Rewrite electricity-logger to use an sqlite3 database

include/util/date.hpp

@@ -0,0 +1,151 @@
+#pragma once
+#include <cstdio>
+#include <ctime>
+#include <string>
+
+namespace Util
+{
+    inline bool IsValidYear(int const year) { return year > 1900 && year < 9999; }
+
+    inline bool IsValidMonth(int const month) { return month > 0 && month < 13; }
+
+    inline bool IsValidDay(int const day) { return day > 0 && day < 32; }
+
+    inline long GetEpoch(long year, unsigned month, unsigned day)
+    {
+        year -= month <= 2;
+        const long era = (year >= 0 ? year : year - 399) / 400;
+        const unsigned yoe = static_cast<unsigned>(year - era * 400); // [0, 399]
+        const unsigned doy = (153 * (month + (month > 2 ? -3 : 9)) + 2) / 5 + day - 1; // [0, 365]
+        const unsigned doe = yoe * 365 + yoe / 4 - yoe / 100 + doy; // [0, 146096]
+
+        // Multiply by the day length in seconds
+        return (era * 146097 + doe - 719468) * (24l * 60l * 60l);
+    }
+
+    inline long ToEpoch(std::string const & date)
+    {
+        int year, month, day;
+        if(std::sscanf(date.c_str(), "%d-%d-%d", &year, &month, &day) != 3)
+        {
+            return -1;
+        }
+
+        return GetEpoch(year, month, day);
+    }
+
+    inline unsigned ToSeconds(unsigned hours, unsigned minutes, unsigned seconds)
+    {
+        return (hours * 60 * 60) + (minutes * 60) + seconds;
+    }
+
+    inline int ToSecondsFromTimeString(char const * string)
+    {
+        int hour, minute, second;
+        if(std::sscanf(string, "%d:%d:%d", &hour, &minute, &second) != 3)
+        {
+            return -1;
+        }
+
+        return ToSeconds(hour, minute, second);
+    }
+
+    inline std::string GetSqliteDate(time_t const epochTime)
+    {
+        auto const dateTime = *std::gmtime(&epochTime);
+
+        char dateStringBuffer[64];
+        std::sprintf(dateStringBuffer, "%i-%02i-%02i", dateTime.tm_year + 1900, dateTime.tm_mon + 1, dateTime.tm_mday);
+
+        return std::string(dateStringBuffer);
+    }
+
+    inline std::string GetSqliteUtcTime(time_t const epochTime)
+    {
+        auto const dateTime = *std::gmtime(&epochTime);
+
+        char timeStringBuffer[64];
+        std::sprintf(timeStringBuffer, "%02i:%02i:%02i", dateTime.tm_hour, dateTime.tm_min, dateTime.tm_sec);
+
+        return std::string(timeStringBuffer);
+    }
+
+    class Date {
+    private:
+        unsigned year;
+        unsigned month;
+        unsigned day;
+
+    public:
+        unsigned Year() const { return year; }
+        unsigned Month() const { return month; }
+        unsigned Day() const { return day; }
+
+        void AddMonth()
+        {
+            ++month;
+            if(month > 12)
+            {
+                month = 1;
+                ++year;
+            }
+        }
+
+        void SetDayToEndOfMonth() { day = 31; }
+
+        bool IsValid() const { return IsValidYear(year) && IsValidMonth(month) && IsValidDay(day); }
+
+        long ToEpoch() const { return GetEpoch(year, month, day); }
+
+        bool IsBefore(unsigned const otherYear, unsigned const otherMonth, unsigned const otherDay) const
+        {
+            return (year < otherYear) || (year == otherYear && month < otherMonth)
+                || (year == otherYear && month == otherMonth && day < otherDay);
+        }
+
+        bool IsBefore(Date const & other) const { return IsBefore(other.year, other.month, other.day); }
+
+        bool IsAfter(unsigned const otherYear, unsigned const otherMonth, unsigned const otherDay) const
+        {
+            return (year > otherYear) || (year == otherYear && month > otherMonth)
+                || (year == otherYear && month == otherMonth && day > otherDay);
+        }
+
+        std::string ToISOString() const
+        {
+            char buffer[11];
+            std::sprintf(buffer, "%04i-%02i-%02i", year, month, day);
+
+            return std::string(buffer);
+        }
+
+        bool TryParse(std::string const & date)
+        {
+            Date result;
+
+            if(sscanf(date.c_str(), "%d-%d-%d", &year, &month, &day) != 3)
+            {
+                result.year = 0;
+                result.month = 0;
+                result.day = 0;
+                return false;
+            }
+
+            return true;
+        }
+
+        Date() : year(0), month(0), day(0) { }
+
+        Date(std::string const & date) : year(0), month(0), day(0) { TryParse(date); }
+
+        Date(long const epoch)
+        {
+            std::tm dateTime = *std::gmtime(&epoch);
+            year = 1900 + dateTime.tm_year;
+            month = 1 + dateTime.tm_mon;
+            day = dateTime.tm_mday;
+        }
+
+        static Date UtcNow() { return Date(std::time(nullptr)); }
+    };
+}