"""
Walker v4: alternate [10 NN] data chunks and [00 NN] (or other) marker tags.

Hypothesis:
- [10 NN]: data block, length NN/2 + 2 bytes (2-byte tag + NN/2 bytes data)
- [00 NN]: 2-byte marker block (no data)
- [20/30/40 NN]: special blocks with type-dependent length
"""
import sys
sys.path.insert(0, ".")
from analysis.load_bundle import load_bundle


def walk(body, start):
    i = start
    blocks = []
    while i + 1 < len(body):
        t0 = body[i]
        t1 = body[i + 1]
        if t0 == 0x10 and t1 % 4 == 0 and 0 < t1 <= 0x80:
            # data chunk: length NN/2 + 2
            length = t1 // 2 + 2
            blocks.append((i, "10", t1, bytes(body[i + 2 : i + length]), length))
            i += length
        elif t0 == 0x00 and t1 % 4 == 0:
            # 2-byte marker
            blocks.append((i, "00", t1, b"", 2))
            i += 2
        elif t0 == 0x20 and t1 % 4 == 0:
            # type 2 — try length 2+t1/2 (similar to 10) OR fixed
            length = t1 // 2 + 2
            blocks.append((i, "20", t1, bytes(body[i + 2 : i + length]), length))
            i += length
        elif t0 == 0x30 and t1 % 4 == 0:
            length = t1 // 2 + 2
            blocks.append((i, "30", t1, bytes(body[i + 2 : i + length]), length))
            i += length
        elif t0 == 0x40 and t1 == 0x02:
            # Special "footer transition" block — try fixed 22 bytes
            length = 22
            blocks.append((i, "40", t1, bytes(body[i + 2 : i + length]), length))
            i += length
        else:
            # Unknown tag — stop
            blocks.append((i, "??", t0, bytes(body[i:i+8]), 0))
            break
    return blocks, i


def main():
    for name in ("event-c", "event-d", "event-a", "event-b"):
        b = load_bundle(name)
        body = b.body
        # Auto-detect start
        for s in range(15):
            if body[s] == 0x10 and body[s+1] % 4 == 0 and 0 < body[s+1] <= 0x80:
                start = s
                break
        else:
            start = 7
        blocks, end = walk(body, start)
        # Categorize
        from collections import Counter
        types = Counter(b[1] for b in blocks)
        print(f"\n=== {name} === body={len(body)} N={len(b.samples['Tran'])}  start={start}")
        print(f"  total blocks: {len(blocks)}, walk ended at {end}/{len(body)}")
        print(f"  type counts: {dict(types)}")
        # Print last 5 blocks
        print(f"  last 5 blocks: {[(bb[0], bb[1], bb[2]) for bb in blocks[-5:]]}")
        if end < len(body):
            print(f"  bytes at end: {body[end:end+24].hex(' ')}")


if __name__ == "__main__":
    main()