# frozen_string_literal: true

class Imports::Watcher
  class UnsupportedSourceError < StandardError; end

  WATCHED_DIR_PATH = Rails.root.join('tmp/imports/watched')
  SUPPORTED_FORMATS = %w[.gpx .json .rec].freeze

  def call
    user_directories.each do |user_email|
      user = User.find_by(email: user_email)

      next unless user

      user_directory_path = File.join(WATCHED_DIR_PATH, user_email)
      file_names = file_names(user_directory_path)

      file_names.each do |file_name|
        create_import(user, user_directory_path, file_name)
      end
    end
  end

  private

  def user_directories
    Dir.entries(WATCHED_DIR_PATH).select do |entry|
      path = File.join(WATCHED_DIR_PATH, entry)

      File.directory?(path) && !['.', '..'].include?(entry)
    end
  end

  def file_names(directory_path)
    Dir.entries(directory_path).select { |file| SUPPORTED_FORMATS.include?(File.extname(file)) }
  end

  def create_import(user, directory_path, file_name)
    file_path = File.join(directory_path, file_name)
    import = Import.find_or_initialize_by(user:, name: file_name)

    return if import.persisted?

    import.source = source(file_name)
    import.file.attach(
      io: File.open(file_path),
      filename: file_name,
      content_type: mime_type(import.source)
    )

    import.save!
  end

  def source(file_name)
    case file_name.split('.').last.downcase
    when 'json'
      if file_name.match?(/location-history/i)
        :google_phone_takeout
      elsif file_name.match?(/Records/i)
        :google_records
      elsif file_name.match?(/\d{4}_\w+/i)
        :google_semantic_history
      else
        :geojson
      end
    when 'rec' then :owntracks
    when 'gpx' then :gpx
    else raise UnsupportedSourceError, 'Unsupported source '
    end
  end

  def mime_type(source)
    case source&.to_sym
    when :gpx then 'application/xml'
    when :json, :geojson, :google_phone_takeout, :google_records, :google_semantic_history
      'application/json'
    when :owntracks
      'application/octet-stream'
    when nil
      'application/octet-stream' # fallback MIME type for nil source
    else
      raise UnsupportedSourceError, "Unsupported source: #{source}"
    end
  end
end