# Server-owned version identities, attributes and field types. No client SQL is accepted.
class CountsResourceDefinition
  COMMON = { 'resource_id' => :integer, 'version_no' => :integer,
             'event_type' => :enum, 'user' => :integer, 'created_at' => :datetime }.freeze
  DEFINITIONS = {
      'posts' => [PostVersion, ['post_id'], {
          'title' => :string, 'url' => :string, 'thumbnail_base' => :string,
          'tags_json' => :json, 'parent_post_ids' => :string, 'video_ms' => :integer,
          'original_created_from' => :datetime, 'original_created_before' => :datetime }],
      'tags' => [TagVersion, ['tag_id'], {
          'name' => :string, 'names' => :json, 'category' => :enum, 'aliases' => :string,
          'parent_tag_ids' => :string, 'deprecated_at' => :datetime }],
      'nico_tags' => [NicoTagVersion, ['tag_id'], {
          'name' => :string, 'linked_tags' => :string }],
      'tag_descriptions' => [TagDescriptionVersion, ['tag_id', 'language_code'], {
          'language_code' => :enum, 'body' => :string,
          'source_language_code' => :enum, 'source_version_no' => :integer }],
      'tag_groups' => [TagGroupVersion, ['tag_group_id'], {
          'name' => :string, 'description' => :string,
          'members' => :json, 'placements' => :json }],
      'materials' => [MaterialVersion, ['material_id'], {
          'url' => :string, 'parent_id' => :integer, 'tag_id' => :integer,
          'tag_name' => :string, 'tag_category' => :enum,
          'discarded_at' => :datetime, 'updated_at' => :datetime,
          'updated_by_user_id' => :integer, 'export_paths_json' => :json,
          'file_blob_id' => :integer, 'file_filename' => :string,
          'file_content_type' => :string, 'file_byte_size' => :integer,
          'file_checksum' => :string, 'file_sha256' => :string,
          'source_kind' => :enum, 'source_uri' => :string, 'source_path' => :string,
          'source_file_id' => :string, 'normalized_source_key' => :string }] }.freeze
  OPERATORS = {
      string: ['eq', 'ne', 'like'], enum: ['eq', 'ne'], boolean: ['eq', 'ne'],
      integer: ['eq', 'ne', 'gt', 'lt', 'ge', 'le', 'range'],
      datetime: ['eq', 'ne', 'gt', 'lt', 'ge', 'le', 'range'] }.freeze

  attr_reader :model, :keys, :fields, :resource

  def initialize(resource)
    @resource = resource
    @model, @keys, attributes = DEFINITIONS.fetch(resource) { raise ArgumentError }
    @fields = COMMON.merge(attributes)
  end

  def table = model.table_name
  def time_column = 'created_at'
  def column(key)
    raise ArgumentError unless fields.key?(key)

    { 'resource_id' => keys.first, 'user' => 'created_by_user_id' }.fetch(key, key)
  end

  def expression(key, row = 'v') = "#{ row }.#{ column(key) }"
  def changes = fields.keys - COMMON.keys - ['updated_at', 'updated_by_user_id']
  def axes(history)
    fields.reject { |_key, type| type == :json }.keys +
        (resource == 'posts' ? ['tags'] : []) + (history ? ['changed_field'] : [])
  end

  def metadata
    fields.map do |key, type|
      { key:, type:, nullable: model.columns_hash.fetch(column(key)).null,
        operators: OPERATORS.fetch(type, []) }
    end
  end
end