class PostCreatePlan
  def initialize attributes:
    @attributes = attributes.symbolize_keys
  end

  def build!
    Tag.normalise_tags!(tag_names, with_tagme: false, deny_deprecated: true,
                                   with_sections: true) =>
        { tags:, sections: }

    tags = Tag.expand_parent_tags(tags).reject(&:deprecated?)
    video_ms = normalise_video_ms(tags)
    validate_video_sections!(video_ms, sections)
    parent_post_ids = normalise_parent_post_ids
    validate_parent_post_ids!(parent_post_ids)

    {
        url: @attributes[:url],
        title: @attributes[:title].to_s,
        thumbnail_base: @attributes[:thumbnail_base].presence,
        original_created_from: @attributes[:original_created_from].presence,
        original_created_before: @attributes[:original_created_before].presence,
        tags: serialised_tags(tags, sections),
        duration: @attributes[:duration].to_s,
        video_ms: video_ms,
        parent_post_ids: parent_post_ids.join(' '),
        normalised_tags: tags,
        tag_sections: sections,
        normalised_parent_post_ids: parent_post_ids }
  end

  private

  def tag_names = @attributes[:tags].to_s.split

  def normalise_parent_post_ids
    Array(@attributes[:parent_post_ids]).flat_map { _1.to_s.split }.map { |token|
      id = Integer(token, exception: false)
      raise ArgumentError, "親投稿 Id. が不正です: #{ token }" if id.nil? || id <= 0

      id
    }.uniq.sort
  end

  def validate_parent_post_ids! ids
    missing = ids - Post.where(id: ids).pluck(:id)
    raise ArgumentError, "存在しない親投稿 Id. があります: #{ missing.join(' ') }" if missing.present?
  end

  def serialised_tags tags, sections
    tags.uniq(&:id).map { |tag|
      "#{ tag.name }#{ sections[tag.id].to_a.map { Post.section_literal(_1) }.join }"
    }.sort.join(' ')
  end

  def normalise_video_ms tags
    return nil unless tags.any? { _1.id == Tag.video.id }

    video_ms = @attributes[:video_ms]
    if video_ms.present?
      value = Integer(video_ms, exception: false)
      raise PostCreator::VideoMsParseError unless value&.positive?

      return value
    end

    duration = @attributes[:duration]
    return nil if duration.blank?

    value = Tag.time_to_ms!(duration.to_s, tag_name: '動画時間')
    raise PostCreator::VideoMsParseError unless value.positive?

    value
  rescue Tag::SectionLiteralParseError
    raise PostCreator::VideoMsParseError
  end

  def validate_video_sections! video_ms, sections
    return unless video_ms

    sections.each_value do |ranges|
      ranges.each do |begin_ms, end_ms|
        post = Post.new
        if begin_ms >= video_ms
          post.errors.add :video_ms, 'タグ区間の開始が動画時間以上です．'
          raise ActiveRecord::RecordInvalid, post
        end
        if end_ms && end_ms > video_ms
          post.errors.add :video_ms, 'タグ区間の終端が動画時間を超えてゐます．'
          raise ActiveRecord::RecordInvalid, post
        end
      end
    end
  end
end