# Only confirmed combinations belong here; all others retain the existing behaviour.
class CountsDefaults
  POST_COLUMNS = ['resource_id', 'version_no', 'is_latest', 'title', 'url',
                  'thumbnail_base', 'tags', 'parents', 'original_created_from',
                  'original_created_before', 'event_type', 'user', 'created_at'].freeze

  def self.entries(resource)
    result = [{ definition: 'history', mode: 'summary', params: {
        'rows' => [{ field: 'created_at', grain: 'month' }].to_json,
        'cols' => [{ field: 'event_type' }].to_json,
        'sort' => 'a0:desc', 'conditions' => '[]' } }]
    if resource == 'posts'
      result += [{ definition: 'latest', mode: 'summary', params: {
          'rows' => '[]', 'cols' => '[]', 'conditions' => '[]', 'tags' => '' } },
          { definition: 'latest', mode: 'details', params: {
              'columns' => POST_COLUMNS.join(','), 'order' => POST_COLUMNS.join(','),
              'children' => 'tags.name,parents.id', 'nested_json' => '0',
              'conditions' => '[]', 'tags' => '' } }]
    end
    result
  end

  def self.for(params)
    settings = entries(params.fetch('resource', 'posts')).find do |entry|
      entry[:definition] == params.fetch('definition', 'latest') &&
          entry[:mode] == params.fetch('mode', 'summary')
    end&.fetch(:params) || {}
    if settings.key?('sort') && params.key?('rows')
      actual = JSON.parse(params['rows'])
      expected = JSON.parse(settings.fetch('rows'))
      compatible = actual.is_a?(Array) && actual.first.is_a?(Hash) &&
          actual.first['field'] == expected.first['field'] &&
          actual.first.fetch('grain', 'month') == expected.first['grain']
      unless compatible
        settings = settings.except('sort')
      end
    end
    settings
  end

  def self.metadata(resource)
    entries(resource).map do |entry|
      entry.merge(params: entry[:params].map { |key, value| { key:, value: } })
    end
  end
end