// Igneum live devnet feed. GET /api/live returns what tools/observer wrote to Neon:
// {now, state (incl. height = chain block number), blocks (last 90 s, or ?window=N up to 300), miners (last 10 min), events (last 30), finality (checkpoints, newest lock),
//  proving (activation and 10-minute counts; every chain block carries shards: [{i, state, prover, lag, payout}])}.
// Five queries, all on indexed columns. Cached one second at the edge.
// LIVE_TABLE_PREFIX (default empty) reads a test observer's tables (fintest_live_*, provtest_live_*) instead of the devnet's.
// Zero dependencies: Neon's HTTP SQL endpoint over Node's built-in fetch.

const STALE_AFTER_S = 30;
const T = (process.env.LIVE_TABLE_PREFIX || '').replace(/[^a-z0-9_]/gi, '');

function neon() {
  const url = process.env.DATABASE_URL;
  if (!url) throw new Error('DATABASE_URL is not set');
  const host = new URL(url).hostname.replace('-pooler', '');
  return async (query, params = []) => {
    const r = await fetch(`https://${host}/sql`, {
      method: 'POST',
      headers: { 'Neon-Connection-String': url, 'Content-Type': 'application/json' },
      body: JSON.stringify({ query, params }),
    });
    const j = await r.json();
    if (!r.ok) throw new Error(j.message || JSON.stringify(j));
    return j.rows || [];
  };
}

const num = v => (v === null || v === undefined ? null : Number(v));
const short = h => (h ? String(h).slice(0, 16) : null);
const minerId = vk => (vk ? String(vk).slice(0, 8) : null);

export default async function handler(req, res) {
  res.setHeader('Cache-Control', 'public, max-age=1');
  res.setHeader('Access-Control-Allow-Origin', '*');
  if (req.method !== 'GET') {
    res.setHeader('Allow', 'GET');
    return res.status(405).json({ ok: false, error: 'method not allowed' });
  }
  try {
    const sql = neon();
    // ?window=N seconds of blocks (30 to 300, default 90): the page's diagnostic long view; the row cap keeps a busy DAG bounded
    const q = new URL(req.url || '/', 'http://x').searchParams;
    const windowS = Math.max(30, Math.min(300, Number(q.get('window')) || 90));
    const [head, blockRows, minerRows, checkpointRows, proofRows] = await Promise.all([
      sql(`SELECT now() AS now,
                  (SELECT row_to_json(s) FROM ${T}live_state s WHERE s.id = 1) AS state,
                  (SELECT json_agg(e) FROM (SELECT ts, kind, text FROM ${T}live_events ORDER BY ts DESC LIMIT 30) e) AS events,
                  (SELECT max(number) FROM ${T}live_blocks WHERE number IS NOT NULL AND received_at > now() - interval '10 minutes') AS height`),
      sql(`SELECT hash, blue_score, daa_score, timestamp_ms, parent_hashes, is_chain_block, vote_key_hash, received_at, color, number
             FROM ${T}live_blocks
            WHERE received_at > now() - ($1 || ' seconds')::interval
            ORDER BY received_at DESC
            LIMIT 2000`, [String(windowS)]),
      sql(`SELECT vote_key_hash, count(*)::int AS blocks, max(received_at) AS last_seen, max(engine) AS engine, max(miner_address) AS address
             FROM ${T}live_blocks
            WHERE received_at > now() - interval '10 minutes' AND vote_key_hash IS NOT NULL
            GROUP BY vote_key_hash
            ORDER BY blocks DESC, last_seen DESC`),
      // Finality v2: the most recent checkpoints; an older observer has no table yet, so this query may fail
      sql(`SELECT index, hash, blue_score, daa_score, state, signed_weight, active_weight, total_weight, fraction_active, fraction_total, votes_seen, voters, locked_at, updated_at
             FROM ${T}live_checkpoints
            ORDER BY index DESC
            LIMIT 40`).catch(() => []),
      // Proving v0: the planned shards of the chain blocks in the window and what became of them (an older observer has no table)
      sql(`SELECT block_hash, shard, shards, state, prover, lag_daa, payout_wei, pgas
             FROM ${T}live_proofs
            WHERE received_at > now() - ($1 || ' seconds')::interval
            ORDER BY block_hash, shard`, [String(windowS + 30)]).catch(() => []),
    ]);

    const now = new Date(head[0].now).getTime();
    const s = head[0].state || null;
    const updated = s && s.updated_at ? new Date(s.updated_at).getTime() : null;
    const age_s = updated === null ? null : Math.max(0, (now - updated) / 1000);
    const stale = age_s === null || age_s > STALE_AFTER_S;
    const total10m = minerRows.reduce((a, m) => a + m.blocks, 0);

    const state = {
      stale,
      age_s: age_s === null ? null : Math.round(age_s * 10) / 10,
      network: s ? s.network : null,
      node_version: s ? s.node_version : null,
      // 6 Oct 2026: height is the chain block number (the EVM block number of the newest chain block the observer planned),
      // the same field /api/stats reports; block_count counts every DAG block the node holds (pruned nodes hold fewer)
      height: num(head[0].height),
      block_count: s ? num(s.block_count) : null,
      header_count: s ? num(s.header_count) : null,
      blue_score: s ? num(s.blue_score) : null,
      difficulty: s ? num(s.difficulty) : null,
      hashes_per_second_estimate: s ? num(s.hashes_per_second_estimate) : null,
      peers: s ? num(s.peers) : null,
      mempool: s ? num(s.mempool) : null,
      blocks_60s: s ? num(s.blocks_60s) : null,
      blocks_per_second_60s: s && s.blocks_60s !== null ? Math.round(num(s.blocks_60s) / 60 * 1000) / 1000 : null,
      blocks_per_minute: s ? s.blocks_per_minute || [] : [],
      miners_10m: minerRows.length,
      observer_started_at: s ? s.observer_started_at : null,
      // 4 Oct 2026: how far the observer's newest stored block is behind the clock, and what it still has queued
      observer_lag_s: s ? num(s.observer_lag_s) : null,
      queue_depth: s ? num(s.queue_depth) : null,
      updated_at: s ? s.updated_at : null,
    };

    const fin = (s && s.finality) || null;
    const checkpoints = checkpointRows.reverse().map(c => ({
      index: num(c.index), hash: short(c.hash), blue_score: num(c.blue_score), daa: num(c.daa_score), state: c.state,
      signed: num(c.signed_weight), active: num(c.active_weight), total: num(c.total_weight),
      fraction_active: num(c.fraction_active), fraction_total: num(c.fraction_total), votes: num(c.votes_seen), voters: num(c.voters),
      locked_at: c.locked_at, updated_at: c.updated_at,
    }));
    const lockedHashes = new Set(checkpoints.filter(c => c.state === 'locked').map(c => c.hash));
    const newestLock = checkpoints.filter(c => c.state === 'locked').slice(-1)[0] || null;
    const finality = {
      supported: !!fin,
      active: fin ? !!fin.finality_active : false,
      next_index: fin ? num(fin.next_index) : null,
      latest_locked_index: newestLock ? newestLock.index : (fin ? num(fin.latest_locked_index) || null : null),
      latest_locked_hash: newestLock ? newestLock.hash : null,
      latest_locked_blue_score: newestLock ? newestLock.blue_score : null,
      params: fin ? fin.params || null : null,
      weights: fin ? fin.weights || null : null,
      checkpoints,
    };

    // proving v0: one cell per planned shard; payout in IGN (wei / 1e18) to four decimals, never an address (R4.6.8)
    const shardsOf = new Map();
    for (const r of proofRows) {
      const k = short(r.block_hash);
      if (!shardsOf.has(k)) shardsOf.set(k, []);
      let payout = null;
      if (r.payout_wei) { try { payout = Number(BigInt(r.payout_wei) / 100000000000000n) / 10000; } catch { payout = null; } }
      shardsOf.get(k).push({ i: num(r.shard), n: num(r.shards), state: r.state, prover: r.prover || null, lag: num(r.lag_daa), payout, pgas: num(r.pgas) });
    }
    const pv = (s && s.proving) || null;
    const proving = pv && pv.supported ? {
      supported: true, active: !!pv.active, activation_daa: num(pv.activation_daa), tip_daa: num(pv.tip_daa), verifier: pv.verifier || null, pool: pv.pool || null,
      paid_shards_total: num(pv.paid_shards_total), shard_budget_pgas: num(pv.shard_budget_pgas),
      blocks_10m: num(pv.blocks_10m), blocks_fully_proven_10m: num(pv.blocks_fully_proven_10m), shards_proven_10m: num(pv.shards_proven_10m), shards_paid_10m: num(pv.shards_paid_10m),
      median_proof_lag_s: num(pv.median_proof_lag_s), provers_10m: num(pv.provers_10m),
    } : { supported: false, reason: pv ? (pv.reason || 'node without proving') : 'observer has not reported the proving layer' };

    const blocks = blockRows.reverse().map(b => ({
      hash: short(b.hash),
      // the chain block number (the EVM block number) once the observer has planned the block; null off the chain or before the plan
      number: num(b.number),
      blue_score: num(b.blue_score),
      daa: num(b.daa_score),
      ts: num(b.timestamp_ms),
      rx: new Date(b.received_at).getTime(),
      parents: (b.parent_hashes || []).map(short),
      chain: !!b.is_chain_block,
      miner: minerId(b.vote_key_hash),
      // GHOSTDAG colour from the observer: blue (merged by a chain block, paid), red (excluded) or pending (not merged yet)
      color: b.color === 'blue' || b.color === 'red' ? b.color : 'pending',
      // Finality v2: a locked checkpoint block, and whether the block sits at or before the newest lock
      locked: lockedHashes.has(short(b.hash)),
      final: !!(newestLock && b.is_chain_block && num(b.blue_score) <= newestLock.blue_score),
      // Proving v0: the chain block's shards (planned, proving, verified, paid) and whether every shard is proven
      shards: shardsOf.get(short(b.hash)) || [],
      proven: (shardsOf.get(short(b.hash)) || []).length > 0 && (shardsOf.get(short(b.hash)) || []).every(x => x.state === 'verified' || x.state === 'paid'),
    }));

    const miners = minerRows.map(m => ({
      id: minerId(m.vote_key_hash),
      blocks: m.blocks,
      share: total10m ? Math.round(m.blocks / total10m * 1000) / 10 : 0,
      last_seen: m.last_seen,
      engine: m.engine || null,
    }));

    // peer events never carry an address on the public API (review round 4, R4.6.2); older stored rows are redacted here too
    const events = (head[0].events || []).map(e => ({ ts: e.ts, kind: e.kind, text: String(e.text).replace(/\b\d{1,3}(\.\d{1,3}){3}(:\d+)?\b/g, 'a peer') }));

    return res.status(200).json({ ok: true, now: new Date(now).toISOString(), state, blocks, miners, events, finality, proving });
  } catch (e) {
    res.setHeader('Cache-Control', 'no-store');
    return res.status(500).json({ ok: false, error: String(e.message || e) });
  }
}