import_service.rb

# frozen_string_literal: true

class ImportService

  class Error < StandardError
  end

  def initialize
    raise ImportService::Error.new("To be implemented by subclass")
  end

  def importer
    raise ImportService::Error.new("To be implemented by subclass")
  end

  def record_class
    raise ImportService::Error.new("To be implemented by subclass")
  end

  def process_import
    csv = importer.csv
    download = csv.download
    if csv.attached? && csv.download
      CSV.parse(download) do |row|
        if @is_non_headers_row || !importer.first_row_headers
          record = build_record_from_row(row)
          save_record_for_import(record)
        end
        @is_non_headers_row ||= true
      end
    else
      importer.update_attributes(status: "invalid", invalid_reason: "#{record_class}Import::Invalid::MISSING_CSV".constantize)
    end
  end

  def build_record_from_row(row)
    record = record_class.new(account_id: importer.account_id)
    importer.headers.each do |key, value|
      if record.respond_to?(value)
        record[value] = row[key.to_i]
      else
        record.custom_fields[value] = row[key.to_i] if value.present?
      end
    end
    record
  end

  def save_record_for_import(record)
    return true if record.save
    add_record_to_invalidity_list(record)
    update_invalid_status
    false
  end

  def add_record_to_invalidity_list(record)
    invalid_list.push(record.attributes)
  end

  def update_invalid_status
    if invalid_list.length > "#{record_class}Import::Invalid::INVALID_#{record_class.to_s.underscore.upcase}S_THRESHOLD".constantize
      importer.update_attributes(status: "invalid", invalid_reason: "#{record_class}Import::Invalid::INVALID_#{record_class.to_s.underscore.upcase}S".constantize)
    else
      importer.save
    end
  end

  def invalid_list
    importer.send("invalid_#{record_class.to_s.underscore.pluralize}")
  end

end