feat: add streak reward and 100-achievement milestone system

backend/tests/achievement_service_test.cc

@@ -0,0 +1,108 @@
+#include <catch2/catch_test_macros.hpp>
+
+#include "csp/db/sqlite_db.h"
+#include "csp/services/achievement_service.h"
+#include "csp/services/auth_service.h"
+#include "csp/services/user_service.h"
+
+#include <sqlite3.h>
+
+#include <cstdint>
+#include <stdexcept>
+#include <string>
+
+namespace {
+
+void CheckSqlite(int rc, sqlite3* db, const char* what) {
+  if (rc == SQLITE_OK || rc == SQLITE_ROW || rc == SQLITE_DONE) return;
+  throw std::runtime_error(std::string(what) + ": " + sqlite3_errmsg(db));
+}
+
+int64_t InsertProblem(sqlite3* db, const std::string& slug, int64_t created_at) {
+  sqlite3_stmt* stmt = nullptr;
+  const char* sql =
+      "INSERT INTO problems(slug,title,statement_md,difficulty,source,created_at) "
+      "VALUES(?,?,?,?,?,?)";
+  CheckSqlite(sqlite3_prepare_v2(db, sql, -1, &stmt, nullptr), db,
+              "prepare insert problem");
+  CheckSqlite(sqlite3_bind_text(stmt, 1, slug.c_str(), -1, SQLITE_TRANSIENT), db,
+              "bind slug");
+  CheckSqlite(sqlite3_bind_text(stmt, 2, slug.c_str(), -1, SQLITE_TRANSIENT), db,
+              "bind title");
+  CheckSqlite(sqlite3_bind_text(stmt, 3, "stub", -1, SQLITE_STATIC), db,
+              "bind statement");
+  CheckSqlite(sqlite3_bind_int(stmt, 4, 1), db, "bind difficulty");
+  CheckSqlite(sqlite3_bind_text(stmt, 5, "test", -1, SQLITE_STATIC), db,
+              "bind source");
+  CheckSqlite(sqlite3_bind_int64(stmt, 6, created_at), db, "bind created_at");
+  CheckSqlite(sqlite3_step(stmt), db, "insert problem");
+  sqlite3_finalize(stmt);
+  return sqlite3_last_insert_rowid(db);
+}
+
+void InsertSubmission(sqlite3* db, int64_t user_id, int64_t problem_id,
+                      int64_t created_at) {
+  sqlite3_stmt* stmt = nullptr;
+  const char* sql =
+      "INSERT INTO submissions(user_id,problem_id,language,code,status,score,time_ms,memory_kb,created_at) "
+      "VALUES(?,?,?,?,?,?,?,?,?)";
+  CheckSqlite(sqlite3_prepare_v2(db, sql, -1, &stmt, nullptr), db,
+              "prepare insert submission");
+  CheckSqlite(sqlite3_bind_int64(stmt, 1, user_id), db, "bind user_id");
+  CheckSqlite(sqlite3_bind_int64(stmt, 2, problem_id), db, "bind problem_id");
+  CheckSqlite(sqlite3_bind_text(stmt, 3, "cpp", -1, SQLITE_STATIC), db,
+              "bind language");
+  CheckSqlite(sqlite3_bind_text(stmt, 4, "int main(){return 0;}", -1, SQLITE_STATIC),
+              db, "bind code");
+  CheckSqlite(sqlite3_bind_text(stmt, 5, "AC", -1, SQLITE_STATIC), db,
+              "bind status");
+  CheckSqlite(sqlite3_bind_int(stmt, 6, 100), db, "bind score");
+  CheckSqlite(sqlite3_bind_int(stmt, 7, 1), db, "bind time");
+  CheckSqlite(sqlite3_bind_int(stmt, 8, 1), db, "bind memory");
+  CheckSqlite(sqlite3_bind_int64(stmt, 9, created_at), db, "bind created_at");
+  CheckSqlite(sqlite3_step(stmt), db, "insert submission");
+  sqlite3_finalize(stmt);
+}
+
+}  // namespace
+
+TEST_CASE("achievement snapshot grants milestone bonus once per milestone") {
+  auto db = csp::db::SqliteDb::OpenMemory();
+  csp::db::ApplyMigrations(db);
+
+  csp::services::AuthService auth(db);
+  const auto login = auth.Register("achievement_user", "password123");
+  csp::services::UserService users(db);
+  csp::services::AchievementService achievements(db);
+
+  sqlite3* raw = db.raw();
+  int64_t now = 1700000000;
+  for (int i = 0; i < 40; ++i) {
+    const auto pid = InsertProblem(raw, "ach-test-" + std::to_string(i + 1), now + i);
+    InsertSubmission(raw, login.user_id, pid, now + i);
+  }
+
+  const auto before = users.GetById(login.user_id);
+  REQUIRE(before.has_value());
+  REQUIRE(before->rating == 1);  // register triggers one login_checkin reward
+
+  const auto snap1 = achievements.GetSnapshot(login.user_id);
+  REQUIRE(snap1.items.size() == 100);
+  REQUIRE(snap1.summary.total_count == 100);
+  REQUIRE(snap1.summary.completed_count >= 10);
+  REQUIRE(snap1.summary.bonus_milestones_added_now >= 1);
+  REQUIRE(snap1.summary.bonus_rating_added_now ==
+          snap1.summary.bonus_milestones_added_now * 20);
+
+  const auto after_first = users.GetById(login.user_id);
+  REQUIRE(after_first.has_value());
+  REQUIRE(after_first->rating == before->rating + snap1.summary.bonus_rating_added_now);
+
+  const auto snap2 = achievements.GetSnapshot(login.user_id);
+  REQUIRE(snap2.summary.bonus_milestones_added_now == 0);
+  REQUIRE(snap2.summary.bonus_rating_added_now == 0);
+
+  const auto after_second = users.GetById(login.user_id);
+  REQUIRE(after_second.has_value());
+  REQUIRE(after_second->rating == after_first->rating);
+}