// DigiByte (DGB) chain adapter — thin bridge over the @dgb-wallet/* packages
// vendored under lib/dgb/ from D:\Dev\SilentCode\Digibyte\packages\{core,psbt}.
// Address derivation, network params and PSBT construction come from the
// upstream design; Aegis provides the runtime shell (ElectrumX transport,
// gap-limit scanning, wallet-manager plumbing).
//
// Backend: DGB ElectrumX pool via Theseus's existing lib/electrum.js — same
// TCP-over-wss stack the BCH wallet uses, no separate protocol adapter.
// Optional Blockbook mode is on the roadmap; ElectrumX is the default
// because it matches Aegis's transport shape and needs no per-server keys.
//
// Only BIP84 (m/84'/20'/0'/0/x → dgb1q…) is exposed in this rev; the
// vendored core also supports BIP44 (D…) and BIP49 (S…) — plumb them by
// switching the purpose passed to accountNode(). Address recovery from any
// BIP39 tool at coin type 20 is guaranteed by bitcoinjs-lib's Network
// object, so a seed exported here can be restored on iancoleman.io/bip39
// or the SilentCode Digibyte web-wallet with matching addresses.

const NETWORK = "mainnet";
const DEFAULT_PURPOSE = 84;
const EXPLORER_TX = "https://digiexplorer.info/tx/";
const EXPLORER_ADDR = "https://digiexplorer.info/address/";
const DEFAULT_SERVERS = [
  "wss://electrum1.cyberbits.eu:50022",
  "wss://electrum3.cyberbits.eu:50022",
  "wss://electrum1.digibyteblockexplorer.com:50022",
];

module.exports = function makeDgbAdapter({
  dgbCore,          // ESM namespace of @dgb-wallet/core (vendored)
  dgbPsbt,          // ESM namespace of @dgb-wallet/psbt (vendored)
  bitcoinjs,        // require("bitcoinjs-lib")
  bip32Factory,     // require("bip32").BIP32Factory
  ecpairFactory,    // require("ecpair").ECPairFactory
  ecc,              // require("@bitcoinerlab/secp256k1")
  sha256,           // @noble/hashes/sha2 (only used for scripthash reversal)
  electrum,
}) {
  if (!dgbCore || !dgbPsbt || !bitcoinjs || !bip32Factory || !ecpairFactory || !ecc || !electrum) {
    throw new Error("chain-dgb: missing dep");
  }
  const { rootFromSeed, accountNode, addressNode, p2wpkhAddress, digibyte, DGB_COIN_TYPE } = dgbCore;
  const { buildPsbt, signAllInputs, finalizeAndExtract, feeSats } = dgbPsbt;
  const { payments, Psbt } = bitcoinjs;
  const bip32 = bip32Factory(ecc);
  const ECPair = ecpairFactory(ecc);

  const toHex = (b) => Buffer.from(b).toString("hex");
  // Electrum scripthash: sha256(scriptPubKey), byte-reversed, hex.
  function scripthashOf(scriptBuf) {
    const h = sha256(scriptBuf);
    const rev = Buffer.from(h).reverse();
    return rev.toString("hex");
  }
  function scriptPubKeyBuf(pubkeyBuf) {
    return payments.p2wpkh({ pubkey: pubkeyBuf, network: digibyte }).output;
  }

  // ---- keys --------------------------------------------------------------
  // The HD node is the sole owner of the private key material; every derived
  // entry keeps a reference so PSBT.signInput(index, node) can sign each
  // input under its own key.
  class WalletKeys {
    constructor(root32, accountPath) {
      const purpose = parsePurposeFromPath(accountPath) || DEFAULT_PURPOSE;
      this._purpose = purpose;
      // bip32.fromSeed uses bitcoinjs-lib's Network object — pass DGB's so
      // extended keys serialize with the right BIP32 magic (0x0488B21E).
      this._root = bip32.fromSeed(Buffer.from(root32), digibyte);
      this._account = this._root.derivePath(`m/${purpose}'/${DGB_COIN_TYPE}'/0'`);
      this._accountPath = `m/${purpose}'/${DGB_COIN_TYPE}'/0'`;
      this._branch = [this._account.derive(0), this._account.derive(1)];
      this._cache = new Map();
    }
    get xpub() { return this._account.neutered().toBase58(); }
    get xprv() { return this._account.toBase58(); }
    get accountPath() { return this._accountPath; }
    entry(branch, index) {
      const k = branch + "/" + index;
      let e = this._cache.get(k);
      if (!e) {
        const node = this._branch[branch].derive(index);
        const pubkey = Buffer.from(node.publicKey);
        const address = p2wpkhAddress(node, digibyte);
        const script = Buffer.from(scriptPubKeyBuf(pubkey));
        e = {
          branch, index, path: this._accountPath + "/" + branch + "/" + index,
          publicKey: pubkey, script, scriptHex: script.toString("hex"),
          scripthash: scripthashOf(script),
          address,
          _node: node,
        };
        this._cache.set(k, e);
      }
      return e;
    }
    signerFor(entry) {
      // bitcoinjs-lib's PSBT accepts anything with .publicKey + .sign(hash).
      // BIP32Interface fits, but ECPair.fromPrivateKey gives a plain signer
      // that matches what the DGB web-wallet uses — pick that for parity.
      return ECPair.fromPrivateKey(Buffer.from(entry._node.privateKey), { network: digibyte });
    }
    wipe() {
      // BIP32Interface holds Buffers; drop references so GC picks them up.
      for (const e of this._cache.values()) e._node = null;
      this._cache.clear();
      this._branch = null;
      this._account = null;
      this._root = null;
    }
  }
  function parsePurposeFromPath(p) {
    const m = /^m\/(\d+)'\/\d+'\/\d+'$/.exec(String(p || ""));
    return m ? Number(m[1]) : null;
  }

  // ---- vsize model (fee estimation ahead of PSBT.getFee) -----------------
  const OVERHEAD_VB = 10.5;
  const P2WPKH_INPUT_VB = 68;
  const P2WPKH_OUTPUT_VB = 31;
  const feeVb = (nIn, nOut, feePerVb) => Math.ceil((OVERHEAD_VB + nIn * P2WPKH_INPUT_VB + nOut * P2WPKH_OUTPUT_VB) * feePerVb);

  function scopedStorage(storage, keyPrefix) {
    const k = (key) => keyPrefix + key;
    return {
      get: (key, fallback = null) => storage.get(k(key), fallback),
      set: (key, value) => storage.set(k(key), value),
    };
  }

  // ---- wallet ------------------------------------------------------------
  class DgbWallet {
    constructor(root32, {
      walletId, storage, log = () => {}, onChange = () => {}, servers,
      accountPath,
    } = {}) {
      if (!walletId) throw new Error("chain-dgb: walletId required");
      this.walletId = walletId;
      this.chain = "dgb";
      this.network = NETWORK;
      this.log = log;
      this.onChange = onChange;
      this.storage = scopedStorage(storage, `wallets/${walletId}/`);
      this._servers = Array.isArray(servers) && servers.length ? servers : DEFAULT_SERVERS.slice();
      this._keys = new WalletKeys(root32, accountPath);
      this._root = new Uint8Array(root32);
      this._client = new electrum.Client(this._servers);
      this._client.onServer = () => this._emit();
      this._state = {
        used: new Set(),
        watched: new Map(),
        height: 0,
        balance: { confirmed: 0, unconfirmed: 0 },
        utxos: [],
        history: [],
        receiveIndex: 0,
        scanning: false,
        error: null,
      };
      this._refreshTimer = null;
      this._subscribedHeaders = false;
      this._client.onNotify = (method, params) => {
        if (method === "blockchain.headers.subscribe") {
          const h = params && params[0] && params[0].height;
          if (h) { this._state.height = h; this._scheduleRefresh(1500); }
        } else if (method === "blockchain.scripthash.subscribe") {
          this._scheduleRefresh(800);
        }
      };
    }

    _emit() { try { this.onChange(); } catch {} }

    // ---- discovery (gap-limit) -----------------------------------------
    async _historyOf(entry) {
      const h = await this._client.call("blockchain.scripthash.get_history", [entry.scripthash]);
      return Array.isArray(h) ? h : [];
    }
    async _scan() {
      const cursor = Number(this.storage.get("receiveCursor", 0)) || 0;
      const GAP = 20;
      for (const branch of [0, 1]) {
        let gap = 0, i = 0;
        const minIndex = branch === 0 ? cursor + 1 : 0;
        while (gap < GAP || i < minIndex + GAP) {
          const batch = [];
          for (let k = 0; k < 10; k++) batch.push(this._keys.entry(branch, i + k));
          const results = await Promise.all(batch.map((e) => this._historyOf(e)));
          for (let k = 0; k < batch.length; k++) {
            const e = batch[k];
            this._state.watched.set(e.scripthash, e);
            if (results[k].length) { this._state.used.add(branch + "/" + e.index); gap = 0; } else gap++;
            i++;
            if (gap >= GAP && i >= minIndex + GAP) break;
          }
        }
      }
      let r = cursor;
      while (this._state.used.has("0/" + r)) r++;
      this._state.receiveIndex = r;
      this._state.watched.set(this._keys.entry(0, r).scripthash, this._keys.entry(0, r));
    }
    async _subscribeAll() {
      if (!this._subscribedHeaders) {
        this._subscribedHeaders = true;
        const tip = await this._client.subscribe("blockchain.headers.subscribe", []);
        if (tip && tip.height) this._state.height = tip.height;
      }
      await Promise.all([...this._state.watched.values()].map((e) =>
        this._client.subscribe("blockchain.scripthash.subscribe", [e.scripthash]).catch(() => {})));
    }
    async _loadUtxos() {
      const lists = await Promise.all([...this._state.watched.values()].map(async (e) => {
        const u = await this._client.call("blockchain.scripthash.listunspent", [e.scripthash]);
        return (Array.isArray(u) ? u : []).map((x) => ({ txid: x.tx_hash, vout: x.tx_pos, value: x.value, height: x.height, entry: e }));
      }));
      this._state.utxos = lists.flat();
      let confirmed = 0, unconfirmed = 0;
      for (const u of this._state.utxos) { if (u.height > 0) confirmed += u.value; else unconfirmed += u.value; }
      this._state.balance = { confirmed, unconfirmed };
    }
    async _loadHistory() {
      // Best-effort tx-history summary: pull the transactions listed against
      // any used scripthash, sum ours-vs-not to get a delta per tx. Fine on
      // the DGB electrum pool (get_transaction verbose is supported).
      const entries = [...this._state.watched.values()].filter((e) => this._state.used.has(e.branch + "/" + e.index));
      const merged = new Map();
      const lists = await Promise.all(entries.map((e) => this._historyOf(e)));
      for (const list of lists) for (const h of list) {
        const prev = merged.get(h.tx_hash);
        if (!prev || (h.height > 0 && prev.height <= 0)) merged.set(h.tx_hash, { txid: h.tx_hash, height: h.height });
      }
      const ordered = [...merged.values()].sort((a, b) => {
        const ha = a.height > 0 ? a.height : Infinity, hb = b.height > 0 ? b.height : Infinity;
        return hb - ha;
      }).slice(0, 25);
      const ours = new Set([...this._state.watched.values()].map((e) => e.scriptHex));
      const out = [];
      for (const h of ordered) {
        let received = 0, spent = 0;
        try {
          const t = await this._client.call("blockchain.transaction.get", [h.txid, true]);
          for (const o of t.vout || []) {
            const hex = o.scriptPubKey && o.scriptPubKey.hex;
            if (hex && ours.has(hex)) received += Math.round(Number(o.value || 0) * 1e8);
          }
          for (const i of t.vin || []) {
            if (!i.txid) continue;
            try {
              const p = await this._client.call("blockchain.transaction.get", [i.txid, true]);
              const po = p.vout && p.vout[i.vout];
              const hex = po && po.scriptPubKey && po.scriptPubKey.hex;
              if (hex && ours.has(hex)) spent += Math.round(Number(po.value || 0) * 1e8);
            } catch {}
          }
          out.push({
            txid: h.txid, height: h.height, confirmations: t.confirmations || 0,
            time: t.blocktime || t.time || 0,
            delta: received - spent, fee: null, to: null,
            status: (t.confirmations || 0) > 0 ? "confirmed" : "pending",
            kind: "transfer",
          });
        } catch {
          out.push({ txid: h.txid, height: h.height, confirmations: 0, time: 0, delta: 0, fee: null, to: null, status: "pending", kind: "transfer" });
        }
      }
      this._state.history = out;
    }
    async refresh(full = false) {
      if (this._state.scanning) return;
      this._state.scanning = true; this._state.error = null; this._emit();
      try {
        if (full || !this._state.watched.size) await this._scan();
        else {
          let r = Number(this.storage.get("receiveCursor", 0)) || 0;
          while (this._state.used.has("0/" + r)) r++;
          this._state.receiveIndex = r;
          this._state.watched.set(this._keys.entry(0, r).scripthash, this._keys.entry(0, r));
        }
        await this._loadUtxos();
        await this._loadHistory();
        await this._subscribeAll();
        for (const u of this._state.utxos) this._state.used.add(u.entry.branch + "/" + u.entry.index);
        let r = Number(this.storage.get("receiveCursor", 0)) || 0;
        while (this._state.used.has("0/" + r)) r++;
        this._state.receiveIndex = r;
      } catch (e) {
        this._state.error = e?.message || String(e);
        this.log("refresh failed:", this._state.error);
      } finally {
        this._state.scanning = false;
        this._emit();
      }
    }
    _scheduleRefresh(ms = 800) {
      clearTimeout(this._refreshTimer);
      this._refreshTimer = setTimeout(() => this.refresh(false), ms);
    }

    current() { return this._keys.entry(0, this._state.receiveIndex); }
    nextAddress() {
      let r = this._state.receiveIndex + 1;
      while (this._state.used.has("0/" + r)) r++;
      this.storage.set("receiveCursor", r);
      this._state.receiveIndex = r;
      const e = this._keys.entry(0, r);
      this._state.watched.set(e.scripthash, e);
      this._client.subscribe("blockchain.scripthash.subscribe", [e.scripthash]).catch(() => {});
      this._emit();
      return this.current();
    }
    _changeEntry() {
      let i = 0;
      while (this._state.used.has("1/" + i)) i++;
      return this._keys.entry(1, i);
    }

    setServers(list) {
      this._servers = Array.isArray(list) && list.length ? list : DEFAULT_SERVERS.slice();
      this._client.setServers(this._servers);
    }

    // ---- plan + sign (via @dgb-wallet/psbt) -----------------------------
    plan({ to, amount, feeRate = 20, sendMax = false }) {
      const rate = Math.min(500, Math.max(1, Number(feeRate) || 20));
      const dest = String(to || "");
      // The `payments` decoder will reject anything that isn't a valid
      // DGB address; catch and re-raise as a sane error.
      try { payments.address({ address: dest, network: digibyte }); }
      catch {
        // bitcoinjs-lib's address decoder is `address.toOutputScript`, not
        // payments.address; use it for validation.
        try { bitcoinjs.address.toOutputScript(dest, digibyte); }
        catch (e) { throw new Error(`bad DGB address: ${e?.message || dest}`); }
      }
      const spendable = this._state.utxos.slice().sort((a, b) => (b.height > 0) - (a.height > 0));
      const change = this._changeEntry();
      if (sendMax) {
        const chosen = spendable;
        const sum = chosen.reduce((a, u) => a + u.value, 0);
        const fee = feeVb(chosen.length, 1, rate);
        if (sum <= fee) throw new Error("balance does not cover the fee");
        return {
          _chosen: chosen, _rate: rate, _to: dest, _sendMax: true, _change: change,
          recipients: [{ to: dest, value: sum - fee }],
          fee, feeRate: rate, change: 0,
          total: sum,
        };
      }
      const value = Math.round(Number(amount) || 0);
      if (!(value > 0)) throw new Error("amount must be > 0");
      let sum = 0; const chosen = [];
      for (const u of spendable) {
        chosen.push(u); sum += u.value;
        const withChange = feeVb(chosen.length, 2, rate);
        if (sum >= value + withChange) {
          const changeVal = sum - value - withChange;
          const fee = changeVal > 546 ? withChange : sum - value;
          return {
            _chosen: chosen, _rate: rate, _to: dest, _value: value,
            _change: change, _changeVal: changeVal > 546 ? changeVal : 0,
            recipients: [{ to: dest, value }],
            fee, feeRate: rate,
            change: changeVal > 546 ? changeVal : 0,
            total: value + fee,
          };
        }
      }
      throw new Error("insufficient funds");
    }

    async signAndBroadcast(plan) {
      const psbtInputs = plan._chosen.map((u) => ({
        txid: u.txid,
        vout: u.vout,
        witness: { scriptHex: u.entry.scriptHex, value: u.value },
      }));
      const psbtOutputs = [{ address: plan._to, value: plan._sendMax ? plan.recipients[0].value : plan._value }];
      if (!plan._sendMax && plan._changeVal > 0) {
        psbtOutputs.push({ address: plan._change.address, value: plan._changeVal });
      }
      const psbt = buildPsbt({ inputs: psbtInputs, outputs: psbtOutputs }, digibyte);
      // Sign per-input with the exact key that funded that UTXO. signAllInputs
      // would work when all inputs share a key, but each derived address
      // has its own key, so we go per-input.
      for (let i = 0; i < plan._chosen.length; i++) {
        const signer = this._keys.signerFor(plan._chosen[i].entry);
        psbt.signInput(i, signer);
      }
      const { hex, txid } = finalizeAndExtract(psbt);
      const broadcast = await this._client.call("blockchain.transaction.broadcast", [hex]);
      if (typeof broadcast !== "string" || broadcast.length !== 64) {
        throw new Error("broadcast rejected: " + JSON.stringify(broadcast));
      }
      this.log("broadcast", txid);
      this._scheduleRefresh(1200);
      return { txid, hex, fee: plan.fee };
    }

    // BIP-137-style: 65-byte recoverable signature over sha256d(magic || msg).
    signMessage(message) {
      const enc = new TextEncoder();
      const varstr = (s) => { const b = enc.encode(s); if (b.length >= 0xfd) throw new Error("too long"); return Uint8Array.from([b.length, ...b]); };
      const MAGIC = "DigiByte Signed Message:\n";
      const payload = Uint8Array.from([...varstr(MAGIC), ...varstr(String(message))]);
      const digest = sha256(sha256(payload));
      const entry = this.current();
      const signer = this._keys.signerFor(entry);
      // ECPair's `signSchnorr` and `sign` don't emit recoverable sigs; fall
      // back to node's ecc.signRecoverable through @bitcoinerlab/secp256k1
      // (which the vendored @dgb-wallet/core already loaded).
      const sig = ecc.signRecoverable(Buffer.from(digest), signer.privateKey);
      const out = Buffer.alloc(65);
      out[0] = 27 + sig.recoveryId + 4;   // +4 = compressed pubkey
      Buffer.from(sig.signature).copy(out, 1);
      return { address: entry.address, signature: out.toString("base64") };
    }

    recovery() {
      return { accountPath: this._keys.accountPath, xpub: this._keys.xpub, xprv: this._keys.xprv };
    }

    snapshot() {
      const cur = this.current();
      return {
        chain: "dgb", network: NETWORK, ticker: "DGB", decimals: 8,
        address: cur.address, addressIndex: this._state.receiveIndex,
        addressPath: cur.path,
        balance: this._state.balance,
        height: this._state.height,
        history: this._state.history,
        scanning: this._state.scanning,
        error: this._state.error,
        server: this._client.url || null,
        servers: this._servers,
        accountPath: this._keys.accountPath,
        xpub: this._keys.xpub,
        explorerTx: EXPLORER_TX, explorerAddr: EXPLORER_ADDR, faucet: null,
      };
    }

    dispose() {
      clearTimeout(this._refreshTimer);
      try { this._keys.wipe(); } catch {}
      try { this._client.disconnect(); } catch {}
      if (this._root) this._root.fill(0);
    }
  }

  return { DgbWallet, EXPLORER_TX, EXPLORER_ADDR };
};