#!/usr/bin/env python3
"""Generate test_vectors.h for the victronble core host tests.

Plaintext payloads are packed here from human-readable field values
(mirroring Victron's Extra Manufacturer Data layouts) and encrypted with
the openssl CLI — an implementation independent of the library's bundled
tiny-AES — so the vectors cross-check the AES-CTR semantics as well as
the parsers. The generated header is committed; python/openssl are only
needed to regenerate it.
"""

import subprocess
from pathlib import Path

COMPANY_ID = 0x02E1
PRODUCT_ADV = 0x10
KEY = bytes.fromhex("0df4d0395b7d5d4f5a0d0af52e1b4c1e")


def aes_ctr(key: bytes, nonce: int, plaintext: bytes) -> bytes:
    iv = bytes([nonce & 0xFF, (nonce >> 8) & 0xFF] + [0] * 14)
    return subprocess.run(
        ["openssl", "enc", "-aes-128-ctr", "-K", key.hex(), "-iv", iv.hex(),
         "-nopad"],
        input=plaintext, capture_output=True, check=True).stdout


def frame(record_type: int, model_id: int, readout: int, nonce: int,
          plaintext: bytes, key: bytes = KEY) -> bytes:
    head = bytes([COMPANY_ID & 0xFF, COMPANY_ID >> 8, PRODUCT_ADV,
                  model_id & 0xFF, model_id >> 8, readout, record_type,
                  nonce & 0xFF, (nonce >> 8) & 0xFF, key[0]])
    return head + aes_ctr(key, nonce, plaintext)


def le16(v: int) -> bytes:
    return bytes([v & 0xFF, (v >> 8) & 0xFF])


def pad21(b: bytes) -> bytes:
    assert len(b) <= 21
    return b + bytes(21 - len(b))


def pack_bits(fields):
    """fields: list of (value, width). LSB-first bit packing."""
    total = sum(w for _, w in fields)
    out = bytearray((total + 7) // 8)
    bit = 0
    for value, width in fields:
        for i in range(width):
            if (value >> i) & 1:
                out[(bit + i) >> 3] |= 1 << ((bit + i) & 7)
        bit += width
    return bytes(out)


# --- Payloads ---------------------------------------------------------------

# Solar charger: bulk, no error, 13.24 V, 5.4 A, 1.20 kWh today, 340 W,
# no load output (9-bit 0x1FF).
solar = pad21(bytes([3, 0]) + le16(1324) + le16(54) + le16(120) + le16(340) +
              le16(0x1FF))

# Battery monitor: TTG 600 min, 12.80 V, alarms lowV|lowSOC, aux mode 2
# (temperature 25.00 C = 29815 * 0.01 K), current -2.5 A, consumed 50.0 Ah,
# SOC 85.5 %.
batmon = pad21(pack_bits([
    (600, 16),            # TTG minutes
    (1280, 16),           # voltage, 0.01 V
    (0x0005, 16),         # alarm bitmask
    (29815, 16),          # aux raw (0.01 K)
    (2, 2),               # aux mode = temperature
    (-2500 & 0x3FFFFF, 22),  # current, 0.001 A
    (500, 20),            # consumed, 0.1 Ah
    (855, 10),            # SOC, 0.1 %
]))

# Inverter: inverting, 25.86 V, -12.34 A, -230 W, overload alarm.
inverter = pad21(bytes([9, 0]) + le16(2586) + le16(-1234 & 0xFFFF) +
                 ((-230) & 0xFFFFFF).to_bytes(3, "little") + bytes([0x08]))

# DC-DC converter: float, no error, in 25.30 V, out 13.31 V, 7.65 A.
dcdc = pad21(bytes([5, 0]) + le16(2530) + le16(1331) + le16(765))

# AC charger: absorption, no error, out1 14.40 V / 10.0 A, out2/3 absent,
# temp 35 C, AC current 1.2 A.
accharger = pad21(pack_bits([
    (4, 8), (0, 8),
    (1440, 13), (100, 11),
    (0x1FFF, 13), (0x7FF, 11),
    (0x1FFF, 13), (0x7FF, 11),
    (35 + 40, 7),
    (12, 9),
]))

VECTORS = [
    ("solar", frame(0x01, 0xA060, 0x00, 0x1234, solar)),
    ("batmon", frame(0x02, 0xA389, 0x00, 0xBEEF, batmon)),
    ("inverter", frame(0x03, 0xA2FA, 0x00, 0x0001, inverter)),
    ("dcdc", frame(0x04, 0xA3C0, 0x00, 0xFFFF, dcdc)),
    ("accharger", frame(0x08, 0xA339, 0x00, 0x00C8, accharger)),
    # Multi RS record type decodes via the inverter parser.
    ("multirs", frame(0x0B, 0xA512, 0x00, 0x0042, inverter)),
    # GX device: recognised record type, no decoder -> ERR_UNSUPPORTED.
    ("gx", frame(0x07, 0xA100, 0x00, 0x0007, pad21(b""))),
]


def main():
    out = Path(__file__).with_name("test_vectors.h")
    lines = [
        "/* Generated by gen_vectors.py — do not edit by hand.",
        " * Ciphertext produced with `openssl enc -aes-128-ctr`, independent",
        " * of the library's bundled AES. */",
        "",
        f'static const char VEC_KEY_HEX[] = "{KEY.hex()}";',
        "",
    ]
    for name, data in VECTORS:
        arr = ", ".join(f"0x{b:02x}" for b in data)
        lines.append(f"static const uint8_t VEC_{name.upper()}[] = {{ {arr} }};")
    lines.append("")
    out.write_text("\n".join(lines))
    print(f"wrote {out} ({len(VECTORS)} vectors)")


if __name__ == "__main__":
    main()