627 lines
19 KiB
Ruby
627 lines
19 KiB
Ruby
require 'set'
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class Comment < ApplicationRecord
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belongs_to :user
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belongs_to :story,
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:inverse_of => :comments
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has_many :votes,
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:dependent => :delete_all
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belongs_to :parent_comment,
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:class_name => "Comment",
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:inverse_of => false,
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:optional => true
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has_one :moderation,
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:class_name => "Moderation",
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:inverse_of => :comment,
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:dependent => :destroy
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belongs_to :hat,
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:optional => true
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has_many :taggings, through: :story
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attr_accessor :current_vote, :previewing, :indent_level
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attribute :depth
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before_validation :on => :create do
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self.assign_short_id_and_score
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self.assign_initial_confidence
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self.assign_thread_id
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end
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after_create :record_initial_upvote, :mark_submitter, :deliver_reply_notifications,
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:deliver_mention_notifications, :log_hat_use
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after_destroy :unassign_votes
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scope :deleted, -> { where(is_deleted: true) }
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scope :not_deleted, -> { where(is_deleted: false) }
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scope :not_moderated, -> { where(is_moderated: false) }
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scope :active, -> { not_deleted.not_moderated }
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scope :accessible_to_user, ->(user) { user && user.is_moderator? ? all : active }
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scope :for_presentation, -> {
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includes(:user, :hat, :moderation => :moderator, :story => :user, :votes => :user)
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}
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scope :not_on_story_hidden_by, ->(user) {
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user ? where.not(
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HiddenStory.select('TRUE')
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.where(Arel.sql('hidden_stories.story_id = stories.id'))
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.by(user).arel.exists
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) : where('true')
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}
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# workaround: if this select is in #parents, calling .count produces invalid SQL
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scope :with_relative_depth, -> {
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select('comments.*, comments_recursive.depth as depth')
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}
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FLAGGABLE_DAYS = 7
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DELETEABLE_DAYS = FLAGGABLE_DAYS * 2
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# the lowest a score can go
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FLAGGABLE_MIN_SCORE = -10
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# the score at which a comment should be collapsed
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COLLAPSE_SCORE = -5
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# after this many minutes old, a comment cannot be edited
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MAX_EDIT_MINS = (60 * 6)
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# story_threads builds a confidence_order_path in SQL this many characters long:
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# the longest reply chain in prod data is 31 comments (so, depth 30) * 3b confidence_order
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COP_LENGTH = 31 * 3
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# Stop accepting replies this deep. Recursive CTE requires a fixed max (COP_LENGTH),
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# but in practice all deep reply chains have gone off-topic and/or tuned into flamewars.
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MAX_DEPTH = 18
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SCORE_RANGE_TO_HIDE = (-2 .. 4).freeze
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validates :short_id, length: { maximum: 10 }
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validates :user_id, presence: true
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validates :story_id, presence: true
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validates :markeddown_comment, length: { maximum: 16_777_215 }
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validates :comment, presence: { with: true, message: "cannot be empty." }
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validate do
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self.parent_comment && self.parent_comment.is_gone? &&
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errors.add(:base, "Comment was deleted by the author or a mod while you were writing.")
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self.parent_comment && !self.parent_comment.depth_permits_reply? &&
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ModNote.tattle_on_max_depth_limit(self.user, self.parent_comment) &&
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errors.add(:base, "You have replied too greedily and too deep.")
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(m = self.comment.to_s.strip.match(/\A(t)his([\.!])?$\z/i)) &&
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errors.add(:base, (m[1] == "T" ? "N" : "n") + "ope" + m[2].to_s)
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self.comment.to_s.strip.match(/\Atl;?dr.?$\z/i) &&
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errors.add(:base, "Wow! A blue car!")
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self.comment.to_s.strip.match(/\A([[[:upper:]][[:punct:]]] )+[[[:upper:]][[:punct:]]]?$\z/) &&
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errors.add(:base, "D O N ' T")
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self.comment.to_s.strip.match(/\A(me too|nice)([\.!])?\z/i) &&
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errors.add(:base, "Please just upvote the parent post instead.")
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self.hat.present? && self.user.wearable_hats.exclude?(self.hat) &&
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errors.add(:hat, "not wearable by user")
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# .try so tests don't need to persist a story and user
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self.story.try(:accepting_comments?) ||
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errors.add(:base, "Story is no longer accepting comments.")
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end
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def self.regenerate_markdown
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Comment.record_timestamps = false
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Comment.all.find_each do |c|
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c.markeddown_comment = c.generated_markeddown_comment
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c.save(:validate => false)
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end
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Comment.record_timestamps = true
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nil
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end
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def as_json(_options = {})
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h = [
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:short_id,
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:short_id_url,
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:created_at,
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:updated_at,
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:is_deleted,
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:is_moderated,
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:score,
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:flags,
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{ :parent_comment => self.parent_comment && self.parent_comment.short_id },
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{ :comment => (self.is_gone? ? "<em>#{self.gone_text}</em>" : :markeddown_comment) },
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{ :comment_plain => (self.is_gone? ? self.gone_text : :comment) },
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:url,
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:indent_level,
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{ :commenting_user => :user },
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]
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js = {}
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h.each do |k|
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if k.is_a?(Symbol)
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js[k] = self.send(k)
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elsif k.is_a?(Hash)
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if k.values.first.is_a?(Symbol)
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js[k.keys.first] = self.send(k.values.first)
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else
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js[k.keys.first] = k.values.first
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end
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end
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end
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js
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end
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def assign_initial_confidence
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self.confidence = self.calculated_confidence
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# See comment explaining confidence_order in update_score_and_recalculate!
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# 0 is a placeholder, don't have an id before save.
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# This will move it up so it gets seen + voted on.
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self.confidence_order =
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[65_536 - (((self.confidence - -0.2) * 65_535) / 1.2).floor].pack('S>') +
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[0].pack('C')
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end
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def assign_short_id_and_score
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self.short_id = ShortId.new(self.class).generate
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self.score ||= 1 # tests are allowed to fake out the score
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end
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def assign_thread_id
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if self.parent_comment.present?
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self.thread_id = self.parent_comment.thread_id
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else
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self.thread_id = Keystore.incremented_value_for("thread_id")
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end
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end
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# http://evanmiller.org/how-not-to-sort-by-average-rating.html
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# https://github.com/reddit/reddit/blob/master/r2/r2/lib/db/_sorts.pyx
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def calculated_confidence
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n = (self.score + self.flags * 2).to_f
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return 0 if n == 0.0
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upvotes = self.score + self.flags
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z = 1.281551565545 # 80% confidence
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p = upvotes.to_f / n
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left = p + (1 / ((2.0 * n) * z * z))
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right = z * Math.sqrt((p * ((1.0 - p) / n)) + (z * (z / (4.0 * n * n))))
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under = 1.0 + ((1.0 / n) * z * z)
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return (left - right) / under
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end
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def comment=(com)
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self[:comment] = com.to_s.rstrip
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self.markeddown_comment = self.generated_markeddown_comment
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end
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def delete_for_user(user, reason = nil)
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Comment.record_timestamps = false
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self.is_deleted = true
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if user.is_moderator? && user.id != self.user_id
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self.is_moderated = true
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m = Moderation.new
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m.comment_id = self.id
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m.moderator_user_id = user.id
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m.action = "deleted comment"
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if reason.present?
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m.reason = reason
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end
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m.save
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User.update_counters self.user_id, karma: (self.votes.count * -2)
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end
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self.save(:validate => false)
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Comment.record_timestamps = true
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self.story.update_comments_count!
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self.user.refresh_counts!
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end
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def deliver_mention_notifications
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self.plaintext_comment.scan(/\B\@([\w\-]+)/).flatten.uniq.each do |mention|
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if (u = User.active.find_by(:username => mention))
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if u.id == self.user.id
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next
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end
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if u.email_mentions?
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begin
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EmailReply.mention(self, u).deliver_now
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rescue => e
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Rails.logger.error "error e-mailing #{u.email}: #{e}"
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end
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end
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if u.pushover_mentions?
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u.pushover!(
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:title => "#{Rails.application.name} mention by " <<
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"#{self.user.username} on #{self.story.title}",
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:message => self.plaintext_comment,
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:url => self.url,
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:url_title => "Reply to #{self.user.username}",
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)
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end
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end
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end
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end
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def users_following_thread
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users_following_thread = Set.new
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if self.user.id != self.story.user.id && self.story.user_is_following
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users_following_thread << self.story.user
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end
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if self.parent_comment_id &&
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(u = self.parent_comment.try(:user)) &&
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u.id != self.user.id &&
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u.is_active?
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users_following_thread << u
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end
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users_following_thread
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end
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def deliver_reply_notifications
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users_following_thread.each do |u|
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if u.email_replies?
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begin
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EmailReply.reply(self, u).deliver_now
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rescue => e
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Rails.logger.error "error e-mailing #{u.email}: #{e}"
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end
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end
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if u.pushover_replies?
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u.pushover!(
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:title => "#{Rails.application.name} reply from " <<
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"#{self.user.username} on #{self.story.title}",
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:message => self.plaintext_comment,
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:url => self.url,
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:url_title => "Reply to #{self.user.username}",
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)
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end
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end
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end
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def depth_permits_reply?
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# Top-level replies (eg parent_comment_id == null) have depth 0, then each reply is +1.
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# Alternate definition: depth is the number of ancestor comments.
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return false if self.new_record? # can't reply to unsaved comments
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# Most commonly, depth is set by merged_comments. But we need to count parents when executing as
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# a validation on reply.
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self.depth ||= self.parents.count
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depth < MAX_DEPTH
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end
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def generated_markeddown_comment
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Markdowner.to_html(self.comment)
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end
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# TODO: race condition: if two votes arrive at the same time, the second one
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# won't take the first's score change into effect for calculated_confidence
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def update_score_and_recalculate!(score_delta, flag_delta)
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self.score += score_delta
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self.flags += flag_delta
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# confidence_order allows sorting sibling comments by confidence in queries like story_threads.
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# confidence_order must sort in ascending order so that it's in the right order when
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# concatenated into confidence_order_path, which the database sorts lexiographically. It is 3
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# bytes wide. The first two bytes map confidence to a big-endian unsigned integer, inverted so
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# that high-confidence have low values. confidence is based on the number of upvotes and flags,
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# so some values (like the one for 1 vote, 0 flags) are very common, causing sibling comments to
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# tie. If we don't specify a tiebreaker, the database will return results in an arbitrary order,
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# which means sibling comments will swap positions on page reloads (infrequently and
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# intermittently, real fun to debug). So the third byte is the low byte of the comment id. Being
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# assigned sequentially, mostly the tiebreaker sorts earlier comments sooner. We average ~200
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# comments per weekday so seeing rollover between sibling comments is rare. Importantly, even
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# when it is 'wrong', it gives a stable sort.
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Comment.connection.execute <<~SQL
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UPDATE comments SET
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score = (select coalesce(sum(vote), 0) from votes where comment_id = comments.id),
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flags = (select count(*) from votes where comment_id = comments.id and vote = -1),
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confidence = #{self.calculated_confidence},
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confidence_order = concat(lpad(char(65536 - floor(((confidence - -0.2) * 65535) / 1.2) using binary), 2, '0'), char(id & 0xff using binary))
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WHERE id = #{self.id.to_i}
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SQL
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self.story.recalculate_hotness!
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end
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def gone_text
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if self.is_moderated?
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"Comment removed by moderator " <<
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self.moderation.try(:moderator).try(:username).to_s << ": " <<
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(self.moderation.try(:reason) || "No reason given")
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elsif self.user.is_banned?
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"Comment from banned user removed"
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else
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"Comment removed by author"
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end
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end
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def has_been_edited?
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self.updated_at && (self.updated_at - self.created_at > 1.minute)
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end
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def is_deletable_by_user?(user)
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if user && user.is_moderator?
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return true
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elsif user && user.id == self.user_id
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return self.created_at >= DELETEABLE_DAYS.days.ago
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else
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return false
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end
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end
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def is_disownable_by_user?(user)
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user && user.id == self.user_id && self.created_at && self.created_at < DELETEABLE_DAYS.days.ago
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end
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def is_flaggable?
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if self.created_at && self.score > FLAGGABLE_MIN_SCORE
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Time.current - self.created_at <= FLAGGABLE_DAYS.days
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else
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false
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end
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end
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def is_editable_by_user?(user)
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if user && user.id == self.user_id
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if self.is_moderated?
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return false
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else
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return (Time.current.to_i - (self.updated_at ? self.updated_at.to_i :
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self.created_at.to_i) < (60 * MAX_EDIT_MINS))
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end
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else
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return false
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end
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end
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def is_gone?
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is_deleted? || is_moderated?
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end
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def is_undeletable_by_user?(user)
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if user && user.is_moderator?
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return true
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elsif user && user.id == self.user_id && !self.is_moderated?
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return true
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else
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return false
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end
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end
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def log_hat_use
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return unless self.hat && self.hat.modlog_use
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m = Moderation.new
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m.created_at = self.created_at
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m.comment_id = self.id
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m.moderator_user_id = user.id
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m.action = "used #{self.hat.hat} hat"
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m.save!
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end
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def mark_submitter
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Keystore.increment_value_for("user:#{self.user_id}:comments_posted")
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end
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def mailing_list_message_id
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[
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"comment",
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self.short_id,
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self.is_from_email ? "email" : nil,
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created_at.to_i,
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].reject(&:!).join(".") << "@" << Rails.application.domain
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end
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def parents
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return Comment.none if self.parent_comment_id.nil?
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# starts from parent_comment_id so it works on new records
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Comment
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.joins(<<~SQL
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inner join (
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with recursive parents as (
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select id target_id, id, parent_comment_id, 0 as depth
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from comments where id = #{self.parent_comment_id}
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union all
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select parents.target_id, c.id, c.parent_comment_id, depth - 1
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from comments c join parents on parents.parent_comment_id = c.id
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) select id, depth from parents
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) as comments_recursive on comments.id = comments_recursive.id
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SQL
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)
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.order('id asc')
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end
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def path
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self.story.comments_path + "#c_#{self.short_id}"
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end
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def plaintext_comment
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# TODO: linkify then strip tags and convert entities back
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comment
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end
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def record_initial_upvote
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Vote.vote_thusly_on_story_or_comment_for_user_because(
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1, self.story_id, self.id, self.user_id, nil, false
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)
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self.story.update_comments_count!
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end
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def score_for_user(u)
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if self.show_score_to_user?(u)
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score
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elsif u && u.can_flag?(self)
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"~"
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else
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" ".html_safe
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end
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end
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def short_id_url
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Rails.application.root_url + "c/#{self.short_id}"
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end
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def show_score_to_user?(u)
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return true if u && u.is_moderator?
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# hide score on new/near-zero comments to cut down on threads about voting
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# also hide if user has flagged the story/comment to make retaliatory flagging less fun
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(
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(self.created_at && self.created_at < 36.hours.ago) ||
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!SCORE_RANGE_TO_HIDE.include?(self.score)
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) && (!current_vote || current_vote[:vote] >= 0)
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end
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def to_param
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self.short_id
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end
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def unassign_votes
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self.story.update_comments_count!
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end
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def url
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self.story.comments_url + "#c_#{self.short_id}"
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end
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def vote_summary_for_user(u)
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r_counts = {}
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r_users = {}
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# don't includes(:user) here and assume the caller did this already
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self.votes.each do |v|
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r_counts[v.reason.to_s] ||= 0
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r_counts[v.reason.to_s] += v.vote
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|
|
|
r_users[v.reason.to_s] ||= []
|
|
r_users[v.reason.to_s].push v.user.username
|
|
end
|
|
|
|
r_counts.keys.map {|k|
|
|
next if k == ""
|
|
|
|
o = "#{r_counts[k]} #{Vote::ALL_COMMENT_REASONS[k]}"
|
|
if u && u.is_moderator? && self.user_id != u.id
|
|
o << " (#{r_users[k].join(', ')})"
|
|
end
|
|
o
|
|
}.compact.join(", ")
|
|
end
|
|
|
|
def undelete_for_user(user)
|
|
Comment.record_timestamps = false
|
|
|
|
self.is_deleted = false
|
|
|
|
if user.is_moderator?
|
|
self.is_moderated = false
|
|
|
|
if user.id != self.user_id
|
|
m = Moderation.new
|
|
m.comment_id = self.id
|
|
m.moderator_user_id = user.id
|
|
m.action = "undeleted comment"
|
|
m.save
|
|
end
|
|
end
|
|
|
|
self.save(:validate => false)
|
|
Comment.record_timestamps = true
|
|
|
|
self.story.update_comments_count!
|
|
self.user.refresh_counts!
|
|
end
|
|
|
|
def self.recent_threads(user)
|
|
return Comment.none unless user.try(:id)
|
|
|
|
thread_ids = Comment
|
|
.where(user: user)
|
|
.group(:thread_id)
|
|
.order('id desc')
|
|
.limit(20)
|
|
.pluck(:thread_id)
|
|
|
|
Comment
|
|
.joins(<<~SQL
|
|
inner join (
|
|
with recursive discussion as (
|
|
select
|
|
c.id,
|
|
0 as depth,
|
|
cast(confidence_order as char(#{Comment::COP_LENGTH}) character set binary) as confidence_order_path
|
|
from comments c
|
|
where
|
|
thread_id in (#{thread_ids.join(', ')}) and
|
|
parent_comment_id is null
|
|
union all
|
|
select
|
|
c.id,
|
|
discussion.depth + 1,
|
|
cast(concat(
|
|
left(discussion.confidence_order_path, 3 * (depth + 1)),
|
|
c.confidence_order
|
|
) as char(#{Comment::COP_LENGTH}) character set binary)
|
|
from comments c join discussion on c.parent_comment_id = discussion.id
|
|
)
|
|
select * from discussion as comments
|
|
) as comments_recursive on comments.id = comments_recursive.id
|
|
SQL
|
|
)
|
|
.order('comments.thread_id desc, comments_recursive.confidence_order_path')
|
|
.select('comments.*, comments_recursive.depth as depth')
|
|
end
|
|
|
|
# select in thread order with preloading for _comment.html.erb
|
|
def self.story_threads(story)
|
|
return Comment.none unless story.id # unsaved Stories have no comments
|
|
|
|
# If the story_ids predicate is in the outer select the query planner doesn't push it down into
|
|
# the recursive CTE, so that subquery would build the tree for the entire comments table.
|
|
Comment
|
|
.joins(<<~SQL
|
|
inner join (
|
|
with recursive discussion as (
|
|
select
|
|
c.id,
|
|
0 as depth,
|
|
cast(confidence_order as char(#{Comment::COP_LENGTH}) character set binary) as confidence_order_path
|
|
from comments c
|
|
join stories on stories.id = c.story_id
|
|
where
|
|
(stories.id = #{story.id} or stories.merged_story_id = #{story.id}) and
|
|
parent_comment_id is null
|
|
union all
|
|
select
|
|
c.id,
|
|
discussion.depth + 1,
|
|
cast(concat(
|
|
left(discussion.confidence_order_path, 3 * (depth + 1)),
|
|
c.confidence_order
|
|
) as char(#{Comment::COP_LENGTH}) character set binary)
|
|
from comments c join discussion on c.parent_comment_id = discussion.id
|
|
)
|
|
select * from discussion as comments
|
|
) as comments_recursive on comments.id = comments_recursive.id
|
|
SQL
|
|
)
|
|
.order('comments_recursive.confidence_order_path')
|
|
.select('comments.*, comments_recursive.depth as depth')
|
|
end
|
|
end
|