import { execFile } from "node:child_process";
import { fileURLToPath } from "node:url";
import { promisify } from "node:util";
import type { AnalyzeOptions, CompileOptions, CompileExecutableResult, CoverageInput } from "@scriptc/compiler";

const execFileAsync = promisify(execFile);
const root = fileURLToPath(new URL("../../", import.meta.url));
const api = new URL("../../packages/compiler/src/index.ts", import.meta.url).href;

// Large synchronous frontend passes must leave Vitest's worker RPC responsive.
// Execute the source API in a child and return only JSON-compatible results.
async function compilerProcess(operation: "analyze" | "compile", entry: string, options: object): Promise<unknown> {
  const { stdout, stderr } = await execFileAsync(process.execPath, [
    "--max-old-space-size=8192", "--import", "tsx", "--input-type=module", "--eval",
    `import { analyze, compile } from ${JSON.stringify(api)};
     const options = JSON.parse(process.argv[3]);
     const result = process.argv[1] === 'analyze'
       ? analyze(process.argv[2], options).coverage
       : await compile(process.argv[2], options);
     console.log(JSON.stringify(result, (key, value) => key === 'sourceTexts' ? undefined : value));`,
    operation, entry, JSON.stringify(options),
  ], { cwd: root, timeout: 300_000, maxBuffer: 16 * 1024 * 1024 });
  if (stderr !== "") throw new Error(stderr);
  return JSON.parse(stdout);
}

export async function analyzeInChild(entry: string, options: AnalyzeOptions): Promise<CoverageInput> {
  return await compilerProcess("analyze", entry, options) as CoverageInput;
}

type ExecutableResult =
  | Extract<CompileExecutableResult, { ok: true }>
  | Omit<Extract<CompileExecutableResult, { ok: false }>, "sourceTexts">;

export async function compileInChild(entry: string, options: CompileOptions): Promise<ExecutableResult> {
  return await compilerProcess("compile", entry, options) as ExecutableResult;
}