yt_monocular.sh

#!/bin/bash
#================================================================
# HEADER
#================================================================
#% SYNOPSIS
#+    ${SCRIPT_NAME} [-h] channelId
#%
#% DESCRIPTION
#%    Download the latest audio from a channel. The channelId can be found in
#%    the url for the channel or in the channel's html. It should start with "UC".
#%    Setting YOUTUBE_API_KEY is required in order to use this script.
#%    
#%
#% OPTIONS
#%    -h, --help                    Print this help
#%    -v, --version                 Print script information
#%
#% EXAMPLES
#%    ${SCRIPT_NAME} UCVI66VMGYg0dLPEkWPrCkBw
#%
#================================================================
#- IMPLEMENTATION
#-    version         ${SCRIPT_NAME} 0.0.1
#-    author          Pat O'Connor
#-    license         MIT
#-
#================================================================
#  DEBUG OPTION
#    set -n  # Uncomment to check your syntax, without execution.
#    set -x  # Uncomment to debug this shell script
     set -e  # stop if an error occurs
#
#================================================================
# END_OF_HEADER
#================================================================

#== needed variables ==#
SCRIPT_HEADSIZE=$(head -200 ${0} |grep -n "^# END_OF_HEADER" | cut -f1 -d:)
SCRIPT_NAME="$(basename ${0})"

#== usage functions ==#
usage() { printf "Usage: "; head -${SCRIPT_HEADSIZE:-99} ${0} | grep -e "^#+" | sed -e "s/^#+[ ]*//g" -e "s/\${SCRIPT_NAME}/${SCRIPT_NAME}/g" ; }
usagefull() { head -${SCRIPT_HEADSIZE:-99} ${0} | grep -e "^#[%+-]" | sed -e "s/^#[%+-]//g" -e "s/\${SCRIPT_NAME}/${SCRIPT_NAME}/g" ; }
scriptinfo() { head -${SCRIPT_HEADSIZE:-99} ${0} | grep -e "^#-" | sed -e "s/^#-//g" -e "s/\${SCRIPT_NAME}/${SCRIPT_NAME}/g"; }
check_dependencies() {
    for dep in "ffmpeg" "jq" "sqlite3" "youtube-dl"; do
        if ! command -v ${dep} &> /dev/null; then
            echo "ERROR: ${dep} required in order to proceed."
            exit 8
        fi
    done

}
init_sqlite() {
    sqlite3 monocular.db <<EOL
    CREATE TABLE IF NOT EXISTS video (
      id varchar(32) PRIMARY KEY,
      title text
    );
EOL
}
select_video_id() {
    echo "SELECT id FROM video WHERE id='$1'" | sqlite3 monocular.db
}
insert_video() {
    echo "INSERT INTO video (id, title) VALUES ('$1', '$2')" | sqlite3 monocular.db
}

# Define list of arguments expected in the input
optstring=":hv"

while getopts ${optstring} arg; do
  case "${arg}" in
    h) usagefull; exit 0;;
    v) scriptinfo; exit 0;;
    ?)
      echo "ERROR: Invalid option: -${OPTARG}."
      echo
      usagefull
      exit 1
      ;;
  esac
done

if test "$1" = ""; then
    echo "ERROR: Missing channelId"
    usagefull
    exit 2
fi

if test "${YOUTUBE_API_KEY}" = ""; then
    echo "ERROR: YOUTUBE_API_KEY is not set. Please set this env variable."
    exit 4
fi

main() {
    local channelId="$1"
    local limit=10
    local url="https://www.googleapis.com/youtube/v3/search?key=${YOUTUBE_API_KEY}&channelId=${channelId}&maxResults=${limit}&order=date&type=video&videoDuration=long&part=snippet"
    # results should come back in the for of '<videoId> <title>' this format
    # should allow us to capture each field with cut
    mapfile -t tuples <<<"$(curl -s ${url} | jq -r '.items[] | [.id.videoId, .snippet.title] | @sh' | xargs -n 2)"
    init_sqlite
    i=0
    while [ "$i" -ne $limit ]
    do
        local id=$(echo "${tuples[$i]}" | cut -d ' ' -f1)
        if test "${id}" = ""; then
            echo "ERROR: There was an issue fetching youtube results."
            exit 16
        fi
        local title=$(echo "${tuples[$i]}" | cut -d ' ' -f2-)
        if test "$(select_video_id ${id})" = ""; then
            youtube-dl -f bestaudio --extract-audio --audio-format mp3 --embed-thumbnail -o "%(title)s.%(ext)s" "https://www.youtube.com/watch?v=${id}"
            insert_video "$id" "$title"
        fi
        i=$((i + 1))
    done
}

check_dependencies
main "$1"