package utils

import (
	"time"
)

// UserLocation resolves an IANA timezone name to a *time.Location, falling
// back to UTC for empty or invalid values. The single resolution point for
// server-side display conversion: the server owns timezone rendering, so
// clients receive display-ready strings (or tz-aware instants) and never
// convert themselves.
func UserLocation(timezone string) *time.Location {
	if timezone == "" {
		return time.UTC
	}
	loc, err := time.LoadLocation(timezone)
	if err != nil || loc == nil {
		return time.UTC
	}
	return loc
}

// FormatTimeInTimezone renders t in the given IANA timezone as
// MM-DD-YYYY HH:MM AM/PM (the established display format across the
// templates). Zero times render empty.
func FormatTimeInTimezone(t time.Time, timezone string) string {
	if t.IsZero() {
		return ""
	}
	return t.In(UserLocation(timezone)).Format("01-02-2006 03:04 PM")
}