#!/usr/bin/env ruby

require 'json'
require 'http'

def api_request(instance, path, params)
  uri = URI::HTTPS.build(host: instance, path: path,
                         query: URI.encode_www_form(params))
  res = HTTP.headers(accept: 'application/json').get(uri)
  raise("HTTP error #{res.status.to_i}") unless res.status.ok?
  [res.headers, res.parse]
end

def proceed_Yn(prompt)
  print("#{prompt} [Yn] ")
  answer = STDIN.gets
  return nil unless answer
  answer.strip!
  return true if answer.empty? || answer[/y/i]
end

def check_meta(instance)
  _, meta = api_request(instance, '/api/v1/instance', {})
  puts "Title: #{meta['title']}"
  puts "Description: #{meta['short_description']}"
  puts "Version: #{meta['version']}"
  puts "Users: #{meta['stats']['user_count']}"
  puts "Max chars: #{meta['max_toot_chars'] || 'unknown'}"
  puts "Languages: #{meta['languages']}"
  puts "Registrations: #{meta['registrations'] ? 'open' : 'closed'}"
  puts "Admin: #{meta['contact_account'] && meta['contact_account']['url']}"
end

def find_next_link(header)
  parts = header.split(', ')
  part = parts.grep(/rel="next"/)[0]
  return unless part
  part[/<([^>]*>)/] && $1
end

def check_post(post)
  puts "User: #{post['account']['url']}"
  puts "Date: #{post['created_at']}"
  puts "Content: #{post['content']}"
  attachments = post['media_attachments']
  puts "Media: #{attachments.map { |a| a['url'] }}" unless attachments.empty?
end

def check_posts(instance)
  params = { 'local' => 'true', 'limit' => '10' }
  loop do
    headers, posts = api_request(instance, '/api/v1/timelines/public', params)
    has_next_link = headers['Link'].include?('rel="next"')
    break unless has_next_link && proceed_Yn('Continue?')
    posts.each { |p| check_post(p) }
    puts
    params['max_id'] = posts[-1]['id']
  end
end

def check(instance)
  check_meta(instance)
  puts
  check_posts(instance)
end

def die(msg)
  STDERR.puts(msg)
  exit(1)
end

die("usage: #{$PROGRAM_NAME} <host>") unless ARGV.count == 1
check(ARGV[0])