# Server-owned version identities, attributes and field types. No client SQL is accepted.
class CountsResourceDefinition
  # Compatibility belongs at the request boundary, not in field definitions.
  def self.normalise_params(params)
    params.each_with_object({}) do |(key, value), result|
      result[key] = value
      next unless value.is_a?(String)

      if ['columns', 'order', 'sort', 'rows', 'cols', 'axis'].include?(key)
        result[key] = value.split(/ /, -1).map { |token|
          token.sub(/\Ais_latest(?=:|\z)/, 'latest')
        }.join(' ')
      elsif (key.match?(/\A(?:conditions|drill)\.[0-9]+\.field\z/) &&
          value == 'is_latest')
        result[key] = 'latest'
      end
    end
  end

  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'],
      interval: ['range'] }.freeze
  LABELS = {
      'resource_id' => 'counts:columns.resourceId', 'version_no' => 'counts:columns.version',
      'latest' => 'counts:columns.latest', 'event_type' => 'counts:eventType',
      'user' => 'history:actor', 'created_at' => 'counts:columns.changedAt',
      'thumbnail' => 'counts:columns.thumbnailDisplay',
      'thumbnail_base' => 'counts:columns.thumbnailURL',
      'title' => 'counts:columns.postTitle', 'url' => 'counts:columns.postURL',
      'tags' => 'counts:columns.tags', 'tags_json' => 'counts:columns.tags',
      'video_ms' => 'shared:labels.duration', 'name' => 'counts:columns.name',
      'names' => 'counts:columns.names', 'category' => 'common:categoryLabel',
      'aliases' => 'tags:aliases', 'deprecated' => 'counts:columns.deprecated',
      'original_created_from' => 'counts:columns.originalFrom',
      'original_created_before' => 'counts:columns.originalBefore',
      'language_code' => 'counts:columns.language' }.freeze
  CHILD_LABELS = {
      'id' => 'counts:columns.resourceId', 'versionNo' => 'history:version',
      'kind' => 'counts:columns.kind', 'name' => 'history:name',
      'category' => 'common:categoryLabel', 'sections' => 'counts:columns.sections',
      'names' => 'counts:columns.names', 'aliases' => 'tags:aliases',
      'languageCode' => 'counts:columns.language',
      'scriptCode' => 'history:nameChanges.script',
      'autoGenerated' => 'history:nameChanges.automatic',
      'tagId' => 'counts:attributes.tag_id', 'tagGroupId' => 'counts:resources.tag_groups',
      'sectionName' => 'counts:attributes.section_name',
      'description' => 'counts:attributes.description',
      'children' => 'counts:attributes.children', 'profile' => 'counts:attributes.profile',
      'path' => 'counts:attributes.path' }.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

  def field_label(key) = LABELS.fetch(key, "counts:attributes.#{ key }")

  def output_fields
    content = case resource
              when 'posts'
                ['thumbnail', 'title', 'url', 'thumbnail_base', 'tags', 'parents', 'video_ms',
                 'original_created_from', 'original_created_before']
              when 'tags' then ['name', 'names', 'category', 'aliases', 'parents', 'deprecated']
              else fields.keys - COMMON.keys
              end
    keys = ['resource_id', 'version_no', 'latest'] + (content - ['thumbnail']) +
        ['event_type', 'user', 'created_at']
    keys.unshift('thumbnail') if content.include?('thumbnail')
    keys.map do |key|
      label = if key == 'parents'
                resource == 'tags' ? 'tags:parents' : 'shared:labels.parentPosts'
              else field_label(key)
              end
      field = { key:, label: }
      children = child_fields(key)
      field[:children] = children if children.any?
      field
    end
  end

  def child_fields(key, depth = 4)
    keys = case key
           when 'tags' then ['id', 'versionNo', 'kind', 'name', 'category', 'sections', 'names']
           when 'names' then ['languageCode', 'scriptCode', 'name', 'aliases', 'autoGenerated']
           when 'aliases'
             resource == 'tags' ? ['languageCode', 'name', 'scriptCode'] : ['name', 'scriptCode']
           when 'parents' then resource == 'tags' ? ['id', 'name'] : ['id']
           when 'members' then ['tagId', 'tagGroupId', 'versionNo']
           when 'export_paths_json' then ['profile', 'path']
           when 'placements', 'children'
             scalar = ['sectionName', 'description', 'tagId', 'tagGroupId']
             scalar + (depth > 0 ? ['children'] : [])
           else []
           end
    keys.map do |child|
      label = key == 'members' && child == 'tagId' ?
          'counts:columns.resourceId' : CHILD_LABELS.fetch(child)
      field = { key: child, label: }
      children = child_fields(child, child == 'children' ? depth - 1 : depth)
      # Language is attached to top-level aliases, not to aliases inside a language entry.
      children = children.reject { _1[:key] == 'languageCode' } if child == 'aliases'
      field[:children] = children if children.any?
      field
    end
  end

  def filter_metadata = @filter_metadata ||= CountsCondition.fields(self)
end