/*
 *
 * Copyright 2015, Google Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
 *     * Neither the name of Google Inc. nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

package main

import (
	"encoding/json"
	"flag"
	"io"
	"io/ioutil"
	"log"
	"math"
	"net"
	"strconv"
	"time"

	"golang.org/x/net/context"
	"google.golang.org/grpc"

	"google.golang.org/grpc/credentials"

	pb "google.golang.org/grpc/examples/route_guide"
)

var (
	useTLS     = flag.Bool("use_tls", false, "Connection uses TLS if true, else plain TCP")
	certFile   = flag.String("tls_cert_file", "testdata/server1.pem", "The TLS cert file")
	keyFile    = flag.String("tls_key_file", "testdata/server1.key", "The TLS key file")
	jsonDBFile = flag.String("route_guide_db", "testdata/route_guide_db.json", "A json file containing a list of features")
	port       = flag.Int("port", 10000, "The server port")
)

type routeGuideServer struct {
	savedFeatures []pb.Feature
	routeNotes    map[pb.Point][]*pb.RouteNote
}

// GetFeature returns the feature at the given point.
func (s *routeGuideServer) GetFeature(ctx context.Context, point *pb.Point) (*pb.Feature, error) {
	for _, feature := range s.savedFeatures {
		if *(feature.Location) == *point {
			return &feature, nil
		}
	}
	// No feature was found, return an unnamed feature
	return &pb.Feature{"", point}, nil
}

// ListFeatures lists all features comtained within the given bounding Rectangle.
func (s *routeGuideServer) ListFeatures(rect *pb.Rectangle, stream pb.RouteGuide_ListFeaturesServer) error {
	left := math.Min(float64(rect.Lo.Longitude), float64(rect.Hi.Longitude))
	right := math.Max(float64(rect.Lo.Longitude), float64(rect.Hi.Longitude))
	top := math.Max(float64(rect.Lo.Latitude), float64(rect.Hi.Latitude))
	bottom := math.Min(float64(rect.Lo.Latitude), float64(rect.Hi.Latitude))
	for _, feature := range s.savedFeatures {
		if float64(feature.Location.Longitude) >= left &&
			float64(feature.Location.Longitude) <= right &&
			float64(feature.Location.Latitude) >= bottom &&
			float64(feature.Location.Latitude) <= top {
			if err := stream.Send(&feature); err != nil {
				return err
			}
		}
	}
	return nil
}

// RecordRoute records a route composited of a sequence of points.
//
// It gets a stream of points, and responds with statistics about the "trip":
// number of points,  number of known features visited, total distance traveled, and
// total time spent.
func (s *routeGuideServer) RecordRoute(stream pb.RouteGuide_RecordRouteServer) error {
	var pointCount, featureCount, distance int32
	var lastPoint *pb.Point
	startTime := time.Now()
	for {
		point, err := stream.Recv()
		if err == io.EOF {
			endTime := time.Now()
			return stream.SendAndClose(&pb.RouteSummary{
				PointCount:   pointCount,
				FeatureCount: featureCount,
				Distance:     distance,
				ElapsedTime:  int32(endTime.Sub(startTime).Seconds()),
			})
		}
		if err != nil {
			return err
		}
		pointCount++
		for _, feature := range s.savedFeatures {
			if *(feature.Location) == *point {
				featureCount++
			}
		}
		if lastPoint != nil {
			distance += calcDistance(lastPoint, point)
		}
		lastPoint = point
	}
}

// RouteChat receives a stream of message/location pairs, and responds with a stream of all
// previous messages at each of those locations.
func (s *routeGuideServer) RouteChat(stream pb.RouteGuide_RouteChatServer) error {
	for {
		in, err := stream.Recv()
		if err == io.EOF {
			return nil
		}
		if err != nil {
			return err
		}
		point := *(in.Location)
		if _, present := s.routeNotes[point]; !present {
			s.routeNotes[point] = []*pb.RouteNote{in}

		} else {
			s.routeNotes[point] = append(s.routeNotes[point], in)
		}
		for _, note := range s.routeNotes[point] {
			if err := stream.Send(note); err != nil {
				return err
			}
		}
	}
}

// loadFeatures loads features from a JSON file.
func (s *routeGuideServer) loadFeatures(filePath string) {
	file, err := ioutil.ReadFile(filePath)
	if err != nil {
		log.Fatal("Failed to load default features: %v\n", err)
	}
	if err := json.Unmarshal(file, &(s.savedFeatures)); err != nil {
		log.Fatal("Failed to load default features: %v\n", err)
	}
}

func toRadians(num float64) float64 {
	return num * math.Pi / float64(180)
}

func calcDistance(p1 *pb.Point, p2 *pb.Point) int32 {
	const COORD_FACTOR float64 = 1e7
	const R float64 = float64(6371000) // metres
	lat1 := float64(p1.Latitude) / COORD_FACTOR
	lat2 := float64(p2.Latitude) / COORD_FACTOR
	lon1 := float64(p1.Longitude) / COORD_FACTOR
	lon2 := float64(p2.Longitude) / COORD_FACTOR
	φ1 := toRadians(lat1)
	φ2 := toRadians(lat2)
	Δφ := toRadians(lat2 - lat1)
	Δλ := toRadians(lon2 - lon1)

	a := math.Sin(Δφ/2)*math.Sin(Δφ/2) +
		math.Cos(φ1)*math.Cos(φ2)*
			math.Sin(Δλ/2)*math.Sin(Δλ/2)
	c := 2 * math.Atan2(math.Sqrt(a), math.Sqrt(1-a))

	distance := R * c
	return int32(distance)
}

func newServer() *routeGuideServer {
	s := new(routeGuideServer)
	s.loadFeatures(*jsonDBFile)
	s.routeNotes = make(map[pb.Point][]*pb.RouteNote, 0)
	return s
}

func main() {
	flag.Parse()
	p := strconv.Itoa(*port)
	lis, err := net.Listen("tcp", ":"+p)
	if err != nil {
		log.Fatalf("failed to listen: %v", err)
	}
	grpcServer := grpc.NewServer()
	pb.RegisterRouteGuideServer(grpcServer, newServer())
	if *useTLS {
		creds, err := credentials.NewServerTLSFromFile(*certFile, *keyFile)
		if err != nil {
			log.Fatalf("Failed to generate credentials %v", err)
		}
		grpcServer.Serve(creds.NewListener(lis))
	} else {
		grpcServer.Serve(lis)
	}
}