#!/bin/bash

FILE="$1"
TYPE="$2"
SPLITSIZE="50M"
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

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

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

INFO="$FOLDER/$INFO.cfg"

BIGNAME=$(basename $FILE)
BIGSIZE=$(du $FILE | awk -F" " '{ print $1 }')
BIGMD5=$(md5sum $FILE | awk -F" " '{ print $1 }')

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

split -a 4 -b $SPLITSIZE $FILE $FOLDER/dl-

# List all splitted files, measure size and md5sum
SMALLNO=$(ls $FOLDER | grep -v info.cfg | wc -l)
echo "SMALLNO=$SMALLNO" >> $INFO

NO=0
ls $FOLDER | grep -v info.cfg | while read -r line; do 
  
  SMALLNAME=$line
  SMALLSIZE=$(du $FOLDER/$SMALLNAME | awk -F" " '{ print $1 }')
  SMALLMD5=$(md5sum $FOLDER/$SMALLNAME | awk -F" " '{ print $1 }')
  
  echo "SMALLNAME[$NO]=$SMALLNAME" >> $INFO
  echo "SMALLSIZE[$NO]=$SMALLSIZE" >> $INFO
  echo "SMALLMD5[$NO]=$SMALLMD5" >> $INFO
  
  let NO=NO+1
done

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

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 $SMALLNO files."
  echo "Already downloaded "$(du -s $FOLDER | awk -F" " '{ print $1 }')" of $BIGSIZE bytes."
  echo 
    
  # File doesn't exist yet, so start fresh download
  if [ ! -e $SMALLPATH ]; then
    echo "[INFO] File doesn't exits yet. Starting new download."
    wget -O $SMALLPATH $SMALLURL
    
  # File already exists but not finished yet
  elif [ -e $SMALLPATH ] && [ $(du $SMALLPATH | awk -F" " '{ print $1 }') != $SMALLSIZE ]; then
    echo "[INFO] Continuing download."
    wget -c -O $SMALLPATH $SMALLURL
    
  # File already exists, has correct size, but has wrong MD5
  elif [ -e $SMALLPATH ] && [ $(du $SMALLPATH | awk -F" " '{ print $1 }') == $SMALLSIZE ] && [ $(md5sum $SMALLPATH | awk -F" " '{ print $1 }') != $SMALLMD5 ]; then
    echo "[ERROR] MD5 is different but file has same size."
    echo "[INFO] Deleting file and starting new download." 
    wget -O $SMALLPATH $SMALLURL
  
  # File already exists, has correct size, and has correct MD5
  elif [ -e $SMALLPATH ] && [ $(du $SMALLPATH | awk -F" " '{ print $1 }') == $SMALLSIZE ] && [ $(md5sum $SMALLPATH | awk -F" " '{ print $1 }') == $SMALLMD5 ]; then
    echo "[SUCCESS] File already exists and is valid."
    if [ $NO -lt $SMALLNO ]; then
      echo "[INFO] Starting next download."
    else
      echo "[SUCCESS] Downloading finished."
    fi
  
  # This shouldn't happen...
  else
    echo "Dafuq?!"
  fi
    
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

sleep 2   # In rare cases, this can prevent a wrong du size
SIZE=$(du $BIGNAME | awk -F" " '{ print $1 }')
MD5=$(md5sum $BIGNAME | awk -F" " '{ print $1 }')
# Compare sizes
if [ "$SIZE" == "$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 [ "$MD5" == "$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