#!/usr/bin/env node
/**
 * 建立議題之間的相依。
 *
 *   --depends  這顆被誰擋住（它的先決）
 *   --blocks   這顆擋住誰
 *
 * 冪等：先讀現況，只補缺的那幾條。重跑不會在 Gitea 上堆出重複的相依。
 *
 * `--dry-run` 不寫入但會讀——要列出「將建立哪幾條」就得先知道哪幾條已經存在。
 *
 * 用法：
 *   node scripts/issue-link.js --repo owner/name --index 12
 *                              [--depends 10,11] [--blocks 13] [--host <網址>] [--dry-run]
 */
import {
  ScriptError,
  expectOk,
  giteaRequest,
  main,
  parseFlags,
  parseRepo,
  preflight,
  resolveLogin,
} from './lib.js';

/** 兩種相依各自的端點與意義 */
const KINDS = {
  depends: { path: 'dependencies', label: '先決' },
  blocks: { path: 'blocks', label: '阻擋' },
};

main(async () => {
  const flags = parseFlags(process.argv.slice(2), {
    required: ['repo', 'index'],
    optional: ['depends', 'blocks', 'host'],
    booleans: ['dry-run'],
  });
  const repo = parseRepo(flags.repo);
  const [owner, name] = repo.split('/');
  const index = parseIndex(flags.index, '--index');
  const wanted = {
    depends: parseIndexList(flags.depends, index),
    blocks: parseIndexList(flags.blocks, index),
  };

  if (wanted.depends.length === 0 && wanted.blocks.length === 0) {
    throw new ScriptError('NOTHING_TO_LINK', '至少要指定 --depends 或 --blocks 其中一個');
  }

  const login = resolveLogin({ host: flags.host });
  if (!flags['dry-run']) await preflight(login, repo);

  const added = {};
  const skipped = {};
  const planned = [];

  for (const [kind, { path }] of Object.entries(KINDS)) {
    const endpoint = `/repos/${repo}/issues/${index}/${path}`;
    const existing = new Set(
      (expectOk(await giteaRequest(login, 'GET', endpoint), `GET ${endpoint}`) ?? []).map(
        (issue) => issue.number,
      ),
    );

    added[kind] = wanted[kind].filter((target) => !existing.has(target));
    skipped[kind] = wanted[kind].filter((target) => existing.has(target));

    for (const target of added[kind]) {
      const body = { owner, repo: name, index: target };
      if (flags['dry-run']) {
        planned.push({ method: 'POST', path: endpoint, body });
        continue;
      }
      expectOk(await giteaRequest(login, 'POST', endpoint, { body }), `POST ${endpoint}`);
    }
  }

  if (flags['dry-run']) {
    return { dryRun: true, repo, index, requests: planned, added, skipped };
  }
  return { repo, index, added, skipped };
});

function parseIndex(value, what) {
  if (!/^[1-9]\d*$/.test(String(value))) {
    throw new ScriptError('BAD_INDEX', `${what} 需為正整數，收到的是 ${value}`);
  }
  return Number(value);
}

/**
 * 解析逗號分隔的議題編號。
 * 自己依賴自己在 Gitea 上會被接受但毫無意義，而且會讓後續的拓撲排序永遠排不完，
 * 所以擋在發出請求之前。
 */
function parseIndexList(value, self) {
  if (value === undefined) return [];

  const indexes = value
    .split(',')
    .map((item) => item.trim())
    .filter((item) => item !== '')
    .map((item) => parseIndex(item, '相依編號'));

  if (indexes.includes(self)) {
    throw new ScriptError('SELF_DEPENDENCY', `議題 #${self} 不能是自己的先決或阻擋對象`);
  }
  return indexes;
}