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import importlib
import os
import platform
import signal

from subprocess import Popen, PIPE
from paimon_python_java import constants


def on_windows():
    return platform.system() == "Windows"


def find_java_executable():
    java_executable = "java.exe" if on_windows() else "java"
    java_home = None

    if java_home is None and "JAVA_HOME" in os.environ:
        java_home = os.environ["JAVA_HOME"]

    if java_home is not None:
        java_executable = os.path.join(java_home, "bin", java_executable)

    return java_executable


def launch_gateway_server_process(env):
    java_executable = find_java_executable()
    # TODO construct Java module log settings
    log_settings = []
    jvm_args = env.get(constants.PYPAIMON_JVM_ARGS, '').split()
    classpath = _get_classpath(env)
    main_args = env.get(constants.PYPAIMON_MAIN_ARGS, '').split()
    command = [
        java_executable,
        *jvm_args,
        # default jvm args
        "-XX:+IgnoreUnrecognizedVMOptions",
        "--add-opens=jdk.proxy2/jdk.proxy2=ALL-UNNAMED",
        *log_settings,
        "-cp",
        classpath,
        "-c",
        constants.PYPAIMON_MAIN_CLASS,
        *main_args
    ]

    if not on_windows():
        def preexec_func():
            # ignore ctrl-c / SIGINT
            signal.signal(signal.SIGINT, signal.SIG_IGN)

        preexec_fn = preexec_func
    return Popen(list(filter(lambda c: len(c) != 0, command)),
                 stdin=PIPE, stderr=PIPE, preexec_fn=preexec_fn, env=env)


_JAVA_IMPL_MODULE = 'paimon_python_java'
_JAVA_DEPS = 'java_dependencies'
_JAVA_BRIDGE = 'paimon-python-java-bridge'


def _get_classpath(env):
    classpath = []

    module = importlib.import_module(_JAVA_IMPL_MODULE)
    builtin_java_bridge = os.path.join(*module.__path__, _JAVA_DEPS, _JAVA_BRIDGE + '.jar')
    classpath.append(builtin_java_bridge)

    # user defined
    if constants.PYPAIMON_JAVA_CLASSPATH in env:
        classpath.append(env[constants.PYPAIMON_JAVA_CLASSPATH])

    # hadoop
    hadoop_classpath = _get_hadoop_classpath(env)
    if hadoop_classpath is not None:
        classpath.append(hadoop_classpath)

    return os.pathsep.join(classpath)


def _get_hadoop_classpath(env):
    if constants.PYPAIMON_HADOOP_CLASSPATH in env:
        return env[constants.PYPAIMON_HADOOP_CLASSPATH]

    if 'HADOOP_CLASSPATH' in env:
        return None
    else:
        raise EnvironmentError(f"You haven't set '{constants.PYPAIMON_HADOOP_CLASSPATH}', \
 and 'HADOOP_CLASSPATH' is also not set. Ensure one of them is set.")