#!/bin/bash
set -Eeo pipefail

script_name() { echo 'ggdrive.sh'; }
version() { echo "$(script_name)0.0.3" && exit 0; }
die() { echo "$*" >&2; exit 2; }
msg() { echo >&2 -e "${1-}"; }
#============================
# USAGE HELP & MESSAGING
#============================
usage() {
   cat <<EOF
Usage: <GAPI_KEY=XXXX> $(script_name) [-h/--help] [-v] [-e] [-g <g_api>] [-t <tempfile>] [-u <user_agent>] [csv_file]
EOF
}

usage_full() {
   usage
   cat <<EOF

Description:
   Download google drive file exports, eg gdocs -> pdf

Environoment variables:
   GAPI_KEY          REQUIRED Google Cloud API Key with access to Google Drive API

Arguments:
   csv_file          Path/to/file.csv. Leave blank for NOOP.

Flags:
   -e, --export      export functions. Use w/o [csv_file] for custom handling
   -g, --g_api       Specify endpoint of the google drive api
                     {'https://www.googleapis.com/drive/v2'}
   -t, --tempfile    If you want to be particular about the tempfile
                     {tempfile}
   -u, --user_agent  I don't think Google actually cares, but hey
                     {'github.com/knzai'}

   -h, --help        Print this help
   -v, --version     Print script information

Examples
   # Standard usage
   $(script_name)path/to/csv

   # Do nothing except export functions for your own use
   $(script_name) -e 

   # Specify a different version of the google drive api
   $(script_name) -g https://www.googleapis.com/drive/v3 path/to/csv

Curl
   curl -s -L https://gist.github.com/knzai/75702a336a25646e6c0039f96d5732b9/raw | bash -s -- gdrive_files.csv

EOF
   exit 0
}

#============================
# PARSE PARAMETERS
#============================
if [ $# -eq 0 ]; then usage && exit; fi;

#defaults
export=false
g_api='https://www.googleapis.com/drive/v2'
tempfile='tempfile'
user_agent='github.com/knzai'

#flags and options
while getopts eg:t:u:hv-: OPT; do
   # support long options: https://stackoverflow.com/a/28466267/519360
   if [ "$OPT" = "-" ]; then    # long option: reformulate OPT and OPTARG
      OPT="${OPTARG%%=*}"       # extract long option name
      OPTARG="${OPTARG#"$OPT"}" # extract long option argument (may be empty)
      OPTARG="${OPTARG#=}"      # if long option argument, remove assigning `=`
   fi
   case "$OPT" in
      e|export    ) export=true           ;;
      g|g_api     ) g_api="$OPTARG"       ;;
      t|tempfile  ) tempfile="$OPTARG"    ;;
      u|user_agent) user_agent="$OPTARG"  ;;

      h|help      ) usage_full;           ;;
      v|version   ) version;              ;;
      *           ) exit 2                ;;
   esac
done
shift $((OPTIND-1)) # remove parsed options and args from $@ list

#positional args
csv_file=$1

#============================
# ALIAS AND FUNCTIONS
#============================
get_gdrive_files() {
   if [ ! -f $1 ]; then die "$1 file not found"; fi
   oldifs=$IFS
   IFS=','
   while read gd_id mime dest min_size
   do
      gdrive_export $gd_id $mime
      replace_if_valid $dest $min_size
   done < $1
   IFS=$oldifs
}
gdrive_export() {
   #$1: google_file_id
   #$2: mime_type
   wget -O $tempfile --user-agent=$user_agent "$g_api/files/$1/export?mimeType=$2&key=$GAPI_KEY"
}
replace_if_valid() {
   #$1: dest
   #$2: min_size
   if [ $(du -k $tempfile | cut -f1) -gt $2 ]; then
      mv $tempfile "$1"
   else
      echo "Problem fetching file"
      exit 1
   fi
}

#============================
# MAIN SCRIPT
#============================

if [ $csv_file ]; then
   get_gdrive_files $csv_file
elif $export; then
  export -f get_gdrive_files
  export -f gdrive_export
  export -f replace_if_valid
else
   die 'NOOP: neither --export nor <csvfile> passed in'
fi



#===============================================================================
# AUTHOR & COPYRIGHT
#    version         ggdrive.sh 0.0.3
#    author          Kenzi Connor
#    copyright       Copyright (c) Public Domain
#    license         Public Domain via Unlicense
#    site            knz.ai/ggdrive
#
#===============================================================================
# HISTORY
#    2024/07/10 : 0.0.1 : Script creation
#    2024/07/11 : 0.0.2 : Cleaned up, comment, add help and usage
#    2024/07/11 : 0.0.3 : Simplify usage() to make curling easier
# 
#===============================================================================
# LICENSE: Public Domain via Unlicense
#
# This is free and unencumbered software released into the public domain.
#
# Anyone is free to copy, modify, publish, use, compile, sell, or
# distribute this software, either in source code form or as a compiled
# binary, for any purpose, commercial or non-commercial, and by any
# means.
#
# In jurisdictions that recognize copyright laws, the author or authors
# of this software dedicate any and all copyright interest in the
# software to the public domain. We make this dedication for the benefit
# of the public at large and to the detriment of our heirs and
# successors. We intend this dedication to be an overt act of
# relinquishment in perpetuity of all present and future rights to this
# software under copyright law.
# 
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
# IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
# OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
# ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
# OTHER DEALINGS IN THE SOFTWARE.
#
# For more information, please refer to <http://unlicense.org/>