From 2250cb0a8f01bc9e704de150e316d01e80a08dd3 Mon Sep 17 00:00:00 2001
From: Zac Gaetano <zgaetano@wilddragon.net>
Date: Fri, 17 Apr 2026 08:44:30 -0400
Subject: [PATCH] feat(webrtc): add Config with defaults and validation

---
 core/webrtc/config.go      | 59 ++++++++++++++++++++++++++++++++++++++
 core/webrtc/config_test.go | 48 +++++++++++++++++++++++++++++++
 2 files changed, 107 insertions(+)
 create mode 100644 core/webrtc/config.go
 create mode 100644 core/webrtc/config_test.go

diff --git a/core/webrtc/config.go b/core/webrtc/config.go
new file mode 100644
index 0000000..521e009
--- /dev/null
+++ b/core/webrtc/config.go
@@ -0,0 +1,59 @@
+package webrtc
+
+import "fmt"
+
+// PortRange represents an inclusive UDP port range.
+type PortRange struct {
+	Low, High int
+}
+
+// Config controls the WebRTC egress module.
+type Config struct {
+	// Enabled toggles the entire module. When false, no endpoints are served.
+	Enabled bool
+
+	// WHEPListen is the address the WHEP HTTP endpoint binds to (e.g. ":8787").
+	WHEPListen string
+
+	// PublicIP is the server's externally-reachable IP, advertised in ICE
+	// candidates via NAT1To1. Empty means rely on STUN discovery.
+	PublicIP string
+
+	// UDPPortRange bounds the local UDP ports allocated for FFmpeg→Pion RTP.
+	UDPPortRange PortRange
+
+	// ICEServers is the list of STUN/TURN URIs given to each PeerConnection.
+	ICEServers []string
+
+	// MaxPeersTotal is a hard safety cap on concurrent subscribers.
+	MaxPeersTotal int
+}
+
+// DefaultConfig returns production-reasonable defaults.
+func DefaultConfig() Config {
+	return Config{
+		Enabled:       true,
+		WHEPListen:    ":8787",
+		PublicIP:      "",
+		UDPPortRange:  PortRange{Low: 10000, High: 10100},
+		ICEServers:    []string{"stun:stun.cloudflare.com:3478", "stun:stun.l.google.com:19302"},
+		MaxPeersTotal: 32,
+	}
+}
+
+// Validate returns an error if the config is internally inconsistent.
+func (c Config) Validate() error {
+	if c.WHEPListen == "" {
+		return fmt.Errorf("webrtc: WHEPListen must not be empty")
+	}
+	if c.UDPPortRange.Low <= 0 || c.UDPPortRange.High <= 0 {
+		return fmt.Errorf("webrtc: UDPPortRange must have positive bounds, got %v", c.UDPPortRange)
+	}
+	if c.UDPPortRange.Low > c.UDPPortRange.High {
+		return fmt.Errorf("webrtc: UDPPortRange.Low > High (%d > %d)", c.UDPPortRange.Low, c.UDPPortRange.High)
+	}
+	if c.MaxPeersTotal <= 0 {
+		return fmt.Errorf("webrtc: MaxPeersTotal must be positive, got %d", c.MaxPeersTotal)
+	}
+	return nil
+}
diff --git a/core/webrtc/config_test.go b/core/webrtc/config_test.go
new file mode 100644
index 0000000..95bb5f7
--- /dev/null
+++ b/core/webrtc/config_test.go
@@ -0,0 +1,48 @@
+package webrtc
+
+import (
+	"testing"
+)
+
+func TestConfig_Defaults(t *testing.T) {
+	c := DefaultConfig()
+	if !c.Enabled {
+		t.Error("default Enabled should be true")
+	}
+	if c.WHEPListen != ":8787" {
+		t.Errorf("default WHEPListen = %q, want :8787", c.WHEPListen)
+	}
+	if c.UDPPortRange.Low != 10000 || c.UDPPortRange.High != 10100 {
+		t.Errorf("default UDPPortRange = %v, want 10000-10100", c.UDPPortRange)
+	}
+	if c.MaxPeersTotal != 32 {
+		t.Errorf("default MaxPeersTotal = %d, want 32", c.MaxPeersTotal)
+	}
+	if len(c.ICEServers) == 0 {
+		t.Error("default ICEServers should have at least one STUN entry")
+	}
+}
+
+func TestConfig_Validate(t *testing.T) {
+	tests := []struct {
+		name    string
+		mutate  func(*Config)
+		wantErr bool
+	}{
+		{"defaults are valid", func(c *Config) {}, false},
+		{"empty listen", func(c *Config) { c.WHEPListen = "" }, true},
+		{"inverted port range", func(c *Config) { c.UDPPortRange.Low = 20000; c.UDPPortRange.High = 10000 }, true},
+		{"zero max peers", func(c *Config) { c.MaxPeersTotal = 0 }, true},
+		{"negative max peers", func(c *Config) { c.MaxPeersTotal = -1 }, true},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			c := DefaultConfig()
+			tt.mutate(&c)
+			err := c.Validate()
+			if (err != nil) != tt.wantErr {
+				t.Errorf("Validate() err = %v, wantErr %v", err, tt.wantErr)
+			}
+		})
+	}
+}