Method start_of_season

Returns a new ParsiDate instance representing the first day of the season in which the current date falls.

Description

This method calculates the starting date of the Persian season corresponding to the ParsiDate instance (self).

It first determines the season (Bahar, Tabestan, Paeez, Zemestan) of the self instance based on its month. Then, it constructs and returns a new ParsiDate with the following components:

• Year: The same year as the original date (self.year).
• Month: The first month of the determined season:
  • 1 (Farvardin) for Bahar (Spring)
  • 4 (Tir) for Tabestan (Summer)
  • 7 (Mehr) for Paeez (Autumn)
  • 10 (Dey) for Zemestan (Winter)
• Day: Always set to 1.

Assumption: This method relies on the validity of the month component of the self instance to correctly determine the season. If self contains an invalid month, an error is returned.

Returns

• Ok(ParsiDate): If the original date (self) is valid, returns a new ParsiDate instance representing the first day of the corresponding season (Month 1, 4, 7, or 10, Day 1), wrapped in Ok.
• Err(DateError::InvalidDate): If the original ParsiDate instance (self) holds invalid data (specifically an invalid month), preventing the determination of the season. This error is likely propagated from an internal check or call to determine the season.

Examples (Rust)

use parsidate::{ParsiDate, Season, DateError}; // Assuming these types exist

// Example 1: Date in Paeez (Autumn) - Month 8 (Aban)
let date_paeez = ParsiDate::new(1403, 8, 20).unwrap();
let start_paeez = date_paeez.start_of_season().unwrap();
// Paeez starts on Month 7 (Mehr), Day 1
assert_eq!(start_paeez, ParsiDate::new(1403, 7, 1).unwrap());

// Example 2: Date in Bahar (Spring) - Month 1 (Farvardin)
let date_bahar = ParsiDate::new(1403, 1, 5).unwrap();
let start_bahar = date_bahar.start_of_season().unwrap();
// Bahar starts on Month 1 (Farvardin), Day 1
assert_eq!(start_bahar, ParsiDate::new(1403, 1, 1).unwrap());

// Example 3: Date in Tabestan (Summer) - Month 6 (Shahrivar)
let date_tabestan = ParsiDate::new(1404, 6, 31).unwrap();
let start_tabestan = date_tabestan.start_of_season().unwrap();
// Tabestan starts on Month 4 (Tir), Day 1
assert_eq!(start_tabestan, ParsiDate::new(1404, 4, 1).unwrap());

// Example 4: Date in Zemestan (Winter) - Month 11 (Bahman)
let date_zemestan = ParsiDate::new(1399, 11, 22).unwrap();
let start_zemestan = date_zemestan.start_of_season().unwrap();
// Zemestan starts on Month 10 (Dey), Day 1
assert_eq!(start_zemestan, ParsiDate::new(1399, 10, 1).unwrap());

// Example 5: Handling an invalid date created unsafely
let invalid_date = unsafe { ParsiDate::new_unchecked(1403, 0, 15) }; // Invalid month 0
let result = invalid_date.start_of_season();
// Expect an error because the season cannot be determined
assert!(result.is_err());
assert_eq!(result, Err(DateError::InvalidDate));