initial commit

src/timezone_helper.cpp

@@ -0,0 +1,150 @@
+#include "timezone_helper.h"
+#include <cstdlib>
+#include <ctime>
+#include <iomanip>
+#include <mutex>
+#include <sstream>
+
+namespace radiantwave::timezone {
+
+namespace {
+
+static std::mutex g_tz_mutex;
+
+const std::vector<CountryTimeZones> G_COUNTRIES = {
+    {
+        "United States",
+        {
+            {"Eastern Time (New York, Miami)", "America/New_York"},
+            {"Central Time (Chicago, Dallas)", "America/Chicago"},
+            {"Mountain Time (Denver)", "America/Denver"},
+            {"Pacific Time (Los Angeles, Seattle)", "America/Los_Angeles"},
+            {"Alaska Time (Anchorage)", "America/Anchorage"},
+            {"Hawaii Time (Honolulu)", "Pacific/Honolulu"},
+            {"Arizona (No DST)", "America/Phoenix"},
+            {"Indiana (Indianapolis)", "America/Indiana/Indianapolis"}
+        }
+    },
+    {
+        "Canada",
+        {
+            {"Eastern Time (Toronto)", "America/Toronto"},
+            {"Central Time (Winnipeg)", "America/Winnipeg"},
+            {"Mountain Time (Edmonton)", "America/Edmonton"},
+            {"Pacific Time (Vancouver)", "America/Vancouver"},
+            {"Atlantic Time (Halifax)", "America/Halifax"},
+            {"Newfoundland Time (St. Johns)", "America/St_Johns"}
+        }
+    },
+    {
+        "United Kingdom & Ireland",
+        {
+            {"London / Dublin (GMT/BST)", "Europe/London"}
+        }
+    },
+    {
+        "Australia",
+        {
+            {"Eastern Time (Sydney, Melbourne)", "Australia/Sydney"},
+            {"Central Time (Adelaide)", "Australia/Adelaide"},
+            {"Western Time (Perth)", "Australia/Perth"},
+            {"Queensland (Brisbane)", "Australia/Brisbane"},
+            {"Northern Territory (Darwin)", "Australia/Darwin"}
+        }
+    },
+    {
+        "Europe (Mainland)",
+        {
+            {"Central European Time (Berlin, Paris, Rome)", "Europe/Berlin"},
+            {"Western European Time (Lisbon, Amsterdam)", "Europe/Paris"},
+            {"Eastern European Time (Athens, Helsinki)", "Europe/Helsinki"}
+        }
+    },
+    {
+        "Japan & East Asia",
+        {
+            {"Japan Standard Time (Tokyo)", "Asia/Tokyo"},
+            {"China Standard Time (Beijing, Shanghai)", "Asia/Shanghai"},
+            {"Hong Kong Time", "Asia/Hong_Kong"},
+            {"Korea Standard Time (Seoul)", "Asia/Seoul"},
+            {"Singapore Time", "Asia/Singapore"}
+        }
+    },
+    {
+        "India & South Asia",
+        {
+            {"India Standard Time (Kolkata, Mumbai)", "Asia/Kolkata"}
+        }
+    },
+    {
+        "Latin America",
+        {
+            {"Brazil (Sao Paulo)", "America/Sao_Paulo"},
+            {"Mexico (Mexico City)", "America/Mexico_City"},
+            {"Argentina (Buenos Aires)", "America/Argentina/Buenos_Aires"}
+        }
+    },
+    {
+        "Coordinated Universal Time",
+        {
+            {"UTC (Universal Time)", "UTC"}
+        }
+    }
+};
+
+} // anonymous namespace
+
+const std::vector<CountryTimeZones>& getStandardTimeZones() {
+    return G_COUNTRIES;
+}
+
+std::string formatUtcToTimezone(time_t utc_time, const std::string& iana_code, const std::string& format) {
+    std::lock_guard<std::mutex> lock(g_tz_mutex);
+
+    const char* old_tz = std::getenv("TZ");
+    std::string old_tz_str = old_tz ? old_tz : "";
+
+    // Set target timezone temporarily
+    if (!iana_code.empty()) {
+        setenv("TZ", iana_code.c_str(), 1);
+    } else {
+        setenv("TZ", "UTC", 1);
+    }
+    tzset();
+
+    struct tm tm_buf;
+#if defined(_WIN32)
+    localtime_s(&tm_buf, &utc_time);
+#else
+    localtime_r(&utc_time, &tm_buf);
+#endif
+
+    char buf[128];
+    std::strftime(buf, sizeof(buf), format.c_str(), &tm_buf);
+
+    // Restore original process TZ
+    if (!old_tz_str.empty()) {
+        setenv("TZ", old_tz_str.c_str(), 1);
+    } else {
+        unsetenv("TZ");
+    }
+    tzset();
+
+    return std::string(buf);
+}
+
+std::string getUtcTimestampIso() {
+    time_t now = std::time(nullptr);
+    struct tm gmt_buf;
+#if defined(_WIN32)
+    gmtime_s(&gmt_buf, &now);
+#else
+    gmtime_r(&now, &gmt_buf);
+#endif
+
+    char buf[64];
+    std::strftime(buf, sizeof(buf), "%Y-%m-%d %H:%M:%S UTC", &gmt_buf);
+    return std::string(buf);
+}
+
+} // namespace radiantwave::timezone