// bytecode.js, opcode-aware static analysis of EVM runtime bytecode for
// quantum exposure. Zero dependencies.
//
// Two techniques make this honest rather than a grep:
//
//  1. Opcode-aware decoding. A naive search for "610ae1" (PUSH2 0x0AE1) in the
//     hex produces false positives, because those bytes can appear inside
//     another PUSH's immediate data or straddle an instruction boundary. The
//     decoder walks the instruction stream, skipping each PUSH's immediate, so a
//     matched constant is a genuine PUSH of that value.
//
//  2. Local stack simulation to resolve CALL targets. The real question is not
//     "does the constant 0x0AE1 appear" but "is a CALL/STATICCALL actually made
//     TO that address". We simulate the stack per basic block (reset at
//     JUMPDEST / after JUMP,JUMPI / after terminators) tracking constant PUSH
//     values, and at every CALL-family opcode we read the address argument (the
//     2nd stack item). This distinguishes a precompile call to 0x0AE1 from the
//     bare number 0x0AE5 used as a memory length near an unrelated staticcall
//     (the false positive a proximity heuristic would hit).
//
// Fallback: the constants 0x0AE1..0x0AE4 (2785..2788) are not round numbers or
// common offsets, so a genuine opcode-aligned PUSH of one is a medium-confidence
// signal even when the CALL target is loaded from memory and cannot be resolved
// locally. The common literals 0x01, 0x100 and 0x0AE5 are NEVER used as a
// fallback signal; they only count when stack simulation resolves them as an
// actual CALL target.

import { CLASSICAL, PQC, knownAddressTable } from './precompiles.js';

const CALL_NAME = { 0xf1: 'CALL', 0xf2: 'CALLCODE', 0xf4: 'DELEGATECALL', 0xfa: 'STATICCALL' };
const CALL_OPS = new Set([0xf1, 0xf2, 0xf4, 0xfa]);
// pops before the address arg is consumed: CALL/CALLCODE take (gas,addr,value,..)
// STATICCALL/DELEGATECALL take (gas,addr,..); in all four addr is the 2nd item.
const CALL_ARITY = { 0xf1: 7, 0xf2: 7, 0xf4: 6, 0xfa: 6 };
const HALTS = new Set([0x00, 0xf3, 0xfd, 0xfe, 0xff]); // STOP RETURN REVERT INVALID SELFDESTRUCT

// (pops, pushes) for opcodes whose stack effect we model to keep alignment.
// PUSH/DUP/SWAP/CALL-family are handled specially and are not in this table.
const ARITY = {
  0x01: [2, 1], 0x02: [2, 1], 0x03: [2, 1], 0x04: [2, 1], 0x05: [2, 1], 0x06: [2, 1], 0x07: [2, 1],
  0x08: [3, 1], 0x09: [3, 1], 0x0a: [2, 1], 0x0b: [2, 1],
  0x10: [2, 1], 0x11: [2, 1], 0x12: [2, 1], 0x13: [2, 1], 0x14: [2, 1], 0x15: [1, 1],
  0x16: [2, 1], 0x17: [2, 1], 0x18: [2, 1], 0x19: [1, 1], 0x1a: [2, 1], 0x1b: [2, 1], 0x1c: [2, 1], 0x1d: [2, 1],
  0x20: [2, 1],
  0x30: [0, 1], 0x31: [1, 1], 0x32: [0, 1], 0x33: [0, 1], 0x34: [0, 1], 0x35: [1, 1], 0x36: [0, 1],
  0x37: [3, 0], 0x38: [0, 1], 0x39: [3, 0], 0x3a: [0, 1], 0x3b: [1, 1], 0x3c: [4, 0], 0x3d: [0, 1],
  0x3e: [3, 0], 0x3f: [1, 1],
  0x40: [1, 1], 0x41: [0, 1], 0x42: [0, 1], 0x43: [0, 1], 0x44: [0, 1], 0x45: [0, 1], 0x46: [0, 1],
  0x47: [0, 1], 0x48: [0, 1], 0x49: [1, 1], 0x4a: [0, 1],
  0x50: [1, 0], 0x51: [1, 1], 0x52: [2, 0], 0x53: [2, 0], 0x54: [1, 1], 0x55: [2, 0],
  0x56: [1, 0], 0x57: [2, 0], 0x58: [0, 1], 0x59: [0, 1], 0x5a: [0, 1], 0x5b: [0, 0],
  0x5c: [1, 1], 0x5d: [2, 0], 0x5e: [3, 0],
  0xa0: [2, 0], 0xa1: [3, 0], 0xa2: [4, 0], 0xa3: [5, 0], 0xa4: [6, 0],
  0xf0: [3, 1], 0xf5: [4, 1],
};

/**
 * Decode runtime bytecode into a flat instruction list.
 * @param {Uint8Array} code
 */
export function decode(code) {
  const ops = [];
  let pc = 0;
  let i = 0;
  while (pc < code.length) {
    const op = code[pc];
    if (op >= 0x60 && op <= 0x7f) {
      const n = op - 0x5f;
      let val = 0n;
      for (let k = 1; k <= n && pc + k < code.length; k++) val = (val << 8n) | BigInt(code[pc + k]);
      ops.push({ i: i++, pc, op, push: val, pushLen: n });
      pc += 1 + n;
    } else {
      ops.push({ i: i++, pc, op });
      pc += 1;
    }
  }
  return ops;
}

/**
 * Resolve CALL-family targets via per-basic-block local stack simulation.
 * @returns {Array<{op:number, name:string, pc:number, target:bigint|null}>}
 */
export function resolveCallTargets(ops) {
  const calls = [];
  let stack = []; // items: bigint (known) or null (unknown)

  const pop = () => (stack.length ? stack.pop() : null);

  for (const o of ops) {
    const op = o.op;

    if (op === 0x5b) { stack = []; continue; } // JUMPDEST starts a new block

    if (op >= 0x60 && op <= 0x7f) { stack.push(o.push); continue; } // PUSHn (0x5f PUSH0 handled below)
    if (op === 0x5f) { stack.push(0n); continue; } // PUSH0

    if (op >= 0x80 && op <= 0x8f) { // DUPk
      const k = op - 0x80 + 1;
      stack.push(stack.length >= k ? stack[stack.length - k] : null);
      continue;
    }
    if (op >= 0x90 && op <= 0x9f) { // SWAPk
      const k = op - 0x90 + 1;
      const idx = stack.length - 1 - k;
      if (stack.length >= 1 && idx >= 0) {
        const top = stack.length - 1;
        const tmp = stack[top]; stack[top] = stack[idx]; stack[idx] = tmp;
      }
      continue;
    }

    if (CALL_OPS.has(op)) {
      // address is the 2nd stack item from the top (below gas)
      const target = stack.length >= 2 ? stack[stack.length - 2] : null;
      calls.push({ op, name: CALL_NAME[op], pc: o.pc, target });
      for (let k = 0; k < CALL_ARITY[op]; k++) pop();
      stack.push(null); // success flag
      if (op === 0x56 || op === 0x57) stack = [];
      continue;
    }

    if (op === 0x56 || op === 0x57) { // JUMP / JUMPI
      const arity = ARITY[op];
      for (let k = 0; k < arity[0]; k++) pop();
      stack = []; // next instruction is a new block
      continue;
    }

    if (HALTS.has(op)) {
      const a = ARITY[op];
      if (a) for (let k = 0; k < a[0]; k++) pop();
      stack = [];
      continue;
    }

    const a = ARITY[op];
    if (a) {
      for (let k = 0; k < a[0]; k++) pop();
      for (let k = 0; k < a[1]; k++) stack.push(null);
    } else {
      // unknown opcode: be conservative, drop the block alignment
      stack = [];
    }
  }
  return calls;
}

/**
 * Analyze runtime bytecode for classical and post-quantum precompile usage.
 * @param {Uint8Array} code runtime bytecode (empty => caller treats as EOA)
 */
// SINGURA SURSA a vocabularului de verdicte. Exportata anume, fiindca doua consumatoare si-au
// scris fiecare propria lista si una a scris AMBER acolo unde scanerul scrie YELLOW: un contract
// hibrid, adica exact clientul care a inceput deja migrarea si e cel mai probabil sa plateasca,
// cadea in NOT MEASURED atat in raportul platit cat si in scanul gratuit. Masurat 2026-08-16.
// Cine adauga un verdict il adauga AICI, si consumatoarele il primesc fara sa fie atinse.
export const VERDICTE = Object.freeze(['GREEN', 'YELLOW', 'RED']);

// Cum se citeste verdictul dintr-o iesire de text. Consumatoarele cheama ASTA, nu isi scriu
// propriul tipar: un tipar copiat e a doua sursa a aceluiasi adevar, si exact asta a fost
// defectul. Nu foloseste expresii regulate, ca sa nu existe nici macar un sir de escapat gresit.
// Intoarce numele verdictului, sau null daca textul nu poarta niciunul.
export function citesteVerdict(text) {
  for (const linie of String(text).split(/\r?\n/)) {
    const cuvant = linie.trim().split(/[^A-Z]+/).filter(Boolean)[0];
    if (cuvant && VERDICTE.includes(cuvant)) return cuvant;
  }
  return null;
}

export function analyzeBytecode(code) {
  const ops = decode(code);
  const table = knownAddressTable();
  const calls = resolveCallTargets(ops);

  // Resolved CALL targets that land on a known band address (definitive).
  const resolved = calls
    .filter((c) => c.target !== null && table.has(c.target))
    .map((c) => ({ ...table.get(c.target), address: '0x' + c.target.toString(16), callOpcode: c.name, pc: c.pc }));

  const pqcResolved = resolved.filter((r) => r.band === 'pqc-live');
  const pqcTestnetResolved = resolved.filter((r) => r.band === 'pqc-testnet');
  const ecrecoverResolved = resolved.filter((r) => r.key === 'ecrecover');
  const p256Resolved = resolved.filter((r) => r.key === 'p256');

  // Fallback presence signal: an opcode-aligned PUSH of a SIGNATURE-verify PQC
  // address 0x0AE1..0x0AE4 (not 0x0AE5, not the common literals). Medium
  // confidence: the constant is genuinely present even if we could not resolve
  // the CALL target locally (e.g. it was staged through memory).
  const sigPqcAddrs = new Set([PQC.falcon512.address, PQC.falcon1024.address, PQC.mldsa44.address, PQC.slhdsa128s.address]);
  const pqcConstPresent = [];
  for (const o of ops) {
    if (o.push !== undefined && sigPqcAddrs.has(o.push)) {
      const d = table.get(o.push);
      pqcConstPresent.push({ address: '0x' + o.push.toString(16), name: d.name, pc: o.pc });
    }
  }

  const uniqByAddr = (arr) => {
    const m = new Map();
    for (const x of arr) if (!m.has(x.address)) m.set(x.address, x);
    return [...m.values()];
  };

  const pqcResolvedU = uniqByAddr(pqcResolved);
  const pqcConstU = uniqByAddr(pqcConstPresent).filter((c) => !pqcResolvedU.find((r) => r.address === c.address));

  const pqcUsed = pqcResolvedU.length > 0 || pqcConstU.length > 0;
  const classicalUsed = ecrecoverResolved.length > 0 || p256Resolved.length > 0;

  let readiness;
  if (pqcUsed && classicalUsed) readiness = 'YELLOW';
  else if (pqcUsed) readiness = 'GREEN';
  else readiness = 'RED';

  const pqcLivePrecompiles = [
    ...pqcResolvedU.map((r) => ({ address: r.address, name: r.name, callProximate: true, confidence: 'high' })),
    ...pqcConstU.map((c) => ({ address: c.address, name: c.name, callProximate: false, confidence: 'medium' })),
  ];

  return {
    kind: 'contract',
    readiness,
    bytecodeLength: code.length,
    signals: {
      pqcLivePrecompiles,
      pqcTestnetPrecompiles: uniqByAddr(pqcTestnetResolved).map((r) => ({ address: r.address, name: r.name })),
      p256: p256Resolved.length > 0
        ? { address: '0x100', name: CLASSICAL.p256.name, count: p256Resolved.length, confidence: 'high' }
        : null,
      ecrecover: ecrecoverResolved.length > 0
        ? { address: '0x1', name: CLASSICAL.ecrecover.name, count: ecrecoverResolved.length, confidence: 'high' }
        : null,
    },
    flags: buildFlags({ pqcResolvedU, pqcConstU, pqcTestnetResolved, pqcUsed }),
    detail: {
      callsAnalyzed: calls.length,
      resolvedBandCalls: resolved.length,
    },
  };
}

function buildFlags({ pqcResolvedU, pqcConstU, pqcTestnetResolved, pqcUsed }) {
  const flags = [];
  if (pqcConstU.length > 0 && pqcResolvedU.length === 0) {
    flags.push('[VERIFY] A live PQC precompile address (0x0AE1..0x0AE4) is pushed but no CALL to it was resolved by local stack analysis; the call target may be staged through memory. Confirm against source or a call trace.');
  }
  if (pqcTestnetResolved.length > 0) {
    flags.push('[VERIFY] Call to a TESTNET-only PQC precompile (0x0AE6..0x0AE8); these are NOT live on mainnet 2800 and return empty there.');
  }
  if (!pqcUsed) {
    flags.push('Bytecode scanning only sees NATIVE precompile calls (0x0AE1..0x0AE5). A contract that verifies Falcon via the SOLIDITY AereFalcon512Verifier (0x4E8e...D8fFC) delegates to a normal contract address and will read as RED here even though it is PQC-capable. Confirm the auth path against source.');
  }
  return flags;
}