const fs = require("fs");

const ALLOWED_U5 = new Set([0x20, 0x22, 0x30]);

function readU32LE(buffer, offset) {
  return buffer.readUInt32LE(offset);
}

function readU16LE(buffer, offset) {
  return buffer.readUInt16LE(offset);
}

function isStructuredCandidate(record) {
  if (record[0] >= 0x200) {
    return false;
  }
  if (record[1] === 0 && record[2] === 0) {
    return false;
  }
  if (record[1] >= 0x4000 || record[2] >= 0x4000) {
    return false;
  }
  if (record[3] > 0x20 || record[4] > 0x04) {
    return false;
  }
  return ALLOWED_U5.has(record[5]);
}

function probeFile(filePath) {
  const data = fs.readFileSync(filePath);
  const headerSize = readU32LE(data, 0);
  const audioSize = readU32LE(data, 4);
  const sectionSizes = [];
  for (let offset = 8; offset < 0x38; offset += 4) {
    sectionSizes.push(readU32LE(data, offset));
  }

  let cursor = headerSize + audioSize;
  const sections = [];
  for (let index = 0; index < sectionSizes.length; index += 1) {
    const size = sectionSizes[index];
    const start = cursor;
    const end = start + size;
    const bytes = data.subarray(start, end);
    cursor = end;

    let rowCount = null;
    let rootHits = 0;
    let bulkHits = 0;

    if (bytes.length >= 4) {
      rowCount = readU32LE(bytes, 0);
      for (let rowIndex = 0; rowIndex < Math.min(rowCount, 5000); rowIndex += 1) {
        const base = 4 + rowIndex * 24;
        if (base + 24 > bytes.length) {
          break;
        }
        const words = [];
        for (let wordIndex = 0; wordIndex < 12; wordIndex += 1) {
          words.push(readU16LE(bytes, base + wordIndex * 2));
        }
        const left = [words[4], words[5], words[0], words[1], words[2], words[3]];
        const right = [words[10], words[11], words[6], words[7], words[8], words[9]];
        if (isStructuredCandidate(left)) {
          rootHits += 1;
        }
        if (isStructuredCandidate(right)) {
          rootHits += 1;
        }
      }
    }

    const usableSize = bytes.length - (bytes.length % 24);
    for (let offset = 0; offset < usableSize; offset += 24) {
      for (const sideOffset of [0, 12]) {
        const base = offset + sideOffset;
        const record = [
          readU16LE(bytes, base),
          readU16LE(bytes, base + 2),
          readU16LE(bytes, base + 4),
          readU16LE(bytes, base + 6),
          readU16LE(bytes, base + 8),
          readU16LE(bytes, base + 10)
        ];
        if (isStructuredCandidate(record)) {
          bulkHits += 1;
        }
      }
    }

    sections.push({
      index,
      start,
      size,
      rowCount,
      rootHits,
      bulkHits
    });
  }

  return {
    filePath,
    headerSize,
    audioSize,
    sections
  };
}

for (const filePath of process.argv.slice(2)) {
  console.log(JSON.stringify(probeFile(filePath), null, 2));
}