From 79161ce5df2e7f96b95412bfdf4c36ef85ef8023 Mon Sep 17 00:00:00 2001
From: Sam Rose <samwho@lbak.co.uk>
Date: Tue, 23 Jul 2019 11:14:48 +0100
Subject: [PATCH] Make actions track their active contexts.

---
 action.go | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++
 client.go |  9 +++------
 2 files changed, 54 insertions(+), 6 deletions(-)

diff --git a/action.go b/action.go
index af3b177..5b7e2a7 100644
--- a/action.go
+++ b/action.go
@@ -1,10 +1,61 @@
 package streamdeck
 
+import (
+	"context"
+
+	sdcontext "github.com/samwho/streamdeck/context"
+)
+
 type Action struct {
 	uuid     string
 	handlers map[string][]EventHandler
+	contexts map[string]context.Context
+}
+
+func newAction(uuid string) *Action {
+	action := &Action{
+		uuid:     uuid,
+		handlers: make(map[string][]EventHandler),
+		contexts: make(map[string]context.Context),
+	}
+
+	action.RegisterHandler(WillAppear, func(ctx context.Context, client *Client, event Event) error {
+		action.addContext(ctx)
+		return nil
+	})
+
+	action.RegisterHandler(WillDisappear, func(ctx context.Context, client *Client, event Event) error {
+		action.removeContext(ctx)
+		return nil
+	})
+
+	return action
 }
 
 func (action *Action) RegisterHandler(eventName string, handler EventHandler) {
 	action.handlers[eventName] = append(action.handlers[eventName], handler)
 }
+
+func (action *Action) Contexts() []context.Context {
+	cs := make([]context.Context, len(action.contexts))
+	for _, c := range action.contexts {
+		cs = append(cs, c)
+	}
+	return cs
+}
+
+func (action *Action) addContext(ctx context.Context) {
+	if sdcontext.Context(ctx) == "" {
+		panic("passed non-streamdeck context to addContext")
+	}
+
+	action.contexts[sdcontext.Context(ctx)] = ctx
+}
+
+func (action *Action) removeContext(ctx context.Context) {
+	if sdcontext.Context(ctx) == "" {
+		panic("passed non-streamdeck context to addContext")
+	}
+
+	delete(action.contexts, sdcontext.Context(ctx))
+}
diff --git a/client.go b/client.go
index 0ed0674..118ff72 100644
--- a/client.go
+++ b/client.go
@@ -36,10 +36,7 @@ func NewClient(ctx context.Context, params RegistrationParams) *Client {
 func (client *Client) Action(uuid string) *Action {
 	_, ok := client.actions[uuid]
 	if !ok {
-		client.actions[uuid] = &Action{
-			uuid:     uuid,
-			handlers: make(map[string][]EventHandler),
-		}
+		client.actions[uuid] = newAction(uuid)
 	}
 	return client.actions[uuid]
 }
@@ -99,8 +96,8 @@ func (client *Client) Run() error {
 
 			action, ok := client.actions[event.Action]
 			if !ok {
-				log.Printf("received event for nonexistent action: %v\n", event.Action)
-				continue
+				action = client.Action(event.Action)
+				action.addContext(ctx)
 			}
 
 			for _, f := range action.handlers[event.Event] {