/**
 * `celilo module changeset [<module-dir>] --bump <major|minor|patch> [-m <msg>]`
 * — author a changeset for a module (ISS-0151 / openspec/changes/module-version-semantics/proposal.md).
 *
 * Writes `.changeset/<name>.md` keyed by the MODULE id (Option A), the same
 * on-disk format `celilo module version` consumes. This is the thin authoring
 * helper that stands in for `bunx changeset add` (which is npm-package-centric
 * and can't target a celilo module id).
 */

import { mkdir, writeFile } from 'node:fs/promises';
import { join, resolve } from 'node:path';
import { parse as parseYaml } from 'yaml';
import { isBumpType } from '../../module/versioning/changeset-version';
import { getFlag } from '../parser';
import type { CommandResult } from '../types';

/** A short, collision-resistant, filename-safe slug for the changeset file. */
function changesetName(bump: string): string {
  const rand = crypto.randomUUID().replace(/-/g, '').slice(0, 10);
  return `${bump}-${rand}`;
}

export async function handleModuleChangeset(
  args: string[],
  flags: Record<string, string | boolean>,
): Promise<CommandResult> {
  const moduleDir = args[0] ?? '.';
  const dir = resolve(moduleDir);

  const bump = getFlag(flags, 'bump', '');
  if (!isBumpType(bump)) {
    return {
      success: false,
      error: 'A bump is required: --bump <major|minor|patch>',
    };
  }
  const message = getFlag(flags, 'message', '');

  let id: string;
  try {
    const manifest = parseYaml(await Bun.file(join(dir, 'manifest.yml')).text()) as { id?: string };
    if (!manifest.id) {
      return { success: false, error: `${moduleDir}: manifest.yml missing id` };
    }
    id = manifest.id;
  } catch {
    return { success: false, error: `${moduleDir}: could not read manifest.yml in ${dir}` };
  }

  const name = getFlag(flags, 'name', '') || changesetName(bump);
  const body = message.trim() || `${bump} change to ${id}.`;
  const content = `---\n"${id}": ${bump}\n---\n\n${body}\n`;

  const changesetDir = join(dir, '.changeset');
  await mkdir(changesetDir, { recursive: true });
  const file = join(changesetDir, `${name}.md`);
  await writeFile(file, content);

  return {
    success: true,
    message: `Wrote .changeset/${name}.md (${id}: ${bump}).`,
    data: { id, bump, file },
  };
}