user/get_ytpljson.sh

   1 #!/bin/bash
   2 # Usage: get_ytpljson.sh arg1 arg2
   3 # Input: posargs: arg1: YouTube playlist ID
   4 #                 arg2: Google API key
   5 # Output: file: JSON file
   6 # Version: 0.0.1
   7
   8 max_api_calls="100";
   9
  10 yell() { echo "$0: $*" >&2; } # print script path and all args to stderr
  11 die() { yell "$*"; exit 111; } # same as yell() but non-zero exit status
  12 must() { "$@" || die "cannot $*"; } # runs args as command, reports args if command fails
  13 get_response() {
  14     # Input: arg1: YouTube playlist ID
  15     #        arg2: Google API key
  16     #        arg3: pageToken (optional)
  17     # Output: stdout: JSON response from googleapis.com
  18     # Depends: curl 7.81.0
  19     #          BK-2020-03: die()
  20
  21     local PLAYLIST_ID API_KEY PAGE_TOKEN URL;
  22
  23     # Set the playlist ID and API key
  24     PLAYLIST_ID="$1";
  25     API_KEY="$2";
  26     PAGE_TOKEN="$3";
  27
  28     # Check inputs
  29     if [[ $# -lt 2 ]]; then die "FATAL:Incorrect arg count:$#"; fi;
  30
  31     # Base URL
  32     URL="https://www.googleapis.com/youtube/v3/playlistItems?part=snippet";
  33
  34     # Append playlist ID
  35     URL="$URL""&playlistId=""$PLAYLIST_ID";
  36
  37     # Append API key
  38     URL="$URL""&key=""$API_KEY";
  39
  40     # Append page token if it exists
  41     if [[ -n "$PAGE_TOKEN" ]]; then
  42         URL="$URL""&pageToken=""$PAGE_TOKEN";
  43     fi;
  44
  45     curl -s "$URL";
  46     #curl -s "https://www.googleapis.com/youtube/v3/playlistItems?part=snippet&playlistId=$PLAYLIST_ID&key=$API_KEY"; # example
  47
  48 }; # Stdout: JSON from YouTube v3 API
  49 check_next_page() {
  50     # Input: arg1: json string
  51     # Depends: jq 1.6
  52
  53     # Checks if key ".nextPageToken" present
  54     if jq -e '.nextPageToken' < <(printf "%s" "$1") 1>/dev/random 2>&1; then
  55         return 0;
  56     else
  57         return 1;
  58     fi;
  59
  60 }; # returns true if '.nextPageToken' present
  61 get_next_page() {
  62     # Input: arg1: json string containing the key 'nextPageToken'
  63     # Output: stdout: the value of the first 'nextPageToken' key
  64     #         exit code: 0: key '.nextPageToken' detected
  65     #                    1: key '.nextPageToken' not detected
  66     # Depends: jq 1.6
  67     local output;
  68     if [[ $# -ne 1 ]]; then die "Incorrect arg count:$#"; fi;
  69
  70     if jq -e '.nextPageToken' < <(printf "%s" "$1") 1>/dev/random 2>&1; then
  71         output="$(jq -r '.nextPageToken' < <(printf "%s" "$1") | head -n1)";
  72         printf "%s" "$output";
  73         return 0;
  74     else
  75         return 1;
  76     fi;
  77 }; # stdout: value from key "pageToken"
  78
  79 main() {
  80     # Depends: bash 5.1.16, GNU Coreutils 8.32 (date)
  81     #          BK-2020-03: yell()
  82     # Ref/Attrib: [1]: "Obtaining authorization credentials" https://developers.google.com/youtube/registering_an_application
  83     #             [2]: "Implementation: Playlists" https://developers.google.com/youtube/v3/guides/implementation/playlists
  84     #             [3]: "Implementation: Pagination", https://developers.google.com/youtube/v3/guides/implementation/pagination
  85
  86     local n out_path;
  87     declare -a out_list;
  88
  89     # Check input
  90     if [[ $# -ne 2 ]]; then die "FATAL:Incorrect number of args:$#"; fi;
  91
  92     # Set the playlist ID and API key
  93     playlistId="$1"; # See ref [2]
  94     apiKey="$2"; # See ref [1]
  95
  96     # Set dynamic variables according to environment
  97     out_dir="$(pwd)"; # output to present working directory
  98     out_filename="$(date +%Y%m%dT%H%M%S%z)"_"$playlistId"..playlist_items.json;
  99     out_path="$out_dir"/"$out_filename";
 100
 101     # Make initial curl request to the YouTube Data API
 102     response="$(get_response "$playlistId" "$apiKey")";
 103
 104     # # debug
 105     # if check_next_page "$response"; then
 106     #     yell "DEBUG:nextPageToken detected";
 107     # fi;
 108
 109     # Make follow-up requests. See ref [3]
 110     n=0;
 111     while check_next_page "$response"; do
 112         # Get page token from response
 113         pageToken="$(get_next_page "$response")";
 114         # Update response
 115         response="$(get_response "$playlistId" "$apiKey" "$pageToken")";
 116         # Record response
 117         out_list+=("$response");
 118
 119         # Sanity check
 120         if [[ $n -gt $max_api_calls ]]; then die "FATAL:Too many API calls:$n"; fi;
 121         ((n++));
 122     done;
 123
 124     # Write results
 125     printf "%s\n" "${out_list[@]}" > "$out_path";
 126
 127     # Print stats
 128     yell "STATUS:Performed $n API calls."
 129     out_lc="$(printf "%s\n" "${out_list[@]}" | wc -l)";
 130     yell "STATUS:Wrote $out_lc lines to $out_path";
 131
 132     # Use jq to extract the publishedAt field for each playlist item
 133     #PUBLISHED_AT=$(echo "$response" | jq -r '.items[].snippet.publishedAt')
 134
 135 }; # main program
 136
 137 main "$@";
 138
 139 # Author: Steven Baltakatei Sandoval
 140 # License: GPLv3+