module Reprioritizable

# File lib/reprioritizable.rb, line 44
def decrease_priority(column)
  eval("self.#{column} -= 1")
end

# File lib/reprioritizable.rb, line 40
def increase_priority(column)
  eval("self.#{column} += 1")
end

# File lib/reprioritizable.rb, line 30
def reprioritize(scope, &_block)
  attributes = scope.map do |prioritable|
    yield(prioritable)
    prioritable.updated_at = Time.zone.now
    prioritable.attributes
  end
  scope.klass.upsert_all(attributes) if attributes.any?
end

# File lib/reprioritizable.rb, line 8
def reprioritize!(column:, scope:, instance:, new_priority:)
  instance.restrict_max_priority!(column, new_priority, scope)
  instance.restrict_minimum_priority!(column, new_priority, scope)

  before_priority = instance.send(column)
  if before_priority > new_priority
    reprioritize(
      scope.where("#{column} >= ?", new_priority).where("#{column} < ?", before_priority)
    ) do |record|
      record.increase_priority(column)
    end
  elsif before_priority < new_priority
    reprioritize(
      scope.where("#{column} <= ?", new_priority).where("#{column} > ?", before_priority)
    ) do |record|
      record.decrease_priority(column)
    end
  end

  instance.update!("#{column}": new_priority)
end

# File lib/reprioritizable.rb, line 48
def restrict_max_priority!(column, new_priority, scope)
  max_size = scope.maximum(column)
  errors.add(:base, "Please register with a value of #{max_size} or less.") if max_size < new_priority

  raise ActiveRecord::RecordInvalid, self if errors.any?
end

# File lib/reprioritizable.rb, line 55
def restrict_minimum_priority!(column, new_priority, scope)
  minimum_size = scope.minimum(column)
  errors.add(:base, "Please register with a value of #{minimum_size} or more.") if minimum_size > new_priority

  raise ActiveRecord::RecordInvalid, self if errors.any?
end