/**
* Ensures a datetime string from the backend is treated as UTC.
*
* Backend datetime strings may not include timezone information.
* This function ensures they are correctly parsed as UTC by:
* 1. Checking if timezone info is already present
* 2. Converting space-separated format to ISO format (YYYY-MM-DD HH:MM:SS -> YYYY-MM-DDTHH:MM:SS)
* 3. Appending 'Z' to indicate UTC if no timezone info exists
*
* @param dateTimeString - Datetime string from backend (e.g., "2025-11-21 12:00:00" or "2025-11-21T12:00:00Z")
* @returns Date object with correct UTC interpretation
*/
export function parseUTCDate(dateTimeString: string): Date {
if (!dateTimeString) {
return new Date();
}
let utcDateString = dateTimeString.trim();
// Check if timezone info is already present
const hasTimezone =
utcDateString.endsWith('Z') ||
utcDateString.includes('+') ||
utcDateString.includes('-', 10); // Check for +/- after position 10 (after "YYYY-MM-DD")
if (!hasTimezone) {
// Replace space with 'T' for ISO format
utcDateString = utcDateString.replace(' ', 'T');
// Append 'Z' to indicate UTC
utcDateString += 'Z';
}
return new Date(utcDateString);
}
/**
* Formats a datetime string for display in the user's local timezone.
*
* @param dateTimeString - Datetime string from backend
* @returns Formatted string in user's local timezone (e.g., "12:30:45 PM")
*/
export function formatLocalTime(dateTimeString: string): string {
return parseUTCDate(dateTimeString).toLocaleTimeString();
}
/**
* Formats a datetime string for display in the user's local timezone with date.
*
* @param dateTimeString - Datetime string from backend
* @returns Formatted string in user's local timezone (e.g., "11/21/2025, 12:30:45 PM")
*/
export function formatLocalDateTime(dateTimeString: string): string {
return parseUTCDate(dateTimeString).toLocaleString();
}
/**
* Formats a datetime string explicitly as UTC.
*
* @param dateTimeString - Datetime string from backend
* @returns Formatted string as "YYYY-MM-DD HH:MM:SS UTC"
*/
export function formatUTCDateTime(dateTimeString: string): string {
const date = parseUTCDate(dateTimeString);
const year = date.getUTCFullYear();
const month = String(date.getUTCMonth() + 1).padStart(2, '0');
const day = String(date.getUTCDate()).padStart(2, '0');
const hours = String(date.getUTCHours()).padStart(2, '0');
const minutes = String(date.getUTCMinutes()).padStart(2, '0');
const seconds = String(date.getUTCSeconds()).padStart(2, '0');
return `${year}-${month}-${day} ${hours}:${minutes}:${seconds} UTC`;
}
/**
* Calculates relative time from now (e.g., "2m ago", "3h ago", "5d ago").
*
* @param dateTimeString - Datetime string from backend
* @returns Relative time string
*/
export function formatRelativeTime(dateTimeString: string): string {
const date = parseUTCDate(dateTimeString);
const now = new Date();
const diffMs = now.getTime() - date.getTime();
const diffMins = Math.floor(diffMs / 60000);
const diffHours = Math.floor(diffMs / 3600000);
const diffDays = Math.floor(diffMs / 86400000);
if (diffMins < 1) return 'just now';
if (diffMins < 60) return `${diffMins}m ago`;
if (diffHours < 24) return `${diffHours}h ago`;
if (diffDays < 7) return `${diffDays}d ago`;
return date.toLocaleDateString();
}
/**
* Calculates duration between two datetime strings.
*
* @param startTimeString - Start datetime string from backend
* @param endTimeString - End datetime string from backend
* @returns Duration string (e.g., "2h 15m", "45m 30s", "25s")
*/
export function calculateDuration(
startTimeString: string,
endTimeString: string
): string {
const start = parseUTCDate(startTimeString);
const end = parseUTCDate(endTimeString);
const durationMs = end.getTime() - start.getTime();
const seconds = Math.floor(durationMs / 1000);
const minutes = Math.floor(seconds / 60);
const hours = Math.floor(minutes / 60);
if (hours > 0) return `${hours}h ${minutes % 60}m`;
if (minutes > 0) return `${minutes}m ${seconds % 60}s`;
return `${seconds}s`;
}
