Function parse_fixed_offset

graphlite/src/functions/timezone_functions.rs:60–103

Parse fixed offset strings like "+05:30", "-04:00", "+0530", "-0400"

(offset_str: &str)

/// Parse fixed offset strings like "+05:30", "-04:00", "+0530", "-0400"
fn parse_fixed_offset(offset_str: &str) -> Result<FixedOffset, String> {
    let trimmed = offset_str.trim();

    if trimmed.len() < 3 {
        return Err("Invalid offset format".to_string());
    }

    let sign = match trimmed.chars().next() {
        Some('+') => 1,
        Some('-') => -1,
        _ => return Err("Offset must start with + or -".to_string()),
    };

    let offset_part = &trimmed[1..];

    // Handle formats like "05:30" or "0530"
    let (hours, minutes) = if offset_part.contains(':') {
        let parts: Vec<&str> = offset_part.split(':').collect();
        if parts.len() != 2 {
            return Err("Invalid offset format".to_string());
        }
        (
            parts[0].parse::<i32>().map_err(|_| "Invalid hours")?,
            parts[1].parse::<i32>().map_err(|_| "Invalid minutes")?,
        )
    } else if offset_part.len() == 4 {
        // Format like "0530"
        let hours_str = &offset_part[0..2];
        let minutes_str = &offset_part[2..4];
        (
            hours_str.parse::<i32>().map_err(|_| "Invalid hours")?,
            minutes_str.parse::<i32>().map_err(|_| "Invalid minutes")?,
        )
    } else {
        return Err("Invalid offset format".to_string());
    };

    if hours > 23 || minutes > 59 {
        return Err("Invalid offset values".to_string());
    }

    let total_seconds = sign * (hours * 3600 + minutes * 60);
    FixedOffset::east_opt(total_seconds).ok_or_else(|| "Invalid offset".to_string())
}

/// Timezone type enum for handling both named timezones and fixed offsets
#[derive(Debug, Clone)]