/**
 * Deletes completed Actions runs older than a given age.
 *
 * Gitea 1.27.3 has retention for a run's logs (`LOG_RETENTION_DAYS`) and its
 * artifacts, but none for the run record itself — so the Actions list grows
 * without limit while the entries on it become empty shells once their logs
 * expire. This removes the shells. See #324.
 *
 * Dry run unless APPLY is exactly "true". Deleting a run cannot be undone and
 * there is no confirmation step once this starts, so the default has to be the
 * harmless one.
 *
 * Environment:
 *   GITEA_HOST           origin of the instance, scheme included, e.g.
 *                        https://gitea.example.com or http://gitea:3000
 *   GITEA_REPO           "owner/name"
 *   GITEA_ACCESS_TOKEN   token permitted to delete runs
 *   KEEP_DAYS            keep runs newer than this many days (default 7)
 *   APPLY                "true" to delete; anything else reports only
 */

const https = require('https');
const http = require('http');
const { URL } = require('url');

const HOST = process.env.GITEA_HOST;
const REPO = process.env.GITEA_REPO;
const TOKEN = process.env.GITEA_ACCESS_TOKEN;
const KEEP_DAYS = Number(process.env.KEEP_DAYS || 7);
const APPLY = process.env.APPLY === 'true';

for (const [name, value] of Object.entries({ GITEA_HOST: HOST, GITEA_REPO: REPO, GITEA_ACCESS_TOKEN: TOKEN })) {
  if (!value) {
    console.error(`${name} is required`);
    process.exit(1);
  }
}
if (!Number.isFinite(KEEP_DAYS) || KEEP_DAYS < 0) {
  console.error(`KEEP_DAYS must be a non-negative number, got ${process.env.KEEP_DAYS}`);
  process.exit(1);
}

const origin = new URL(HOST);

/**
 * The transport GITEA_HOST actually asks for, rather than the one assumed.
 *
 * This was hardcoded to https, which worked when the host was typed by hand and
 * failed the moment the workflow started taking it from `github.server_url`.
 * Inside the runner that is the address act_runner reaches Gitea on, which here
 * is plain HTTP on a container port — and a TLS handshake sent to a plaintext
 * port does not fail as a connection error. It fails as:
 *
 *     write EPROTO ... ssl3_get_record:wrong version number
 *
 * which reads like a TLS misconfiguration and sends you looking at certificates
 * and protocol versions. It is neither. The server answered in cleartext and
 * OpenSSL tried to parse that as a TLS record.
 *
 * So the scheme is honoured rather than guessed, and the default port follows
 * from it. Anything other than the two is refused up front: this script only
 * speaks HTTP, and a URL naming some other scheme is a mistake worth reporting
 * as one instead of failing later inside a request.
 */
if (origin.protocol !== 'https:' && origin.protocol !== 'http:') {
  console.error(`GITEA_HOST must be an http or https URL, got ${HOST}`);
  process.exit(1);
}
const secure = origin.protocol === 'https:';
const transport = secure ? https : http;
const PORT = origin.port || (secure ? 443 : 80);

const BASE = `/api/v1/repos/${REPO}/actions/runs`;

function call(method, path) {
  return new Promise((resolve, reject) => {
    const req = transport.request(
      { hostname: origin.hostname, port: PORT, path, method, headers: { Authorization: `token ${TOKEN}` } },
      (res) => {
        let body = '';
        res.on('data', (d) => (body += d));
        res.on('end', () => resolve({ status: res.statusCode, body }));
      }
    );
    req.on('error', reject);
    req.end();
  });
}

async function listAllRuns() {
  const runs = [];
  // Bounded rather than `while (true)`: a paging bug against an API that keeps
  // answering would otherwise loop until the job times out.
  for (let page = 1; page <= 200; page++) {
    const res = await call('GET', `${BASE}?page=${page}&limit=50`);
    if (res.status >= 400) throw new Error(`listing runs failed: ${res.status} ${res.body.slice(0, 200)}`);
    const batch = JSON.parse(res.body).workflow_runs || [];
    if (batch.length === 0) break;
    runs.push(...batch);
    if (batch.length < 50) break;
  }
  return runs;
}

const EPOCH_GUARD = new Date('2000-01-01').getTime();

/**
 * When a run happened, from whichever timestamp it actually has.
 *
 * `started_at` is preferred and is usually right, but a run **cancelled before
 * it ever started** reports an epoch value there while carrying a real
 * `completed_at`. Reading only `started_at` therefore made every cancelled run
 * look undateable, and a first pass at this left 19 of them — from three weeks
 * earlier — sitting in a list that was supposed to hold seven days.
 *
 * Returns null when neither timestamp is usable, which is the case that must
 * stay conservative: an epoch date treated as "1969, therefore old" would
 * delete precisely the runs that have not happened yet.
 */
function runTimeMs(run) {
  for (const stamp of [run.started_at, run.completed_at]) {
    const ms = stamp ? new Date(stamp).getTime() : NaN;
    if (Number.isFinite(ms) && ms >= EPOCH_GUARD) return ms;
  }
  return null;
}

/**
 * Runs old enough to remove, and the reasons the others were left.
 *
 * A run that is not completed is never a candidate — which is also what stops
 * this deleting the very run it is executing in.
 */
function selectDoomed(runs, cutoffMs) {
  const doomed = [];
  const kept = { recent: 0, unfinished: 0, undated: 0 };

  for (const run of runs) {
    if (run.status !== 'completed') {
      kept.unfinished++;
      continue;
    }
    const ms = runTimeMs(run);
    if (ms === null) {
      kept.undated++;
      continue;
    }
    if (ms >= cutoffMs) {
      kept.recent++;
      continue;
    }
    doomed.push({ id: run.id, startedAt: run.started_at, when: new Date(ms).toISOString() });
  }

  doomed.sort((a, b) => a.id - b.id);
  return { doomed, kept };
}

(async () => {
  // Printed before the first request rather than after it succeeds. A transport
  // failure here says nothing about where it was pointed, and the last one cost
  // a round trip to find out that the answer was "somewhere plaintext".
  console.log(`endpoint   : ${origin.protocol}//${origin.hostname}:${PORT}`);

  const runs = await listAllRuns();
  const cutoffMs = Date.now() - KEEP_DAYS * 86400000;
  const { doomed, kept } = selectDoomed(runs, cutoffMs);

  console.log(`repository : ${REPO}`);
  console.log(`total runs : ${runs.length}`);
  console.log(`keeping    : ${kept.recent} newer than ${KEEP_DAYS}d, ${kept.unfinished} unfinished, ${kept.undated} undated`);
  console.log(`to delete  : ${doomed.length}`);
  if (doomed.length > 0) {
    console.log(`  oldest   : run ${doomed[0].id} (${doomed[0].when})`);
    console.log(`  newest   : run ${doomed[doomed.length - 1].id} (${doomed[doomed.length - 1].when})`);
  }
  console.log('');

  if (!APPLY) {
    console.log('DRY RUN — nothing deleted. Re-run with apply set to "true".');
    return;
  }
  if (doomed.length === 0) {
    console.log('Nothing to delete.');
    return;
  }

  let deleted = 0;
  const failures = [];
  for (const run of doomed) {
    const res = await call('DELETE', `${BASE}/${run.id}`);
    if (res.status >= 200 && res.status < 300) deleted++;
    else failures.push(`${run.id}:${res.status}`);

    const done = deleted + failures.length;
    if (done % 50 === 0) console.log(`  ...${done}/${doomed.length}`);
  }

  console.log('');
  console.log(`deleted : ${deleted}`);
  console.log(`failed  : ${failures.length}`);
  if (failures.length > 0) {
    console.log(`  ${failures.slice(0, 20).join(' ')}${failures.length > 20 ? ' …' : ''}`);
    // A partial delete is not a success. Most likely the token cannot delete
    // runs, and reporting green here would hide that behind a job that
    // appeared to work.
    process.exitCode = 1;
  }
})().catch((err) => {
  console.error(`FAILED: ${err.message}`);
  process.exit(1);
});