client/robot.go

package botclient

import (
	"encoding/gob"
	"encoding/json"
	"errors"
	"fmt"
	"log"
	"math"
	"math/rand"
	"sync"

	"bitbucket.org/hackerbots/botserv"
	"bitbucket.org/hackerbots/vector"
	"code.google.com/p/go.net/websocket"
)

const maxSpeed = 100
const safeDistance = 40
const maxSearchIterations = 20

func connect(server string, port int) (*websocket.Conn, error) {
	origin := "http://localhost/"
	url := fmt.Sprintf("ws://%s:%d/ws/", server, port)
	return websocket.Dial(url, "", origin)
}

type Robot struct {
	verbose         bool
	forceJSON       bool
	Server          string
	Port            int
	ws              *websocket.Conn
	game            botserv.GameParam
	playerId        string
	Name            string
	GameName        string
	StatsReq        botserv.StatsRequest
	statsCalculated botserv.Stats

	speed          float32
	moveto         *govector.Point2d
	fireat         *govector.Point2d
	boardstate     botserv.Boardstate
	me             botserv.Robot
	KnownObstacles map[string]botserv.Obstacle
	nearestEnemy   *botserv.OtherRobot

	// TODO: don't know if I like how this is done ... I would rather send
	// a signal over a chanel
	Wg *sync.WaitGroup
}

type encoder interface {
	Encode(v interface{}) error
}

type decoder interface {
	Decode(v interface{}) error
}

func (r *Robot) negociate() (err error) {
	if r.verbose {
		log.Printf("%s: trying to connect to game '%s'", r.Name, r.GameName)
	}
	r.ws, err = connect(r.Server, r.Port)
	if err != nil {
		return errors.New(fmt.Sprintf("connection failure: %s", err))
	}

	err = websocket.JSON.Send(r.ws, struct {
		Id string `json:"id"`
	}{
		r.GameName,
	})
	if err != nil {
		return err
	}

	var idreq struct {
		Type     string `json:"type"`
		PlayerId string `json:"id"`
	}
	err = websocket.JSON.Receive(r.ws, &idreq)
	if err != nil || idreq.Type == "failure" {
		return errors.New(fmt.Sprintf("failure: %+v", idreq))
	}
	if r.verbose {
		log.Printf("%s: idreq: %+v", r.Name, idreq)
	}

	err = websocket.JSON.Send(r.ws, struct {
		Type      string `json:"type"`
		Name      string `json:"name"`
		Useragent string `json:"useragent"`
	}{
		Name:      r.Name,
		Useragent: "gobot",
		Type:      "robot",
	})
	if err != nil {
		return err
	}

	supportedEncs := []string{"bson", "json", "gob"}
	if r.forceJSON {
		supportedEncs = []string{"json"}
	}
	err = websocket.JSON.Send(r.ws, supportedEncs)
	if err != nil {
		return errors.New(fmt.Sprintf("failure: %+v", err))
	}

	err = websocket.JSON.Receive(r.ws, &r.game)
	if r.game.Type != "gameparam" {
		return errors.New("didn't receive a good gameparam")
	}
	if r.verbose {
		log.Printf("%s: game parameters: %+v", r.Name, r.game)
	}

	conf := botserv.ClientConfig{
		ID: r.GameName,
		Stats: map[string]botserv.StatsRequest{
			r.Name: r.StatsReq,
		},
	}

	err = websocket.JSON.Send(r.ws, conf)

	var handshake struct {
		Id      string `json:"id"`
		Success bool   `json:"success"`
		Type    string `json:"type"`
		botserv.Failure
	}
	websocket.JSON.Receive(r.ws, &handshake)
	if !handshake.Success {
		return errors.New(handshake.Reason)
	}
	r.playerId = handshake.Id
	if r.verbose {
		log.Printf("%s: handshake: %+v", r.Name, handshake)
	}

	dstats := struct {
		Stats map[string]botserv.Stats `json:"stats"`
		Type  string                   `json:"type"`
	}{}
	err = websocket.JSON.Receive(r.ws, &dstats)
	if err != nil {
		return err
	}
	log.Printf("%s: recv stats", r.Name)

	// this player only ever has one robot, so we're just picking off our own
	// stats
	_, ok := dstats.Stats[r.Name]
	if !ok {
		return errors.New("my name not found in stats map")
	}
	r.statsCalculated = dstats.Stats[r.Name]

	return nil
}

func (r *Robot) Play() {
	defer r.Wg.Done()
	var err error
	err = r.negociate()
	if err != nil {
		log.Printf("%s: failed to negociate: %s", r.Name, err)
		return
	}

	log.Printf("%s: starting loop", r.Name)

	var enc encoder
	var dec decoder

	if r.game.Encoding == "json" {
		enc = json.NewEncoder(r.ws)
		dec = json.NewDecoder(r.ws)
	} else {
		enc = gob.NewEncoder(r.ws)
		dec = gob.NewDecoder(r.ws)
	}

	for {
		r.speed = float32(maxSpeed)
		if r.verbose {
			log.Printf("%s: about to wait on boardstate", r.Name)
		}
		err = dec.Decode(&r.boardstate)
		if err != nil {
			log.Printf("%s: Connection lost", r.Name)
			return
		}
		if r.verbose {
			log.Printf("%s: one recv boardstate", r.Name)
		}
		// TODO: I need a truly-verbose flag?
		// if r.verbose {
		// 	log.Printf("\n\n%#v\n\n", r.boardstate)
		// }

		r.recon()

		if len(r.boardstate.MyRobots) > 0 {
			r.me = r.boardstate.MyRobots[0]
		} else {
			continue
		}

		if r.verbose {
			log.Printf("%s before: %+v", r.Name, r.moveto)
		}
		r.navigate()
		if r.verbose {
			log.Printf("%s after: %+v", r.Name, r.moveto)
		}

		instruction := map[string]botserv.Instruction{
			r.me.Id: {
				MoveTo:      r.moveto,
				TargetSpeed: &r.speed,
				FireAt:      r.fireat,
			},
		}
		err = enc.Encode(instruction)
		if err != nil {
			log.Println(err)
			return
		}
	}
}

func (r *Robot) recon() {
	for _, o := range r.boardstate.Objects {
		obj := MiniObstacle(o)
		if _, ok := r.KnownObstacles[obj.id()]; !ok {
			r.KnownObstacles[obj.id()] = obj.toObstacle()
		}
	}

	// simplest shooting strategy ... need to do the following:
	// not shoot through buildings
	// shoot at where the robot will be, not where it was.
	r.nearestEnemy = nil
	r.fireat = nil
	closest := float32(math.Inf(1))
	for _, enemy := range r.boardstate.OtherRobots {
		dist := r.me.Position.Sub(enemy.Position).Mag()
		if dist < closest && dist > safeDistance {
			r.nearestEnemy = &enemy
		}
	}
	if r.nearestEnemy != nil {
		point := r.nearestEnemy.Position.Add(r.nearestEnemy.Heading.Scale(safeDistance))
		r.fireat = &point
	}
}

func (r *Robot) randomDirection() *govector.Point2d {
	p := govector.Vector2d{
		X: rand.Float32() * r.game.BoardSize.Width,
		Y: rand.Float32() * r.game.BoardSize.Height,
	}.ToPoint()
	return &p
}

func (r *Robot) probe(destination govector.Point2d) bool {
	// XXX: make test for this
	for _, v := range r.KnownObstacles {
		collided, _, _ := govector.RectIntersection(
			v.Bounds,
			r.me.Position,
			destination.Sub(r.me.Position),
		)
		if collided {
			return false
		}
	}
	return true
}

func (r *Robot) navigate() {

	if r.moveto == nil {
		if r.verbose {
			log.Printf("%s: nil", r.Name)
		}
		r.moveto = r.randomDirection()
	}

	togo := r.me.Position.Sub(*r.moveto).Mag()
	if togo < safeDistance+5 {
		if r.verbose {
			log.Printf("%s got to destination", r.Name)
		}
		r.moveto = r.randomDirection()
		return
	}
	if !r.probe(r.me.Position.Add(r.me.Heading.Scale(safeDistance))) {
		if r.verbose {
			log.Printf("%s going to run into something", r.Name)
		}
		r.speed = 0
		if !r.probe(*r.moveto) {
			if r.verbose {
				log.Printf("%s unsafe to move, choose new direction", r.Name)
			}
			r.moveto = r.randomDirection()
			return
		}
	}
	if r.me.Collision != nil {
		// XXX: I am being told I am here ...
		if r.verbose {
			log.Printf("%s apparent collision: %#v", r.Name, r.me.Collision)
		}
		r.moveto = r.randomDirection()
		r.speed = 0
		return
	}
}