module Jekyll::Algolia::Indexer

def self.index
  @index
end

def self.init
  ::Algolia.init(
    application_id: Configurator.application_id,
    api_key: Configurator.api_key
  )
  @index = ::Algolia::Index.new(Configurator.index_name)
  set_user_agent
  self
end

def self.local_object_ids(records)
  records.map { |record| record[:objectID] }.compact.sort
end

def self.local_setting_id
  settings = Configurator.settings
  settings.delete('userData')
  AlgoliaHTMLExtractor.uuid(settings)
end

def self.remote_object_ids
  list = []
  Logger.verbose(
    "I:Inspecting existing records in index #{index.name}..."
  )
  begin
    index.browse(attributesToRetrieve: 'objectID') do |hit|
      list << hit['objectID']
    end
  rescue StandardError
    # The index might not exist if it's the first time we use the plugin
    # so we'll consider that it means there are no records there
    return []
  end
  list.sort
end

def self.remote_settings
  index.get_settings
rescue StandardError
  nil
end

def self.run(records)
  init
  # Indexing zero record is surely a misconfiguration
  if records.length.zero?
    files_to_exclude = Configurator.algolia('files_to_exclude').join(', ')
    Logger.known_message(
      'no_records_found',
      'files_to_exclude' => files_to_exclude,
      'nodes_to_index' => Configurator.algolia('nodes_to_index')
    )
    exit 1
  end
  # Update settings
  update_settings
  # Getting list of objectID in remote and locally
  remote_ids = remote_object_ids
  local_ids = local_object_ids(records)
  # Getting list of what to add and what to delete
  old_records_ids = remote_ids - local_ids
  new_records_ids = local_ids - remote_ids
  new_records = records.select do |record|
    new_records_ids.include?(record[:objectID])
  end
  update_records(old_records_ids, new_records)
  Logger.log('I:✔ Indexing complete')
end

def self.set_settings(settings)
  index.set_settings!(settings)
rescue StandardError => error
  ErrorHandler.stop(error, settings: settings)
end

def self.set_user_agent
  user_agent = [
    "Jekyll Integration (#{VERSION})",
    "Algolia for Ruby (#{::Algolia::VERSION})",
    "Jekyll (#{::Jekyll::VERSION})",
    "Ruby (#{RUBY_VERSION})"
  ].join('; ')
  ::Algolia.set_extra_header('User-Agent', user_agent)
end

def self.update_records(old_records_ids, new_records)
  # Stop if nothing to change
  if old_records_ids.empty? && new_records.empty?
    Logger.log('I:Content is already up to date.')
    return
  end
  Logger.log("I:Updating records in index #{index.name}...")
  Logger.log("I:Records to delete: #{old_records_ids.length}")
  Logger.log("I:Records to add:    #{new_records.length}")
  return if Configurator.dry_run?
  # We group delete and add operations into the same batch. Delete
  # operations should still come first, to avoid hitting an overquota too
  # soon
  operations = []
  old_records_ids.each do |object_id|
    operations << {
      action: 'deleteObject', indexName: index.name,
      body: { objectID: object_id }
    }
  end
  operations += new_records.map do |new_record|
    { action: 'addObject', indexName: index.name, body: new_record }
  end
  # Run the batches in slices if they are too large
  batch_size = Configurator.algolia('indexing_batch_size')
  slices = operations.each_slice(batch_size).to_a
  should_have_progress_bar = (slices.length > 1)
  if should_have_progress_bar
    progress_bar = ProgressBar.create(
      total: slices.length,
      format: 'Pushing records (%j%%) |%B|'
    )
  end
  slices.each do |slice|
    begin
      ::Algolia.batch!(slice)
      progress_bar.increment if should_have_progress_bar
    rescue StandardError => error
      records = slice.map do |record|
        record[:body]
      end
      ErrorHandler.stop(error, records: records)
    end
  end
end

def self.update_settings
  current_remote_settings = remote_settings || {}
  remote_setting_id = current_remote_settings.dig('userData', 'settingID')
  settings = Configurator.settings
  setting_id = local_setting_id
  are_settings_forced = Configurator.force_settings?
  # The config we're about to push is the same we pushed previously. We
  # won't push again.
  if setting_id == remote_setting_id && !are_settings_forced
    Logger.log('I:Settings are already up to date.')
    # Check if remote config has been changed outside of the plugin, so we
    # can warn users that they should not alter their config from outside
    # of the plugin.
    current_remote_settings.delete('userData')
    changed_keys = Utils.diff_keys(settings, current_remote_settings)
    unless changed_keys.nil?
      warn_of_manual_dashboard_editing(changed_keys)
    end
    return
  end
  # Settings have changed, we push them
  settings['userData'] = {
    'settingID' => setting_id,
    'pluginVersion' => VERSION
  }
  Logger.log("I:Updating settings of index #{index.name}")
  return if Configurator.dry_run?
  set_settings(settings)
end

def self.warn_of_manual_dashboard_editing(changed_keys)
  # Transform the hash into readable YAML
  yaml_lines = changed_keys
               .to_yaml(indentation: 2)
               .split("\n")[1..-1]
  yaml_lines.map! do |line|
    line = line.gsub(/^ */) { |spaces| ' ' * spaces.length }
    line = line.gsub('- ', '  - ')
    "W:    #{line}"
  end
  Logger.known_message(
    'settings_manually_edited',
    settings: yaml_lines.join("\n")
  )
end