export type ToastLevel = "info" | "warn" | "error";

export type Toast = {
    id: number;
    level: ToastLevel;
    message: string;
    detail?: string;
    expiresAt?: number;
};

const listeners = new Set<(toasts: Toast[]) => void>();
const queue: Toast[] = [];
let nextId = 1;
const MAX_TOASTS = 4;

function emitUpdate() {
    listeners.forEach((fn) => fn([...queue]));
}

export function pushToast(toast: Omit<Toast, "id">) {
    const entry: Toast = {
        id: nextId++,
        ...toast,
    };
    queue.push(entry);
    if (queue.length > MAX_TOASTS) queue.shift();
    emitUpdate();
}

export function dismissToast(id: number) {
    const idx = queue.findIndex((t) => t.id === id);
    if (idx >= 0) {
        queue.splice(idx, 1);
        emitUpdate();
    }
}

export function subscribeToasts(fn: (toasts: Toast[]) => void) {
    listeners.add(fn);
    fn([...queue]);
    return () => { listeners.delete(fn); };
}

export function toastError(message: string, detail?: string) {
    const expiresAt = Date.now() + 7000;
    pushToast({ level: "error", message, detail, expiresAt });
}

export function toastInfo(message: string, detail?: string) {
    const expiresAt = Date.now() + 4000;
    pushToast({ level: "info", message, detail, expiresAt });
}