115 行
2.6 KiB
Ruby
115 行
2.6 KiB
Ruby
class TheatrePostSelector
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Candidate = Struct.new(:post, :weight, :penalty, :tags, keyword_init: true)
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def initialize theatre:
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@theatre = theatre
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end
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def select
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candidates = weighted_candidates
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return nil if candidates.empty?
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total = candidates.sum(&:weight)
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target = rand * total
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candidates.each do |candidate|
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target -= candidate.weight
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return candidate.post if target <= 0
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end
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candidates.last.post
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end
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def weight_json limit: 20
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candidates = weighted_candidates
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sorted = candidates.sort_by { |candidate| [candidate.weight, candidate.post.id] }
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{ tag_penalties: tag_penalty_json,
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lightest_posts: post_weight_json(sorted.first(limit)),
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heaviest_posts: post_weight_json(sorted.reverse.first(limit)) }
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end
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private
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attr_reader :theatre
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def weighted_candidates
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@weighted_candidates ||= begin
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penalties = tag_penalties
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posts = eligible_posts.includes(tags: :tag_name).to_a
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posts.map do |post|
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post_tags = post.tags.to_a
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penalty = post_tags.sum { |tag| penalties[tag.id].to_i }
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Candidate.new(
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post:,
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penalty:,
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tags: post_tags,
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weight: 1.0 / (1.0 + penalty))
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end
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end
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end
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def eligible_posts
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posts = Post.where("url LIKE '%nicovideo.jp%'")
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posts = posts.where.not(id: theatre.current_post_id) if theatre.current_post_id
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posts
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end
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def active_user_ids
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@active_user_ids ||= theatre.watching_users.ids
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end
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def tag_penalties
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@tag_penalties ||=
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if active_user_ids.empty?
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{}
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else
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TheatreSkipEventVoter
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.joins(theatre_skip_event: :event_tags)
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.where(user_id: active_user_ids)
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.group('theatre_skip_event_tags.tag_id')
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.count
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end
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end
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def tag_penalty_json
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return [] if tag_penalties.empty?
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tags = Tag.where(id: tag_penalties.keys).includes(:tag_name).index_by(&:id)
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tag_penalties
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.map { |tag_id, penalty|
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tag = tags[tag_id]
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next unless tag
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{ tag: light_tag_json(tag),
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penalty: }
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}
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.compact
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.sort_by { |row| [-row[:penalty], row[:tag][:name].to_s] }
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end
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def post_weight_json candidates
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candidates.map { |candidate|
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{ post: light_post_json(candidate.post),
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weight: candidate.weight,
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penalty: candidate.penalty,
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tags: candidate.tags.map { |tag| light_tag_json(tag) } }
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}
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end
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def light_post_json post
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{ id: post.id,
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title: post.title,
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url: post.url }
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end
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def light_tag_json tag
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{ id: tag.id,
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name: tag.name,
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category: tag.category }
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end
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end
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