# frozen_string_literal: true
require 'open3'

module Krane
  class Kubectl
    ERROR_MATCHERS = {
      not_found: /NotFound/,
      client_timeout: /Client\.Timeout exceeded while awaiting headers/,
      empty: /\A\z/,
      context_deadline: /context deadline exceeded/,
    }
    DEFAULT_TIMEOUT = 15
    MAX_RETRY_DELAY = 16
    SERVER_DRY_RUN_MIN_VERSION = "1.13"

    class ResourceNotFoundError < StandardError; end

    delegate :namespace, :context, :logger, :kubeconfig, to: :@task_config

    def initialize(task_config:, log_failure_by_default:, default_timeout: DEFAULT_TIMEOUT,
      output_is_sensitive_default: false)
      @task_config = task_config
      @log_failure_by_default = log_failure_by_default
      @default_timeout = default_timeout
      @output_is_sensitive_default = output_is_sensitive_default
    end

    def run(*args, log_failure: nil, use_context: true, use_namespace: true, output: nil,
      raise_if_not_found: false, attempts: 1, output_is_sensitive: nil, retry_whitelist: nil)
      raise ArgumentError, "namespace is required" if namespace.blank? && use_namespace
      log_failure = @log_failure_by_default if log_failure.nil?
      output_is_sensitive = @output_is_sensitive_default if output_is_sensitive.nil?
      cmd = build_command_from_options(args, use_namespace, use_context, output)
      out, err, st = nil

      (1..attempts).to_a.each do |current_attempt|
        logger.debug("Running command (attempt #{current_attempt}): #{cmd.join(' ')}")
        env = { 'KUBECONFIG' => kubeconfig }
        out, err, st = Open3.capture3(env, *cmd)

        # https://github.com/Shopify/krane/issues/395
        unless out.valid_encoding?
          out = out.dup.force_encoding(Encoding::UTF_8)
        end

        if logger.debug? && !output_is_sensitive
          # don't do the gsub unless we're going to print this
          logger.debug("Kubectl out: " + out.gsub(/\s+/, ' '))
        end

        break if st.success?
        raise(ResourceNotFoundError, err) if err.match(ERROR_MATCHERS[:not_found]) && raise_if_not_found

        if log_failure
          warning = if current_attempt == attempts
            "The following command failed (attempt #{current_attempt}/#{attempts})"
          elsif retriable_err?(err, retry_whitelist)
            "The following command failed and will be retried (attempt #{current_attempt}/#{attempts})"
          else
            "The following command failed and cannot be retried"
          end
          logger.warn("#{warning}: #{Shellwords.join(cmd)}")
          logger.warn(err) unless output_is_sensitive
        else
          logger.debug("Kubectl err: #{output_is_sensitive ? '<suppressed sensitive output>' : err}")
        end
        StatsD.client.increment('kubectl.error', 1, tags: { context: context, namespace: namespace, cmd: cmd[1],
                                                            max_attempt: attempts, current_attempt: current_attempt })

        break unless retriable_err?(err, retry_whitelist) && current_attempt < attempts
        sleep(retry_delay(current_attempt))
      end

      [out.chomp, err.chomp, st]
    end

    def retry_delay(attempt)
      # exponential backoff starting at 1s with cap at 16s, offset by up to 0.5s
      [2**(attempt - 1), MAX_RETRY_DELAY].min - Random.rand(0.5).round(1)
    end

    def version_info
      @version_info ||=
        begin
          response, _, status = run("version", output: "json", use_namespace: false, log_failure: true, attempts: 2)
          raise KubectlError, "Could not retrieve kubectl version info" unless status.success?

          version_data = JSON.parse(response)
          client_version = platform_agnostic_version(version_data.dig("clientVersion", "gitVersion").to_s)
          server_version = platform_agnostic_version(version_data.dig("serverVersion", "gitVersion").to_s)
          unless client_version && server_version
            raise KubectlError, "Received invalid kubectl version data: #{version_data}"
          end

          { client: client_version, server: server_version }
        end
    end

    def client_version
      version_info[:client]
    end

    def server_version
      version_info[:server]
    end

    def server_dry_run_enabled?
      server_version >= Gem::Version.new(SERVER_DRY_RUN_MIN_VERSION)
    end

    def dry_run_flag
      if client_version >= Gem::Version.new("1.18")
        "--dry-run=server"
      else
        "--server-dry-run"
      end
    end

    private

    def build_command_from_options(args, use_namespace, use_context, output)
      cmd = ["kubectl"] + args
      cmd.push("--namespace=#{namespace}")              if use_namespace
      cmd.push("--context=#{context}")                  if use_context
      cmd.push("--output=#{output}")                     if output
      cmd.push("--request-timeout=#{@default_timeout}")  if @default_timeout
      cmd
    end

    def retriable_err?(err, retry_whitelist)
      return !err.match(ERROR_MATCHERS[:not_found]) if retry_whitelist.nil?
      retry_whitelist.any? do |retriable|
        raise NotImplementedError, "No matcher defined for #{retriable.inspect}" unless ERROR_MATCHERS.key?(retriable)
        err.match(ERROR_MATCHERS[retriable])
      end
    end

    def platform_agnostic_version(version_string)
      if match = version_string.match(/v(?<version>\d+\.\d+\.\d+)/)
        Gem::Version.new(match[:version])
      end
    end
  end
end