#!/bin/bash
# manually created arrays for file types and extensions
types_arr=('MPEG' 'JPEG' 'PNG' 'GIF' 'WebM' 'RIFF')
exts_arr=('mp4' 'jpg' 'png' 'gif' 'webm' 'webp')
tmp_file="$1/download.tmp"

# check for existance of $1 or if $2 is a file
if [ -z $1 ] || [ ! -f "$2" ]; then
  echo "Usage: $0 <output_directory> <file_list>"
  echo "ExaMPLE: download_file_list Downloads to_download.txt"
  exit 1
fi

# create the out dir if not extant
if [ ! -d "$1" ]; then
  echo "Output directory does not exist: $1 Creating"
  mkdir "$1"
fi

# read the input file and loop through it
cat "$2" | \
	while read line; do
    # download the file to a tmp
    echo "Downloading $line to $1"
		curl -s -o "$tmp_file" "$line"

    # get the file type
    type=$(file "$tmp_file" | awk '{print $2}')

    # md5 hash the file for a deterministic file name
    namehash=$(md5sum "$tmp_file" | awk '{print $1}')

    # map the file type to the corresponding extension
    count=0
    # loop through types for patch with file type
    for item in "${types_arr[@]}"; do
      if [[ " ${types_arr[@]} " =~ " ${type} " ]]; then
        # if type matches
        if [[ "$item" == "$type" ]]; then
          # rename the downloaded file
          new_name="$1/$namehash.$(echo ${exts_arr[$count]})"
          echo "Renaming $tmp_file to $new_name"
          mv "$tmp_file" "$new_name"
        fi
      else
        echo "$(basename $line) not a supported format: $type! Deleting"
        rm -f "$tmp_file"
      fi

      # increment the count regardless
      count=$((count + 1))
    done
  done