import grpc
import demo_pb2
import demo_pb2_grpc
from concurrent import futures
import time
import random
import os

import googleclouddebugger

# TODO(morganmclean,ahmetb) tracing currently disabled due to memory leak (see TODO below)
# from opencensus.trace.ext.grpc import server_interceptor
# from opencensus.trace.samplers import always_on
# from opencensus.trace.exporters import stackdriver_exporter
# from opencensus.trace.exporters import print_exporter

class RecommendationService(demo_pb2_grpc.RecommendationServiceServicer):
    def ListRecommendations(self, request, context):
        max_responses = 5
        # fetch list of products from product catalog stub
        cat_response = stub.ListProducts(demo_pb2.Empty())
        product_ids = [x.id for x in cat_response.products]
        filtered_products = list(set(product_ids)-set(request.product_ids))
        num_products = len(filtered_products)
        num_return = min(max_responses, num_products)
        # sample list of indicies to return
        indices = random.sample(range(num_products), num_return)
        # fetch product ids from indices
        prod_list = [filtered_products[i] for i in indices]
        print("[Recv ListRecommendations] product_ids={}".format(prod_list))
        # build and return response
        response = demo_pb2.ListRecommendationsResponse()
        response.product_ids.extend(prod_list)
        return response

if __name__ == "__main__":
    print("initializing recommendationservice")

    # TODO(morganmclean,ahmetb) enabling the tracing interceptor/sampler below
    # causes an unbounded memory leak eventually OOMing the container.
    # ----
    # try:
    #     sampler = always_on.AlwaysOnSampler()
    #     exporter = stackdriver_exporter.StackdriverExporter()
    #     tracer_interceptor = server_interceptor.OpenCensusServerInterceptor(sampler, exporter)
    # except:
    #     tracer_interceptor = server_interceptor.OpenCensusServerInterceptor()

    try:
        googleclouddebugger.enable(
            module='recommendationserver',
            version='1.0.0'
        )
    except Exception, err:
        print("could not enable debugger")
        traceback.print_exc()
        pass

    port = os.environ.get('PORT', "8080")
    catalog_addr = os.environ.get('PRODUCT_CATALOG_SERVICE_ADDR', '')
    if catalog_addr == "":
        raise Exception('PRODUCT_CATALOG_SERVICE_ADDR environment variable not set')
    print("product catalog address: " + catalog_addr)

    # stub for product catalog service
    channel = grpc.insecure_channel(catalog_addr)
    stub = demo_pb2_grpc.ProductCatalogServiceStub(channel)
    
    # create gRPC server
    server = grpc.server(futures.ThreadPoolExecutor(max_workers=10)) # ,interceptors=(tracer_interceptor,))

    # add class to gRPC server
    demo_pb2_grpc.add_RecommendationServiceServicer_to_server(RecommendationService(), server)

    # start server
    print("listening on port: " + port)
    server.add_insecure_port('[::]:'+port)
    server.start()

    # keep alive
    try:
         while True:
            time.sleep(10000)
    except KeyboardInterrupt:
            server.stop(0)