From cc2b54eac305d52ddd5aa309089888594e90e532 Mon Sep 17 00:00:00 2001
From: Branden J Brown <zephyrtronium@gmail.com>
Date: Fri, 26 Jan 2024 11:28:14 -0600
Subject: [PATCH] add game actor

---
 game.go | 96 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 96 insertions(+)
 create mode 100644 game.go

diff --git a/game.go b/game.go
new file mode 100644
index 0000000..9ab0f6a
--- /dev/null
+++ b/game.go
@@ -0,0 +1,96 @@
+package main
+
+import (
+	"context"
+	"errors"
+	"time"
+
+	"nhooyr.io/websocket"
+	"nhooyr.io/websocket/wsjson"
+
+	"git.sunturtle.xyz/studio/shotgun/game"
+	"git.sunturtle.xyz/studio/shotgun/player"
+)
+
+// An action is a request to change the game state.
+type action struct {
+	Action string    `json:"action"`
+	Param  string    `json:"param"`
+	Player player.ID `json:"-"`
+}
+
+// gameActor is an actor that updates a game's state and relays changes to all
+// observers.
+func gameActor(ctx context.Context, g *game.Game, dealer, chall person, join chan person) {
+	// Games should generally be on the order of minutes. A four hour game is
+	// definitely expired.
+	ctx, stop := context.WithTimeoutCause(ctx, 4*time.Hour, errGameExpired)
+	defer stop()
+	var obs []person
+	actions := make(chan action, 2)
+	go playerActor(ctx, dealer, actions)
+	go playerActor(ctx, chall, actions)
+	// TODO(zeph): send round start info
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		case p := <-join:
+			// Deliver the game state just to the new observer.
+			if err := wsjson.Write(ctx, p.conn, g.DTO(p.id)); err != nil {
+				// We don't need to track them as an observer. Just close their
+				// conn and move on.
+				go p.conn.Close(websocket.StatusNormalClosure, "looks like you dropped")
+				continue
+			}
+			obs = append(obs, p)
+			// TODO(zeph): CloseRead returns a context we can use to drop the
+			// observer when they disconnect
+			p.conn.CloseRead(ctx)
+		case a := <-actions:
+			// TODO(zeph): transform the action into a game state change
+			_ = a
+			broadcast(ctx, g, dealer, chall, obs)
+		}
+	}
+}
+
+func playerActor(ctx context.Context, p person, actions chan<- action) {
+	for {
+		a := action{Player: p.id}
+		if err := wsjson.Read(ctx, p.conn, &a); err != nil {
+			// If we fail to read, then we consider them to have quit.
+			a.Action = "quit"
+			select {
+			case <-ctx.Done():
+			case actions <- a:
+			}
+			return
+		}
+		select {
+		case <-ctx.Done():
+			return
+		case actions <- a:
+		}
+	}
+}
+
+func broadcast(ctx context.Context, g *game.Game, dealer, chall person, obs []person) {
+	// TODO(zeph): this probably should return an error or some other signal
+	// if a player drops so that the actor knows to quit
+	if err := wsjson.Write(ctx, dealer.conn, g.DTO(dealer.id)); err != nil {
+		// TODO(zeph): concede, but we need to be careful not to recurse
+		// TODO(zeph): log
+	}
+	if err := wsjson.Write(ctx, chall.conn, g.DTO(chall.id)); err != nil {
+		// TODO(zeph): concede, but we need to be careful not to recurse
+		// TODO(zeph): log
+	}
+	for _, p := range obs {
+		if err := wsjson.Write(ctx, p.conn, g.DTO(p.id)); err != nil {
+			// TODO(zeph): log
+		}
+	}
+}
+
+var errGameExpired = errors.New("there is a time limit on games please")