feat(backend): implement HTTP API, auth, chat, and admin surfaces

Expose learning, registration controls, mentor chat, realtime WebSocket, and staff administration.

backend/internal/api/rate_limit_test.go

@@ -0,0 +1,104 @@
+package api_test
+
+import (
+	"encoding/json"
+	"net/http"
+	"testing"
+
+	"pargar/backend/internal/api"
+)
+
+func TestGlobalAPIRateLimit(t *testing.T) {
+	e := setup(t)
+	prev := api.SetAPIGlobalLimitForTest(5)
+	t.Cleanup(func() { api.SetAPIGlobalLimitForTest(prev) })
+
+	hitLimit := false
+	var retryAfter string
+	for i := 0; i < 12; i++ {
+		req, _ := http.NewRequest("GET", e.server.URL+"/api/auth/register-status", nil)
+		req.Header.Set("X-Forwarded-For", "198.51.100.50")
+		resp, err := http.DefaultClient.Do(req)
+		if err != nil {
+			t.Fatalf("request: %v", err)
+		}
+		var body map[string]any
+		_ = json.NewDecoder(resp.Body).Decode(&body)
+		_ = resp.Body.Close()
+
+		if resp.StatusCode == http.StatusTooManyRequests {
+			if body["error"] != "تعداد درخواست‌ها زیاد است؛ لطفاً کمی صبر کنید" {
+				t.Fatalf("unexpected message: %v", body)
+			}
+			retryAfter = resp.Header.Get("Retry-After")
+			if retryAfter == "" {
+				t.Fatal("expected Retry-After header")
+			}
+			hitLimit = true
+			break
+		}
+		if resp.StatusCode != http.StatusOK {
+			t.Fatalf("request %d: expected 200 or 429, got %d %v", i+1, resp.StatusCode, body)
+		}
+	}
+	if !hitLimit {
+		t.Fatal("expected global API rate limit")
+	}
+
+	// Health must stay excluded from the global bucket (docker probes).
+	for i := 0; i < 20; i++ {
+		req, _ := http.NewRequest("GET", e.server.URL+"/api/health", nil)
+		req.Header.Set("X-Forwarded-For", "198.51.100.50")
+		resp, err := http.DefaultClient.Do(req)
+		if err != nil {
+			t.Fatalf("health: %v", err)
+		}
+		_ = resp.Body.Close()
+		if resp.StatusCode != http.StatusOK {
+			t.Fatalf("health must not be rate-limited, got %d", resp.StatusCode)
+		}
+	}
+
+	// A different IP still has budget — proves the limit is per-IP, not global process-wide.
+	code, body := e.doHeaders(t, "GET", "/api/auth/register-status", "", map[string]string{
+		"X-Forwarded-For": "198.51.100.51",
+	}, nil)
+	if code != http.StatusOK {
+		t.Fatalf("other IP should succeed, got %d %v", code, body)
+	}
+}
+
+func TestGlobalRateLimitDoesNotClearAuthTokens(t *testing.T) {
+	e := setup(t)
+	token := login(t, e, bootstrapAdminEmail)
+
+	prev := api.SetAPIGlobalLimitForTest(3)
+	t.Cleanup(func() { api.SetAPIGlobalLimitForTest(prev) })
+
+	// Burn the budget with authenticated calls from a fixed IP.
+	for i := 0; i < 8; i++ {
+		req, _ := http.NewRequest("GET", e.server.URL+"/api/auth/me", nil)
+		req.Header.Set("Authorization", "Bearer "+token)
+		req.Header.Set("X-Forwarded-For", "203.0.113.90")
+		resp, err := http.DefaultClient.Do(req)
+		if err != nil {
+			t.Fatalf("me: %v", err)
+		}
+		_ = resp.Body.Close()
+		if resp.StatusCode == http.StatusTooManyRequests {
+			break
+		}
+	}
+
+	// After 429, the same token must still authenticate once the counter is cleared —
+	// proving 429 did not revoke the session server-side.
+	if err := e.rdb.FlushDB(t.Context()).Err(); err != nil {
+		t.Fatalf("flush: %v", err)
+	}
+	code, body := e.doHeaders(t, "GET", "/api/auth/me", token, map[string]string{
+		"X-Forwarded-For": "203.0.113.90",
+	}, nil)
+	if code != http.StatusOK {
+		t.Fatalf("token should still work after rate limit, got %d %v", code, body)
+	}
+}