# frozen_string_literal: true

module Clusters
  module Platforms
    class Kubernetes < ApplicationRecord
      include Gitlab::Kubernetes
      include AfterCommitQueue
      include ReactiveCaching
      include NullifyIfBlank
      include Gitlab::EncryptedAttribute

      RESERVED_NAMESPACES = %w[gitlab-managed-apps].freeze
      REQUIRED_K8S_MIN_VERSION = 23

      MAX_TOKEN_LENGTH = 8192
      MAX_CA_CERT_LENGTH = 65535
      MAX_API_URL_LENGTH = 2048

      IGNORED_CONNECTION_EXCEPTIONS = [
        Gitlab::HTTP_V2::UrlBlocker::BlockedUrlError,
        Kubeclient::HttpError,
        Errno::ECONNREFUSED,
        URI::InvalidURIError,
        Errno::EHOSTUNREACH,
        OpenSSL::X509::StoreError,
        OpenSSL::SSL::SSLError
      ].freeze

      FailedVersionCheckError = Class.new(StandardError)

      self.table_name = 'cluster_platforms_kubernetes'
      self.reactive_cache_work_type = :external_dependency

      belongs_to :cluster, inverse_of: :platform_kubernetes, class_name: 'Clusters::Cluster'
      belongs_to :organization, class_name: 'Organizations::Organization', optional: true
      belongs_to :group, optional: true
      belongs_to :project, optional: true

      attr_encrypted :password,
        mode: :per_attribute_iv,
        key: :db_key_base_truncated,
        algorithm: 'aes-256-cbc'

      attr_encrypted :token,
        mode: :per_attribute_iv,
        key: :db_key_base_truncated,
        algorithm: 'aes-256-cbc'

      before_validation :enforce_namespace_to_lower_case
      before_validation :enforce_ca_whitespace_trimming

      validates :namespace,
        allow_nil: true,
        length: 1..63,
        format: {
          with: Gitlab::Regex.kubernetes_namespace_regex,
          message: Gitlab::Regex.kubernetes_namespace_regex_message
        }

      validates :namespace, exclusion: { in: RESERVED_NAMESPACES }

      validate :no_namespace, unless: :allow_user_defined_namespace?

      # We expect to be `active?` only when enabled and cluster is created (the api_url is assigned)
      validates :api_url, public_url: true, presence: true
      validates :token, presence: true
      validates :ca_cert, certificate: true, allow_blank: true, length: 1..MAX_CA_CERT_LENGTH, if: :ca_cert_changed?

      validates :api_url, length: 1..MAX_API_URL_LENGTH, if: :api_url_changed?
      validates :token, length: 1..MAX_TOKEN_LENGTH, if: :token_changed?

      validate :prevent_modification, on: :update

      alias_attribute :ca_pem, :ca_cert

      enum :authorization_type, {
        unknown_authorization: nil,
        rbac: 1,
        abac: 2
      }, default: :rbac

      nullify_if_blank :namespace

      def enabled?
        !!cluster&.enabled?
      end
      alias_method :active?, :enabled?

      def provided_by_user?
        !!cluster&.provided_by_user?
      end

      def allow_user_defined_namespace?
        !!cluster&.allow_user_defined_namespace?
      end

      def predefined_variables(project:, environment_name:, kubernetes_namespace: nil)
        Gitlab::Ci::Variables::Collection.new.tap do |variables|
          variables.append(key: 'KUBE_URL', value: api_url)

          if ca_pem.present?
            variables
              .append(key: 'KUBE_CA_PEM', value: ca_pem)
              .append(key: 'KUBE_CA_PEM_FILE', value: ca_pem, file: true)
          end

          if !cluster.managed? || cluster.management_project == project
            namespace = kubernetes_namespace || default_namespace(project, environment_name: environment_name)

            variables
              .append(key: 'KUBE_TOKEN', value: token, public: false, masked: true)
              .append(key: 'KUBE_NAMESPACE', value: namespace)
              .append(key: 'KUBECONFIG', value: kubeconfig(namespace), public: false, file: true)

          elsif persisted_namespace = find_persisted_namespace(project, environment_name: environment_name)
            variables.concat(persisted_namespace.predefined_variables)
          end

          variables.concat(cluster.predefined_variables)
        end
      end

      def calculate_reactive_cache_for(environment)
        return unless enabled?

        pods = []
        deployments = []
        ingresses = []

        begin
          pods = read_pods(environment.deployment_namespace)
          deployments = read_deployments(environment.deployment_namespace)

          ingresses = read_ingresses(environment.deployment_namespace)
        rescue *IGNORED_CONNECTION_EXCEPTIONS => e
          log_kube_connection_error(e)

          # Return hash with default values so that it is cached.
          return {
            pods: pods, deployments: deployments, ingresses: ingresses
          }
        end

        # extract only the data required for display to avoid unnecessary caching
        {
          pods: extract_relevant_pod_data(pods),
          deployments: extract_relevant_deployment_data(deployments),
          ingresses: extract_relevant_ingress_data(ingresses)
        }
      end

      def terminals(environment, data)
        pods = filter_by_project_environment(data[:pods], environment.project.full_path_slug, environment.slug)
        terminals = pods.flat_map { |pod| terminals_for_pod(api_url, environment.deployment_namespace, pod) }.compact
        terminals.each { |terminal| add_terminal_auth(terminal, **terminal_auth) }
      end

      def kubeclient
        @kubeclient ||= build_kube_client!
      end

      def rollout_status(environment, data)
        project = environment.project

        deployments = filter_by_project_environment(data[:deployments], project.full_path_slug, environment.slug)
        pods = filter_by_project_environment(data[:pods], project.full_path_slug, environment.slug)
        ingresses = data[:ingresses].presence || []

        ::Gitlab::Kubernetes::RolloutStatus.from_deployments(*deployments, pods_attrs: pods, ingresses: ingresses)
      end

      def ingresses(namespace)
        ingresses = read_ingresses(namespace)
        ingresses.map { |ingress| ::Gitlab::Kubernetes::Ingress.new(ingress) }
      end

      def patch_ingress(namespace, ingress, data)
        kubeclient.patch_ingress(ingress.name, data, namespace)
      end

      def kubeconfig(namespace)
        to_kubeconfig(
          url: api_url,
          namespace: namespace,
          token: token,
          ca_pem: ca_pem)
      end

      private

      def default_namespace(project, environment_name:)
        Gitlab::Kubernetes::DefaultNamespace.new(
          cluster,
          project: project
        ).from_environment_name(environment_name)
      end

      def find_persisted_namespace(project, environment_name:)
        Clusters::KubernetesNamespaceFinder.new(
          cluster,
          project: project,
          environment_name: environment_name
        ).execute
      end

      def read_pods(namespace)
        kubeclient.get_pods(namespace: namespace).as_json
      rescue Kubeclient::ResourceNotFoundError
        []
      end

      def read_deployments(namespace)
        kubeclient.get_deployments(namespace: namespace).as_json
      rescue Kubeclient::ResourceNotFoundError
        []
      end

      def read_ingresses(namespace)
        kubeclient.get_ingresses(namespace: namespace).as_json
      rescue Kubeclient::ResourceNotFoundError
        []
      rescue NoMethodError => e
        # We get NoMethodError for Kubernetes versions < 1.19. Since we only support >= 1.23
        # we will ignore this error for previous versions. For more details read:
        # https://gitlab.com/gitlab-org/gitlab/-/issues/371249#note_1079866043
        return [] if server_version < REQUIRED_K8S_MIN_VERSION

        raise e
      end

      def server_version
        full_url = Gitlab::UrlSanitizer.new("#{api_url}/version").full_url

        # We can't use `kubeclient` to check the cluster version because it does not support it
        # https://github.com/ManageIQ/kubeclient/issues/309
        response = Gitlab::HTTP.perform_request(
          Net::HTTP::Get, full_url,
          headers: { "Authorization" => "Bearer #{token}" },
          cert_store: kubeclient_ssl_options[:cert_store])

        Gitlab::ErrorTracking.track_exception(FailedVersionCheckError.new) unless response.success?

        json_response = Gitlab::Json.safe_parse(response.body) || {}
        json_response["minor"].to_i
      end

      def build_kube_client!
        raise "Incomplete settings" unless api_url

        raise "Either username/password or token is required to access API" unless (username && password) || token

        Gitlab::Kubernetes::KubeClient.new(
          api_url,
          auth_options: kubeclient_auth_options,
          ssl_options: kubeclient_ssl_options,
          http_proxy_uri: ENV['http_proxy']
        )
      end

      def kubeclient_ssl_options
        opts = { verify_ssl: OpenSSL::SSL::VERIFY_PEER }

        if ca_pem.present?
          opts[:cert_store] = OpenSSL::X509::Store.new

          file = Tempfile.new('cluster_ca_pem_temp')
          begin
            file.write(ca_pem)
            file.rewind
            opts[:cert_store].add_file(file.path)
          ensure
            file.close
            file.unlink # deletes the temp file
          end
        end

        opts
      end

      def kubeclient_auth_options
        { bearer_token: token }
      end

      def terminal_auth
        {
          token: token,
          ca_pem: ca_pem,
          max_session_time: Gitlab::CurrentSettings.terminal_max_session_time
        }
      end

      def enforce_namespace_to_lower_case
        self.namespace = self.namespace&.downcase
      end

      def enforce_ca_whitespace_trimming
        self.ca_pem = self.ca_pem&.strip
        self.token = self.token&.strip
      end

      def no_namespace
        errors.add(:namespace, 'only allowed for project cluster') if namespace
      end

      def prevent_modification
        return if provided_by_user?

        if api_url_changed? || attribute_changed?(:token) || ca_pem_changed?
          errors.add(:base, _('Cannot modify managed Kubernetes cluster'))
          return false
        end

        true
      end

      def extract_relevant_pod_data(pods)
        pods.map do |pod|
          {
            'metadata' => pod.fetch('metadata', {})
                             .slice('name', 'generateName', 'labels', 'annotations', 'creationTimestamp'),
            'status' => pod.fetch('status', {}).slice('phase'),
            'spec' => {
              'containers' => pod.fetch('spec', {})
                                 .fetch('containers', [])
                                 .map { |c| c.slice('name') }
            }
          }
        end
      end

      def extract_relevant_deployment_data(deployments)
        deployments.map do |deployment|
          {
            'metadata' => deployment.fetch('metadata', {}).slice('name', 'generation', 'labels', 'annotations'),
            'spec' => deployment.fetch('spec', {}).slice('replicas'),
            'status' => deployment.fetch('status', {}).slice('observedGeneration')
          }
        end
      end

      def extract_relevant_ingress_data(ingresses)
        ingresses.map do |ingress|
          {
            'metadata' => ingress.fetch('metadata', {}).slice('name', 'labels', 'annotations')
          }
        end
      end

      def log_kube_connection_error(error)
        logger.error({
          exception: {
            class: error.class.name,
            message: error.message
          },
          status_code: error.try(:error_code),
          namespace: self.namespace,
          class_name: self.class.name,
          event: :kube_connection_error
        })
      end

      def logger
        @logger ||= Gitlab::Kubernetes::Logger.build
      end
    end
  end
end
