defmodule Google.Api.RoutingRule do
  @moduledoc """
  Specifies the routing information that should be sent along with the request
  in the form of routing header.
  **NOTE:** All service configuration rules follow the "last one wins" order.

  The examples below will apply to an RPC which has the following request type:

  Message Definition:

      message Request {
        // The name of the Table
        // Values can be of the following formats:
        // - `projects/<project>/tables/<table>`
        // - `projects/<project>/instances/<instance>/tables/<table>`
        // - `region/<region>/zones/<zone>/tables/<table>`
        string table_name = 1;

        // This value specifies routing for replication.
        // It can be in the following formats:
        // - `profiles/<profile_id>`
        // - a legacy `profile_id` that can be any string
        string app_profile_id = 2;
      }

  Example message:

      {
        table_name: projects/proj_foo/instances/instance_bar/table/table_baz,
        app_profile_id: profiles/prof_qux
      }

  The routing header consists of one or multiple key-value pairs. Every key
  and value must be percent-encoded, and joined together in the format of
  `key1=value1&key2=value2`.
  The examples below skip the percent-encoding for readability.

  Example 1

  Extracting a field from the request to put into the routing header
  unchanged, with the key equal to the field name.

  annotation:

      option (google.api.routing) = {
        // Take the `app_profile_id`.
        routing_parameters {
          field: "app_profile_id"
        }
      };

  result:

      x-goog-request-params: app_profile_id=profiles/prof_qux

  Example 2

  Extracting a field from the request to put into the routing header
  unchanged, with the key different from the field name.

  annotation:

      option (google.api.routing) = {
        // Take the `app_profile_id`, but name it `routing_id` in the header.
        routing_parameters {
          field: "app_profile_id"
          path_template: "{routing_id=**}"
        }
      };

  result:

      x-goog-request-params: routing_id=profiles/prof_qux

  Example 3

  Extracting a field from the request to put into the routing
  header, while matching a path template syntax on the field's value.

  NB: it is more useful to send nothing than to send garbage for the purpose
  of dynamic routing, since garbage pollutes cache. Thus the matching.

  Sub-example 3a

  The field matches the template.

  annotation:

      option (google.api.routing) = {
        // Take the `table_name`, if it's well-formed (with project-based
        // syntax).
        routing_parameters {
          field: "table_name"
          path_template: "{table_name=projects/*/instances/*/**}"
        }
      };

  result:

      x-goog-request-params:
      table_name=projects/proj_foo/instances/instance_bar/table/table_baz

  Sub-example 3b

  The field does not match the template.

  annotation:

      option (google.api.routing) = {
        // Take the `table_name`, if it's well-formed (with region-based
        // syntax).
        routing_parameters {
          field: "table_name"
          path_template: "{table_name=regions/*/zones/*/**}"
        }
      };

  result:

      <no routing header will be sent>

  Sub-example 3c

  Multiple alternative conflictingly named path templates are
  specified. The one that matches is used to construct the header.

  annotation:

      option (google.api.routing) = {
        // Take the `table_name`, if it's well-formed, whether
        // using the region- or projects-based syntax.

        routing_parameters {
          field: "table_name"
          path_template: "{table_name=regions/*/zones/*/**}"
        }
        routing_parameters {
          field: "table_name"
          path_template: "{table_name=projects/*/instances/*/**}"
        }
      };

  result:

      x-goog-request-params:
      table_name=projects/proj_foo/instances/instance_bar/table/table_baz

  Example 4

  Extracting a single routing header key-value pair by matching a
  template syntax on (a part of) a single request field.

  annotation:

      option (google.api.routing) = {
        // Take just the project id from the `table_name` field.
        routing_parameters {
          field: "table_name"
          path_template: "{routing_id=projects/*}/**"
        }
      };

  result:

      x-goog-request-params: routing_id=projects/proj_foo

  Example 5

  Extracting a single routing header key-value pair by matching
  several conflictingly named path templates on (parts of) a single request
  field. The last template to match "wins" the conflict.

  annotation:

      option (google.api.routing) = {
        // If the `table_name` does not have instances information,
        // take just the project id for routing.
        // Otherwise take project + instance.

        routing_parameters {
          field: "table_name"
          path_template: "{routing_id=projects/*}/**"
        }
        routing_parameters {
          field: "table_name"
          path_template: "{routing_id=projects/*/instances/*}/**"
        }
      };

  result:

      x-goog-request-params:
      routing_id=projects/proj_foo/instances/instance_bar

  Example 6

  Extracting multiple routing header key-value pairs by matching
  several non-conflicting path templates on (parts of) a single request field.

  Sub-example 6a

  Make the templates strict, so that if the `table_name` does not
  have an instance information, nothing is sent.

  annotation:

      option (google.api.routing) = {
        // The routing code needs two keys instead of one composite
        // but works only for the tables with the "project-instance" name
        // syntax.

        routing_parameters {
          field: "table_name"
          path_template: "{project_id=projects/*}/instances/*/**"
        }
        routing_parameters {
          field: "table_name"
          path_template: "projects/*/{instance_id=instances/*}/**"
        }
      };

  result:

      x-goog-request-params:
      project_id=projects/proj_foo&instance_id=instances/instance_bar

  Sub-example 6b

  Make the templates loose, so that if the `table_name` does not
  have an instance information, just the project id part is sent.

  annotation:

      option (google.api.routing) = {
        // The routing code wants two keys instead of one composite
        // but will work with just the `project_id` for tables without
        // an instance in the `table_name`.

        routing_parameters {
          field: "table_name"
          path_template: "{project_id=projects/*}/**"
        }
        routing_parameters {
          field: "table_name"
          path_template: "projects/*/{instance_id=instances/*}/**"
        }
      };

  result (is the same as 6a for our example message because it has the instance
  information):

      x-goog-request-params:
      project_id=projects/proj_foo&instance_id=instances/instance_bar

  Example 7

  Extracting multiple routing header key-value pairs by matching
  several path templates on multiple request fields.

  NB: note that here there is no way to specify sending nothing if one of the
  fields does not match its template. E.g. if the `table_name` is in the wrong
  format, the `project_id` will not be sent, but the `routing_id` will be.
  The backend routing code has to be aware of that and be prepared to not
  receive a full complement of keys if it expects multiple.

  annotation:

      option (google.api.routing) = {
        // The routing needs both `project_id` and `routing_id`
        // (from the `app_profile_id` field) for routing.

        routing_parameters {
          field: "table_name"
          path_template: "{project_id=projects/*}/**"
        }
        routing_parameters {
          field: "app_profile_id"
          path_template: "{routing_id=**}"
        }
      };

  result:

      x-goog-request-params:
      project_id=projects/proj_foo&routing_id=profiles/prof_qux

  Example 8

  Extracting a single routing header key-value pair by matching
  several conflictingly named path templates on several request fields. The
  last template to match "wins" the conflict.

  annotation:

      option (google.api.routing) = {
        // The `routing_id` can be a project id or a region id depending on
        // the table name format, but only if the `app_profile_id` is not set.
        // If `app_profile_id` is set it should be used instead.

        routing_parameters {
          field: "table_name"
          path_template: "{routing_id=projects/*}/**"
        }
        routing_parameters {
           field: "table_name"
           path_template: "{routing_id=regions/*}/**"
        }
        routing_parameters {
          field: "app_profile_id"
          path_template: "{routing_id=**}"
        }
      };

  result:

      x-goog-request-params: routing_id=profiles/prof_qux

  Example 9

  Bringing it all together.

  annotation:

      option (google.api.routing) = {
        // For routing both `table_location` and a `routing_id` are needed.
        //
        // table_location can be either an instance id or a region+zone id.
        //
        // For `routing_id`, take the value of `app_profile_id`
        // - If it's in the format `profiles/<profile_id>`, send
        // just the `<profile_id>` part.
        // - If it's any other literal, send it as is.
        // If the `app_profile_id` is empty, and the `table_name` starts with
        // the project_id, send that instead.

        routing_parameters {
          field: "table_name"
          path_template: "projects/*/{table_location=instances/*}/tables/*"
        }
        routing_parameters {
          field: "table_name"
          path_template: "{table_location=regions/*/zones/*}/tables/*"
        }
        routing_parameters {
          field: "table_name"
          path_template: "{routing_id=projects/*}/**"
        }
        routing_parameters {
          field: "app_profile_id"
          path_template: "{routing_id=**}"
        }
        routing_parameters {
          field: "app_profile_id"
          path_template: "profiles/{routing_id=*}"
        }
      };

  result:

      x-goog-request-params:
      table_location=instances/instance_bar&routing_id=prof_qux
  """

  use Protobuf,
    full_name: "google.api.RoutingRule",
    protoc_gen_elixir_version: "0.16.0",
    syntax: :proto3

  field :routing_parameters, 2,
    repeated: true,
    type: Google.Api.RoutingParameter,
    json_name: "routingParameters"
end

defmodule Google.Api.RoutingParameter do
  @moduledoc """
  A projection from an input message to the GRPC or REST header.
  """

  use Protobuf,
    full_name: "google.api.RoutingParameter",
    protoc_gen_elixir_version: "0.16.0",
    syntax: :proto3

  field :field, 1, type: :string
  field :path_template, 2, type: :string, json_name: "pathTemplate"
end