# Released under the MIT License. See LICENSE for details.
#
"""Functionality related to managing cloud based assets."""

from __future__ import annotations

from typing import TYPE_CHECKING
from pathlib import Path
import threading
import urllib.request
import logging
import weakref
import time
import os
import sys

from efro import entity

if TYPE_CHECKING:
    from bacommon.assets import AssetPackageFlavor
    from typing import List


class FileValue(entity.CompoundValue):
    """State for an individual file."""


class State(entity.Entity):
    """Holds all persistent state for the asset-manager."""

    files = entity.CompoundDictField('files', str, FileValue())


class AssetManager:
    """Wrangles all assets."""

    _state: State

    def __init__(self, rootdir: Path) -> None:
        print('AssetManager()')
        assert isinstance(rootdir, Path)
        self.thread_ident = threading.get_ident()
        self._rootdir = rootdir
        self._started = False
        if not self._rootdir.is_dir():
            raise RuntimeError(f'Provided rootdir does not exist: "{rootdir}"')

        self.load_state()

    def __del__(self) -> None:
        print('~AssetManager()')
        if self._started:
            logging.warning('AssetManager dying in a started state.')

    def launch_gather(
        self,
        packages: List[str],
        flavor: AssetPackageFlavor,
        account_token: str,
    ) -> AssetGather:
        """Spawn an asset-gather operation from this manager."""
        print('would gather', packages, 'and flavor', flavor, 'with token',
              account_token)
        return AssetGather(self)

    def update(self) -> None:
        """Can be called periodically to perform upkeep."""

    def start(self) -> None:
        """Tell the manager to start working.

        This will initiate network activity and other processing.
        """
        if self._started:
            logging.warning('AssetManager.start() called on running manager.')
        self._started = True

    def stop(self) -> None:
        """Tell the manager to stop working.

        All network activity should be ceased before this function returns.
        """
        if not self._started:
            logging.warning('AssetManager.stop() called on stopped manager.')
        self._started = False
        self.save_state()

    @property
    def rootdir(self) -> Path:
        """The root directory for this manager."""
        return self._rootdir

    @property
    def state_path(self) -> Path:
        """The path of the state file."""
        return Path(self._rootdir, 'state')

    def load_state(self) -> None:
        """Loads state from disk. Resets to default state if unable to."""
        print('ASSET-MANAGER LOADING STATE')
        try:
            state_path = self.state_path
            if state_path.exists():
                with open(self.state_path) as infile:
                    self._state = State.from_json_str(infile.read())
                    return
        except Exception:
            logging.exception('Error loading existing AssetManager state')
        self._state = State()

    def save_state(self) -> None:
        """Save state to disk (if possible)."""

        print('ASSET-MANAGER SAVING STATE')
        try:
            with open(self.state_path, 'w') as outfile:
                outfile.write(self._state.to_json_str())
        except Exception:
            logging.exception('Error writing AssetManager state')


class AssetGather:
    """Wrangles a gathering of assets."""

    def __init__(self, manager: AssetManager) -> None:
        assert threading.get_ident() == manager.thread_ident
        self._manager = weakref.ref(manager)
        # self._valid = True
        print('AssetGather()')
        # url = 'https://files.ballistica.net/bombsquad/promo/BSGamePlay.mov'
        # url = 'http://www.python.org/ftp/python/2.7.3/Python-2.7.3.tgz'
        # fetch_url(url,
        #           filename=Path(manager.rootdir, 'testdl'),
        #           asset_gather=self)
        # print('fetch success')
        thread = threading.Thread(target=self._run)
        thread.run()

    def _run(self) -> None:
        """Run the gather in a background thread."""
        print('hello from gather bg')

        # First, do some sort of.

    # @property
    # def valid(self) -> bool:
    #     """Whether this gather is still valid.

    #     A gather becomes in valid if its originating AssetManager dies.
    #     """
    #     return True

    def __del__(self) -> None:
        print('~AssetGather()')


def fetch_url(url: str, filename: Path, asset_gather: AssetGather) -> None:
    """Fetch a given url to a given filename for a given AssetGather.

    """

    import socket

    # We don't want to keep the provided AssetGather alive, but we want
    # to abort if it dies.
    assert isinstance(asset_gather, AssetGather)
    # weak_gather = weakref.ref(asset_gather)

    # Pass a very short timeout to urllib so we have opportunities
    # to cancel even with network blockage.
    req = urllib.request.urlopen(url, timeout=1)
    file_size = int(req.headers['Content-Length'])
    print(f'\nDownloading: {filename} Bytes: {file_size:,}')

    def doit() -> None:
        time.sleep(1)
        print('dir', type(req.fp), dir(req.fp))
        print('WOULD DO IT', flush=True)
        # req.close()
        # req.fp.close()

    threading.Thread(target=doit).run()

    with open(filename, 'wb') as outfile:
        file_size_dl = 0

        block_sz = 1024 * 1024 * 1000
        time_outs = 0
        while True:
            try:
                data = req.read(block_sz)
            except ValueError:
                import traceback
                traceback.print_exc()
                print('VALUEERROR', flush=True)
                break
            except socket.timeout:
                print('TIMEOUT', flush=True)
                # File has not had activity in max seconds.
                if time_outs > 3:
                    print('\n\n\nsorry -- try back later')
                    os.unlink(filename)
                    raise
                print('\nHmmm... little issue... '
                      'I\'ll wait a couple of seconds')
                time.sleep(3)
                time_outs += 1
                continue

            # We reached the end of the download!
            if not data:
                sys.stdout.write('\rDone!\n\n')
                sys.stdout.flush()
                break

            file_size_dl += len(data)
            outfile.write(data)
            percent = file_size_dl * 1.0 / file_size
            status = f'{file_size_dl:20,} Bytes [{percent:.2%}] received'
            sys.stdout.write('\r' + status)
            sys.stdout.flush()
    print('done with', req.fp)
