package webrtc

import (
	"testing"

	"github.com/pion/webrtc/v4"
)

func TestBuildICEConfig_Defaults(t *testing.T) {
	c := DefaultConfig()
	rtcConfig, _, err := BuildICEConfig(c)
	if err != nil {
		t.Fatalf("BuildICEConfig: %v", err)
	}
	if len(rtcConfig.ICEServers) == 0 {
		t.Error("ICEServers should not be empty")
	}
	// First default is Cloudflare STUN.
	if rtcConfig.ICEServers[0].URLs[0] != "stun:stun.cloudflare.com:3478" {
		t.Errorf("first ICE server = %q, want stun:stun.cloudflare.com:3478",
			rtcConfig.ICEServers[0].URLs[0])
	}
}

func TestBuildICEConfig_PublicIP(t *testing.T) {
	c := DefaultConfig()
	c.PublicIP = "203.0.113.10"
	_, se, err := BuildICEConfig(c)
	if err != nil {
		t.Fatalf("BuildICEConfig: %v", err)
	}
	if se == nil {
		t.Fatal("SettingEngine should not be nil when PublicIP is set")
	}
	// We can't introspect NAT1To1IPs directly from Pion's public API; the
	// smoke test is that building an API from this engine works.
	api := webrtc.NewAPI(webrtc.WithSettingEngine(*se))
	if api == nil {
		t.Fatal("NewAPI returned nil")
	}
}

func TestBuildICEConfig_InvalidConfig(t *testing.T) {
	c := DefaultConfig()
	c.WHEPListen = ""
	_, _, err := BuildICEConfig(c)
	if err == nil {
		t.Error("BuildICEConfig should reject invalid config")
	}
}

// TestBuildICEConfig_NAT1To1IPs_Multi verifies that a list of multiple
// NAT1To1 IPs is accepted and a SettingEngine is returned, allowing
// dual-homed servers to advertise host candidates on all interfaces.
func TestBuildICEConfig_NAT1To1IPs_Multi(t *testing.T) {
	c := DefaultConfig()
	c.NAT1To1IPs = []string{"10.0.0.1", "203.0.113.10"}
	_, se, err := BuildICEConfig(c)
	if err != nil {
		t.Fatalf("BuildICEConfig with multiple NAT1To1IPs: %v", err)
	}
	if se == nil {
		t.Fatal("SettingEngine should not be nil when NAT1To1IPs is set")
	}
	// Smoke-test: Pion should accept the engine without panicking.
	api := webrtc.NewAPI(webrtc.WithSettingEngine(*se))
	if api == nil {
		t.Fatal("NewAPI returned nil")
	}
}

// TestBuildICEConfig_NAT1To1IPs_FallsBackToPublicIP verifies that when
// NAT1To1IPs is empty but PublicIP is set, the single IP is promoted to
// the NAT1To1 list (backward-compat path).
func TestBuildICEConfig_NAT1To1IPs_FallsBackToPublicIP(t *testing.T) {
	c := DefaultConfig()
	c.PublicIP = "198.51.100.1"
	c.NAT1To1IPs = nil
	_, se, err := BuildICEConfig(c)
	if err != nil {
		t.Fatalf("BuildICEConfig (PublicIP fallback): %v", err)
	}
	if se == nil {
		t.Fatal("SettingEngine should be set when PublicIP is used as fallback")
	}
}

// TestBuildICEConfig_NAT1To1IPs_TakesPrecedenceOverPublicIP verifies that
// when both NAT1To1IPs and PublicIP are set, a SettingEngine is still
// returned (the subsystem merges them; BuildICEConfig sees only NAT1To1IPs).
func TestBuildICEConfig_NAT1To1IPs_TakesPrecedenceOverPublicIP(t *testing.T) {
	c := DefaultConfig()
	c.PublicIP = "198.51.100.1"
	c.NAT1To1IPs = []string{"10.0.0.1", "198.51.100.1"}
	_, se, err := BuildICEConfig(c)
	if err != nil {
		t.Fatalf("BuildICEConfig (NAT1To1IPs + PublicIP): %v", err)
	}
	if se == nil {
		t.Fatal("SettingEngine should not be nil when NAT1To1IPs is set")
	}
}

// TestBuildICEConfig_NAT1To1IPs_NeitherSet verifies that with no IP hints
// the function still succeeds (STUN-only mode). A SettingEngine is still
// returned because the default UDPPortRange is non-zero.
func TestBuildICEConfig_NAT1To1IPs_NeitherSet(t *testing.T) {
	c := DefaultConfig()
	c.PublicIP = ""
	c.NAT1To1IPs = nil
	_, se, err := BuildICEConfig(c)
	if err != nil {
		t.Fatalf("BuildICEConfig (STUN-only): %v", err)
	}
	// UDPPortRange.Low > 0 in DefaultConfig, so se is non-nil; verify it
	// builds without error.
	if se != nil {
		api := webrtc.NewAPI(webrtc.WithSettingEngine(*se))
		if api == nil {
			t.Fatal("NewAPI returned nil in STUN-only mode")
		}
	}
}