"""Probe SYS4 script headers across the DATA1 corpus.

Header hypothesis (offsets in bytes):
  0x00  char magic[8]      "SYS4422 "
  0x08  u32 F0..F12        13 fields
  0x3C  body (dword stream)

Tests invariants and prints field stats.
"""
import struct
import sys
from pathlib import Path
from collections import Counter

ROOT = Path(__file__).resolve().parents[2] / "extracted" / "DATA1"

def parse(path):
    data = path.read_bytes()
    magic = data[:8]
    fields = struct.unpack_from("<13I", data, 8)
    return data, magic, fields

def main():
    files = sorted(ROOT.glob("*.BIN"))
    print(f"files: {len(files)}")

    magics = Counter()
    distinct = [Counter() for _ in range(13)]
    fail_f12 = []      # F12 != filedwords - 15
    fail_f6 = []       # F6 != 0x1C
    fail_f11 = []      # F11 != 0
    rel_a = Counter()  # F8 + F9 vs F12
    rel_b = Counter()  # F10 + F11 vs F12
    body_first = Counter()

    for p in files:
        data, magic, f = parse(p)
        magics[magic] += 1
        nd = len(data) // 4
        for i, v in enumerate(f):
            distinct[i][v] += 1
        if f[12] != nd - 15:
            fail_f12.append((p.name, f[12], nd - 15))
        if f[6] != 0x1C:
            fail_f6.append((p.name, f[6]))
        if f[11] != 0:
            fail_f11.append((p.name, f[10], f[11], f[12]))
        rel_a["F8+F9==F12" if f[8] + f[9] == f[12] else
              ("F8+F9<F12" if f[8] + f[9] < f[12] else "F8+F9>F12")] += 1
        rel_b["F10+F11==F12" if f[10] + f[11] == f[12] else
              ("F10+F11<F12" if f[10] + f[11] < f[12] else "F10+F11>F12")] += 1
        if len(data) >= 0x40:
            body_first[struct.unpack_from("<I", data, 0x3C)[0]] += 1

    print("magics:", dict(magics))
    print("\nfield value diversity (distinct count; top values):")
    for i, c in enumerate(distinct):
        top = ", ".join(f"{v:#x}x{n}" for v, n in c.most_common(4))
        print(f"  F{i:<2} @0x{8+i*4:02X}: {len(c):4} distinct | {top}")
    print(f"\nF6==0x1C fails: {len(fail_f6)} {fail_f6[:5]}")
    print(f"F12==dwords-15 fails: {len(fail_f12)} {fail_f12[:5]}")
    print(f"F11!=0 count: {len(fail_f11)} {fail_f11[:5]}")
    print("rel F8+F9 vs F12:", dict(rel_a))
    print("rel F10+F11 vs F12:", dict(rel_b))
    print("\nfirst body dword (top 15):",
          ", ".join(f"{v:#x}x{n}" for v, n in body_first.most_common(15)))

if __name__ == "__main__":
    main()