feat: add streak reward and 100-achievement milestone system

backend/tests/daily_task_service_test.cc

@@ -5,6 +5,130 @@
 #include "csp/services/daily_task_service.h"
 #include "csp/services/user_service.h"
 
+#include <sqlite3.h>
+
+#include <array>
+#include <optional>
+#include <sstream>
+#include <stdexcept>
+#include <string>
+#include <tuple>
+
+namespace {
+
+int CivilToDays(int year, unsigned month, unsigned day) {
+  year -= month <= 2 ? 1 : 0;
+  const int era = (year >= 0 ? year : year - 399) / 400;
+  const unsigned yoe = static_cast<unsigned>(year - era * 400);
+  const unsigned doy =
+      (153 * (month + (month > 2 ? -3 : 9)) + 2) / 5 + day - 1;
+  const unsigned doe = yoe * 365 + yoe / 4 - yoe / 100 + doy;
+  return era * 146097 + static_cast<int>(doe) - 719468;
+}
+
+std::tuple<int, unsigned, unsigned> DaysToCivil(int z) {
+  z += 719468;
+  const int era = (z >= 0 ? z : z - 146096) / 146097;
+  const unsigned doe = static_cast<unsigned>(z - era * 146097);
+  const unsigned yoe = (doe - doe / 1460 + doe / 36524 - doe / 146096) / 365;
+  int year = static_cast<int>(yoe) + era * 400;
+  const unsigned doy = doe - (365 * yoe + yoe / 4 - yoe / 100);
+  const unsigned mp = (5 * doy + 2) / 153;
+  const unsigned day = doy - (153 * mp + 2) / 5 + 1;
+  const unsigned month = mp < 10 ? mp + 3 : mp - 9;
+  year += month <= 2 ? 1 : 0;
+  return {year, month, day};
+}
+
+std::optional<int> DaySerialFromKey(const std::string& day_key) {
+  if (day_key.size() != 10 || day_key[4] != '-' || day_key[7] != '-') {
+    return std::nullopt;
+  }
+  try {
+    const int year = std::stoi(day_key.substr(0, 4));
+    const int month = std::stoi(day_key.substr(5, 2));
+    const int day = std::stoi(day_key.substr(8, 2));
+    if (month < 1 || month > 12 || day < 1 || day > 31) return std::nullopt;
+    return CivilToDays(year, static_cast<unsigned>(month),
+                       static_cast<unsigned>(day));
+  } catch (...) {
+    return std::nullopt;
+  }
+}
+
+std::string ShiftDayKey(const std::string& day_key, int delta_days) {
+  const auto serial = DaySerialFromKey(day_key);
+  REQUIRE(serial.has_value());
+  const auto [year, month, day] = DaysToCivil(*serial + delta_days);
+  std::ostringstream out;
+  out << year << '-';
+  if (month < 10) out << '0';
+  out << month << '-';
+  if (day < 10) out << '0';
+  out << day;
+  return out.str();
+}
+
+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));
+}
+
+void InsertDailyTaskLog(sqlite3* db, int64_t user_id, const std::string& task_code,
+                        const std::string& day_key, int reward, int64_t created_at) {
+  sqlite3_stmt* stmt = nullptr;
+  const char* sql =
+      "INSERT INTO daily_task_logs(user_id,task_code,day_key,reward,created_at) "
+      "VALUES(?,?,?,?,?)";
+  CheckSqlite(sqlite3_prepare_v2(db, sql, -1, &stmt, nullptr), db,
+              "prepare insert daily_task_logs");
+  CheckSqlite(sqlite3_bind_int64(stmt, 1, user_id), db, "bind user_id");
+  CheckSqlite(sqlite3_bind_text(stmt, 2, task_code.c_str(), -1, SQLITE_TRANSIENT),
+              db, "bind task_code");
+  CheckSqlite(sqlite3_bind_text(stmt, 3, day_key.c_str(), -1, SQLITE_TRANSIENT),
+              db, "bind day_key");
+  CheckSqlite(sqlite3_bind_int(stmt, 4, reward), db, "bind reward");
+  CheckSqlite(sqlite3_bind_int64(stmt, 5, created_at), db, "bind created_at");
+  CheckSqlite(sqlite3_step(stmt), db, "insert daily_task_logs");
+  sqlite3_finalize(stmt);
+}
+
+void DeleteDailyTaskLog(sqlite3* db, int64_t user_id, const std::string& task_code,
+                        const std::string& day_key) {
+  sqlite3_stmt* stmt = nullptr;
+  const char* sql =
+      "DELETE FROM daily_task_logs WHERE user_id=? AND task_code=? AND day_key=?";
+  CheckSqlite(sqlite3_prepare_v2(db, sql, -1, &stmt, nullptr), db,
+              "prepare delete daily_task_logs");
+  CheckSqlite(sqlite3_bind_int64(stmt, 1, user_id), db, "bind user_id");
+  CheckSqlite(sqlite3_bind_text(stmt, 2, task_code.c_str(), -1, SQLITE_TRANSIENT),
+              db, "bind task_code");
+  CheckSqlite(sqlite3_bind_text(stmt, 3, day_key.c_str(), -1, SQLITE_TRANSIENT),
+              db, "bind day_key");
+  CheckSqlite(sqlite3_step(stmt), db, "delete daily_task_logs");
+  sqlite3_finalize(stmt);
+}
+
+int CountTaskLog(sqlite3* db, int64_t user_id, const std::string& task_code,
+                 const std::string& day_key) {
+  sqlite3_stmt* stmt = nullptr;
+  const char* sql =
+      "SELECT COUNT(1) FROM daily_task_logs WHERE user_id=? AND task_code=? AND day_key=?";
+  CheckSqlite(sqlite3_prepare_v2(db, sql, -1, &stmt, nullptr), db,
+              "prepare count daily_task_logs");
+  CheckSqlite(sqlite3_bind_int64(stmt, 1, user_id), db, "bind user_id");
+  CheckSqlite(sqlite3_bind_text(stmt, 2, task_code.c_str(), -1, SQLITE_TRANSIENT),
+              db, "bind task_code");
+  CheckSqlite(sqlite3_bind_text(stmt, 3, day_key.c_str(), -1, SQLITE_TRANSIENT),
+              db, "bind day_key");
+  REQUIRE(sqlite3_step(stmt) == SQLITE_ROW);
+  const int count = sqlite3_column_int(stmt, 0);
+  sqlite3_finalize(stmt);
+  return count;
+}
+
+}  // namespace
+
 TEST_CASE("daily task reward only once per day") {
   auto db = csp::db::SqliteDb::OpenMemory();
   csp::db::ApplyMigrations(db);
@@ -30,5 +154,50 @@ TEST_CASE("daily task reward only once per day") {
   REQUIRE(after->rating == 2);
 
   const auto tasks = daily.ListTodayTasks(user.user_id);
-  REQUIRE(tasks.size() == 4);
+  REQUIRE(tasks.size() == 5);
+}
+
+TEST_CASE("learning streak reward grants +1 when streak >= 3 days") {
+  auto db = csp::db::SqliteDb::OpenMemory();
+  csp::db::ApplyMigrations(db);
+
+  csp::services::AuthService auth(db);
+  const auto user = auth.Register("daily_task_streak_user", "password123");
+
+  csp::services::UserService users(db);
+  csp::services::DailyTaskService daily(db);
+  sqlite3* raw = db.raw();
+
+  const std::string today = daily.CurrentDayKey();
+  const std::string yesterday = ShiftDayKey(today, -1);
+  const std::string two_days_ago = ShiftDayKey(today, -2);
+
+  // Register inserts today's login_checkin automatically; remove it so this test
+  // can call login_checkin and verify reward delta in one step.
+  DeleteDailyTaskLog(raw, user.user_id,
+                     csp::services::DailyTaskService::kTaskLoginCheckin, today);
+
+  InsertDailyTaskLog(raw, user.user_id,
+                     csp::services::DailyTaskService::kTaskLoginCheckin,
+                     yesterday, 1, 0);
+  InsertDailyTaskLog(raw, user.user_id,
+                     csp::services::DailyTaskService::kTaskLoginCheckin,
+                     two_days_ago, 1, 0);
+
+  const auto before = users.GetById(user.user_id);
+  REQUIRE(before.has_value());
+
+  REQUIRE(daily.CompleteTaskIfFirstToday(
+      user.user_id, csp::services::DailyTaskService::kTaskLoginCheckin));
+  REQUIRE_FALSE(daily.CompleteTaskIfFirstToday(
+      user.user_id, csp::services::DailyTaskService::kTaskLoginCheckin));
+
+  const auto after = users.GetById(user.user_id);
+  REQUIRE(after.has_value());
+  // login_checkin + streak bonus
+  REQUIRE(after->rating == before->rating + 2);
+
+  REQUIRE(CountTaskLog(raw, user.user_id,
+                       csp::services::DailyTaskService::kTaskLearningStreak3Days,
+                       today) == 1);
 }