// [DEF:toasts_module:Module]
// @SEMANTICS: notification, toast, feedback, state
// @PURPOSE: Manages toast notifications using a Svelte writable store.
// @LAYER: UI-State

import { writable } from 'svelte/store';

// [DEF:toasts:Data]
// @PURPOSE: Writable store containing the list of active toasts.
export const toasts = writable([]);
// [/DEF:toasts:Data]

const TOAST_DEDUP_WINDOW_MS = 1200;
const recentToastByKey = new Map();

function buildToastKey(message, type) {
    return `${String(type || 'info')}::${String(message || '')}`;
}

function shouldSkipDuplicateToast(message, type) {
    const key = buildToastKey(message, type);
    const now = Date.now();
    const previousAt = recentToastByKey.get(key);
    if (previousAt && now - previousAt < TOAST_DEDUP_WINDOW_MS) {
        return true;
    }
    recentToastByKey.set(key, now);
    return false;
}

// [DEF:addToast:Function]
// @PURPOSE: Adds a new toast message.
// @PRE: message string is provided.
// @POST: New toast is added to the store and scheduled for removal.
// @PARAM: message (string) - The message text.
// @PARAM: type (string) - The type of toast (info, success, error).
// @PARAM: duration (number) - Duration in ms before the toast is removed.
export function addToast(message, type = 'info', duration = 3000) {
    if (shouldSkipDuplicateToast(message, type)) {
        console.log(`[toasts.addToast][Action] Duplicate skipped context={{'type': '${type}', 'message': '${message}'}}`);
        return;
    }
    const id = Math.random().toString(36).substr(2, 9);
    console.log(`[toasts.addToast][Action] Adding toast context={{'id': '${id}', 'type': '${type}', 'message': '${message}'}}`);
    toasts.update(all => [...all, { id, message, type }]);
    setTimeout(() => removeToast(id), duration);
}
// [/DEF:addToast:Function]

// [DEF:removeToast:Function]
// @PURPOSE: Removes a toast message by ID.
// @PRE: id is provided.
// @POST: Toast is removed from the store.
// @PARAM: id (string) - The ID of the toast to remove.
function removeToast(id) {
    console.log(`[toasts.removeToast][Action] Removing toast context={{'id': '${id}'}}`);
    toasts.update(all => all.filter(t => t.id !== id));
}
// [/DEF:removeToast:Function]
// [/DEF:toasts_module:Module]