"""Recover wire metadata from the last C# revision, without transpiling method bodies.

Run from the repository root: python tools/migration/generate_protocol.py
"""
import json
from pathlib import Path
import re
import subprocess

BASE = "ca2e80f"
PREFIX = "Ananta.Server/Ananta.Core/Protocol/Client4229938/"


def source(name):
    return subprocess.check_output(["git", "show", f"{BASE}:{PREFIX}{name}"]).decode("utf-8-sig")


ids = {name: int(value) for name, value in re.findall(
    r"const uint (\w+)\s*=\s*(\d+)", source("MethodId.cs"))}
Path("pkg/protocol/testdata/legacy_method_ids.json").write_text(
    json.dumps(ids, indent=2) + "\n", encoding="utf-8")
header = f"// Code generated from {BASE} C# protocol metadata; DO NOT EDIT.\npackage protocol\n\n"
names = header + "var canonicalMethodIDs = map[string]uint32{\n"
names += "".join(f'{json.dumps(name)}: {value},\n' for name, value in ids.items())
names += "}\n"
Path("pkg/protocol/method_names_generated.go").write_text(names, encoding="utf-8")

rows = re.findall(
    r'case (\d+)u: body = (Array.Empty<byte>\(\)|\[[^\]]*\]); shape = "([^"]*)"; return true;',
    source("DefaultReturnCatalog4229938.cs"))
assert len(rows) == 2356, "C# return catalog changed; review before generating"
out = [header, "var defaultReturnBodies = map[uint32]string{"]
for mid, body, shape in rows:
    data = b"" if body.startswith("Array") else bytes(
        int(value.strip(), 16) for value in body[1:-1].split(",") if value.strip())
    encoded = "".join(f"\\x{value:02x}" for value in data)
    out.append(f'{mid}: "{encoded}", // {shape}')
out += ["}", "", "// DefaultReturnBody returns an independent payload for the client return reader.",
        "func DefaultReturnBody(methodID uint32) ([]byte, bool) {",
        "body, ok := defaultReturnBodies[methodID]", "return []byte(body), ok", "}"]
Path("pkg/protocol/default_returns_generated.go").write_text("\n".join(out) + "\n", encoding="utf-8")
subprocess.run(["gofmt", "-w", "pkg/protocol/default_returns_generated.go",
                "pkg/protocol/method_names_generated.go"], check=True)
print(f"Recovered {len(ids)} names and {len(rows)} return contracts from {BASE}")