class Google::Cloud::Bigquery::Model

def self.from_gapi_json gapi_json, service
  new.tap do |m|
    m.instance_variable_set :@gapi_json, gapi_json
    m.instance_variable_set :@service, service
  end
end

def self.new_reference project_id, dataset_id, model_id, service
  raise ArgumentError, "project_id is required" unless project_id
  raise ArgumentError, "dataset_id is required" unless dataset_id
  raise ArgumentError, "model_id is required" unless model_id
  raise ArgumentError, "service is required" unless service
  new.tap do |m|
    reference_gapi_json = Google::Apis::BigqueryV2::ModelReference.new(
      project_id: project_id,
      dataset_id: dataset_id,
      model_id:   model_id
    )
    m.instance_variable_set :@reference, reference_gapi_json
    m.instance_variable_set :@service, service
  end
end

def created_at
  return nil if reference?
  Convert.millis_to_time @gapi_json[:creationTime]
end

def dataset_id
  return @reference.dataset_id if reference?
  @gapi_json[:modelReference][:datasetId]
end

def delete
  ensure_service!
  service.delete_model dataset_id, model_id
  # Set flag for #exists?
  @exists = false
  true
end

def description
  return nil if reference?
  ensure_full_data!
  @gapi_json[:description]
end

def description= new_description
  ensure_full_data!
  patch_gapi! description: new_description
end

def encryption
  return nil if reference?
  return nil if @gapi_json[:encryptionConfiguration].nil?
  # We have to create a gapic object from the hash because that is what
  # EncryptionConfiguration is expecing.
  json_cmek = @gapi_json[:encryptionConfiguration].to_json
  gapi_cmek = Google::Apis::BigqueryV2::EncryptionConfiguration.from_json json_cmek
  EncryptionConfiguration.from_gapi(gapi_cmek).freeze
end

def encryption= value
  ensure_full_data!
  # We have to create a hash from the gapic object's JSON because that
  # is what Model is expecing.
  json_cmek = JSON.parse value.to_gapi.to_json, symbolize_names: true
  patch_gapi! encryptionConfiguration: json_cmek
end

def ensure_full_data!
  reload! unless resource_full?
end

def ensure_gapi_json!
  ensure_service!
  return unless reference?
  reload!
end

def ensure_job_succeeded! job
  return unless job.failed?
  begin
    # raise to activate ruby exception cause handling
    raise job.gapi_error
  rescue StandardError => e
    # wrap Google::Apis::Error with Google::Cloud::Error
    raise Google::Cloud::Error.from_error(e)
  end
end

def ensure_service!
  raise "Must have active connection" unless service
end

def etag
  return nil if reference?
  ensure_full_data!
  @gapi_json[:etag]
end

def exists? force: false
  return resource_exists? if force
  # If we have a value, return it
  return @exists unless @exists.nil?
  # Always true if we have a gapi_json object
  return true if resource?
  resource_exists?
end

def expires_at
  return nil if reference?
  ensure_full_data!
  Convert.millis_to_time @gapi_json[:expirationTime]
end

def expires_at= new_expires_at
  ensure_full_data!
  new_expires_millis = Convert.time_to_millis new_expires_at
  patch_gapi! expirationTime: new_expires_millis
end

def extract extract_url, format: nil, reservation: nil, &block
  job = extract_job extract_url, format: format, reservation: reservation, &block
  job.wait_until_done!
  ensure_job_succeeded! job
  true
end

def extract_job extract_url, format: nil, job_id: nil, prefix: nil, labels: nil, reservation: nil
  ensure_service!
  options = { format: format, job_id: job_id, prefix: prefix, labels: labels, reservation: reservation }
  updater = ExtractJob::Updater.from_options service, model_ref, extract_url, options
  updater.location = location if location # may be model reference
  yield updater if block_given?
  job_gapi = updater.to_gapi
  gapi = service.extract_table job_gapi
  Job.from_gapi gapi, service
end

def feature_columns
  ensure_full_data!
  Array(@gapi_json[:featureColumns]).map do |field_gapi_json|
    field_gapi = Google::Apis::BigqueryV2::StandardSqlField.from_json field_gapi_json.to_json
    StandardSql::Field.from_gapi field_gapi
  end
end

def initialize
  @service = nil
  @gapi_json = nil
  @reference = nil
end

def label_columns
  ensure_full_data!
  Array(@gapi_json[:labelColumns]).map do |field_gapi_json|
    field_gapi = Google::Apis::BigqueryV2::StandardSqlField.from_json field_gapi_json.to_json
    StandardSql::Field.from_gapi field_gapi
  end
end

def labels
  return nil if reference?
  m = @gapi_json[:labels]
  m = m.to_h if m.respond_to? :to_h
  m.dup.freeze
end

def labels= new_labels
  ensure_full_data!
  patch_gapi! labels: new_labels
end

def location
  return nil if reference?
  ensure_full_data!
  @gapi_json[:location]
end

def model_id
  return @reference.model_id if reference?
  @gapi_json[:modelReference][:modelId]
end

def model_ref
  return @reference if reference?
  Google::Apis::BigqueryV2::ModelReference.new(
    project_id: project_id,
    dataset_id: dataset_id,
    model_id:   model_id
  )
end

def model_type
  return nil if reference?
  @gapi_json[:modelType]
end

def modified_at
  return nil if reference?
  Convert.millis_to_time @gapi_json[:lastModifiedTime]
end

def name
  return nil if reference?
  ensure_full_data!
  @gapi_json[:friendlyName]
end

def name= new_name
  ensure_full_data!
  patch_gapi! friendlyName: new_name
end

def patch_gapi! **changes
  return if changes.empty?
  ensure_service!
  patch_gapi = Google::Apis::BigqueryV2::Model.from_json changes.to_json
  patch_gapi.model_reference = model_ref
  @gapi_json = service.patch_model \
    dataset_id, model_id, patch_gapi, etag
  @reference = nil
  # TODO: restore original impl after acceptance test indicates that
  # service etag bug is fixed
  reload!
end

def project_id
  return @reference.project_id if reference?
  @gapi_json[:modelReference][:projectId]
end

def reference?
  @gapi_json.nil?
end

def reload!
  ensure_service!
  @gapi_json = service.get_model dataset_id, model_id
  @reference = nil
  @exists = nil
  self
end

def resource?
  !@gapi_json.nil?
end

def resource_exists?
  reload!
  @exists = true
rescue Google::Cloud::NotFoundError
  @exists = false
end

def resource_full?
  resource? && @gapi_json.key?(:friendlyName)
end

def resource_partial?
  resource? && !resource_full?
end

def training_runs
  ensure_full_data!
  Array @gapi_json[:trainingRuns]
end