#!/bin/bash

error() {
  echo -e "\e[91m$1\e[39m" 1>&2
  exit 1
}

#if this script is being run standalone, not sourced
if [[ "$0" == */api ]];then
  DIRECTORY="$(readlink -f "$(dirname "$0")")"
fi

if [ -z "$DIRECTORY" ] || [ "$DIRECTORY" == "$HOME" ];then
  echo "api: DIRECTORY variable must be set to valid pi-apps folder. Default folder: $HOME/pi-apps"
  return 1
fi

repo_url="$(cat "${DIRECTORY}/etc/git_url" || echo 'https://github.com/Botspot/pi-apps')"

#determine if host system is 64 bit arm64 or 32 bit armhf
if [ "$(od -An -t x1 -j 4 -N 1 "$(readlink -f /sbin/init)")" = ' 02' ];then
  arch=64
elif [ "$(od -An -t x1 -j 4 -N 1 "$(readlink -f /sbin/init)")" = ' 01' ];then
  arch=32
else
  error "Failed to detect OS CPU architecture! Something is very wrong."
fi

list_intersect() { #Outputs only the apps that appear in both stdin and in $1
  #                      change \n to \|     |   remove last "\|"
  grep -x "$(echo "$1" | sed -z 's/\n/\\|/g' | sed -z 's/\\|$/\n/g')"
}

list_subtract() { #Outputs a list of apps from stdin, minus the ones that appear in $1
  #                       change \n to \|     |   remove last "\|"
  grep -vx "$(echo "$1" | sed -z 's/\n/\\|/g' | sed -z 's/\\|$/\n/g')"
}

list_apps() { # $1 can be: installed, uninstalled, corrupted, cpu_installable, hidden, visible, online, online_only, local, local_only
  if [ -z "$1" ] || [ "$1" == local ];then
    #list all apps
    ls "${DIRECTORY}/apps"
    
  elif [ "$1" == all ];then
    #combined list of apps, both online and local. Removes duplicate apps from the list.
    echo -e "$(list_apps local)\n$(list_apps online)" | sort | uniq
    
  elif [ "$1" == installed ];then
    #list installed apps
    #list apps|   only show      (          list of installed apps                      | remove match string  |   basename   )
    list_apps local | list_intersect "$(grep -rx 'installed' "${DIRECTORY}/data/status" | awk -F: '{print $1}' | sed 's!.*/!!')"
    
  elif [ "$1" == corrupted ];then
    #list corrupted apps
    #list apps|only show         (          list of corrupted apps                      | remove match string  |   basename   )
    list_apps local | list_intersect "$(grep -rx 'corrupted' "${DIRECTORY}/data/status" | awk -F: '{print $1}' | sed 's!.*/!!')"
    
  elif [ "$1" == disabled ];then
    #list corrupted apps
    #list apps|only show         (          list of disabled apps                     | remove match string  |   basename   )
    list_apps local | list_intersect "$(grep -rx 'disabled' "${DIRECTORY}/data/status" | awk -F: '{print $1}' | sed 's!.*/!!')"
    
  elif [ "$1" == uninstalled ];then
    #list uninstalled apps
    #list apps that have a status file containing "uninstalled"
    list_apps local | list_intersect "$(grep -rx 'uninstalled' "${DIRECTORY}/data/status" | awk -F: '{print $1}' | sed 's!.*/!!')"
    #also list apps that don't have a status file
    list_apps local | list_subtract "$(ls "${DIRECTORY}/data/status")"
    
  elif [ "$1" == cpu_installable ];then
    #list apps that can be installed on the device's OS architecture (32-bit or 64-bit)
    #find all apps that have install-XX script or an install script
    find "${DIRECTORY}/apps" -type f \( -name "install-$arch" -o -name "install" \) | sed "s+/install-$arch++g" | sed "s+/install++g" | sed "s+${DIRECTORY}/apps/++g" | sort | uniq
    
  elif [ "$1" == hidden ];then
    #list apps that are hidden
    cat "${DIRECTORY}/data/categories/structure" | grep '|hidden' | awk -F'|' '{print $1}'
    
  elif [ "$1" == visible ];then
    #list apps that are in any other category but 'hidden', and aren't disabled
    cat "${DIRECTORY}/data/categories/structure" | grep -v '|hidden' | awk -F'|' '{print $1}' # | list_subtract "$(list_apps disabled)"
    
  elif [ "$1" == online ];then
    #list apps that exist on the online git repo
    if [ -d "${DIRECTORY}/update/pi-apps/apps" ];then
      #if update folder exists, just use that
      ls "${DIRECTORY}/update/pi-apps/apps" | grep .
    else
      #if update folder doesn't exist, then parse github HTML to get a list of online apps. Horrible idea, but it works!
      wget -qO- "${repo_url}/tree/master/apps" | grep 'title=".*" data-pjax=' -o | sed 's/title="//g' | sed 's/" data-pjax=//g'
    fi
    
  elif [ "$1" == online_only ];then
    #list apps that exist only on the git repo, and not locally
    list_apps online | list_subtract "$(list_apps local)"
    
  elif [ "$1" == local_only ];then
    #list apps that exist only locally, and not on the git repo
    list_apps local | list_subtract "$(list_apps online)"
    
  fi
  
}

app_categories() { #lists all apps in a virtual filesystem based on categories file
  #cat "${DIRECTORY}/data/categories/structure" | awk -F'|' '{print $2"/"$1}'
  
  #find apps not in categories file
  {
    missingapps="$(list_apps | list_subtract "$(cat "${DIRECTORY}/data/categories/structure" | awk -F'|' '{print $1}')")"
    
    if [ ! -z "$missingapps" ];then
      PREIFS="$IFS"
      IFS=$'\n'
      for app in $missingapps ;do
        echo "WARNING: $app not found in categories file." 1>&2
        
        if list_apps online | grep -qx "$app" ;then
          #if app found online, then use online category line
          if [ -z "$onlinestructurefile" ];then
            onlinestructurefile="$(wget -qO- 'https://raw.githubusercontent.com/Botspot/pi-apps/master/data/categories/structure')"
          fi
          
          if echo "$onlinestructurefile" | grep -q '^'"$app|" ;then
            #if line found in online structure file
            echo "Putting $app in the $(echo "$onlinestructurefile" | grep '^'"$app|" | awk -F'|' '{print $2}') category." 1>&2
            
            echo "$(echo "$onlinestructurefile" | grep '^'"$app|")" >> "${DIRECTORY}/data/categories/structure"
          else
            #app exists online, but no structure line found
            echo -e "\e[33mHUGE WARNING: the $app exists on github, but no category was found for it on github!\nPlease report this to Botspot.\e[39m" 1>&2
            
            echo "Putting $app in the / category." 1>&2
            #put the app in root directory - no category
            echo "$app|" >> "${DIRECTORY}/data/categories/structure"
          fi
        else
          #app not found online
          
          echo "Putting $app in the / category." 1>&2
          #put the app in root directory - no category
          echo "$app|" >> "${DIRECTORY}/data/categories/structure"
        fi
      done
      IFS="$PREIFS"
    fi
  }
  
  #find apps in categories file that don't exist
  {
    ghostapps="$(cat "${DIRECTORY}/data/categories/structure" | awk -F'|' '{print $1}' | list_subtract "$(list_apps)")"
    
    if [ ! -z "$ghostapps" ];then
      PREIFS="$IFS"
      IFS=$'\n'
      for app in $ghostapps ;do
        echo "WARNING: $app does not exist but it was found in categories file." 1>&2
        echo "Removing $app from the categories file..." 1>&2
        #put the app in root directory - no category
        sed -i "/$app/d" "${DIRECTORY}/data/categories/structure"
        
      done
      IFS="$PREIFS"
    fi
  }
  
  #category file cleaned up past this point
  
  #show normal categories
  cat "${DIRECTORY}/data/categories/structure" | grep . | awk -F'|' '{print $2"/"$1}' | sed 's+^/++g'
  
  #show special Installed category
  list_apps installed | sed 's+^+Installed/+g'
  
  #show special All Apps category
  list_apps cpu_installable | list_intersect "$(list_apps visible)" | sed 's+^+All Apps/+g'
}

usercount() { #Return number of users for specified app. $1 is app name. if empty, all are shown.
  clicklist="$(wget -qO- 'https://raw.githubusercontent.com/Botspot/pi-apps-analytics/main/clicklist')"
  
  [ -z "$clicklist" ] && error "usercount(): clicklist empty. Likely no internet connection"
  
  if [ -z "$1" ];then
    echo "$clicklist"
  else
    # $1 is app
    echo "$clicklist" | grep " $1"'$' | awk '{print $1}' | head -n1
  fi
  
}

text_editor() { #Open user-preferred text editor. $1 is file to open
  [ -z "$1" ] && error "text_editor(): no file specified"
  
  #find the best text editor
  preferrededitor="$(cat "${DIRECTORY}/data/settings/Preferred text editor")"
  
  #change preferred editor if user-default doesn't exist
  if ! command -v "$preferrededitor" >/dev/null;then
    preferrededitor=geany
  fi
  if ! command -v "$preferrededitor" >/dev/null;then
    preferrededitor=mousepad
  fi
  if ! command -v "$preferrededitor" >/dev/null;then
    preferrededitor=leafpad
  fi
  if ! command -v "$preferrededitor" >/dev/null;then
    preferrededitor=nano
  fi
  
  if [ "$preferrededitor" == nano ];then
    #terminal-based text editor
    "${DIRECTORY}/etc/terminal-run" "nano "\""$1"\""" "Editing $(basename "$1")"
  else
    #non-terminal text editor
    "$preferrededitor" "$1"
  fi
}

script_name() { #returns name of install script(s) for the $1 app. outputs: '', 'install-32', 'install-64', 'install', 'install-32 install-64'
  [ -z "$1" ] && error 'script_name(): requires an argument'
  
  #ensure $1 is valid app name
  [ ! -d "${DIRECTORY}/apps/$1" ] && error "script_name: '$1' is an invalid app name.\n${DIRECTORY}/apps/$1 does not exist."
  
  if [ -f "${DIRECTORY}/apps/$1/install-32" ] && [ ! -f "${DIRECTORY}/apps/$1/install-64" ];then
    echo 'install-32'
  elif [ -f "${DIRECTORY}/apps/$1/install-64" ] && [ ! -f "${DIRECTORY}/apps/$1/install-32" ];then
    echo 'install-64'
  elif [ -f "${DIRECTORY}/apps/$1/install-64" ] && [ -f "${DIRECTORY}/apps/$1/install-32" ];then
    echo 'install-32 install-64'
  elif [ -f "${DIRECTORY}/apps/$1/install" ];then
    echo 'install'
  else
    true
    #error "No install script found for the $app app! Please report this to Botspot."
  fi
  
}

script_name_cpu() { #get script name to run based on detected CPU arch
  [ -z "$1" ] && error 'script_name_cpu(): requires an argument.'
  
  #ensure $1 is valid app name
  if ! list_apps all | grep -q "$1" ;then
    error "script_name_cpu: '$1' is an invalid app name."
  fi
  
  #this is used by the updater so we need to check the update folder too
  if [ -f "${DIRECTORY}/apps/$1/install-32" ] && [ $arch == 32 ];then
    echo 'install-32'
  elif [ -f "${DIRECTORY}/apps/$1/install-64" ] && [ $arch == 64 ];then
    echo 'install-64'
  elif [ -f "${DIRECTORY}/apps/$1/install" ];then
    echo 'install'
  elif [ -f "${DIRECTORY}/update/pi-apps/apps/$1/install-32" ] && [ $arch == 32 ];then
    echo 'install-32'
  elif [ -f "${DIRECTORY}/update/pi-apps/apps/$1/install-64" ] && [ $arch == 64 ];then
    echo 'install-64'
  elif [ -f "${DIRECTORY}/update/pi-apps/apps/$1/install" ];then
    echo 'install'
  else
    true #app not compatible with current arch
  fi
}

app_status() { #Gets the $1 app's current status. installed, uninstalled, corrupted, disabled
  
  [ -z "$1" ] && error 'app_status(): requires an argument.'
  [ ! -d "$DIRECTORY/apps/$1" ] && error "app_status(): app $1 doesn't exist!" #check if app exists
  
  if [ -f "${DIRECTORY}/data/status/${1}" ];then
    cat "${DIRECTORY}/data/status/${1}"
  else
    echo 'uninstalled' #if app status file doesn't exist, assume uninstalled
  fi
}

will_reinstall() { #return 0 if $1 app will be reinstalled during an update, otherwise return 1.
  [ -z "$1" ] && error 'will_reinstall(): requires an argument'
  
  #detect which installation script exists and get the hash for that one
  scriptname="$(script_name_cpu "$1")"
  
  oldinstallhash=$(sha1sum "${DIRECTORY}/apps/${1}/${scriptname}" | awk '{print $1}')
  newinstallhash=$(sha1sum "${DIRECTORY}/update/pi-apps/apps/${1}/${scriptname}" 2>/dev/null | awk '{print $1}')
  
  #if install script was changed                              #if installed already
  if [ "$newinstallhash" != "$oldinstallhash" ] && [ "$(app_status "${1}")" == 'installed' ];then
    return 0
  else
    return 1
  fi
}

app_search() { #search all apps for $1
  [ -z "$1" ] && error "app_search(): requires a search query."
  
  #search description and website
  results="$(find "${DIRECTORY}/apps" \( -name description -o -name website -o -name credits \) -exec grep -Fi "$1" {} + | awk -F: '{print $1}' | sed "s+${DIRECTORY}/apps/++g" | sed "s+/description++g" | sed "s+/website++g")"
  #hide incompatible and hidden/disabled apps
  results="$(echo "$results" | list_intersect "$(list_apps visible)" | list_intersect "$(list_apps cpu_installable)" | sort)"
  
  #search app names
  results="$(list_apps cpu_installable | list_intersect "$(list_apps visible)" | grep -i "$1" | sort)
$results"
  
  #remove duplicate entries
  echo "$results" | awk '!seen[$0]++'
  
}

app_search_gui() {
  output="$(yad --title=Search --center --width=310 --window-icon="${DIRECTORY}/icons/logo.png" \
    --text="Searches app names, descriptions, websites, and credits."$'\n'"Case-insensitive." \
    --form --entry='')" || exit 0
  
  results="$(app_search "$output")"
  
  if [ ! -z "$results" ];then
    
    IFS=$'\n'
    LIST=''
    for app in $results ;do
      LIST="$LIST
${DIRECTORY}/apps/${app}/icon-24.png
$app
$(echo "$(cat "${DIRECTORY}/apps/${app}/description" || echo "Description unavailable")" | head -n1)"
    done
    LIST="${LIST:1}" #remove first empty newline
    
    
    
    output="$(echo "$LIST" | yad --title=Results --center --width=310 --height=250 --window-icon="${DIRECTORY}/icons/logo.png" \
      --list --no-headers --column=:IMG --column=name --column=tooltip:HD \
      --print-column=2 --tooltip-column=3 --separator='\n')" || exit 0
    
    echo "$output"
  else
    yad --title=Results --center --width=310 --window-icon="${DIRECTORY}/icons/logo.png" \
      --text="No results found for "\""<b>$output</b>"\""." \
      --button=OK:0
    exit 0
  fi
}

#non-app functions below
runonce() { #run command only if it's never been run before. Useful for one-time migration or setting changes.
  #Runs a script in the form of stdin
  
  script="$(cat /dev/stdin)"
  
  runonce_hash="$(echo "$script" | sha256sum | awk '{print $1}')"
  
  if grep -qx '^'"$runonce_hash"'$' "${DIRECTORY}/data/runonce_hashes" ;then
    #hash found
    #echo "runonce: '$script' already run before. Skipping."
    true
  else
    #run the script.
    bash <(echo "$script")
    #if it succeeds, add the hash to the list to never run it again
    if [ $? == 0 ];then
      echo "$runonce_hash" >> "${DIRECTORY}/data/runonce_hashes"
      echo "'$script' succeeded. Added to list."
    else
      echo "'$script' failed. Not adding hash to list."
    fi
    
  fi
  
}

apt_lock_wait() { #Wait until other apt processes are finished before proceeding
  echo -n "Waiting until APT locks are released... "
  #while sudo fuser /var/lib/dpkg/lock &>/dev/null ; do
  #  sleep 0.5
  #done
  #while sudo fuser /var/lib/dpkg/lock-frontend &>/dev/null ; do
  #  sleep 0.5
  #done
  #while sudo fuser /var/lib/apt/lists/lock &>/dev/null ; do
  #  sleep 0.5
  #done
  #if [ -f /var/log/unattended-upgrades/unattended-upgrades.log ]; then
  #  while sudo fuser /var/log/unattended-upgrades/unattended-upgrades.log &>/dev/null ; do
  #    sleep 0.5
  #  done
  #fi
  
  while sudo fuser /var/{lib/{dpkg,apt/lists},cache/apt/archives}/lock /var/log/unattended-upgrades/unattended-upgrades.log &>/dev/null ;do
    sleep 1
  done
  sleep 0.5
  
  echo "Done"
}

is_supported_system() {
  if uname -m | grep -q 'x86' || uname -m | grep -q 'i686' || uname -m | grep -q 'i386';then
    echo "Pi-Apps is not supported on x86 processors. Expect almost all apps to fail. Consider switching to this x86 port of Pi-Apps: https://github.com/MCRaspRBX/pi-apps-x86"
    return 1
  elif [[ "$(cat /etc/os-release | grep VERSION_CODENAME | tr -d '"' | awk -F= '{print $2}')" == @(stretch|wheezy|jessie) ]];then
    echo "Pi-Apps is not supported on the outdated $(cat /etc/os-release | grep VERSION_CODENAME | tr -d '"' | awk -F= '{print $2}') operating system. Expect many apps to fail. Consider upgrading your operating system."
    return 1
  elif [[ "$(uname -m)" == armv6* ]];then
    echo "Pi-Apps has not been tested on armv6 Raspberry Pi boards. Expect many apps to fail."
    return 1
  elif [ "$(id -u)" == 0 ]; then
    echo "Pi-Apps is not designed to be run as root user."
    return 1
  elif [ "$(df -a / -B 1 --output=avail | tail -1 | tr -d ' ')" -lt $((1*1024*1024*1024)) ];then
    echo "Your system drive has less than 1GB of free space. Watch out for "\""disk full"\"" errors."
    return 1
  else
    return 0
  fi
}

format_log_file() { #remove ANSI escape sequences from a given file, and add OS information to beginning of file
  [ -z "$1" ] && error "format_log_file: no filename given!"
  [ ! -f "$1" ] && error "format_log_file: given filename ($1) does not exist or is not a file!"
  
  echo -e "$(get_device_info)\n\nBEGINNING OF LOG FILE:\n-----------------------\n\n$(cat "$1" | tr '\r' '\n' | sed 's/\x1b\[[0-9;]*m//g' | sed 's/\x1b\[[0-9;]*//g' | sed "s,\x1B\[[0-9;]*[a-zA-Z],,g" | grep -vF '.......... .......... .......... .......... ..........')" > "$1"
  
}

get_device_info() { #returns information about current install and hardware
  echo "OS: $(cat /etc/os-release | grep PRETTY_NAME | tr -d '"' | awk -F= '{print $2}')"
  echo "OS architecture: ${arch}-bit"
  [ ! -z "$DIRECTORY" ] && echo "Pi-Apps local commit ID: $(cd "$DIRECTORY"; git rev-parse HEAD)"
  echo "Kernel: $(uname -m) $(uname -r)"
  echo "Device model: $(cat /proc/cpuinfo | grep Model | sed 's/Model.*: //g')"
  
  if [ -f /etc/rpi-issue ];then
    echo "Raspberry Pi OS image version: $(cat /etc/rpi-issue | grep 'Raspberry Pi reference' | sed 's/Raspberry Pi reference //g')"
  fi
  
  if [ ! -z "$LANG" ];then
    echo "Language: $LANG"
  elif [ ! -z "$LC_ALL" ];then
    echo "Language: $LC_ALL"
  fi
  
}

send_error_report() { #non-interactively send a Pi-Apps error log file to the Botspot discord server
  [ -z "$1" ] && error "send_error_report(): requires an argument"
  [ ! -f "$1" ] && error "send_error_report(): '$1' is not a valid file."
  
  command -v curl >/dev/null || error "send_error_report(): Cannot send report: curl command not found!"
  
  errors="$(bash <(base64 -d <<<"Y3VybCAtRiAiZmlsZT1AXCIK$(base64 <<<"$1")XCI7ZmlsZW5hbWU9XCIK$(base64 <<<"$(basename "$1" | sed 's/\.log.*/.txt/g')")XCIiICIkKHdnZXQgLXFPLSAiJChiYXNlNjQgLWQgPDw8ImFIUjBjSE02THk5eVlYY3VaMmwwYUhWaWRYTmxjbU52Ym5SbGJuUXVZMjl0TDBKdmRITndiM1F2Y0drdFlYQndjeTFoYm1Gc2VYUnBZM012YldGcGJpOWxjbkp2Y2kxc2IyY3RkMlZpYUc5dmF3bz0iKSIgfCAkKGJhc2U2NCAtZCA8PDwiWW1GelpUWTBJQzFrQ2c9PSIpKSIK" | tr -d '\n') 2>&1)"
  [ $? != 0 ] && error "curl failed to upload log file!\nErrors:\n$errors"
  
}

send_error_report_gui() { #Ask user for permission to send error report
  [ -z "$1" ] && error "send_error_report_gui(): requires an argument for error report file!"
  [ ! -f "$1" ] && error "send_error_report_gui(): Given error report file ($1) does not exist!"
  [ -z "$2" ] && error "send_error_report_gui(): requires an argument for window text!"
  
  command -v curl >/dev/null || error "send_error_report_gui(): curl is not installed!"
  
  export -f text_editor
  export DIRECTORY
  
  yad --center --title="Send error report?" --window-icon="${DIRECTORY}/icons/logo.png" \
    --text="$2"$'\n'"Send anonymous error report to Pi-Apps developers?"$'\n'"Support is available on <a href=\"https://discord.gg/RXSTvaUvuu\">Discord</a> and <a href=\"https://github.com/Botspot/pi-apps/issues/new/choose\">Github</a>." --on-top \
    --button='Send report'!"${DIRECTORY}/icons/upload.png":0 \
    --button='View report'!"${DIRECTORY}/icons/log-file.png"!"View the log file to be sent."$'\n'"Feel free to edit the file with more debug information to help us.":"bash -c 'text_editor "\""$1"\""'" \
    --button="Don't send"!"${DIRECTORY}/icons/exit.png":1
  button=$?
  #echo "Button: $button"
  
  if [ "$button" == 0 ];then
    send_error_report "$1"
  fi
  
}

generate_logo() { #display colorized Pi-Apps logo in terminal
  #generate pi-apps logo
  #https://misc.flogisoft.com/bash/tip_colors_and_formatting
  blue='\e[38;5;21m' #blue='\e[38;5;27m' #lighter
  green='\e[38;5;46m'
  red='\e[38;5;197m'
  echo -e "   ${green}┏━━━┓
${blue}┏━━${green}┻${blue}━━━${green}┻${blue}━━┓
${blue}┃  ${red}⬛⬛⬛ ${blue}┃\e[97m  ▕ᑐ • ▁  ʌ
${blue}┃  ${red}⬛⬛⬛ ${blue}┃\e[97m  ▕  │   ╱‾╲▕ᑐ ▕ᑐ Ｓ
${blue}┃  ${red}⬛⬛⬛ ${blue}┃\e[97m            ▕  ▕
\e[38;5;27m╰${blue}━━━━━━━━━\e[38;5;27m╯\e[49m
\e[0m\e[0m"
}

wget() { #this function intercepts all wget commands being used in app scripts. It uses aria2c if possible.
  local file=''
  local url=''
  local use=aria2c
  if command -v aria2c; then
    #convert wget arguments to newline-separated list
    local IFS=$'\n'
    local opts="$(IFS=$'\n'; echo "$*")"
    for opt in $opts ;do
      if [[ "$opt" == '-'* ]]; then
        #this opt is the beginning of a flag
        if [ "$opt" == '-qO' ] || [ "$opt" == '-O' ] || [ "$opt" == '-q' ]; then
          true
        else #any other wget command-flags other than '-qO', '-O', '-q'
          use=wget
          break
        fi
      elif [[ "$opt" == *'://'* ]]; then
        #this opt is web address
        url="$opt"
      elif [[ "$opt" == '/'* ]]; then
        #this opt is file output
        if [ -z "$file" ];then
          file="$opt"
        else #file var already populated
          use=wget
          break
        fi
      else
        #this opt does not begin with '-', contain '://', or begin with '/'. Assume output file specified shorthand
        if [ -z "$file" ];then
          file="$(pwd)/${opt}"
        else #file var already populated
          use=wget
          break
        fi
      fi
    done
    
  else
    #aria2c command not found
    use=wget
  fi
  
  if [ "$use" == wget ];then
    #run the true wget binary with all this function's args
    command wget "$@"
  elif [ "$use" == aria2c ];then
    #make default filename if $file empty
    if [ -z "$file" ];then
      file="$(pwd)/$(basename "$url")"
    fi
    aria2c -c -x 16 -s 16 -m 10 --retry-wait 30 "$url" --dir '/' -o "${file:1}" --allow-overwrite --summary-interval=1
  fi
}

#if this script is being run standalone, not sourced
if [[ "$0" == */api ]];then
  if [ ! -z "$1" ];then
    #if user input a function command, then run it with arguments.
    #Keep in mind this could run any command the user wanted, not necessarily exclusively function commands.
    "$@"
  fi
fi