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require 'redis'
require 'googleauth/token_store'

module Google
  module Auth
    module Stores
      # Implementation of user token storage backed by Redis. Tokens
      # are stored as JSON using the supplied key, prefixed with
      # `g-user-token:`
      class RedisTokenStore < Google::Auth::TokenStore
        DEFAULT_KEY_PREFIX = 'g-user-token:'

        # Create a new store with the supplied redis client.
        #
        # @param [::Redis, String] redis
        #  Initialized redis client to connect to.
        # @param [String] prefix
        #  Prefix for keys in redis. Defaults to 'g-user-token:'
        # @note If no redis instance is provided, a new one is created and
        #  the options passed through. You may include any other keys accepted
        #  by `Redis.new`
        def initialize(options = {})
          redis = options.delete(:redis)
          prefix = options.delete(:prefix)
          case redis
          when Redis
            @redis = redis
          else
            @redis = Redis.new(options)
          end
          @prefix = prefix || DEFAULT_KEY_PREFIX
        end

        # (see Google::Auth::Stores::TokenStore#load)
        def load(id)
          key = key_for(id)
          @redis.get(key)
        end

        # (see Google::Auth::Stores::TokenStore#store)
        def store(id, token)
          key = key_for(id)
          @redis.set(key, token)
        end

        # (see Google::Auth::Stores::TokenStore#delete)
        def delete(id)
          key = key_for(id)
          @redis.del(key)
        end

        private

        # Generate a redis key from a token ID
        #
        # @param [String] id
        #  ID of the token
        # @return [String]
        #  Redis key
        def key_for(id)
          @prefix + id
        end
      end
    end
  end
end