import { createHash } from 'node:crypto';
import type { Pool, PoolClient } from 'pg';
import { z } from 'zod';
import { XMR_RPC_UINT64_MAX } from '../../shared/xmr-amount.ts';
import { CUSTODY_WRITE_LOCK } from './postgres-schema.ts';
import { validateXmrAddress } from './xmr.ts';
import type { MoneroIncomingObservation, MoneroObservationPage } from './monero-observer.ts';

const walletFingerprintSchema = z.string().regex(/^[a-f0-9]{64}$/);
const scanInputSchema = z.object({
  scanId: z.string().uuid(),
  walletFingerprint: walletFingerprintSchema,
  expectedScanHeight: z.number().int().nonnegative().safe(),
  scannedAt: z.number().int().nonnegative().safe(),
  page: z.object({
    network: z.literal('mainnet'), walletHeight: z.number().int().nonnegative().safe(),
    fromHeight: z.number().int().nonnegative().safe(), throughHeight: z.number().int().nonnegative().safe(),
    primaryAddress: z.string().length(95), incoming: z.array(z.unknown()).max(4096),
  }).strict(),
}).strict();
const observationSchema = z.object({
  observationId: z.string().min(1).max(160), transactionId: z.string().regex(/^[a-f0-9]{64}$/),
  address: z.string().length(95),
  amountAtomicXmr: z.string().regex(/^[1-9]\d{0,19}$/),
  height: z.number().int().positive().safe(), confirmations: z.number().int().positive().safe(),
  timestamp: z.number().int().nonnegative().safe(), unlockTime: z.string().regex(/^(0|[1-9]\d{0,19})$/),
  accountIndex: z.number().int().nonnegative().safe(), addressIndex: z.number().int().nonnegative().safe(),
  outputPublicKey: z.string().regex(/^[a-f0-9]{64}$/), globalOutputIndex: z.number().int().nonnegative().safe(),
  locked: z.boolean(), doubleSpendSeen: z.boolean(),
}).strict();
const MAX_SCAN_RANGE = 100_000;
const MAX_OVERLAP = 10_000;

export type PersistObservationScanInput = {
  scanId: string;
  walletFingerprint: string;
  expectedScanHeight: number;
  scannedAt: number;
  page: MoneroObservationPage;
};
export type PersistObservationScanResult = {
  scanId: string;
  scanHeight: number;
  observed: number;
  changed: number;
  reappeared: number;
  notSeen: number;
  replayed: boolean;
};

function digest(value: unknown): string {
  return createHash('sha256').update(JSON.stringify(value)).digest('hex');
}
function rowDigest(observation: MoneroIncomingObservation): string {
  return digest([observation.observationId, observation.transactionId, observation.amountAtomicXmr,
    observation.height, observation.timestamp, observation.unlockTime,
    observation.accountIndex, observation.addressIndex, observation.outputPublicKey, observation.globalOutputIndex,
    observation.locked, observation.doubleSpendSeen]);
}

/**
 * Persist one complete wallet-RPC scan page as observation-only state. This function does not
 * create customer credits or financial journals. A missing transfer produces `not-seen`, not
 * an automatic debit/reversal; operators must reconcile Monero reorgs before any later credit design.
 */
export async function persistMoneroObservationScan(pool: Pool, input: PersistObservationScanInput): Promise<PersistObservationScanResult> {
  const parsed = scanInputSchema.parse(input);
  const page = parsed.page;
  if (page.fromHeight > page.throughHeight || page.throughHeight > page.walletHeight ||
      page.throughHeight - page.fromHeight > MAX_SCAN_RANGE || parsed.expectedScanHeight - page.fromHeight > MAX_OVERLAP ||
      page.fromHeight > parsed.expectedScanHeight || page.throughHeight < parsed.expectedScanHeight) {
    throw new Error('Monero observation scan range is not contiguous with its durable cursor');
  }
  await validateXmrAddress(page.primaryAddress);
  const observations = page.incoming.map(value => observationSchema.parse(value));
  const ids = new Set<string>();
  for (const observation of observations) {
    await validateXmrAddress(observation.address);
    if (observation.observationId !== `${observation.transactionId}:${observation.outputPublicKey}` ||
        BigInt(observation.amountAtomicXmr) > XMR_RPC_UINT64_MAX || observation.height < page.fromHeight ||
        observation.height > page.throughHeight || observation.confirmations !== page.walletHeight - observation.height + 1 ||
        (observation.locked && observation.confirmations <= 0)) throw new Error('Monero observation is inconsistent with its scan page');
    if (ids.has(observation.observationId)) throw new Error('Duplicate Monero observation identity');
    ids.add(observation.observationId);
  }
  const pageDigest = digest([parsed.walletFingerprint, page.fromHeight, page.throughHeight,
    observations.map(row => [row.observationId, rowDigest(row)]).sort((a, b) => String(a[0]).localeCompare(String(b[0])))]);

  const client = await pool.connect();
  try {
    await client.query('BEGIN');
    await client.query('SET LOCAL statement_timeout=\'10s\'; SET LOCAL lock_timeout=\'3s\'; SET LOCAL idle_in_transaction_session_timeout=\'10s\'' );
    await client.query('SELECT pg_advisory_xact_lock($1::bigint)', [CUSTODY_WRITE_LOCK]);
    const priorScan = await client.query(`SELECT payload_digest,through_height FROM wk_custody.monero_observation_scans
      WHERE scan_id=$1`, [parsed.scanId]);
    if (priorScan.rowCount) {
      if (priorScan.rows[0].payload_digest !== pageDigest) throw new Error('Monero scan ID was reused with different observations');
      await client.query('COMMIT');
        return { scanId: parsed.scanId, scanHeight: Number(priorScan.rows[0].through_height), observed: observations.length,
        changed: 0, reappeared: 0, notSeen: 0, replayed: true };
    }
    let state = await client.query(`SELECT network,scan_height FROM wk_custody.monero_observer_state
      WHERE wallet_fingerprint=$1 FOR UPDATE`, [parsed.walletFingerprint]);
    if (!state.rowCount) {
      if (parsed.expectedScanHeight !== 0) throw new Error('First Monero observation scan must start from wallet history height zero');
      await client.query(`INSERT INTO wk_custody.monero_observer_state(wallet_fingerprint,network,scan_height,updated_at)
        VALUES($1,'mainnet',0,$2)`, [parsed.walletFingerprint, parsed.scannedAt]);
      state = await client.query(`SELECT network,scan_height FROM wk_custody.monero_observer_state
        WHERE wallet_fingerprint=$1 FOR UPDATE`, [parsed.walletFingerprint]);
    }
    if (state.rows[0].network !== 'mainnet' || Number(state.rows[0].scan_height) !== parsed.expectedScanHeight) {
      throw new Error('Monero observer cursor changed; reread durable state before retry');
    }

    let changed = 0, reappeared = 0;
    for (const observation of observations) {
      const current = await client.query(`SELECT payload_digest,currently_present,first_observed_at
        FROM wk_custody.monero_transfer_observations
        WHERE wallet_fingerprint=$1 AND observation_id=$2 FOR UPDATE`, [parsed.walletFingerprint, observation.observationId]);
      const payloadDigest = rowDigest(observation);
      const eventType = !current.rowCount ? 'seen' : !current.rows[0].currently_present ? 'reappeared'
        : current.rows[0].payload_digest !== payloadDigest ? 'changed' : null;
      await client.query(`INSERT INTO wk_custody.monero_transfer_observations(
          wallet_fingerprint,observation_id,txid,monero_address,account_index,address_index,output_public_key,global_output_index,
          amount_atomic_xmr,block_height,
          wallet_height,confirmations,timestamp,unlock_time,locked,double_spend_seen,payload_digest,
          currently_present,last_seen_scan_id,first_observed_at,last_observed_at)
        VALUES($1,$2,$3,$4,$5,$6,$7,$8,$9,$10,$11,$12,$13,$14,$15,$16,$17,true,$18,$19,$19)
        ON CONFLICT(wallet_fingerprint,observation_id) DO UPDATE SET
          monero_address=excluded.monero_address,
          output_public_key=excluded.output_public_key,global_output_index=excluded.global_output_index,
          amount_atomic_xmr=excluded.amount_atomic_xmr,block_height=excluded.block_height,wallet_height=excluded.wallet_height,
          confirmations=excluded.confirmations,timestamp=excluded.timestamp,unlock_time=excluded.unlock_time,
          locked=excluded.locked,double_spend_seen=excluded.double_spend_seen,payload_digest=excluded.payload_digest,
          currently_present=true,last_seen_scan_id=excluded.last_seen_scan_id,last_observed_at=excluded.last_observed_at`,
      [parsed.walletFingerprint, observation.observationId, observation.transactionId, observation.address,
        observation.accountIndex, observation.addressIndex, observation.outputPublicKey, observation.globalOutputIndex,
        observation.amountAtomicXmr, observation.height, page.walletHeight, observation.confirmations,
        observation.timestamp, observation.unlockTime, observation.locked, observation.doubleSpendSeen, payloadDigest, parsed.scanId,
        current.rowCount ? Number(current.rows[0].first_observed_at) : parsed.scannedAt]);
      if (eventType) {
        await client.query(`INSERT INTO wk_custody.monero_observation_events
          (wallet_fingerprint,observation_id,scan_id,event_type,payload_digest,wallet_height,observed_at)
          VALUES($1,$2,$3,$4,$5,$6,$7) ON CONFLICT DO NOTHING`,
        [parsed.walletFingerprint, observation.observationId, parsed.scanId, eventType, payloadDigest, page.walletHeight, parsed.scannedAt]);
        if (eventType === 'changed') changed++;
        if (eventType === 'reappeared') reappeared++;
      }
    }

    const missing = await client.query(`SELECT observation_id,payload_digest FROM wk_custody.monero_transfer_observations
      WHERE wallet_fingerprint=$1 AND currently_present=true AND block_height BETWEEN $2 AND $3
        AND last_seen_scan_id<>$4 FOR UPDATE`, [parsed.walletFingerprint, page.fromHeight, page.throughHeight, parsed.scanId]);
    for (const row of missing.rows) {
      await client.query(`UPDATE wk_custody.monero_transfer_observations SET currently_present=false,last_seen_scan_id=$3
        WHERE wallet_fingerprint=$1 AND observation_id=$2`, [parsed.walletFingerprint, row.observation_id, parsed.scanId]);
      await client.query(`INSERT INTO wk_custody.monero_observation_events
        (wallet_fingerprint,observation_id,scan_id,event_type,payload_digest,wallet_height,observed_at)
        VALUES($1,$2,$3,'not-seen',$4,$5,$6) ON CONFLICT DO NOTHING`,
      [parsed.walletFingerprint, row.observation_id, parsed.scanId, row.payload_digest, page.walletHeight, parsed.scannedAt]);
    }
    await client.query(`INSERT INTO wk_custody.monero_observation_scans
      (scan_id,wallet_fingerprint,from_height,through_height,payload_digest,completed_at) VALUES($1,$2,$3,$4,$5,$6)`,
    [parsed.scanId, parsed.walletFingerprint, page.fromHeight, page.throughHeight, pageDigest, parsed.scannedAt]);
    await client.query(`UPDATE wk_custody.monero_observer_state SET scan_height=GREATEST(scan_height,$2),updated_at=$3
      WHERE wallet_fingerprint=$1`, [parsed.walletFingerprint, page.throughHeight, parsed.scannedAt]);
    await client.query('COMMIT');
    return { scanId: parsed.scanId, scanHeight: Math.max(parsed.expectedScanHeight, page.throughHeight),
      observed: observations.length, changed, reappeared, notSeen: missing.rowCount ?? 0, replayed: false };
  } catch (error) { await client.query('ROLLBACK').catch(() => {}); throw error; }
  finally { client.release(); }
}