params are given
if [ "$#" -lt "2" ]; then
  echo "This script requires two arguments: File or Link AND server or client."
  exit 1
fi

# # # #
# FUNCTIONS
# # # #
function checkwait {
  read -p "Continue? Press Ctrl+C to cancel." END
}

function getmd5 {
  md5sum $1 | awk -F" " '{ print $1 }'
}

function compmd5 {
  HASH1=$(getmd5 $1)
  HASH2=$2
  if [ "$HASH1" == "$HASH2" ]; then
    echo "true"
  else
    echo "false"
  fi
}

function getdu {
  du $1 | awk -F" " '{ print $1 }'
}

function compdu {
  DU1=$(getdu $1)
  DU2=$2
  if [ "$DU1" == "$DU2" ]; then
    echo "true"
  else
    echo "false"
  fi
}

function compall {
  FILE=$1
  SIZE=$2
  MD5=$3
  if $(compdu $FILE $SIZE) && $(compmd5 $FILE $MD5); then
    echo="true"
  else
    echo="false"
  fi
}

function checkfolder {
  FOLDER=$1
  # Check if folder already exists. If not, create it
  if [ -d $FOLDER ]; then
    read -p "Destination folder \"$FOLDER\" already exists. Should it be emptied? [y/n]: " YN
    if [ $YN == "y" ]; then
      rm -rf $FOLDER
      mkdir $FOLDER
    else
      if [ "$TYPE" == "server" ]; then
        echo "In server-mode, this isn't recommended. Aborting."
        exit 1
      fi
    fi
  elif [ -e $FOLDER ] && [ ! -d $FOLDER ]; then
    echo "Destination \"$FOLDER\" already exists but is not a folder. Please check."
    exit 1
  else
    mkdir $FOLDER
  fi
}


# # # #
# SERVER MODE
# # # #
if [ $TYPE == "server" ]; then

# Check if file has spaces
if [ $(echo "$FILE" | grep -q " "; echo $?) == "0" ]; then
  read -p "Filename has spaces. Should it be renamed? [y/n]: " YN
  if [ $YN == "y" ]; then
    # replace spaces by underscores
    TMPFILENAME=$(echo "$FILE" | sed "s/ /_/g")
    mv "$FILE" "$TMPFILENAME"
    FILE=$TMPFILENAME
  else
    echo "Aborting."
    exit 1
  fi
fi

# Check if command is executed in directory of file or not
if [ $(basename "$FILE") != "$FILE" ]; then
  echo "Please execute command in the same directory than the file itself."
  exit 1
fi

# Check if file exists
if [ ! -e "$FILE" ]; then
  echo "File does not exist. Aborting."
  exit 1
fi

# Check if it's a file or a directory
if [ ! -f "$FILE" ]; then
  echo "File is not a file. This script doesn't work with directories."
  exit 1
fi

FOLDER="dl-$FILE"

checkfolder $FOLDER

INFONAME=$INFO
INFO="$FOLDER/$INFONAME"

echo "[INFO] Calculating size and MD5 sum..."
BIGNAME=$(basename $FILE)
BIGSIZE=$(getdu $FILE)
BIGMD5=$(getmd5 $FILE)

echo "BIGNAME=$BIGNAME" >> $INFO
echo "BIGSIZE=$BIGSIZE" >> $INFO
echo "BIGMD5=$BIGMD5" >> $INFO
echo >> $INFO

echo "[INFO] Splitting big file into smaller parts..."
split --verbose -a 4 -b $SPLITSIZE $FILE $FOLDER/dl-

# List all splitted files, measure size and md5sum
echo "[INFO] Creating info document with necessary specs..."
SMALLNO=$(ls $FOLDER | grep -v $INFONAME | wc -l)
echo "SMALLNO=$SMALLNO" >> $INFO
NO=0
ls $FOLDER | grep -v $INFONAME | while read -r line; do 
  
  SMALLNAME=$line
  SMALLSIZE=$(getdu $FOLDER/$SMALLNAME)
  SMALLMD5=$(getmd5 $FOLDER/$SMALLNAME)
  
  echo "SMALLNAME[$NO]=$SMALLNAME" >> $INFO
  echo "SMALLSIZE[$NO]=$SMALLSIZE" >> $INFO
  echo "SMALLMD5[$NO]=$SMALLMD5" >> $INFO
  
  let NO=NO+1
done

echo "[SUCCESS] You can now download the splitted files with the client function of this program!"
echo "[INFO] Please move the folder \"$FOLDER\" to a web-accessible directory and use this folder as the first argument for this script."

fi # /SERVER MODE


# # # #
# CLIENT MODE
# # # #
if [ $TYPE == "client" ]; then

URL=$FILE

# Check if remote directory is valid and has an info.cfg file
if [ $(wget -q --spider $URL/$INFO ; echo $?) != "0" ]; then
  echo "Remote directory does not exists or has invalid info.cfg file. Aborting."
  exit 1
fi

if [ -e $INFO ]; then rm $INFO; fi
wget -q $URL/$INFO

source $INFO

FOLDER="dl-$BIGNAME"

# Print basic status
echo
echo "Total filesize: $BIGSIZE"
echo "MD5: $BIGMD5"
echo "Number of splitted files: $SMALLNO"
echo "Download folder: "$(readlink -f $FOLDER)""
echo
checkwait
echo

checkfolder $FOLDER   # Checks and creates folder

until [ "$STATUS" == "F" ]; do
  for ((i = 0; i < ${#SMALLNAME[*]}; i++)); do
    SMALLNAME=${SMALLNAME[$i]}
    SMALLSIZE=${SMALLSIZE[$i]}
    SMALLMD5=${SMALLMD5[$i]}
    
    SMALLURL=$URL/$SMALLNAME
    SMALLPATH=$FOLDER/$SMALLNAME
    
    let NO=i+1
    echo
    echo "------------------"
    echo "Starting file: $SMALLNAME ($SMALLSIZE bytes)"
    echo "This is file $NO of total $SMALLNO files."
    echo "Already downloaded "$(getdu $FOLDER)" of $BIGSIZE bytes."
    echo 
      
    # File doesn't exist yet, so start fresh download
    if [ ! -e $SMALLPATH ]; then
      echo "[INFO] File doesn't exist yet. Starting new download."
      wget -O $SMALLPATH $SMALLURL
      if $(compall $SMALLPATH $SMALLSIZE $SMALLMD5); then
        STATUS="C"
      else 
        # Downloaded file is not valid. Restart for-loop
        echo "[ERROR] Downloaded file is corrupt. Restarting."
        STATUS="E"
        break
      fi
      
    # File already exists but not finished yet
    elif [ -e $SMALLPATH ] && ! $(compdu $SMALLPATH $SMALLSIZE); then
      echo "[INFO] Continuing download."
      wget -c -O $SMALLPATH $SMALLURL
      if $(compall $SMALLPATH $SMALLSIZE $SMALLMD5); then
        STATUS="C"
      else 
        # Downloaded file is not valid. Restart for-loop
        echo "[ERROR] Downloaded file is corrupt. Restarting."
        STATUS="E"
        break
      fi
      
    # File already exists, has correct size, but has wrong MD5
    elif [ -e $SMALLPATH ] && $(compdu $SMALLPATH SMALLSIZE) && ! $(compmd5 $SMALLPATH $SMALLMD5); then
      echo "[ERROR] MD5 is different but file has same size."
      echo "[INFO] Deleting file and starting new download." 
      checkwait
      rm $SMALLPATH
      wget -O $SMALLPATH $SMALLURL
      if $(compall $SMALLPATH $SMALLSIZE $SMALLMD5); then
        STATUS="C"
      else 
        # Downloaded file is not valid. Restart for-loop
        echo "[ERROR] Downloaded file is corrupt. Restarting."
        STATUS="E"
        break
      fi
    
    # File already exists, has correct size, and has correct MD5
    elif [ -e $SMALLPATH ] && $(compdu $SMALLPATH $SMALLSIZE) && $(compmd5 $SMALLPATH $SMALLMD5); then
      echo "[SUCCESS] File already exists and is valid."
      STATUS="C"
      
    # This shouldn't happen...
    else
      echo "Dafuq?!"
      STATUS="E"
    fi
    
    # Check if download is finished
    if [ $NO -lt $SMALLNO ]; then
      echo "[INFO] Starting next download."
      STATUS="C"
    elif [ $NO -ge $SMALLNO ] && [ "$STATUS" == "C" ]; then
      echo "[SUCCESS] Downloading finished."
      STATUS="F"
    else
      echo "Dafuq^2"
    fi
    
  done # /for smallnames
done


read -p "Download seems to be finished. Should the splitted files be rebuilt to the original big file again? [y/n] " YN
if [ $YN == "y" ]; then
  # Destination file already exists
  if [ -e $BIGNAME ]; then
    read -p "Destination file already exists. Should it be overwritten? [y/n] " YN
    
    if [ $YN == "y" ]; then
      cat $FOLDER/dl-* > $BIGNAME
    else
      echo "[INFO] Skipping rebuilding."
    fi
  # Destination file doesn't exist yet
  else
    cat $FOLDER/dl-* > $BIGNAME
  fi
fi

# Check big file for MD5 and size
sleep 2   # In rare cases, this can prevent a wrong du size
echo "[INFO] Checking correct size and MD5 hashsum for rebuilt big file..."

# Compare sizes
if $(compdu $BIGNAME $BIGSIZE); then
  echo "[SUCCESS] The size of the completed file is corrent."
else
  echo "[ERROR] The size of the completed file is incorrect."
fi

# Compare MD5 sum
if $(compmd5 $BIGNAME $BIGMD5); then
  echo "[SUCCESS] The MD5 sum of the completed file is corrent."
else
  echo "[ERROR] The MD5 sum of the completed file is incorrect."
fi


# Clean directories
read -p "Clean the download directory and info.cfg file? [y/n] " YN
if [ $YN == "y" ]; then
  rm $INFO
  rm -r $FOLDER
fi

fi # /CLIENT MODE