import { createHash, randomUUID } from "node:crypto";
import { readFile, writeFile, rename, rm } from "node:fs/promises";
import { dirname, resolve } from "node:path";
import { fileURLToPath } from "node:url";
import openapiTS, { astToString, COMMENT_HEADER } from "openapi-typescript";

const local = new URL("../openapi/openapi.json", import.meta.url);
const manifest = new URL("../openapi/server-manifest.json", import.meta.url);
const generated = new URL("../src/generated/server-api.d.ts", import.meta.url);
const defaultUpstream = new URL("../../next-tjwater-server/contracts/server-v1.openapi.json", import.meta.url);

export function assertContractDigest(raw: string, expected: string) {
  if (createHash("sha256").update(raw).digest("hex") !== expected) throw new Error("Server contract digest differs; run bun run sync:openapi");
}

async function main() {
  const sync = process.argv.includes("--sync");
  const upstreamIndex = process.argv.indexOf("--upstream");
  if (upstreamIndex >= 0 && !process.argv[upstreamIndex + 1]) throw new Error("--upstream requires an OpenAPI file");
  const upstream = upstreamIndex >= 0 ? resolve(process.argv[upstreamIndex + 1]) : defaultUpstream;
  let upstreamRaw: string | undefined;
  try { upstreamRaw = await readFile(upstream, "utf8"); }
  catch (error) {
    if (sync || upstreamIndex >= 0 || (error as NodeJS.ErrnoException).code !== "ENOENT") throw error;
  }
  if (sync) {
    const producerManifest = JSON.parse(await readFile(resolve(
      dirname(upstream instanceof URL ? fileURLToPath(upstream) : upstream), "manifest.json"
    ), "utf8"));
    assertContractDigest(upstreamRaw!, producerManifest.contracts.server.sha256);
    // Complete validation and generation before replacing any checked-in artifact.
    const types = COMMENT_HEADER + astToString(await openapiTS(JSON.parse(upstreamRaw!)));
    const artifacts = [
      { target: local, content: upstreamRaw! },
      { target: manifest, content: JSON.stringify(producerManifest, null, 2) + "\n" },
      { target: generated, content: types },
    ].map((artifact) => ({ ...artifact, temporary: new URL(`${artifact.target.href}.${randomUUID()}.tmp`) }));
    try {
      for (const artifact of artifacts) await writeFile(artifact.temporary, artifact.content);
      for (const artifact of artifacts) await rename(artifact.temporary, artifact.target);
    } finally {
      await Promise.all(artifacts.map((artifact) => rm(artifact.temporary, { force: true })));
    }
    console.log("Server OpenAPI snapshot, producer digest and types synchronized.");
    return;
  }
  const raw = await readFile(local, "utf8");
  const receipt = JSON.parse(await readFile(manifest, "utf8"));
  assertContractDigest(raw, receipt.contracts.server.sha256);
  if (upstreamRaw !== undefined && upstreamRaw !== raw) throw new Error("Upstream Server contract changed; run bun run sync:openapi");
  if (await readFile(generated, "utf8") !== COMMENT_HEADER + astToString(await openapiTS(JSON.parse(raw)))) throw new Error("Generated Server types differ; run bun run generate:openapi");
  console.log(upstreamRaw === undefined
    ? "Local Server contract digest and types checked; upstream unavailable in this checkout."
    : "Upstream Server contract, digest and generated types checked.");
}

if (import.meta.main) await main();