import type { ExtensionAPI } from "@oh-my-pi/pi-coding-agent";

const channel = "workbook:field-notes:selection";

export default function fieldNoteEvents(pi: ExtensionAPI): void {
	let selected: string | null = null;
	const unsubscribe = pi.events.on(channel, data => {
		if (data === "reed" || data === "fern") selected = data;
	});
	pi.on("session_shutdown", () => unsubscribe());
	const { Type } = pi.typebox;
	pi.registerTool({
		name: "field_events",
		label: "Field events",
		description: "Discover or inspect the field-notes channel, query last selection, or act to publish reed/fern. In-process extension-runtime bus; selection survives /new and session switches within this binding, without durable delivery.",
		parameters: Type.Object({
			op: Type.Union([Type.Literal("discover"), Type.Literal("inspect"), Type.Literal("query"), Type.Literal("act")]),
			id: Type.Optional(Type.Union([Type.Literal("reed"), Type.Literal("fern")])),
		}),
		async execute(_id, params) {
			if (params.op === "act") {
				if (!params.id) throw new Error("act requires a note id; nothing published.");
				pi.events.emit(channel, params.id);
			}
			const details = { channel, selected, operations: ["discover", "inspect", "query", "act"], delivery: "synchronous emit; asynchronous listeners are not awaited" };
			return { content: [{ type: "text", text: JSON.stringify(details) }], details };
		},
	});
}