import sys
import asyncio
import logging
import subprocess
import traceback
import time
from functools import partial

from artiq.protocols import pyon
from artiq.tools import (asyncio_process_wait_timeout, asyncio_process_wait,
                         asyncio_wait_or_cancel)


logger = logging.getLogger(__name__)


class WorkerTimeout(Exception):
    pass


class WorkerWatchdogTimeout(Exception):
    pass


class WorkerError(Exception):
    pass


class Worker:
    def __init__(self, handlers=dict(), send_timeout=0.5):
        self.handlers = handlers
        self.send_timeout = send_timeout

        self.rid = None
        self.process = None
        self.watchdogs = dict()  # wid -> expiration (using time.monotonic)

        self.io_lock = asyncio.Lock()
        self.closed = asyncio.Event()

    def create_watchdog(self, t):
        n_user_watchdogs = len(self.watchdogs)
        if -1 in self.watchdogs:
            n_user_watchdogs -= 1
        avail = set(range(n_user_watchdogs + 1)) \
            - set(self.watchdogs.keys())
        wid = next(iter(avail))
        self.watchdogs[wid] = time.monotonic() + t
        return wid

    def delete_watchdog(self, wid):
        del self.watchdogs[wid]

    def watchdog_time(self):
        if self.watchdogs:
            return min(self.watchdogs.values()) - time.monotonic()
        else:
            return None

    @asyncio.coroutine
    def _create_process(self):
        yield from self.io_lock.acquire()
        try:
            if self.closed.is_set():
                raise WorkerError("Attempting to create process after close")
            self.process = yield from asyncio.create_subprocess_exec(
                sys.executable, "-m", "artiq.master.worker_impl",
                stdout=subprocess.PIPE, stdin=subprocess.PIPE)
        finally:
            self.io_lock.release()

    @asyncio.coroutine
    def close(self, term_timeout=1.0):
        """Interrupts any I/O with the worker process and terminates the
        worker process.

        This method should always be called by the user to clean up, even if
        build() or examine() raises an exception."""
        self.closed.set()
        yield from self.io_lock.acquire()
        try:
            if self.process is None:
                # Note the %s - self.rid can be None
                logger.debug("worker was not created (RID %s)", self.rid)
                return
            if self.process.returncode is not None:
                logger.debug("worker already terminated (RID %s)", self.rid)
                if self.process.returncode != 0:
                    logger.warning("worker finished with status code %d"
                                   " (RID %s)", self.process.returncode,
                                   self.rid)
                return
            obj = {"action": "terminate"}
            try:
                yield from self._send(obj, cancellable=False)
            except:
                logger.warning("failed to send terminate command to worker"
                               " (RID %s), killing", self.rid, exc_info=True)
                self.process.kill()
                yield from asyncio_process_wait(self.process)
                return
            try:
                yield from asyncio_process_wait_timeout(self.process,
                                                        term_timeout)
            except asyncio.TimeoutError:
                logger.warning("worker did not exit (RID %s), killing", self.rid)
                self.process.kill()
                yield from asyncio_process_wait(self.process)
            else:
                logger.debug("worker exited gracefully (RID %s)", self.rid)
        finally:
            self.io_lock.release()

    @asyncio.coroutine
    def _send(self, obj, cancellable=True):
        assert self.io_lock.locked()
        line = pyon.encode(obj)
        self.process.stdin.write(line.encode())
        self.process.stdin.write("\n".encode())
        ifs = [self.process.stdin.drain()]
        if cancellable:
            ifs.append(self.closed.wait())
        fs = yield from asyncio_wait_or_cancel(
            ifs, timeout=self.send_timeout,
            return_when=asyncio.FIRST_COMPLETED)
        if all(f.cancelled() for f in fs):
            raise WorkerTimeout("Timeout sending data to worker")
        for f in fs:
            if not f.cancelled() and f.done():
                f.result()  # raise any exceptions
        if cancellable and self.closed.is_set():
            raise WorkerError("Data transmission to worker cancelled")

    @asyncio.coroutine
    def _recv(self, timeout):
        assert self.io_lock.locked()
        fs = yield from asyncio_wait_or_cancel(
            [self.process.stdout.readline(), self.closed.wait()],
            timeout=timeout, return_when=asyncio.FIRST_COMPLETED)
        if all(f.cancelled() for f in fs):
            raise WorkerTimeout("Timeout receiving data from worker")
        if self.closed.is_set():
            raise WorkerError("Data transmission to worker cancelled")
        line = fs[0].result()
        if not line:
            raise WorkerError("Worker ended while attempting to receive data")
        try:
            obj = pyon.decode(line.decode())
        except:
            raise WorkerError("Worker sent invalid PYON data")
        return obj

    @asyncio.coroutine
    def _handle_worker_requests(self):
        while True:
            try:
                yield from self.io_lock.acquire()
                try:
                    obj = yield from self._recv(self.watchdog_time())
                finally:
                    self.io_lock.release()
            except WorkerTimeout:
                raise WorkerWatchdogTimeout
            action = obj["action"]
            if action == "completed":
                return True
            elif action == "pause":
                return False
            del obj["action"]
            if action == "create_watchdog":
                func = self.create_watchdog
            elif action == "delete_watchdog":
                func = self.delete_watchdog
            elif action == "register_experiment":
                func = self.register_experiment
            else:
                func = self.handlers[action]
            if getattr(func, "worker_pass_rid", False):
                func = partial(func, self.rid)
            try:
                data = func(**obj)
                reply = {"status": "ok", "data": data}
            except:
                reply = {"status": "failed",
                         "message": traceback.format_exc()}
            yield from self.io_lock.acquire()
            try:
                yield from self._send(reply)
            finally:
                self.io_lock.release()

    @asyncio.coroutine
    def _worker_action(self, obj, timeout=None):
        if timeout is not None:
            self.watchdogs[-1] = time.monotonic() + timeout
        try:
            yield from self.io_lock.acquire()
            try:
                yield from self._send(obj)
            finally:
                self.io_lock.release()
            try:
                completed = yield from self._handle_worker_requests()
            except WorkerTimeout:
                raise WorkerWatchdogTimeout
        finally:
            if timeout is not None:
                del self.watchdogs[-1]
        return completed

    @asyncio.coroutine
    def build(self, rid, pipeline_name, wd, expid, priority, timeout=15.0):
        self.rid = rid
        yield from self._create_process()
        yield from self._worker_action(
            {"action": "build",
             "rid": rid,
             "pipeline_name": pipeline_name,
             "wd": wd,
             "expid": expid,
             "priority": priority},
            timeout)

    @asyncio.coroutine
    def prepare(self):
        yield from self._worker_action({"action": "prepare"})

    @asyncio.coroutine
    def run(self):
        completed = yield from self._worker_action({"action": "run"})
        if not completed:
            self.yield_time = time.monotonic()
        return completed

    @asyncio.coroutine
    def resume(self):
        stop_duration = time.monotonic() - self.yield_time
        for wid, expiry in self.watchdogs:
            self.watchdogs[wid] += stop_duration
        completed = yield from self._worker_action({"status": "ok",
                                                    "data": None})
        if not completed:
            self.yield_time = time.monotonic()
        return completed

    @asyncio.coroutine
    def analyze(self):
        yield from self._worker_action({"action": "analyze"})

    @asyncio.coroutine
    def write_results(self, timeout=15.0):
        yield from self._worker_action({"action": "write_results"},
                                       timeout)

    @asyncio.coroutine
    def examine(self, file, timeout=20.0):
        yield from self._create_process()
        r = dict()
        def register(class_name, name, arguments):
            r[class_name] = {"name": name, "arguments": arguments}
        self.register_experiment = register
        yield from self._worker_action({"action": "examine",
                                        "file": file}, timeout)
        del self.register_experiment
        return r