import arg from "arg";
import paths from "node:path";
import fs from "node:fs/promises";

const globalArgs = arg(
  {
    "--help": Boolean,
  },
  { argv: process.argv.slice(2), stopAtPositional: true },
);

if (globalArgs["--help"] || globalArgs._.length === 0) {
  process.stdout.write(`postman.ts [...options] <command>

COMMANDS

new - Create new post

OPTIONS
--help - Print this message and exit
`);

  process.exit();
}

const command = globalArgs._[0];
let rest = globalArgs._.slice(1);

function parseNewPostArgsPartial(rest: string[]) {
  return arg(
    {
      "--draft": Boolean,
      "--overwrite": Boolean,
      "--help": Boolean,
    },
    { stopAtPositional: true, argv: rest },
  );
}

const postRoot = paths.resolve(import.meta.dir, "..", "src", "posts");

if (command === "new") {
  const cfg = parseNewPostArgsPartial(rest);
  rest = cfg._.slice(1);
  const postId: string = cfg._[0];

  const hasAdditionalArgs = cfg._.length > 0;

  const partialCfg = parseNewPostArgsPartial(rest);
  Object.assign(cfg, partialCfg);

  if (cfg["--help"] || !hasAdditionalArgs) {
    process.stdout.write(`postman.ts new <postId> [...options]

Create a new post with default content.

OPTIONS

--draft - Create the post as a draft
--overwrite - Overwrite existing file
--help - Print this message and exit
`);

    process.exit();
  }

  if (partialCfg._.length > 0) {
    throw new TypeError(`unexpected positional argument "${partialCfg._[0]}"`);
  }

  const thisPostRoot = paths.join(postRoot, postId);

  await fs.mkdir(thisPostRoot);

  const postContent = `---
title: ${postId}
${cfg["--draft"] ? "visibility: draft" : ""}
---
import More from "~/components/More.astro";

<More />
`;

  const thisPostFilename = paths.join(thisPostRoot, "index.mdx");

  const file = await fs.open(
    thisPostFilename,
    (cfg["--overwrite"]
      ? fs.constants.O_TRUNC
      : fs.constants.O_CREAT | fs.constants.O_EXCL) | fs.constants.O_WRONLY,
  );

  try {
    await fs.writeFile(file, postContent, {
      encoding: "utf-8",
    });
  } finally {
    await file.close();
  }

  const displayedPath = paths.relative(process.cwd(), thisPostFilename);
  process.stdout.write(displayedPath);
} else {
  throw new TypeError(`unknown command ${command}`);
}