felt/frontend/src/lib/stores/toast.svelte.ts

/**
 * Toast notification state using Svelte 5 runes.
 *
 * Provides success/info/warning/error notifications with auto-dismiss.
 * Toasts stack vertically and animate in/out.
 */

export type ToastType = 'success' | 'info' | 'warning' | 'error';

export interface Toast {
	id: string;
	type: ToastType;
	message: string;
	duration: number;
	dismissible: boolean;
	timer?: ReturnType<typeof setTimeout>;
}

/** Default auto-dismiss durations by type (milliseconds). */
const DEFAULT_DURATIONS: Record<ToastType, number> = {
	success: 3000,
	info: 4000,
	warning: 5000,
	error: 8000
};

let nextId = 0;

class ToastState {
	toasts = $state<Toast[]>([]);

	/** Add a success toast (green, 3s auto-dismiss). */
	success(message: string, duration?: number): string {
		return this.add('success', message, duration);
	}

	/** Add an info toast (blue, 4s auto-dismiss). */
	info(message: string, duration?: number): string {
		return this.add('info', message, duration);
	}

	/** Add a warning toast (yellow, 5s auto-dismiss). */
	warning(message: string, duration?: number): string {
		return this.add('warning', message, duration);
	}

	/** Add an error toast (red, 8s auto-dismiss). */
	error(message: string, duration?: number): string {
		return this.add('error', message, duration);
	}

	/** Dismiss a toast by ID. */
	dismiss(id: string): void {
		const toast = this.toasts.find((t) => t.id === id);
		if (toast?.timer) {
			clearTimeout(toast.timer);
		}
		this.toasts = this.toasts.filter((t) => t.id !== id);
	}

	/** Dismiss all toasts. */
	dismissAll(): void {
		for (const t of this.toasts) {
			if (t.timer) clearTimeout(t.timer);
		}
		this.toasts = [];
	}

	private add(type: ToastType, message: string, duration?: number): string {
		const id = `toast-${++nextId}`;
		const dur = duration ?? DEFAULT_DURATIONS[type];

		const toast: Toast = {
			id,
			type,
			message,
			duration: dur,
			dismissible: type === 'error'
		};

		// Auto-dismiss after duration
		toast.timer = setTimeout(() => {
			this.dismiss(id);
		}, dur);

		this.toasts = [...this.toasts, toast];
		return id;
	}
}

/** Singleton toast state instance. */
export const toast = new ToastState();