"""Decoder for the analog/state summary request capture (HCAL roadmap R1.8/R1.9).

Reads the per-config NDJSON captures produced by scripts/Capture-SummaryRequest.ps1
under artifacts/reverse-engineering/instrumented-wcf-writemessage-summary/, extracts
the Retr/StartQuery2 `pRequestBuff` payload from each, hex-dumps it, and diffs every
summary candidate against the baseline-full request so the differing bytes (the native
QueryType / SummaryType / AutoSummaryParameters fields) stand out.

Output is diagnostic. The only printed strings are the SDK-chosen system tag name and
protocol field markers — sanitize before copying any of it into docs/.
"""
import base64
import json
import sys
from pathlib import Path

REPO_ROOT = Path(__file__).resolve().parent.parent
CAPTURE_DIR = REPO_ROOT / "artifacts" / "reverse-engineering" / "instrumented-wcf-writemessage-summary"

ACTION = b"aa/Retr/StartQuery2"
PARAM = b"pRequestBuff"


def extract_request_buffer(records):
    """Return the pRequestBuff bytes from the first StartQuery2 write record, or None."""
    for rec in records:
        if rec.get("Phase") != "WCF.WriteMessage.Body":
            continue
        body = base64.b64decode(rec["Base64"])
        if ACTION not in body:
            continue
        i = body.find(PARAM)
        if i < 0:
            continue
        i += len(PARAM)
        marker = body[i]
        # MDAS length markers (same scheme as the write decoder).
        if marker == 0x9E:
            length = body[i + 1]
            return body[i + 2:i + 2 + length]
        if marker == 0x9F:
            length = int.from_bytes(body[i + 1:i + 3], "little")
            return body[i + 3:i + 3 + length]
        if marker == 0xA0:
            length = int.from_bytes(body[i + 1:i + 3], "little")
            return body[i + 3:i + 3 + length + 1]
        return None
    return None


def hexdump(payload, diff_against=None):
    for off in range(0, len(payload), 16):
        chunk = payload[off:off + 16]
        cells = []
        for j, c in enumerate(chunk):
            mark = ""
            if diff_against is not None:
                k = off + j
                if k >= len(diff_against) or diff_against[k] != c:
                    mark = "*"
            cells.append(f"{c:02X}{mark}")
        hp = " ".join(cells)
        ap = "".join(chr(c) if 32 <= c < 127 else "." for c in chunk)
        print(f"    {off:04X}  {hp:<56}  |{ap}|")


def load(path):
    with path.open(encoding="utf-8-sig") as fh:
        return [json.loads(line) for line in fh if line.strip()]


def main() -> int:
    if not CAPTURE_DIR.exists():
        print(f"Capture dir not found: {CAPTURE_DIR}")
        print("Run scripts/Capture-SummaryRequest.ps1 first.")
        return 1

    captures = sorted(CAPTURE_DIR.glob("summary-capture-*-latest.ndjson"))
    if not captures:
        print(f"No capture files in {CAPTURE_DIR}")
        return 1

    buffers = {}
    for path in captures:
        name = path.stem.replace("summary-capture-", "").replace("-latest", "")
        records = load(path)
        buf = extract_request_buffer(records)
        buffers[name] = buf
        status = f"{len(buf)} bytes" if buf else "<no StartQuery2 request found>"
        print(f"{name:<18} records={len(records):>3}  pRequestBuff={status}")

    baseline = buffers.get("baseline-full")
    print()
    if not baseline:
        print("No baseline-full request buffer captured; cannot diff. Dumping each raw.")
        for name, buf in buffers.items():
            if buf:
                print(f"\n== {name} pRequestBuff ({len(buf)} bytes) ==")
                hexdump(buf)
        return 0

    print(f"== baseline-full pRequestBuff ({len(baseline)} bytes) ==")
    hexdump(baseline)

    for name, buf in buffers.items():
        if name == "baseline-full" or not buf:
            continue
        print(f"\n== {name} pRequestBuff ({len(buf)} bytes) — '*' marks bytes differing from baseline ==")
        hexdump(buf, diff_against=baseline)

    return 0


if __name__ == "__main__":
    sys.exit(main())