import type { ExtensionAPI } from "@earendil-works/pi-coding-agent";
import { Effect } from "effect";
import { Type } from "typebox";
import {
	formatModelAmbiguous,
	formatModelNotFound,
	type ModelSummary,
	resolveModel,
} from "./core.ts";

export default function switchModelExtension(pi: ExtensionAPI) {
	pi.registerTool({
		name: "switch_model",
		label: "Switch Model",
		description:
			'Switch the active model mid-conversation, e.g. when the user says "implement this ' +
			'with 5.6 sol" or "switch to fable". Free-text query — not required to be an exact ' +
			"id. The switch is permanent: stays on the new model until the user or you call this " +
			"again. Conversation history and working tree are unchanged.",
		promptGuidelines: [
			"Call switch_model when the user names a different model to use, then continue the task on the new model in the same reply flow — no approval loop needed.",
			"If switch_model fails, it lists the actual available models; retry once with an exact provider/id from that list.",
		],
		parameters: Type.Object({
			query: Type.String({ description: 'e.g. "5.6 sol", "fable", "sonnet"' }),
		}),
		async execute(_toolCallId, params, _signal, _onUpdate, ctx) {
			const available: ModelSummary[] = ctx.modelRegistry
				.getAvailable()
				.map((model) => ({ provider: model.provider, id: model.id, name: model.name }));

			const resolved = await Effect.runPromise(
				resolveModel(params.query, available).pipe(
					Effect.mapError((error) =>
						error._tag === "ModelNotFoundError"
							? new Error(formatModelNotFound(error))
							: new Error(formatModelAmbiguous(error)),
					),
				),
			);

			const model = ctx.modelRegistry.find(resolved.provider, resolved.id);
			if (!model) {
				throw new Error(`Resolved model disappeared from registry: ${resolved.provider}/${resolved.id}`);
			}
			if (!(await pi.setModel(model))) {
				throw new Error(`No credentials available for ${resolved.provider}/${resolved.id}`);
			}

			return {
				content: [
					{
						type: "text" as const,
						text: `Switched to ${resolved.provider}/${resolved.id}. Staying on this model until asked to switch again.`,
					},
				],
				details: { provider: resolved.provider, id: resolved.id },
			};
		},
	});
}