/**
 * Locale-aware value formatting for charts. Uses the app i18n locale (via
 * `resolveI18n`) instead of a hardcoded locale, with graceful fallbacks.
 */
import { getI18n } from '../../../i18n'

function currentLocale(): string {
	try {
		const loc = getI18n().global.locale as unknown
		const v = (loc as { value?: string })?.value ?? loc
		if (typeof v === 'string' && v) return v
	} catch { /* i18n not initialized — fall through */ }
	if (typeof document !== 'undefined') {
		return document.documentElement.lang || navigator?.language || 'en'
	}
	return 'en'
}

export interface ValueFormat {
	/** ISO currency code (e.g. 'USD', 'ILS'). When set, formats as currency. */
	currency?: string
	prefix?: string
	suffix?: string
	/** Compact large numbers (1.2K, 3.4M). Default true for axis ticks. */
	compact?: boolean
	maximumFractionDigits?: number
}

export function formatValue(value: number, fmt: ValueFormat = {}): string {
	const locale = currentLocale()
	let out: string
	try {
		if (fmt.currency) {
			out = new Intl.NumberFormat(locale, {
				style: 'currency',
				currency: fmt.currency,
				notation: fmt.compact ? 'compact' : 'standard',
				maximumFractionDigits: fmt.maximumFractionDigits ?? (fmt.compact ? 1 : 0),
			}).format(value)
		} else {
			out = new Intl.NumberFormat(locale, {
				notation: fmt.compact ? 'compact' : 'standard',
				maximumFractionDigits: fmt.maximumFractionDigits ?? (fmt.compact ? 1 : 2),
			}).format(value)
		}
	} catch {
		out = String(value)
	}
	return `${fmt.prefix ?? ''}${out}${fmt.suffix ?? ''}`
}

/** Format an x label that may be an ISO date; otherwise pass through. */
export function formatLabel(label: string): string {
	// Only treat as a date if it parses AND looks date-ish (has - or /).
	if (/[-/]/.test(label)) {
		const d = new Date(label)
		if (!Number.isNaN(d.getTime())) {
			try {
				return d.toLocaleDateString(currentLocale(), { month: 'short', day: 'numeric' })
			} catch { /* noop */ }
		}
	}
	return label
}