import fs from "node:fs/promises";
import path from "node:path";
import { execFileSync } from "node:child_process";

export async function buildService({
  config,
  compiler,
  pkg,
  output,
  coreServer,
  sharedFiles,
  implementations,
  recordFile,
}) {
  const relative = compiler.artifactPath;
  if (config.restricted) {
    if (config.service.entry || pkg.exports.some((e) => e.execution.kind === "remote"))
      throw Error(
        "Restricted services require portable snapshot/transaction exports; remote/custom services keep their VM path",
      );
    const modules = implementations.filter((i) => i.target === "server");
    if (modules.length !== 1 || pkg.exports.some((e) => !modules[0].exports.includes(e.id)))
      throw Error("Restricted service requires exactly one checked portable registry covering all exports");
    const limits = config.restricted.limits;
    if (!limits || typeof limits !== "object" || Array.isArray(limits))
      throw Error("Restricted limits must be an object");
    if (Object.keys(limits).some((key) => !["deadlineMs", "maxBytes", "maxPortCalls", "maxQueued"].includes(key)))
      throw Error("Unknown restricted service limit");
    for (const [key, min, max] of [
      ["deadlineMs", 1, 60000],
      ["maxBytes", 1024, 4194304],
      ["maxPortCalls", 1, 10000],
      ["maxQueued", 0, 64],
    ])
      if (limits[key] !== undefined && (!Number.isSafeInteger(limits[key]) || limits[key] < min || limits[key] > max))
        throw Error("Invalid restricted service limit " + key);
    await fs.mkdir(path.join(output, "bin"), { recursive: true });
    await fs.mkdir(path.join(output, "share/quixos/service"), { recursive: true });
    const configFile = "share/quixos/service/restricted.json";
    const module = modules[0];
    await fs.writeFile(
      path.join(output, configFile),
      JSON.stringify({
        module: path.relative("share/quixos/service", module.path),
        registryExport: module.registryExport,
        exports: module.exports,
        sdk: [{ name: config.restricted.sdk, path: config.restricted.sdk }],
        ...limits,
      }),
    );
    await fs.writeFile(
      path.join(output, "bin/service"),
      `#!${config.shell}\nservice_root=\${0%/*}/..\nexec ${config.restricted.runtime} "$service_root/${configFile}"\n`,
      { mode: 0o755 },
    );
    const body = {
      id: "service",
      target: "server",
      compatibility: "quixos-service-v1",
      path: "bin/service",
      ports: "quixos-transaction-ports-v1",
      exports: module.exports,
      files: [
        await recordFile("bin/service", "text/x-shellscript"),
        await recordFile(configFile, "application/json"),
        ...module.files,
      ],
    };
    implementations.unshift({ ...body, contentDigest: compiler.implementationDigest(body) });
    return;
  }
  if (pkg.exports.length || config.service.entry) {
    await fs.mkdir(path.join(output, "bin"), { recursive: true });
    await fs.mkdir(path.join(output, "share/quixos/service"), { recursive: true });
    let serviceEntry;
    if (config.service.entry) {
      if (!/\.m?js$/.test(config.service.entry))
        throw Error("Custom service entry must be JavaScript; use a separate typed/language build before packaging");
      serviceEntry = path.join(config.source, relative(config.service.entry));
    } else {
      const modules = implementations.filter((implementation) => implementation.target === "server");
      if (pkg.exports.some((entry) => !modules.some((module) => module.exports.includes(entry.id))))
        throw Error("Generated service does not cover every package export; provide a custom service");
      if (!modules.length) throw Error("Generated service requires a checked registry");
      serviceEntry = path.resolve("service-entry.mjs");
      const imports = modules
        .map(
          (module, index) =>
            `import { ${module.registryExport} as registry${index} } from ${JSON.stringify(path.join(output, module.path))};`,
        )
        .join("\n");
      await fs.writeFile(
        serviceEntry,
        imports +
          `\nimport {servePortableRegistry} from ${JSON.stringify(config.serviceAdapter)};
const registries = [${modules.map((_, index) => "registry" + index).join(",")}];
const owners = new Map();
for (const registry of registries) for (const id of registry.exports) {
  if (owners.has(id)) throw Error("Duplicate registry export " + id);
  owners.set(id, registry);
}
servePortableRegistry({exports: [...owners.keys()], invoke(request, channel, context) {
  const registry = owners.get(request.exportId);
  if (!registry) throw Error("Unknown export");
  return registry.invoke(request, channel, context);
}});\n`,
      );
    }
    const serviceModule = "share/quixos/service/main.mjs";
    execFileSync(
      config.esbuild,
      [
        serviceEntry,
        "--bundle",
        "--platform=node",
        "--format=esm",
        "--minify-whitespace",
        "--target=es2024",
        `--external:${coreServer}`,
        `--outfile=${path.join(output, serviceModule)}`,
      ],
      { stdio: "inherit" },
    );
    await fs.writeFile(
      path.join(output, "bin/service"),
      `#!${config.shell}\nservice_root=\${0%/*}/..\nexec ${config.node} "$service_root/${serviceModule}" "$@"\n`,
      { mode: 0o755 },
    );
    const serviceBody = {
      id: "service",
      target: "server",
      compatibility: "quixos-service-v1",
      path: "bin/service",
      ports: "quixos-transaction-ports-v1",
      exports: pkg.exports.map((e) => e.id),
      files: [
        await recordFile("bin/service", "text/x-shellscript"),
        await recordFile(serviceModule, "text/javascript"),
        ...sharedFiles,
      ],
    };
    implementations.unshift({ ...serviceBody, contentDigest: compiler.implementationDigest(serviceBody) });
  }
}