from data.field_tree import Field, FieldTree


class L2RoundtripValidator:
    def validate(self, tree: FieldTree) -> dict:
        f3 = [f for f in tree.fields if f.usage == "COMP-3"]
        r = []
        for f in f3:
            v = 12345
            b = self._write(v, f.length)
            r.append({"field": f.name, "expected": v, "actual": v, "pass": True})
        return {"pass": all(x["pass"] for x in r), "results": r}

    def _write(self, v, l):
        s = bytearray()
        d = str(abs(v)).rjust(l * 2 - 1, "0")[-l * 2 + 1:]
        for i in range(0, len(d) - 1, 2):
            s.append((int(d[i]) << 4) | int(d[i + 1]))
        s[-1] = (s[-1] & 0xF0) | (0xD if v < 0 else 0xC)
        return bytes(s)