module DenormalizeFields

# File lib/denormalize_fields.rb, line 50
def apply(changeset, to:, owner:, mapping:)
  return if to.nil?

  to.assign_attributes(changeset)
  return if to.new_record? ? to.valid? : to.save

  DenormalizeFields.copy_errors(to.errors, to_record: owner, mapping: mapping)
  raise(ActiveRecord::RecordInvalid, to)
end

# File lib/denormalize_fields.rb, line 24
def call(record:, relation_name:, mapping:)
  changeset = DenormalizeFields.changeset(record: record, mapping: mapping)
  return if changeset.empty?

  Array(record.send(relation_name)).each do |related_record|
    DenormalizeFields.apply(
      changeset, to: related_record, owner: record, mapping: mapping
    )
  end
end

# File lib/denormalize_fields.rb, line 15
def cast_to_mapping(fields, prefix: nil)
  if fields.is_a?(Hash)
    prefix && raise(ArgumentError, 'pass EITHER a fields Hash OR a prefix')
    fields
  else
    Array(fields).map { |e| [e.to_sym, [prefix, e].join.to_sym] }.to_h
  end
end

# File lib/denormalize_fields.rb, line 35
def changeset(record:, mapping:)
  mapping.each.with_object({}) do |(source, dest), hash|
    if source.is_a?(Array)
      if source.any? { |field| record.saved_change_to_attribute?(field) }
        current_values = record.attributes.values_at(*source.map(&:to_s))
        hash[dest] = current_values.join(' ')
      end
    elsif change = record.saved_change_to_attribute(source)
      hash[dest] = change.last
    end
  end
end

# File lib/denormalize_fields.rb, line 61
def copy_errors(errors, to_record:, mapping:)
  errors.details.each do |key, array|
    field = mapping.rassoc(key.to_sym).first
    array.each do |details|
      to_record.errors.add(field, details[:error], **details.except(:error))
    end
  end
end

# File lib/denormalize_fields.rb, line 7
def denormalize(fields:, from:, onto:, prefix: nil)
  mapping = cast_to_mapping(fields, prefix: prefix)

  from.after_save do
    DenormalizeFields.call(record: self, relation_name: onto, mapping: mapping)
  end
end