import fs from "node:fs";
import path from "node:path";
import { execFileSync } from "node:child_process";
import { fileURLToPath } from "node:url";

const scriptDir = path.dirname(fileURLToPath(import.meta.url));
const repoRoot = path.resolve(scriptDir, "..");
const uiPackagePath = path.join(repoRoot, "packages", "ui", "package.json");
const tokensPackagePath = path.join(repoRoot, "packages", "tokens", "package.json");

function parseArgs(argv) {
  const options = {
    before: null,
    field: null
  };

  for (let index = 0; index < argv.length; index += 1) {
    const current = argv[index];

    if (current === "--before" || current === "--field") {
      const next = argv[index + 1];

      if (!next) {
        throw new Error(`Expected a value after ${current}.`);
      }

      if (current === "--before") {
        options.before = next;
      } else {
        options.field = next;
      }

      index += 1;
      continue;
    }

    throw new Error(`Unknown argument: ${current}`);
  }

  return options;
}

function readVersion(filePath) {
  return JSON.parse(fs.readFileSync(filePath, "utf8")).version;
}

function readVersionAtRef(ref, filePath) {
  if (!ref || /^0{40}$/.test(ref)) {
    return null;
  }

  try {
    const content = execFileSync("git", ["show", `${ref}:${path.relative(repoRoot, filePath)}`], {
      cwd: repoRoot,
      encoding: "utf8"
    });
    return JSON.parse(content).version;
  } catch {
    return null;
  }
}

function getReleaseMetadata(beforeRef) {
  const uiVersion = readVersion(uiPackagePath);
  const tokensVersion = readVersion(tokensPackagePath);

  if (uiVersion !== tokensVersion) {
    throw new Error(
      `Expected @ai-ui/ui and @ai-ui/tokens to share a version. Received ${uiVersion} and ${tokensVersion}.`
    );
  }

  const previousUiVersion = readVersionAtRef(beforeRef, uiPackagePath);
  const previousTokensVersion = readVersionAtRef(beforeRef, tokensPackagePath);
  const changed =
    previousUiVersion === null ||
    previousTokensVersion === null ||
    previousUiVersion !== uiVersion ||
    previousTokensVersion !== tokensVersion;

  return {
    changed,
    tag: `cadence-ui-v${uiVersion}`,
    version: uiVersion
  };
}

const options = parseArgs(process.argv.slice(2));
const metadata = getReleaseMetadata(options.before);

if (options.field) {
  if (!(options.field in metadata)) {
    throw new Error(`Unknown field "${options.field}".`);
  }

  process.stdout.write(String(metadata[options.field]));
} else {
  process.stdout.write(`${JSON.stringify(metadata, null, 2)}\n`);
}