#!/usr/bin/env ruby
# frozen_string_literal: true

# newsboat-yt-feed.rb
# Author: William Woodruff
# ------------------------
# Adds a YouTube channel to newsboat.
# Works with both old (/user/) and new (/channel/)-style YouTube channels.
# ------------------------
# This code is licensed by William Woodruff under the MIT License.
# http://opensource.org/licenses/MIT

require "uri"

DEPS = [
  "newsboat",
].freeze

NEWSBOAT_URL_FILES = [
  # is this is right precedence?
  File.expand_path("~/.config/newsboat/urls"),
].freeze

YOUTUBE_FEED_URLS = {
  chan: "https://www.youtube.com/feeds/videos.xml?channel_id=%<id>s",
  user: "https://www.youtube.com/feeds/videos.xml?user=%<id>s",
}.freeze

def which?(cmd)
  ENV["PATH"].split(File::PATH_SEPARATOR).any? do |path|
    File.executable?(File.join(path, cmd))
  end
end

def add_feed!(feed_url)
  url_file = NEWSBOAT_URL_FILES.find { |f| File.exist? f }

  File.open(url_file, "a") { |io| io.puts "#{feed_url} \"YouTube\"" }
end

abort "Usage: #{$PROGRAM_NAME} <channel url>" if ARGV.empty?

DEPS.each { |d| abort "Fatal: Missing '#{d}'." unless which? d }

chan_url = URI(ARGV.shift)

if chan_url.host.nil? || /youtube/i !~ chan_url.host || chan_url.path.empty?
  abort "Fatal: Not a valid channel URL."
end

type, id = chan_url.path.split("/")[1..2]

case type
when "channel"
  feed_url = YOUTUBE_FEED_URLS[:chan] % { id: id }
when "user"
  feed_url = YOUTUBE_FEED_URLS[:user] % { id: id }
else
  abort "Fatal: Ambiguous channel URL (or not a channel URL)."
end

add_feed!(feed_url)

puts "Added #{feed_url} to newsboat."