#!/usr/bin/env python3
"""Minimal reader for tte-cmix-residual-blocks. This is the whole API."""
import json, numpy as np

def load_block(root, bid):
    M = json.load(open(f"{root}/manifest.json"))
    B = next(b for b in M["blocks"] if b["id"] == bid)
    n, d = M["block_bits"], f"{root}/blocks/{bid}"
    X  = np.fromfile(f"{d}/experts_i8.bin", np.int8).reshape(n, 25)      # 25 expert stretches
    X  = X * np.array(M["int8_scales"], np.float32)                      # -> stretch (logit) domain
    fp = np.fromfile(f"{d}/final_p_u16.bin", np.uint16)                  # cmix P(1) = fp/65536
    fl = np.fromfile(f"{d}/labels_u8.bin",  np.uint8)
    return dict(
        experts=X,                                    # (n,25) float32 stretch
        final_p=fp.astype(np.float32) / 65536.0,      # (n,)   cmix's own P(bit=1)
        y=(fl & 1).astype(np.float32),                # (n,)   the coded bit  <-- LABEL
        lstm_override=(fl >> 1) & 1,                  # (n,)   cmix's lstm_override flag
        bitpos=np.arange(n, dtype=np.int64) % 8,      # (n,)   0 = MSB ... 7 = LSB
        byteoff=B["byte_start"] + np.arange(n, dtype=np.int64) // 8,     # absolute corpus offset
        bytes_ctx=np.fromfile(f"{d}/bytes_ctx.bin", np.uint8),           # [ctx | block] raw bytes
        meta=B, manifest=M,
    )

if __name__ == "__main__":
    import sys
    b = load_block(sys.argv[1] if len(sys.argv) > 1 else ".", sys.argv[2] if len(sys.argv) > 2 else "b000")
    print({k: (v.shape if hasattr(v, "shape") else "…") for k, v in b.items()})