posix_tz.h

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#pragma once
 
#ifdef USE_TIME_TIMEZONE
 
#include <cstdint>
#include <ctime>
 
namespace esphome::time {
 
enum class DSTRuleType : uint8_t {
  NONE = 0,        
  MONTH_WEEK_DAY,  
  JULIAN_NO_LEAP,  
  DAY_OF_YEAR,     
};
 
struct DSTRule {
  int32_t time_seconds;  
  uint16_t day;          
  DSTRuleType type;      
  uint8_t month;         
  uint8_t week;          
  uint8_t day_of_week;   
};
 
struct ParsedTimezone {
  int32_t std_offset_seconds;  
  int32_t dst_offset_seconds;  
  DSTRule dst_start;           
  DSTRule dst_end;             
 
  bool has_dst() const { return this->dst_start.type != DSTRuleType::NONE; }
};
 
bool parse_posix_tz(const char *tz_string, ParsedTimezone &result);
 
bool epoch_to_local_tm(time_t utc_epoch, const ParsedTimezone &tz, struct tm *out_tm);
 
void set_global_tz(const ParsedTimezone &tz);
 
const ParsedTimezone &get_global_tz();
 
bool is_in_dst(time_t utc_epoch, const ParsedTimezone &tz);
 
// Internal helper functions exposed for testing.
// Remove before 2026.9.0: skip_tz_name, parse_offset, parse_dst_rule are only
// used by parse_posix_tz() which is bridge code for backward compatibility.
// The remaining helpers (epoch_to_tm_utc, day_of_week, days_in_month, etc.)
// are used by the conversion functions and will stay.
 
namespace internal {
 
bool skip_tz_name(const char *&p);
 
int32_t parse_offset(const char *&p);
 
bool parse_dst_rule(const char *&p, DSTRule &rule);
 
void julian_to_month_day(int julian_day, int &month, int &day);
 
void day_of_year_to_month_day(int day_of_year, int year, int &month, int &day);
 
int day_of_week(int year, int month, int day);
 
int days_in_month(int year, int month);
 
bool is_leap_year(int year);
 
void epoch_to_tm_utc(time_t epoch, struct tm *out_tm);
 
time_t calculate_dst_transition(int year, const DSTRule &rule, int32_t base_offset_seconds);
 
}  // namespace internal
 
}  // namespace esphome::time
 
#endif  // USE_TIME_TIMEZONE