import os
import pathlib
import pickle
from copy import deepcopy
from unittest import mock
from unittest.mock import Mock

import pytest

from lightning_app import LightningApp, LightningFlow, LightningWork
from lightning_app.runners.multiprocess import MultiProcessRuntime
from lightning_app.storage.payload import Payload
from lightning_app.storage.requests import GetRequest


def test_payload_copy():
    """Test that Payload creates an exact copy when passing a Payload instance to the constructor."""
    payload = Payload(None)
    payload._origin = "origin"
    payload._consumer = "consumer"
    payload._request_queue = "MockQueue"
    payload._response_queue = "MockQueue"
    payload_copy = deepcopy(payload)
    assert payload_copy._origin == payload._origin
    assert payload_copy._consumer == payload._consumer
    assert payload_copy._request_queue == payload._request_queue
    assert payload_copy._response_queue == payload._response_queue


def test_payload_pickable():
    payload = Payload("MyObject")
    payload._origin = "root.x.y.z"
    payload._consumer = "root.p.q.r"
    payload._name = "var_a"
    loaded = pickle.loads(pickle.dumps(payload))

    assert isinstance(loaded, Payload)
    assert loaded._origin == payload._origin
    assert loaded._consumer == payload._consumer
    assert loaded._name == payload._name
    assert loaded._request_queue is None
    assert loaded._response_queue is None


def test_path_attach_queues():
    path = Payload(None)
    request_queue = Mock()
    response_queue = Mock()
    path._attach_queues(request_queue=request_queue, response_queue=response_queue)
    assert path._request_queue is request_queue
    assert path._response_queue is response_queue


class Work(LightningWork):
    def __init__(self):
        super().__init__()
        self.var_a = Payload(None)

    def run(self):
        pass


def test_payload_in_init():
    with pytest.raises(
        AttributeError, match="The Payload object should be set only within the run method of the work."
    ):
        Work()


class WorkRun(LightningWork):
    def __init__(self, tmpdir):
        super().__init__()
        self.var_a = None
        self.tmpdir = tmpdir

    def run(self):
        self.var_a = Payload("something")
        assert self.var_a.name == "var_a"
        assert self.var_a._origin == "root.a"
        assert self.var_a.hash == "9bd514ad51fc33d895c50657acd0f0582301cf3e"
        source_path = pathlib.Path(self.tmpdir, self.var_a.name)
        assert not source_path.exists()
        response = self.var_a._handle_get_request(
            self,
            GetRequest(
                name="var_a",
                hash=self.var_a.hash,
                source="root.a",
                path=str(source_path),
                destination="root",
            ),
        )
        assert source_path.exists()
        assert self.var_a.load(str(source_path)) == "something"
        assert not response.exception


def test_payload_in_run(tmpdir):
    work = WorkRun(str(tmpdir))
    work._name = "root.a"
    work.run()


class Sender(LightningWork):
    def __init__(self):
        super().__init__(parallel=True)
        self.value_all = None
        self.value_b = None
        self.value_c = None

    def run(self):
        self.value_all = Payload(["A", "B", "C"])
        self.value_b = Payload("B")
        self.value_c = Payload("C")


class WorkReceive(LightningWork):
    def __init__(self, expected):
        super().__init__(parallel=True)
        self.expected = expected

    def run(self, generated):
        assert generated.value == self.expected


class Flow(LightningFlow):
    def __init__(self):
        super().__init__()
        self.sender = Sender()
        self.receiver_all = WorkReceive(["A", "B", "C"])
        self.receiver_b = WorkReceive("B")
        self.receiver_c = WorkReceive("C")

    def run(self):
        self.sender.run()
        if self.sender.value_all:
            self.receiver_all.run(self.sender.value_all)
        if self.sender.value_b:
            self.receiver_b.run(self.sender.value_b)
        if self.sender.value_c:
            self.receiver_c.run(self.sender.value_c)
        if self.receiver_all.has_succeeded and self.receiver_b.has_succeeded and self.receiver_c.has_succeeded:
            self._exit()


def test_payload_works(tmpdir):
    """This tests validates the payload api can be used to transfer return values from a work to another."""
    with mock.patch("lightning_app.storage.path.storage_root_dir", lambda: pathlib.Path(tmpdir)):
        app = LightningApp(Flow(), debug=True)
        MultiProcessRuntime(app, start_server=False).dispatch()

    os.remove("value_all")
    os.remove("value_b")
    os.remove("value_c")