#!/usr/bin/env bash
# Based on similar script by Linyos Torovoltos and Alex Epstein

multiline="0" # flag that indicates multiline option
fileoutput="0" # flag indicating the -f option


# Determine which HTTP GET tool installed
getConfiguredClient () {
  if  command -v curl &>/dev/null; then
    configuredClient="curl"
  elif command -v wget &>/dev/null; then
    configuredClient="wget"
  elif command -v http &>/dev/null; then
    configuredClient="httpie"
  elif command -v fetch &>/dev/null; then
    configuredClient="fetch"
  else
    echo "Error: This tool requires either curl, wget, httpie or fetch to be installed." >&2
    return 1
  fi
}

# Call appropriate http get method
httpGet() {
  case "$configuredClient" in
    curl)  curl -A curl -s "$@" ;;
    wget)  wget -qO- "$@" ;;
    httpie) http -b GET "$@" ;;
    fetch) fetch -q "$@" ;;
  esac
}

# Get installed version of Python / show error if none
getConfiguredPython() {
  if command -v python3 &>/dev/null; then
    configuredPython="python3"
  elif  command -v python2 &>/dev/null; then
    configuredPython="python2"
  elif command -v python &>/dev/null; then
    configuredPython="python"
  else
    echo "Error: This tool requires python to be installed."
    return 1
  fi
}

if [[ $(uname) != "Darwin" ]]; then
  python() {
    case "$configuredPython" in
      python3) python3 "$@" ;;
      python2) python2 "$@" ;;
      python)  python "$@" ;;
    esac
  }
fi

# Encode input, and call to qrenco.de to get response
makeqr() {
  input=$(echo "$input" | sed s/" "/%20/g ) ## replace all spaces in the sentence with HTML-encoded space %20
  httpGet qrenco.de/"$input" ## get a response for the qrcode
}

# Redirects returned QR impage into a png file
makeQRFile() {
	input=$(echo "$input" | sed -e s/" "/%20/g -e s/'\\n'/%0A/g ) ##same as in the makeqr function
  addFileExt
	httpGet "api.qrserver.com/v1/create-qr-code/?size=150x150&data=$input" > "$fileName"
}

# If filename doesn't already have .png extension, append it
addFileExt() {
  if ! echo "$fileName" | grep -E -q ".*\.png$|.*\.PNG$"
  then
    fileName="$fileName.png"
  fi
}

makeMultiLineQr() {
  if [[ ${configuredClient} != "curl" ]]; then ## prevent usage without curl it is unreliable
    echo "Multiline currently only supports curl!"
    return 1
  else
    input=$(echo "$input" | sed -e s/" "/%20/g -e s/'\\n'/%0A/g ) ##same as in the makeqr function
    printf "%s" "$input"  | curl -F-=\<- qrenco.de
  fi
}

# Function to get the json response from POST request
decodeQR() {
  local qrFile="$1"
  if ! echo "$fileName" | grep -E -q ".*\.png$|.*\.PNG$|.*\.gif$|.*\.jpg$|.*\.jpeg$|.*\.GIF$|.*\.JPG$|.*\.JPEG$"
  then
    exit 1
  fi

  # only uses curl
  # Cannot use wget because it does not support multipart/form-data (as per the man page)]

  case "$configuredClient" in
    curl) JSONresponse=$(curl -s -F "file=@$qrFile" http://api.qrserver.com/v1/read-qr-code/) || exit 1;;
    wget) echo "Error:-Not supported with wget" >&2 && exit 1;;
    httpie) JSONresponse=$(http -b --form POST http://api.qrserver.com/v1/read-qr-code/ file@"$qrFile") || exit 1;;
    fetch) echo "Error:-Not supported with wget" >&2 && exit 1;;
  esac

  error="$(echo "$JSONresponse" | python -c "from __future__ import print_function; import sys, json; print(json.load(sys.stdin)[0]['symbol'][0]['error'])")"
  
  if [[ "$error" == "None" ]]
  then
    data="$(echo "$JSONresponse" | python -c "from __future__ import print_function; import sys, json; print(json.load(sys.stdin)[0]['symbol'][0]['data'])")"
  else
    echo "Error:-$error" >&2 && exit 1
  fi
}

checkInternet()
{
  httpGet github.com > /dev/null 2>&1 || { echo "Error: no active internet connection" >&2; return 1; } # query github with a get request
}

usage()
{
  cat <<EOF
Qrify
Description: Converts strings or URLs into a QR code.
Usage: qrify [stringtoturnintoqrcode]
    -m  Enable multiline support (feature not working yet)
    -h  Show the help
    -v  Get the tool version
    -f  Store the QR code as a PNG file
    -d  Decode the QR code from a PNG/GIF/JP(E)G file
Examples:
    qrify this is a test string
    qrify -m two\\\\nlines
    qrify github.com (no http:// or https://)
    qrify -f fileoutputName google.com
    qrify -d fileName.png

Please pay attention:
This script needs access to an external API.
Do not use it to encode sensitive data.
EOF
}

getConfiguredClient || exit 1


while getopts "d:f:m:hvu*:" option
do
  case "${option}" in
    h) usage && exit 0 ;;
    m) multiline="1" && echo "Error this is not a supported feature yet" && exit 1 ;;
		f)
			fileName=$OPTARG
			#file name is the first argument of the option -f
			fileoutput="1";;
    d)
      fileName=$OPTARG
      decode="1";;
  esac
done

if [[ $# == "0" ]]; then
  usage
  exit 0
elif [[ $# == "1" ]];then
  if [[ $1 == "help" || $1 == ":help" ]]; then
    usage
    exit 0
  else
    getConfiguredPython || exit 1
	checkInternet || exit 1
    input=$(printf '%s ' "$@")
    makeqr || exit 1
    exit 0
  fi
else
  getConfiguredPython || exit 1
  checkInternet || exit 1
  if [[ $fileoutput == "1" ]]
	then
		input=$(printf '%s ' "${@:3}") # first arg is -f, second is the file name, third onwards is the rest of the argument
		# will have to be changed when implementing multiline QR code
		makeQRFile || exit 1
		exit 0
  elif [[ $decode == "1" ]]
  then
    ( decodeQR "$fileName" && echo "$data" ) || exit 1
    exit 0
  elif [[ $multiline == "0" ]]; then
    input=$(printf '%s ' "$@")
    makeqr || exit 1
    exit 0
  else
    input=$(printf '%s ' "${@:2}")
    makeMultiLineQr || exit 1 ## if multiline that means a flag existed so start from the second argument
    exit 0
  fi
fi