import { failureMessage } from "$lib/api";
import { isAlertEnabled, type AlertKind } from "$lib/alert-prefs";
import { toast, type ToastAction } from "$lib/components/ui/toast-state";

/** Brief confirmation — readable but not sticky. */
const SUCCESS_DURATION_MS = 4000;
/** Errors need more time to read. */
const ERROR_DURATION_MS = 7000;
/** Link actions need dwell time to click. */
const ACTION_DURATION_MS = 10000;

type NotifyOptions = {
	description?: string;
	action?: ToastAction;
	actions?: ToastAction[];
	duration?: number;
	/**
	 * Operator alert category (P0-9). When set, toast is gated by local alert prefs.
	 * Omit for always-on UI feedback (forms, undo, validation).
	 */
	alert?: AlertKind;
};

export type NotifyApiErrorOptions = NotifyOptions & {
	/** When set, used as toast title; failure message becomes the description. */
	title?: string;
};

function hasLinkActions(opts: NotifyOptions): boolean {
	return Boolean(opts.action || opts.actions?.length);
}

function resolveDuration(opts: NotifyOptions, fallbackMs: number): number {
	if (opts.duration !== undefined) return opts.duration;
	if (hasLinkActions(opts)) return ACTION_DURATION_MS;
	return fallbackMs;
}

function shouldShowToast(opts: NotifyOptions): boolean {
	if (!opts.alert) return true;
	// Never mute toasts that carry onClick actions (e.g. Undo cancel).
	const actions = opts.actions?.length ? opts.actions : opts.action ? [opts.action] : [];
	if (actions.some((a) => typeof a.onClick === "function")) return true;
	return isAlertEnabled(opts.alert);
}

/** Show a toast (and keep Alert strings in sync when callers also set local state). */
export function notifySuccess(title: string, descriptionOrOpts?: string | NotifyOptions) {
	const opts =
		typeof descriptionOrOpts === "string"
			? { description: descriptionOrOpts }
			: (descriptionOrOpts ?? {});
	if (!shouldShowToast(opts)) return;
	toast({
		title,
		description: opts.description,
		variant: "default",
		action: opts.action,
		actions: opts.actions,
		duration: resolveDuration(opts, SUCCESS_DURATION_MS)
	});
}

export function notifyError(title: string, descriptionOrOpts?: string | NotifyOptions) {
	const opts =
		typeof descriptionOrOpts === "string"
			? { description: descriptionOrOpts }
			: (descriptionOrOpts ?? {});
	if (!shouldShowToast(opts)) return;
	toast({
		title,
		description: opts.description,
		variant: "destructive",
		action: opts.action,
		actions: opts.actions,
		duration: resolveDuration(opts, ERROR_DURATION_MS)
	});
}

/**
 * Standard path for `api()` failures → toast (and optional page banner).
 * Returns the message so callers can assign `error = notifyApiError(...)`.
 * Message is always returned even when the toast is muted by alert prefs.
 */
export function notifyApiError(
	err: unknown,
	fallback: string,
	opts?: NotifyApiErrorOptions
): string {
	const message = failureMessage(err, fallback);
	const { title, description, action, actions, duration, alert } = opts ?? {};
	const toastOpts: NotifyOptions = { description, action, actions, duration, alert };
	if (title !== undefined) {
		notifyError(title, { ...toastOpts, description: description ?? message });
	} else {
		notifyError(message, toastOpts);
	}
	return message;
}