import type {
	PermissionOption,
	PermissionRequest,
	PermissionResponse,
	PermissionUiContext,
} from "./types.js";
import { isRecord } from "./types.js";

function parsePermissionOption(value: unknown): PermissionOption | undefined {
	if (!isRecord(value)) return undefined;
	if (typeof value.optionId !== "string" || typeof value.name !== "string" || typeof value.kind !== "string") {
		return undefined;
	}
	return { optionId: value.optionId, name: value.name, kind: value.kind };
}

export function parsePermissionRequest(value: unknown): PermissionRequest | undefined {
	if (!isRecord(value)) return undefined;
	const toolCall = isRecord(value.toolCall)
		? {
				...(typeof value.toolCall.toolCallId === "string" ? { toolCallId: value.toolCall.toolCallId } : {}),
				...(typeof value.toolCall.title === "string" ? { title: value.toolCall.title } : {}),
				...(typeof value.toolCall.kind === "string" ? { kind: value.toolCall.kind } : {}),
				...("rawInput" in value.toolCall ? { rawInput: value.toolCall.rawInput } : {}),
			}
		: undefined;
	const options = Array.isArray(value.options)
		? value.options.map(parsePermissionOption).filter((option): option is PermissionOption => option !== undefined)
		: [];
	return {
		...(typeof value.sessionId === "string" ? { sessionId: value.sessionId } : {}),
		...(toolCall ? { toolCall } : {}),
		options,
	};
}

function cancelled(): PermissionResponse {
	return { outcome: { outcome: "cancelled" } };
}

function selected(optionId: string): PermissionResponse {
	return { outcome: { outcome: "selected", optionId } };
}

function rejectionOption(options: readonly PermissionOption[]): PermissionOption | undefined {
	return options.find((option) => option.kind === "reject_once") ?? options.find((option) => option.kind === "reject_always");
}

function formatInput(value: unknown): string {
	if (value === undefined) return "";
	let text: string;
	try {
		text = typeof value === "string" ? value : JSON.stringify(value, null, 2);
	} catch {
		text = "[unserializable input]";
	}
	return text.length > 4_000 ? `${text.slice(0, 4_000)}\n…` : text;
}

function optionLabel(option: PermissionOption, index: number): string {
	return `${index + 1}. ${option.name} [${option.kind}]`;
}

export class PermissionBroker {
	private tail: Promise<void> = Promise.resolve();

	constructor(private readonly getContext: () => PermissionUiContext | undefined) {}

	handle(value: unknown, signal?: AbortSignal): Promise<PermissionResponse> {
		const run = this.tail.then(() => this.handleNow(value, signal));
		this.tail = run.then(
			() => undefined,
			() => undefined,
		);
		return run;
	}

	private async handleNow(value: unknown, signal?: AbortSignal): Promise<PermissionResponse> {
		if (signal?.aborted) return cancelled();
		const request = parsePermissionRequest(value);
		if (!request || !request.options || request.options.length === 0) return cancelled();

		const context = this.getContext();
		if (!context?.hasUI) {
			const reject = rejectionOption(request.options);
			return reject ? selected(reject.optionId) : cancelled();
		}

		const labels = request.options.map(optionLabel);
		const input = formatInput(request.toolCall?.rawInput);
		const title = [
			`Grok Build requests permission: ${request.toolCall?.title ?? request.toolCall?.kind ?? "tool"}`,
			input ? `\n${input}` : "",
		].join("");
		const choice = await context.ui.select(title, labels, signal ? { signal } : undefined);
		if (signal?.aborted) return cancelled();
		const choiceIndex = choice ? labels.indexOf(choice) : -1;
		if (choiceIndex >= 0) {
			const option = request.options[choiceIndex];
			if (option) return selected(option.optionId);
		}
		const reject = rejectionOption(request.options);
		return reject ? selected(reject.optionId) : cancelled();
	}
}