class PostImportRunner
  MAX_ROWS = PostImportSourceParser::MAX_ROWS
  ATTRIBUTE_KEYS = %w[title thumbnail_base original_created_from original_created_before duration tags parent_post_ids video_ms].freeze
  def initialize actor:, rows:, existing: 'skip'
    @actor = actor
    @rows = rows
    @existing = existing == 'error' ? 'error' : 'skip'
  end

  def run
    raise ArgumentError, "取込件数は #{ MAX_ROWS } 件までです．" if @rows.length > MAX_ROWS
    raise ArgumentError, '取込データが大きすぎます．' if @rows.sum { |row| row.to_json.bytesize } > PostImportSourceParser::MAX_BYTES

    normalised_rows = @rows.map { |row| normalise_row(row) }
    source_rows = normalised_rows.map { _1['source_row'] }
    raise ArgumentError, '元行番号が重複しています．' if source_rows.uniq.length != source_rows.length

    results = normalised_rows.map { |row| run_row(row) }
    { created: results.count { _1[:status] == 'created' }, skipped: results.count { _1[:status] == 'skipped' },
      failed: results.count { _1[:status] == 'failed' }, rows: results }
  end

  private

  def run_row row
    validate_row_structure!(row)
    attributes = row.fetch('attributes', { }).to_h.transform_keys { _1.to_s.underscore }
    raise ArgumentError, '取込項目が不正です．' unless (attributes.keys - ATTRIBUTE_KEYS).empty?
    raise ArgumentError, '取込項目が大きすぎます．' if attributes.values.any? { _1.to_s.bytesize > PostImportSourceParser::MAX_CELL_BYTES }
    raise ArgumentError, 'URL が長すぎます．' if row['url'].to_s.bytesize > PostImportSourceParser::MAX_CELL_BYTES
    validate_tag_sources!(row['tag_sources'])
    preview = PostImportPreviewer.new(parsed: { columns: [], rows: [] }, url_column: 0,
                                      mappings: {}, existing: @existing).preview_rows(
                                          rows: [{ source_row: row['source_row'], url: row['url'],
                                                   attributes:, provenance: row['provenance'],
                                                   tag_sources: row['tag_sources'] }],
                                          fetch_metadata: false).first
    if preview[:validation_errors].present?
      return { source_row: row['source_row'], status: 'failed',
               errors: preview[:validation_errors] }
    end
    return row.slice('source_row').merge(status: 'skipped') if @existing == 'skip' && preview[:existing]
    attributes['tags'] = preview[:attributes]['tags']
    attributes['url'] = row['url']
    post = PostCreator.new(actor: @actor, attributes:).create!
    { source_row: row['source_row'], status: 'created', post: PostRepr.base(post) }
  rescue ActiveRecord::RecordInvalid => e
    { source_row: row['source_row'], status: 'failed', errors: e.record.errors.to_hash }
  rescue Tag::NicoTagNormalisationError
    { source_row: row['source_row'], status: 'failed', errors: { tags: ['ニコニコ・タグは直接指定できません．'] } }
  rescue Tag::DeprecatedTagNormalisationError
    { source_row: row['source_row'], status: 'failed', errors: { tags: ['廃止済みタグは付与できません．'] } }
  rescue ArgumentError, PostCreator::VideoMsParseError
    { source_row: row['source_row'], status: 'failed', errors: { base: ['入力値が不正です．'] } }
  rescue StandardError => e
    Rails.logger.error("post_import_runner_failure #{ { error: e.class.name, message: e.message }.to_json }")
    { source_row: row['source_row'], status: 'failed', errors: { base: ['登録中にエラーが発生しました．'] } }
  end

  def validate_tag_sources! sources
    return if sources.blank?

    sources = sources.to_h
    raise ArgumentError unless (sources.keys - %w[automatic mapped fixed manual]).empty?
    raise ArgumentError unless sources.values.all?(String)
    raise ArgumentError if sources.values.any? { _1.bytesize > PostImportSourceParser::MAX_CELL_BYTES }
    raise ArgumentError if sources.values.sum(&:bytesize) > PostImportSourceParser::MAX_CELL_BYTES
  end

  def validate_row_structure! row
    raise ArgumentError unless row['source_row'].is_a?(Integer) && row['source_row'].positive?
    raise ArgumentError unless row['url'].is_a?(String)
    raise ArgumentError unless row['attributes'].is_a?(Hash)
    raise ArgumentError unless row['attributes'].values.all? { _1.is_a?(String) || _1.is_a?(Numeric) || _1 == true || _1 == false || _1.nil? }
    provenance = row['provenance']
    raise ArgumentError unless provenance.is_a?(Hash)
    allowed = ATTRIBUTE_KEYS + ['url']
    raise ArgumentError unless (provenance.keys - allowed).empty?
    raise ArgumentError unless provenance.values.all? { _1.in?(['automatic', 'mapped', 'fixed', 'manual']) }
    metadata_url = row['metadata_url']
    raise ArgumentError unless metadata_url.nil? || metadata_url.is_a?(String)
    raise ArgumentError if metadata_url.to_s.bytesize > PostImportSourceParser::MAX_CELL_BYTES
    raise ArgumentError if row.to_json.bytesize > PostImportSourceParser::MAX_BYTES
    tag_sources = row['tag_sources']
    raise ArgumentError unless tag_sources.nil? || tag_sources.is_a?(Hash)
  end

  def normalise_row row
    unless row.is_a?(Hash)
      raise ArgumentError, '取込行の形式が不正です．'
    end

    normalised = row.deep_transform_keys { _1.to_s.underscore }
    source_row = Integer(normalised['source_row'], exception: false)
    raise ArgumentError, '元行番号が不正です．' if source_row.nil? || source_row <= 0

    normalised['source_row'] = source_row
    normalised
  end
end