#!/usr/bin/env bash
#-*-coding:utf-8 -*-
#Auto updated?
#   Yes
#File:
#   fzf_youtube_subs
#Author:
#   The-Repo-Club [wayne6324@gmail.com]
#Github:
#   https://github.com/The-Repo-Club/
#
#Created:
#   Sun 03 January 2021, 05:09:33 PM [GMT]
#Modified:
#   Thu 20 October 2022, 03:27:18 PM [GMT+1]
#
#Description:
#   Watch your youtube subscriptions without a youtube account
#   via curl, fzf, browser and basic unix commands.
#
#   The $SUBS_FILE is a text file containing usernames or channel IDs
#   comments and blank lines are ignored.
#
#
#Dependencies:
#   fzf
#

fzf_menu() {
  fzf --prompt="Select a video: " --border=rounded --margin=1% --color=dark --height 100% --reverse --header="   YOUTUBE SUBS MENU " --info=hidden --header-first
}

# -/-/-/-/- Settings -/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/
: "${SUBS_FILE:=${HOME}/.config/fzf/subs.ini}"
: "${SUBS_MENU_PROG:=fzf_menu}"
: "${SUBS:=${HOME}/.cache/subs}"
: "${SUBS_LINKS:=$SUBS/links}"
: "${SUBS_OPEN:=$(gobble videoplayer)}"
: "${SUBS_CACHE:=$SUBS/cache}"
: "${SUBS_SLEEP_VALUE:=0.05}" # raise this if you experience problems
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
SEP=^^^^^ # shouldn't need to change this
# -/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/

die() {
  printf >&2 '%s\n' "$*"
  exit 1
}

usage() {
  die 'Usage: fzf_youtube_subs [-c cat_subs] [-g gen_links] [-u update_subs] [-d daemonize]'
}

# -*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*
# Synopsis: $SUBS_FILE [txt] -> $SUBS_LINKS [xml links]
#
# Updates local cache of xml subscription links from the
# subscription file containing either usernames or channel ids.
# -*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*
gen_links() {
  : >"$SUBS_LINKS"

  count=0
  total=$(sed -e '/^$/d' -e '/^#/d' <"$SUBS_FILE" | wc -l)

  while read -r line; do

    # ignore comments and blank lines
    case $line in '' | ' ' | '#'*) continue ;; esac

    # strip off in-line comments and any trailing whitespace
    line=${line%%#*}
    line=${line%% *}

    count=$((count + 1))

    case $line in
    UC*)
      # YT channel IDs always begin with 'UC' and are 24 chars long
      printf "[%s/%s] using channel ID '%s' for xml link\n" "$count" "$total" "$line"

      [ ${#line} -eq 24 ] &&
        printf 'https://youtube.com/feeds/videos.xml?%s\n' \
          "channel_id=$line" >>"$SUBS_LINKS"
      ;;
    *)
      # otherwise we are given a username, we must find out its channel ID
      printf "fetching channel ID for %s...\n" "$line"

      curl -sfL --retry 10 "https://youtube.com/user/$line/about" |
        while read -r line; do
          case $line in
          *channel/UC??????????????????????*)
            line=${line##*channel/}
            line=${line%%\"*}
            printf "[%s/%s] using channel ID '%s' for xml link\n" "$count" "$total" "$line"
            printf 'https://youtube.com/feeds/videos.xml?channel_id=%s\n' \
              "$line" >>"$SUBS_LINKS"
            break
            ;;
          esac
        done &
      sleep "${SUBS_SLEEP_VALUE:-0}"
      ;;
    esac

  done <"$SUBS_FILE"

  count=0
  while [ "$count" -ne "$total" ]; do
    count=$(wc -l <"$SUBS_LINKS")
    printf "[%s/%s] waiting for jobs to complete...\n" "$count" "$total"
    sleep 0.5
  done
}

# -*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*
# Synopsis: $1 [LINK] -> $SUBS_CACHE/$chan_name/concat [CHANNEL INFO]
#
# Takes a channel rss feed link and creates a file
# with a line of its videos dates, titles, and urls.
# -*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*
get_vids() {
  data=$(curl -sfL --retry 15 "$1")

  # hide the first <published> tag which is the channel
  # creation date
  data=${data#*\<\/published\>}

  # trim off outer <name> tags
  chan=${data%%</name*}
  chan=${chan##*name>}

  printf "%s\n" "$data" |
    while read -r line; do
      case $line in
      *'link rel='*)
        line=${line#*href=\"}
        line=${line%\"/\>}
        line=https://${line#*www.}
        url=$line
        ;;
      *'<published>'*)
        line=${line%+00:*}
        line=${line#*<published>}
        date=$line
        ;;
      *'<media:title>'*)
        line=${line%</*}
        line=${line#*:title>}
        title=$line
        printf '%s\n' \
          "${date}${SEP}${chan}${SEP}${title}${SEP}${url}" \
          >>"$SUBS_CACHE/$chan"
        ;;
      esac
    done
}

# -*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*
# Updates the local cache of subscriptions. ([-u] flag)
# -*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*
update_subs() {
  [ -f "$SUBS_LINKS" ] || die 'Subs links have not been generated.'

  rm -r "${SUBS_CACHE:-?}" 2>/dev/null || :
  mkdir -p "$SUBS_CACHE"

  total=$(wc -l <"$SUBS_LINKS")

  count=0
  while read -r link; do
    count=$((count + 1))
    printf 'starting job [%s/%s] for %s\n' "$count" "$total" "$link"
    get_vids "$link" &
    sleep "${SUBS_SLEEP_VALUE:-0}"
  done <"$SUBS_LINKS"

  count=0
  while [ "$count" -ne "$total" ]; do
    count=$(printf '%s\n' "$SUBS_CACHE"/* | wc -l)
    printf "[%s/%s] waiting for fetch jobs to complete...\n" "$count" "$total"
    sleep 0.5
  done

  printf '%s\n\n' 'done!'
}

# -*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*
# Grab current cache of subscriptions, sort by date uploaded
# -*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*
cat_subs() {
  sort -r "$SUBS_CACHE"/* |
    while read -r line; do
      chan=${line#*$SEP}
      chan=${chan%%$SEP*}
      title=${line#*$chan$SEP}
      title=${title%%$SEP*}
      date=${line%%$SEP*}
      date=${date#*-}
      date=${date%T*}
      printf '[%s %s] %s\n' "$date" "$chan" "$title"
    done
}

# Split the concatenated lines into entities, send to menu program.
# Finally, play the result with mpv.
get_sel() {
  if [ -d "$SUBS_CACHE" ]; then
    sel=$(cat_subs | $SUBS_MENU_PROG)
  else
    die 'Subs cache has not been retrieved.'
  fi

  [ "$sel" ] || die Interrupted

  chan="${sel#* }"
  chan="${chan%%] *}"
  title=${sel#*"$chan"\] }
  while read -r line; do
    case $line in
    *"$SEP$title$SEP"*)
      url=${line##*$SEP}
      if [ "$url" ]; then
        printf 'playing: %s\n' "$url"
        # Play the selection.
        # shellcheck disable=2086
        exec devour $SUBS_OPEN "$url"
      fi
      break
      ;;
    esac
  done <"$SUBS_CACHE/$chan"
}

daemonize() {
  # create a cached copy of the subs file to check for changes
  # if changes occur, re-generate links automatically
  daemon_file=${HOME}/.cache/subs_daemon.cache
  if [ ! -f "$daemon_file" ]; then
    cp -f "${SUBS_FILE:=${HOME}/.config/fzf/subs.ini}" "$daemon_file"
  fi

  while true; do
    if ! cmp "${SUBS_FILE:=${HOME}/.config/fzf/subs.ini}" "$daemon_file"; then
      cp -f "${SUBS_FILE:=${HOME}/.config/fzf/subs.ini}" "$daemon_file"
    fi
    gen_links
    update_subs
    interval=${SUBS_DAEMON_INTERVAL:-$((10 * 60))}
    printf 'Sleeping for %s seconds...\n' "$interval"
    sleep "$interval"
  done
}

main() {
  mkdir -p "$SUBS"

  case ${1#-} in
  h) usage ;;
  g) gen_links ;;
  u) update_subs ;;
  c) cat_subs ;;
  d) daemonize ;;
  *) get_sel ;;
  esac
}

main "$@"