import { spawn } from "node:child_process";

export interface ProcessRequest {
	command: string;
	args: string[];
	cwd: string;
	input?: string;
	signal?: AbortSignal;
	env?: NodeJS.ProcessEnv;
}

export interface ProcessResult {
	stdout: string;
	stderr: string;
	exitCode: number;
}

export type ProcessRunner = (request: ProcessRequest) => Promise<ProcessResult>;

export const runProcess: ProcessRunner = (request) =>
	new Promise((resolve, reject) => {
		const child = spawn(request.command, request.args, {
			cwd: request.cwd,
			env: request.env,
			shell: false,
			stdio: ["pipe", "pipe", "pipe"],
		});
		let stdout = "";
		let stderr = "";
		let aborted = false;
		let closed = false;
		let killTimer: NodeJS.Timeout | undefined;

		child.stdout.on("data", (chunk: Buffer) => {
			stdout += chunk.toString("utf8");
		});
		child.stderr.on("data", (chunk: Buffer) => {
			stderr += chunk.toString("utf8");
		});

		const abort = () => {
			aborted = true;
			child.kill("SIGTERM");
			killTimer = setTimeout(() => {
				if (!closed) child.kill("SIGKILL");
			}, 5000);
		};
		if (request.signal?.aborted) abort();
		else request.signal?.addEventListener("abort", abort, { once: true });

		child.on("error", (error) => {
			request.signal?.removeEventListener("abort", abort);
			reject(new Error(`Failed to start ${request.command}: ${error.message}`));
		});
		child.on("close", (exitCode) => {
			closed = true;
			if (killTimer) clearTimeout(killTimer);
			request.signal?.removeEventListener("abort", abort);
			if (aborted) {
				reject(new Error(`${request.command} was aborted`));
				return;
			}
			resolve({ stdout, stderr, exitCode: exitCode ?? 1 });
		});

		if (request.input !== undefined) child.stdin.end(request.input);
		else child.stdin.end();
	});

export async function runChecked(
	runner: ProcessRunner,
	request: ProcessRequest,
): Promise<ProcessResult> {
	const result = await runner(request);
	if (result.exitCode !== 0) {
		const detail =
			result.stderr.trim() || result.stdout.trim() || "no diagnostic output";
		throw new Error(
			`${request.command} exited with ${result.exitCode}: ${detail}`,
		);
	}
	return result;
}