# frozen_string_literal: true

module Anthropic
  module Vertex
    class Client < Anthropic::Client
      DEFAULT_VERSION = "vertex-2023-10-16"

      # @return [String]
      attr_reader :region

      # @return [String]
      attr_reader :project_id

      # @return [Anthropic::Resources::Messages]
      attr_reader :messages

      # @return [Anthropic::Resources::Beta]
      attr_reader :beta

      # Creates and returns a new client for interacting with the GCP Vertex API for Anthropic models.
      #
      # GCP credentials are resolved according to Application Default Credentials, described at
      #   https://cloud.google.com/docs/authentication/provide-credentials-adc
      #
      # @param region [String, nil] Enforce the GCP Region to use. If unset, the region may be set with the CLOUD_ML_REGION environment variable.
      #
      # @param project_id [String, nil] Enforce the GCP Project ID to use. If unset, the project_id may be set with the ANTHROPIC_VERTEX_PROJECT_ID environment variable.
      #
      # @param base_url [String, nil] Override the default base URL for the API, e.g., `"https://api.example.com/v2/"`
      #
      # @param max_retries [Integer] The maximum number of times to retry a request if it fails
      #
      # @param timeout [Float] The number of seconds to wait for a response before timing out
      #
      # @param initial_retry_delay [Float] The number of seconds to wait before retrying a request
      #
      # @param max_retry_delay [Float] The maximum number of seconds to wait before retrying a request
      #
      def initialize(
        region: ENV["CLOUD_ML_REGION"],
        project_id: ENV["ANTHROPIC_VERTEX_PROJECT_ID"],
        base_url: nil,
        max_retries: DEFAULT_MAX_RETRIES,
        timeout: DEFAULT_TIMEOUT_IN_SECONDS,
        initial_retry_delay: DEFAULT_INITIAL_RETRY_DELAY,
        max_retry_delay: DEFAULT_MAX_RETRY_DELAY
      )
        begin
          require("googleauth")
        rescue LoadError
          raise <<~MSG

            In order to access Anthropic models on Vertex you must require the `googleauth` gem.
            You can install it by adding the following to your Gemfile:

                gem "googleauth"

            and then running `bundle install`.

            Alternatively, if you are not using Bundler, simply run:

                gem install googleauth
          MSG
        end

        if region.to_s.empty?
          raise ArgumentError,
                "No region was given. The client should be instantiated with the `region` argument or the `CLOUD_ML_REGION` environment variable should be set."
        end
        @region = region

        if project_id.to_s.empty?
          raise ArgumentError,
                "No project_id was given and it could not be resolved from credentials. The client should be instantiated with the `project_id` argument or the `ANTHROPIC_VERTEX_PROJECT_ID` environment variable should be set."

        end
        @project_id = project_id

        base_url ||= ENV.fetch("ANTHROPIC_VERTEX_BASE_URL", "https://#{@region}-aiplatform.googleapis.com/v1")

        super(
          base_url: base_url,
          timeout: timeout,
          max_retries: max_retries,
          initial_retry_delay: initial_retry_delay,
          max_retry_delay: max_retry_delay,
        )

        @messages = Anthropic::Resources::Messages.new(client: self)
        @beta = Anthropic::Resources::Beta.new(client: self)
      end

      # @private
      #
      # @param req [Hash{Symbol=>Object}] .
      #
      #   @option req [Symbol] :method
      #
      #   @option req [String, Array<String>] :path
      #
      #   @option req [Hash{String=>Array<String>, String, nil}, nil] :query
      #
      #   @option req [Hash{String=>String, nil}, nil] :headers
      #
      #   @option req [Object, nil] :body
      #
      #   @option req [Symbol, nil] :unwrap
      #
      #   @option req [Class, nil] :page
      #
      #   @option req [Anthropic::Converter, Class, nil] :model
      #
      # @param opts [Hash{Symbol=>Object}] .
      #
      #   @option opts [String, nil] :idempotency_key
      #
      #   @option opts [Hash{String=>Array<String>, String, nil}, nil] :extra_query
      #
      #   @option opts [Hash{String=>String, nil}, nil] :extra_headers
      #
      #   @option opts [Hash{Symbol=>Object}, nil] :extra_body
      #
      #   @option opts [Integer, nil] :max_retries
      #
      #   @option opts [Float, nil] :timeout
      #
      # @return [Hash{Symbol=>Object}]
      #
      private def build_request(req, opts)
        fit_req_to_vertex_specs!(req)

        request_input = super

        unless request_input[:headers]["Authorization"]
          authorization = Google::Auth.get_application_default(["https://www.googleapis.com/auth/cloud-platform"])
          request_input[:headers] = authorization.apply(request_input[:headers])
        end

        request_input
      end

      # @private
      #
      # Overrides request components for Vertex-specific request-shape requirements.
      #
      # @param request_components [Hash{Symbol=>Object}] .
      #
      #   @option request_components [Symbol] :method
      #
      #   @option request_components [String, Array<String>] :path
      #
      #   @option request_components [Hash{String=>Array<String>, String, nil}, nil] :query
      #
      #   @option request_components [Hash{String=>String, nil}, nil] :headers
      #
      #   @option request_components [Object, nil] :body
      #
      #   @option request_components [Symbol, nil] :unwrap
      #
      #   @option request_components [Class, nil] :page
      #
      #   @option request_components [Anthropic::Converter, Class, nil] :model
      #
      # @return [Hash{Symbol=>Object}]
      def fit_req_to_vertex_specs!(request_components)
        if (body = request_components[:body]).is_a?(Hash)
          body[:anthropic_version] ||= DEFAULT_VERSION

          if (anthropic_beta = body.delete(:"anthropic-beta"))
            request_components[:headers] ||= {}
            request_components[:headers]["anthropic-beta"] = anthropic_beta.join(",")
          end
        end

        if %w[
          v1/messages
          v1/messages?beta=true
        ].include?(request_components[:path]) && request_components[:method] == :post

          unless body.is_a?(Hash)
            raise Anthropic::Error, "Expected json data to be a hash for post /v1/messages"
          end

          model = body.delete(:model)
          specifier = body[:stream] ? "streamRawPredict" : "rawPredict"

          request_components[:path] =
            "projects/#{@project_id}/locations/#{region}/publishers/anthropic/models/#{model}:#{specifier}"

        end

        if %w[
          v1/messages/count_tokens
          v1/messages/count_tokens?beta=true
        ].include?(request_components[:path]) &&
           request_components[:method] == :post
          request_components[:path] =
            "projects/#{@project_id}/locations/#{region}/publishers/anthropic/models/count-tokens:rawPredict"

        end

        if request_components[:path].start_with?("v1/messages/batches/")
          raise AnthropicError("The Batch API is not supported in the Vertex client yet")
        end

        request_components
      end
    end
  end
end