forked from GoogleCloudPlatform/golang-samples
/
main.go
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/
main.go
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// Copyright 2016 Google Inc. All rights reserved.
// Use of this source code is governed by the Apache 2.0
// license that can be found in the LICENSE file.
// Sample tictactoe implements a tic-tac-toe game using Firebase as a communication mechanism.
package tictactoe
import (
"fmt"
"html/template"
"io/ioutil"
"net/http"
"strconv"
"golang.org/x/net/context"
"google.golang.org/appengine"
"google.golang.org/appengine/datastore"
"google.golang.org/appengine/log"
"google.golang.org/appengine/user"
)
func init() {
http.HandleFunc("/", indexHandler)
http.HandleFunc("/opened", openedHandler)
http.HandleFunc("/move", moveHandler)
http.HandleFunc("/delete", deleteHandler)
}
var tmpl = template.Must(template.ParseFiles("template.html"))
func indexHandler(w http.ResponseWriter, r *http.Request) {
ctx := appengine.NewContext(r)
config, err := ioutil.ReadFile("firebase_config.html")
if err != nil {
handleError(w, r, "Could not read config file", err)
return
}
u := user.Current(ctx)
var game *Game
if gameID := r.FormValue("g"); gameID == "" {
game = NewGame()
game.K = datastore.NewKey(ctx, "Game", u.ID, 0, nil)
game.UserX = u.ID
if _, err := datastore.Put(ctx, game.K, game); err != nil {
handleError(w, r, "Could not start game", err)
return
}
} else {
// Existing game, join it.
if err := datastore.RunInTransaction(ctx, func(ctx context.Context) error {
g, err := gameFromRequest(r)
if err != nil {
return err
}
game = g
if game.UserO == "" {
game.UserO = u.ID
_, err := datastore.Put(ctx, game.K, game)
return err
}
return nil
}, nil); err != nil {
handleError(w, r, "Could not join game", err)
return
}
}
gameKey := game.K.Encode()
channelID := u.ID + gameKey
tok, err := createToken(ctx, channelID)
if err != nil {
handleError(w, r, "Could not create auth token", err)
return
}
d := struct {
GameKey string
GameLink string
Me string
Token string
ChannelID string
FirebaseConfig template.HTML
InitialMessage *Game
}{
FirebaseConfig: template.HTML(config),
Token: tok,
GameKey: gameKey,
GameLink: r.URL.Scheme + "://" + r.URL.Host + "/?g=" + gameKey,
Me: u.ID,
ChannelID: channelID,
InitialMessage: game,
}
if err := tmpl.Execute(w, d); err != nil {
handleError(w, r, "Could not execute template", err)
return
}
}
func gameFromRequest(r *http.Request) (*Game, error) {
ctx := appengine.NewContext(r)
k, err := datastore.DecodeKey(r.FormValue("g"))
if err != nil {
return nil, fmt.Errorf("invalid game ID: %v", err)
}
var g Game
if err := datastore.Get(ctx, k, &g); err != nil {
return nil, err
}
return &g, nil
}
func moveHandler(w http.ResponseWriter, r *http.Request) {
ctx := appengine.NewContext(r)
g, err := gameFromRequest(r)
if err != nil {
handleError(w, r, "Could not get game", err)
return
}
position, err := strconv.Atoi(r.FormValue("i"))
if err != nil {
handleError(w, r, "Invalid position", err)
return
}
if position < 0 || position > 8 {
handleError(w, r, "Expected position between 0 and 8", nil)
return
}
u := user.Current(ctx).ID
expectedUser := g.UserX
if !g.MoveX {
expectedUser = g.UserO
}
if u != expectedUser {
handleError(w, r, "Not your move", nil)
return
}
// Update the game board.
if err := g.MoveAt(position); err != nil {
handleError(w, r, "Could not move", err)
}
g.MoveX = !g.MoveX
if winner, isWon := g.CheckWin(); isWon {
switch winner {
case "O":
g.Winner = g.UserO
case "X":
g.Winner = g.UserX
default:
g.Winner = "No one"
}
g.WinningBoard = g.Board // TODO: implement patterns
}
if _, err := datastore.Put(ctx, g.K, g); err != nil {
handleError(w, r, "Could not save game", err)
return
}
sendUpdate(ctx, g)
}
func deleteHandler(w http.ResponseWriter, r *http.Request) {
ctx := appengine.NewContext(r)
game, err := gameFromRequest(r)
if err != nil {
handleError(w, r, "Could not get game", err)
return
}
fb, err := firebase(ctx)
if err != nil {
log.Errorf(ctx, "getFirebase: %v", err)
}
channelID := user.Current(ctx).ID + game.K.Encode()
if err := fb.Child("channels").Child(channelID).Remove(); err != nil {
handleError(w, r, "Could not delete channel", err)
return
}
log.Infof(ctx, "Deleted channel %v", channelID)
}
func openedHandler(w http.ResponseWriter, r *http.Request) {
ctx := appengine.NewContext(r)
k, err := datastore.DecodeKey(r.FormValue("g"))
if err != nil {
handleError(w, r, "Invalid game ID", err)
return
}
var g Game
if err := datastore.Get(ctx, k, &g); err != nil {
handleError(w, r, "Could not get game", err)
return
}
sendUpdate(ctx, &g)
}
func sendUpdate(ctx context.Context, g *Game) {
fb, err := firebase(ctx)
if err != nil {
log.Errorf(ctx, "getFirebase: %v", err)
}
chans := fb.Child("channels")
gameKey := g.K.Encode()
if g.UserO != "" {
channelID := g.UserO + gameKey
if err := chans.Child(channelID).Set(g); err != nil {
log.Errorf(ctx, "Updating UserO (%s): %v", channelID, err)
} else {
log.Debugf(ctx, "Update O sent.")
}
}
if g.UserX != "" {
channelID := g.UserX + gameKey
if err := chans.Child(channelID).Set(g); err != nil {
log.Errorf(ctx, "Updating UserX (%s): %v", channelID, err)
} else {
log.Debugf(ctx, "Update X sent.")
}
}
}
func handleError(w http.ResponseWriter, r *http.Request, message string, err error) {
if err != nil {
message = fmt.Sprintf("%s: %v", message, err)
}
ctx := appengine.NewContext(r)
http.Error(w, message, 500)
log.Errorf(ctx, "%s", message)
}