package webrtc

import (
	"encoding/json"
	"net/http"
	"net/http/httptest"
	"testing"

	"github.com/labstack/echo/v4"
)

// TestStatsHandler_EmptySubsystem verifies that GET /webrtc/stats returns
// a well-formed JSON body with all-zero counts when no streams or peers
// are active and no WHIP handler is linked.
func TestStatsHandler_EmptySubsystem(t *testing.T) {
	h := NewHandler(newTestSubsystem(t), 0)

	e := echo.New()
	req := httptest.NewRequest(http.MethodGet, "/webrtc/stats", nil)
	rec := httptest.NewRecorder()
	c := e.NewContext(req, rec)

	if err := h.StatsHandler(c); err != nil {
		t.Fatalf("StatsHandler returned error: %v", err)
	}
	if rec.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d: %s", rec.Code, rec.Body.String())
	}

	var stats WebRTCStats
	if err := json.Unmarshal(rec.Body.Bytes(), &stats); err != nil {
		t.Fatalf("invalid JSON: %v\nbody: %s", err, rec.Body.String())
	}
	if stats.ActiveStreams != 0 {
		t.Errorf("ActiveStreams: want 0, got %d", stats.ActiveStreams)
	}
	if stats.ActivePeers != 0 {
		t.Errorf("ActivePeers: want 0, got %d", stats.ActivePeers)
	}
	if stats.ActivePublishers != 0 {
		t.Errorf("ActivePublishers: want 0, got %d", stats.ActivePublishers)
	}
	if stats.UDPPortsInUse != 0 {
		t.Errorf("UDPPortsInUse: want 0, got %d", stats.UDPPortsInUse)
	}
}

// TestStatsHandler_WithWHIPHandler verifies that SetWHIPHandler links the
// WHIP publisher count into the stats response.
func TestStatsHandler_WithWHIPHandler(t *testing.T) {
	sub := newTestSubsystem(t)
	h := NewHandler(sub, 0)

	// Link a real WHIPHandler so that StatsHandler calls PublisherCount().
	wh := NewWHIPHandler(sub, 0)
	h.SetWHIPHandler(wh)

	e := echo.New()
	req := httptest.NewRequest(http.MethodGet, "/webrtc/stats", nil)
	rec := httptest.NewRecorder()
	c := e.NewContext(req, rec)

	if err := h.StatsHandler(c); err != nil {
		t.Fatalf("StatsHandler returned error: %v", err)
	}

	var stats WebRTCStats
	if err := json.Unmarshal(rec.Body.Bytes(), &stats); err != nil {
		t.Fatalf("invalid JSON: %v", err)
	}
	// With no active publishers the count should be 0 — validates the
	// link does not panic and that PublisherCount() is being called.
	if stats.ActivePublishers != 0 {
		t.Errorf("ActivePublishers: want 0, got %d", stats.ActivePublishers)
	}
}

// TestStatsHandler_NilSub verifies that a nil Subsystem (possible during
// early wiring) does not panic and returns zeros.
func TestStatsHandler_NilSub(t *testing.T) {
	h := NewHandler(nil, 0)

	e := echo.New()
	req := httptest.NewRequest(http.MethodGet, "/webrtc/stats", nil)
	rec := httptest.NewRecorder()
	c := e.NewContext(req, rec)

	if err := h.StatsHandler(c); err != nil {
		t.Fatalf("StatsHandler returned error: %v", err)
	}
	if rec.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d", rec.Code)
	}

	var stats WebRTCStats
	if err := json.Unmarshal(rec.Body.Bytes(), &stats); err != nil {
		t.Fatalf("invalid JSON: %v", err)
	}
	if stats.ActiveStreams != 0 || stats.UDPPortsInUse != 0 {
		t.Errorf("expected all zeros with nil sub, got %+v", stats)
	}
}

// TestStatsHandler_JSONFieldNames verifies the JSON key names match the
// contract defined in the issue so consumer scripts don't break.
func TestStatsHandler_JSONFieldNames(t *testing.T) {
	h := NewHandler(newTestSubsystem(t), 0)

	e := echo.New()
	req := httptest.NewRequest(http.MethodGet, "/webrtc/stats", nil)
	rec := httptest.NewRecorder()
	c := e.NewContext(req, rec)

	if err := h.StatsHandler(c); err != nil {
		t.Fatalf("StatsHandler returned error: %v", err)
	}

	var raw map[string]interface{}
	if err := json.Unmarshal(rec.Body.Bytes(), &raw); err != nil {
		t.Fatalf("invalid JSON: %v", err)
	}
	for _, key := range []string{"active_streams", "active_peers", "active_publishers", "udp_ports_in_use"} {
		if _, ok := raw[key]; !ok {
			t.Errorf("JSON response missing required field %q", key)
		}
	}
}