"""Private cgroup fixture. Never run resource commands outside a bounded group."""

import json
import os
import time


allocations = []
for line in iter(input, None):
    message = json.loads(line)
    method = message["method"]
    if method == "initialize":
        params = message["params"]
        result = {
            "protocol": params["protocol"],
            "session": params["session"],
            "commands": [{"id": "echo", "title": "Resource fixture", "description": ""}],
        }
    elif method == "initialized":
        continue
    elif method == "shutdown":
        break
    elif method == "command.invoke":
        action = message["params"]["arguments"].get("action", "location")
        if action == "detach":
            childPid = os.fork()
            if childPid == 0:
                os.setsid()
                time.sleep(300)
                os._exit(0)
            # Synchronize with the detach; inherited stdout stays open.
            while os.getsid(childPid) != childPid:
                time.sleep(0.001)
            result = childPid
        elif action == "tasks":
            childPids = []
            for _ in range(96):
                try:
                    childPid = os.fork()
                except BlockingIOError:
                    break
                if childPid == 0:
                    time.sleep(300)
                    os._exit(0)
                childPids.append(childPid)
            result = len(childPids)
        elif action == "memory":
            allocation = bytearray(message["params"]["arguments"]["bytes"])
            for offset in range(0, len(allocation), 4096):
                allocation[offset] = 1
            allocations.append(allocation)
            result = True
        elif action == "cpu":
            result = True
        else:
            with open("/proc/self/cgroup", encoding="ascii") as source:
                result = source.read().strip()
    else:
        raise RuntimeError("Unexpected method")
    print(json.dumps({"jsonrpc": "2.0", "id": message["id"], "result": result}), flush=True)
    if method == "command.invoke" and action == "cpu":
        while True:
            pass