/// Gateway API client — used when running in gateway mode.
///
/// The gateway mode is detected by checking `GET /gateway/mode`. If it returns
/// `{ "mode": "gateway" }` the frontend switches to the gateway UI.

export interface JoinedAgent {
	id: string;
	label: string;
	address: string;
	registered_at: number;
}

export interface GenerateTokenResponse {
	token: string;
}

export interface ServerMode {
	mode: "gateway" | "standard";
}

async function gatewayRequest<T>(
	path: string,
	options: RequestInit = {},
): Promise<T> {
	const res = await fetch(path, {
		headers: { "Content-Type": "application/json", ...(options.headers ?? {}) },
		...options,
	});
	if (!res.ok) {
		const text = await res.text();
		throw new Error(text || `Request failed (${res.status})`);
	}
	// DELETE /gateway/agents/:id returns 204 No Content.
	if (res.status === 204) {
		return undefined as unknown as T;
	}
	return res.json() as Promise<T>;
}

export const gatewayApi = {
	/// Returns `{ mode: "gateway" }` if this server is a gateway, otherwise rejects.
	getServerMode(): Promise<ServerMode> {
		return gatewayRequest<ServerMode>("/gateway/mode");
	},

	/// Generate a one-time join token for a new build agent.
	generateToken(): Promise<GenerateTokenResponse> {
		return gatewayRequest<GenerateTokenResponse>("/gateway/tokens", {
			method: "POST",
		});
	},

	/// List all build agents that have registered with this gateway.
	listAgents(): Promise<JoinedAgent[]> {
		return gatewayRequest<JoinedAgent[]>("/gateway/agents");
	},

	/// Remove a registered build agent by its ID.
	removeAgent(id: string): Promise<void> {
		return gatewayRequest<void>(`/gateway/agents/${id}`, {
			method: "DELETE",
		});
	},
};