# frozen_string_literal: true

require 'net/http'
require 'uri'
require 'json'
require 'yaml'
require 'date'
require 'time'
require 'openssl'

module JekyllIndico
  class Error < StandardError
  end

  class MissingURL < Error
  end

  # Look for topical meetings
  class Meetings
    attr_accessor :dict

    # ID for IRIS-HEP: 10570
    def initialize(base_url, indico_id, **kargs)
      @dict = {}

      download_and_iterate(base_url, indico_id, **kargs) do |i|
        # Trim paragraph tags
        d = i['description']
        d = d[3..-1] if d.start_with? '<p>'
        d = d[0..-5] if d.end_with? '</p>'

        start_date = Date.parse i['startDate']['date']
        fname = start_date.strftime('%Y%m%d').to_s

        youtube = ''
        urllist = URI.extract(d)
        urllist.each do |url|
          youtube = url if url.include?('youtube') || url.include?('youtu.be')
        end

        @dict[fname] = {
          'name' => i['title'],
          'startdate' => start_date,
          'meetingurl' => i['url'],
          'location' => i['location'],
          'youtube' => youtube,
          'description' => d
        }
      end
    end

    # Write out files (Folder given, by key name)
    def to_files(folder)
      @dict.each do |key, dict|
        yield key if block_given?
        File.write(folder / "#{key}.yml", dict.to_yaml)
      end
    end

    # Get meeting ids from a config
    def self.meeting_ids(config = {})
      config.dig('indico', 'ids')
    end

    # Get base URL from a config
    def self.base_url(config = {})
      url = config.dig('indico', 'url')
      raise MissingURL('indico: url: MISSING from your config!') unless url

      url
    end

    private

    # Run a block over each item in the downloaded results
    def download_and_iterate(base_url, indico_id, **kargs, &block)
      url = build_url(base_url, indico_id, **kargs)
      uri = URI.parse(url)
      response = Net::HTTP.get_response(uri)

      string = response.body
      parsed = JSON.parse(string) # returns a hash

      parsed['results'].each(&block)
    end

    # Put together a dict and an indico ID
    def join_url(indico_id, options)
      apicall = options.sort.to_h.map { |k, v| "#{k}=#{v}" }.join('&')
      "/export/categ/#{indico_id}.json?#{apicall}"
    end

    # Automatically signs request if environment has INDICO_API/SECRET_KEY
    def build_url(base_url, indico_id, **kargs)
      kargs[:pretty] = 'no'

      if ENV['INDICO_API_KEY']
        kargs[:ak] = ENV['INDICO_API_KEY']
        if ENV['INDICO_SECRET_KEY']
          kargs[:timestamp] = Time.new.to_i.to_s
          requeststr = join_url(indico_id, kargs)
          kargs[:signature] = OpenSSL::HMAC.hexdigest('SHA1', ENV['INDICO_SECRET_KEY'], requeststr)
        end
      end

      "#{base_url}#{join_url(indico_id, kargs)}"
    end
  end
end