mediacms/files/tasks.py

import json
import os
import re
import shutil
import subprocess
import tempfile
from datetime import datetime, timedelta

from celery import Task
from celery.decorators import task
from celery.exceptions import SoftTimeLimitExceeded
from celery.signals import task_revoked
from celery.task.control import revoke
from celery.utils.log import get_task_logger
from django.conf import settings
from django.core.cache import cache
from django.core.files import File
from django.db.models import Q

from actions.models import USER_MEDIA_ACTIONS, MediaAction
from actions.models import USER_VOICE_ACTIONS, VoiceAction
from users.models import User

from .backends import FFmpegBackend
from .exceptions import VideoEncodingError
from .helpers import (
    calculate_seconds,
    create_temp_file,
    get_file_name,
    get_file_type,
    media_file_info,
    produce_ffmpeg_commands,
    produce_friendly_token,
    rm_file,
    run_command,
    url_from_path, # Needed to combine video with some voices.
)
from .methods import list_tasks, notify_users, pre_save_action
from .methods import pre_save_action__voice
from .methods import pre_save_action__videowithvoices
from .models import Category, EncodeProfile, Encoding, Media, Rating, Tag
from .models import Voice

logger = get_task_logger(__name__)

VALID_USER_ACTIONS = [action for action, name in USER_MEDIA_ACTIONS]
VALID_VOICE_ACTIONS = [action for action, name in USER_VOICE_ACTIONS]

ERRORS_LIST = [
    "Output file is empty, nothing was encoded",
    "Invalid data found when processing input",
    "Unable to find a suitable output format for",
]


@task(name="chunkize_media", bind=True, queue="short_tasks", soft_time_limit=60 * 30)
def chunkize_media(self, friendly_token, profiles, force=True):
    """Break media in chunks and start encoding tasks"""

    profiles = [EncodeProfile.objects.get(id=profile) for profile in profiles]
    media = Media.objects.get(friendly_token=friendly_token)
    cwd = os.path.dirname(os.path.realpath(media.media_file.path))
    file_name = media.media_file.path.split("/")[-1]
    random_prefix = produce_friendly_token()
    file_format = "{0}_{1}".format(random_prefix, file_name)
    chunks_file_name = "%02d_{0}".format(file_format)
    chunks_file_name += ".mkv"
    cmd = [
        settings.FFMPEG_COMMAND,
        "-y",
        "-i",
        media.media_file.path,
        "-c",
        "copy",
        "-f",
        "segment",
        "-segment_time",
        str(settings.VIDEO_CHUNKS_DURATION),
        chunks_file_name,
    ]
    chunks = []
    ret = run_command(cmd, cwd=cwd)

    if "out" in ret.keys():
        for line in ret.get("error").split("\n"):
            ch = re.findall(r"Opening \'([\W\w]+)\' for writing", line)
            if ch:
                chunks.append(ch[0])
    if not chunks:
        # command completely failed to segment file.putting to normal encode
        logger.info("Failed to break file {0} in chunks." " Putting to normal encode queue".format(friendly_token))
        for profile in profiles:
            if media.video_height and media.video_height < profile.resolution:
                if profile.resolution not in settings.MINIMUM_RESOLUTIONS_TO_ENCODE:
                    continue
            encoding = Encoding(media=media, profile=profile)
            encoding.save()
            enc_url = settings.SSL_FRONTEND_HOST + encoding.get_absolute_url()
            encode_media.delay(friendly_token, profile.id, encoding.id, enc_url, force=force)
        return False

    chunks = [os.path.join(cwd, ch) for ch in chunks]
    to_profiles = []
    chunks_dict = {}
    # calculate once md5sums
    for chunk in chunks:
        cmd = ["md5sum", chunk]
        stdout = run_command(cmd).get("out")
        md5sum = stdout.strip().split()[0]
        chunks_dict[chunk] = md5sum

    for profile in profiles:
        if media.video_height and media.video_height < profile.resolution:
            if profile.resolution not in settings.MINIMUM_RESOLUTIONS_TO_ENCODE:
                continue
        to_profiles.append(profile)

        for chunk in chunks:
            encoding = Encoding(
                media=media,
                profile=profile,
                chunk_file_path=chunk,
                chunk=True,
                chunks_info=json.dumps(chunks_dict),
                md5sum=chunks_dict[chunk],
            )

            encoding.save()
            enc_url = settings.SSL_FRONTEND_HOST + encoding.get_absolute_url()
            if profile.resolution in settings.MINIMUM_RESOLUTIONS_TO_ENCODE:
                priority = 0
            else:
                priority = 9
            encode_media.apply_async(
                args=[friendly_token, profile.id, encoding.id, enc_url],
                kwargs={"force": force, "chunk": True, "chunk_file_path": chunk},
                priority=priority,
            )

    logger.info("got {0} chunks and will encode to {1} profiles".format(len(chunks), to_profiles))
    return True


class EncodingTask(Task):
    def on_failure(self, exc, task_id, args, kwargs, einfo):
        # mainly used to run some post failure steps
        # we get here if a task is revoked
        try:
            if hasattr(self, "encoding"):
                self.encoding.status = "fail"
                self.encoding.save(update_fields=["status"])
                kill_ffmpeg_process(self.encoding.temp_file)
                if hasattr(self.encoding, "media"):
                    self.encoding.media.post_encode_actions()
        except BaseException:
            pass
        return False


@task(
    name="encode_media",
    base=EncodingTask,
    bind=True,
    queue="long_tasks",
    soft_time_limit=settings.CELERY_SOFT_TIME_LIMIT,
)
def encode_media(
    self,
    friendly_token,
    profile_id,
    encoding_id,
    encoding_url,
    force=True,
    chunk=False,
    chunk_file_path="",
):
    """Encode a media to given profile, using ffmpeg, storing progress"""

    logger.info("Encode Media started, friendly token {0}, profile id {1}, force {2}".format(friendly_token, profile_id, force))

    if self.request.id:
        task_id = self.request.id
    else:
        task_id = None
    try:
        media = Media.objects.get(friendly_token=friendly_token)
        profile = EncodeProfile.objects.get(id=profile_id)
    except BaseException:
        Encoding.objects.filter(id=encoding_id).delete()
        return False

    # break logic with chunk True/False
    if chunk:
        # TODO: in case a video is chunkized and this enters here many times
        # it will always run since chunk_file_path is always different
        # thus find a better way for this check
        if Encoding.objects.filter(media=media, profile=profile, chunk_file_path=chunk_file_path).count() > 1 and force is False:
            Encoding.objects.filter(id=encoding_id).delete()
            return False
        else:
            try:
                encoding = Encoding.objects.get(id=encoding_id)
                encoding.status = "running"
                Encoding.objects.filter(
                    media=media,
                    profile=profile,
                    chunk=True,
                    chunk_file_path=chunk_file_path,
                ).exclude(id=encoding_id).delete()
            except BaseException:
                encoding = Encoding(
                    media=media,
                    profile=profile,
                    status="running",
                    chunk=True,
                    chunk_file_path=chunk_file_path,
                )
    else:
        if Encoding.objects.filter(media=media, profile=profile).count() > 1 and force is False:
            Encoding.objects.filter(id=encoding_id).delete()
            return False
        else:
            try:
                encoding = Encoding.objects.get(id=encoding_id)
                encoding.status = "running"
                Encoding.objects.filter(media=media, profile=profile).exclude(id=encoding_id).delete()
            except BaseException:
                encoding = Encoding(media=media, profile=profile, status="running")

    if task_id:
        encoding.task_id = task_id
    encoding.worker = "localhost"
    encoding.retries = self.request.retries
    encoding.save()

    if profile.extension == "gif":
        tf = create_temp_file(suffix=".gif")
        # -ss 5 start from 5 second. -t 25 until 25 sec
        command = [
            settings.FFMPEG_COMMAND,
            "-y",
            "-ss",
            "3",
            "-i",
            media.media_file.path,
            "-hide_banner",
            "-vf",
            "scale=344:-1:flags=lanczos,fps=1",
            "-t",
            "25",
            "-f",
            "gif",
            tf,
        ]
        ret = run_command(command)
        if os.path.exists(tf) and get_file_type(tf) == "image":
            with open(tf, "rb") as f:
                myfile = File(f)
                encoding.status = "success"
                encoding.media_file.save(content=myfile, name=tf)
                rm_file(tf)
                return True
        else:
            return False

    if chunk:
        original_media_path = chunk_file_path
    else:
        original_media_path = media.media_file.path

    # if not media.duration:
    #    encoding.status = "fail"
    #    encoding.save(update_fields=["status"])
    #    return False

    with tempfile.TemporaryDirectory(dir=settings.TEMP_DIRECTORY) as temp_dir:
        tf = create_temp_file(suffix=".{0}".format(profile.extension), dir=temp_dir)
        tfpass = create_temp_file(suffix=".{0}".format(profile.extension), dir=temp_dir)
        ffmpeg_commands = produce_ffmpeg_commands(
            original_media_path,
            media.media_info,
            resolution=profile.resolution,
            codec=profile.codec,
            output_filename=tf,
            pass_file=tfpass,
            chunk=chunk,
        )
        if not ffmpeg_commands:
            encoding.status = "fail"
            encoding.save(update_fields=["status"])
            return False

        encoding.temp_file = tf
        encoding.commands = str(ffmpeg_commands)

        encoding.save(update_fields=["temp_file", "commands", "task_id"])

        # binding these, so they are available on on_failure
        self.encoding = encoding
        self.media = media
        # can be one-pass or two-pass
        for ffmpeg_command in ffmpeg_commands:
            ffmpeg_command = [str(s) for s in ffmpeg_command]
            encoding_backend = FFmpegBackend()
            try:
                encoding_command = encoding_backend.encode(ffmpeg_command)
                duration, n_times = 0, 0
                output = ""
                while encoding_command:
                    try:
                        # TODO: understand an eternal loop
                        # eg h265 with mv4 file issue, and stop with error
                        output = next(encoding_command)
                        duration = calculate_seconds(output)
                        if duration:
                            percent = duration * 100 / media.duration
                            if n_times % 60 == 0:
                                encoding.progress = percent
                                try:
                                    encoding.save(update_fields=["progress", "update_date"])
                                    logger.info("Saved {0}".format(round(percent, 2)))
                                except BaseException:
                                    pass
                            n_times += 1
                    except StopIteration:
                        break
                    except VideoEncodingError:
                        # ffmpeg error, or ffmpeg was killed
                        raise
            except Exception as e:
                try:
                    # output is empty, fail message is on the exception
                    output = e.message
                except AttributeError:
                    output = ""
                if isinstance(e, SoftTimeLimitExceeded):
                    kill_ffmpeg_process(encoding.temp_file)
                encoding.logs = output
                encoding.status = "fail"
                encoding.save(update_fields=["status", "logs"])
                raise_exception = True
                # if this is an ffmpeg's valid error
                # no need for the task to be re-run
                # otherwise rerun task...
                for error_msg in ERRORS_LIST:
                    if error_msg.lower() in output.lower():
                        raise_exception = False
                if raise_exception:
                    raise self.retry(exc=e, countdown=5, max_retries=1)

        encoding.logs = output
        encoding.progress = 100

        success = False
        encoding.status = "fail"
        if os.path.exists(tf) and os.path.getsize(tf) != 0:
            ret = media_file_info(tf)
            if ret.get("is_video") or ret.get("is_audio"):
                encoding.status = "success"
                success = True

                with open(tf, "rb") as f:
                    myfile = File(f)
                    output_name = "{0}.{1}".format(get_file_name(original_media_path), profile.extension)
                    encoding.media_file.save(content=myfile, name=output_name)
                encoding.total_run_time = (encoding.update_date - encoding.add_date).seconds

        try:
            encoding.save(update_fields=["status", "logs", "progress", "total_run_time"])
        # this will raise a django.db.utils.DatabaseError error when task is revoked,
        # since we delete the encoding at that stage
        except BaseException:
            pass

        return success


@task(name="produce_sprite_from_video", queue="long_tasks")
def produce_sprite_from_video(friendly_token):
    """Produces a sprites file for a video, uses ffmpeg"""

    try:
        media = Media.objects.get(friendly_token=friendly_token)
    except BaseException:
        logger.info("failed to get media with friendly_token %s" % friendly_token)
        return False

    with tempfile.TemporaryDirectory(dir=settings.TEMP_DIRECTORY) as tmpdirname:
        try:
            tmpdir_image_files = tmpdirname + "/img%03d.jpg"
            output_name = tmpdirname + "/sprites.jpg"
            cmd = "{0} -i {1} -f image2 -vf 'fps=1/10, scale=160:90' {2}&&files=$(ls {3}/img*.jpg | sort -t '-' -n -k 2 | tr '\n' ' ')&&convert $files -append {4}".format(
                settings.FFMPEG_COMMAND,
                media.media_file.path,
                tmpdir_image_files,
                tmpdirname,
                output_name,
            )
            subprocess.run(cmd, stdout=subprocess.PIPE, shell=True)
            if os.path.exists(output_name) and get_file_type(output_name) == "image":
                with open(output_name, "rb") as f:
                    myfile = File(f)
                    media.sprites.save(
                        content=myfile,
                        name=get_file_name(media.media_file.path) + "sprites.jpg",
                    )
        except BaseException:
            pass
    return True


@task(name="create_hls", queue="long_tasks")
def create_hls(friendly_token):
    """Creates HLS file for media, uses Bento4 mp4hls command"""

    if not hasattr(settings, "MP4HLS_COMMAND"):
        logger.info("Bento4 mp4hls command is missing from configuration")
        return False

    if not os.path.exists(settings.MP4HLS_COMMAND):
        logger.info("Bento4 mp4hls command is missing")
        return False

    try:
        media = Media.objects.get(friendly_token=friendly_token)
    except BaseException:
        logger.info("failed to get media with friendly_token %s" % friendly_token)
        return False

    p = media.uid.hex
    output_dir = os.path.join(settings.HLS_DIR, p)
    encodings = media.encodings.filter(profile__extension="mp4", status="success", chunk=False, profile__codec="h264")
    if encodings:
        existing_output_dir = None
        if os.path.exists(output_dir):
            existing_output_dir = output_dir
            output_dir = os.path.join(settings.HLS_DIR, p + produce_friendly_token())
        files = " ".join([f.media_file.path for f in encodings if f.media_file])
        cmd = "{0} --segment-duration=4 --output-dir={1} {2}".format(settings.MP4HLS_COMMAND, output_dir, files)
        subprocess.run(cmd, stdout=subprocess.PIPE, shell=True)
        if existing_output_dir:
            # override content with -T !
            cmd = "cp -rT {0} {1}".format(output_dir, existing_output_dir)
            subprocess.run(cmd, stdout=subprocess.PIPE, shell=True)
            shutil.rmtree(output_dir)
            output_dir = existing_output_dir
        pp = os.path.join(output_dir, "master.m3u8")
        if os.path.exists(pp):
            if media.hls_file != pp:
                media.hls_file = pp
                media.save(update_fields=["hls_file"])
    return True


@task(name="check_running_states", queue="short_tasks")
def check_running_states():
    # Experimental - unused
    """Check stale running encodings and delete/reencode media"""

    encodings = Encoding.objects.filter(status="running")

    logger.info("got {0} encodings that are in state running".format(encodings.count()))
    changed = 0
    for encoding in encodings:
        now = datetime.now(encoding.update_date.tzinfo)
        if (now - encoding.update_date).seconds > settings.RUNNING_STATE_STALE:
            media = encoding.media
            profile = encoding.profile
            task_id = encoding.task_id
            # terminate task
            if task_id:
                revoke(task_id, terminate=True)
            encoding.delete()
            media.encode(profiles=[profile])
            # TODO: allign with new code + chunksize...
            changed += 1
    if changed:
        logger.info("changed from running to pending on {0} items".format(changed))
    return True


@task(name="check_media_states", queue="short_tasks")
def check_media_states():
    # Experimental - unused
    # check encoding status of not success media
    media = Media.objects.filter(Q(encoding_status="running") | Q(encoding_status="fail") | Q(encoding_status="pending"))

    logger.info("got {0} media that are not in state success".format(media.count()))

    changed = 0
    for m in media:
        m.set_encoding_status()
        m.save(update_fields=["encoding_status"])
        changed += 1
    if changed:
        logger.info("changed encoding status to {0} media items".format(changed))
    return True


@task(name="check_pending_states", queue="short_tasks")
def check_pending_states():
    # Experimental - unused
    # check encoding profiles that are on state pending and not on a queue
    encodings = Encoding.objects.filter(status="pending")

    if not encodings:
        return True

    changed = 0
    tasks = list_tasks()
    task_ids = tasks["task_ids"]
    media_profile_pairs = tasks["media_profile_pairs"]
    for encoding in encodings:
        if encoding.task_id and encoding.task_id in task_ids:
            # encoding is in one of the active/reserved/scheduled tasks list
            continue
        elif (
            encoding.media.friendly_token,
            encoding.profile.id,
        ) in media_profile_pairs:
            continue
            # encoding is in one of the reserved/scheduled tasks list.
            # has no task_id but will be run, so need to re-enter the queue
        else:
            media = encoding.media
            profile = encoding.profile
            encoding.delete()
            media.encode(profiles=[profile], force=False)
            changed += 1
    if changed:
        logger.info("set to the encode queue {0} encodings that were on pending state".format(changed))
    return True


@task(name="check_missing_profiles", queue="short_tasks")
def check_missing_profiles():
    # Experimental - unused

    # check if video files have missing profiles. If so, add them
    media = Media.objects.filter(media_type="video")
    profiles = list(EncodeProfile.objects.all())

    changed = 0

    for m in media:
        existing_profiles = [p.profile for p in m.encodings.all()]
        missing_profiles = [p for p in profiles if p not in existing_profiles]
        if missing_profiles:
            m.encode(profiles=missing_profiles, force=False)
            # since we call with force=False
            # encode_media won't delete existing profiles
            # if they appear on the meanwhile (eg on a big queue)
            changed += 1
    if changed:
        logger.info("set to the encode queue {0} profiles".format(changed))
    return True


@task(name="clear_sessions", queue="short_tasks")
def clear_sessions():
    """Clear expired sessions"""

    try:
        from importlib import import_module

        from django.conf import settings

        engine = import_module(settings.SESSION_ENGINE)
        engine.SessionStore.clear_expired()
    except BaseException:
        return False
    return True


@task(name="save_user_action", queue="short_tasks")
def save_user_action(user_or_session, friendly_token=None, action="watch", extra_info=None):
    """Short task that saves a user action"""

    if action not in VALID_USER_ACTIONS:
        return False

    try:
        media = Media.objects.get(friendly_token=friendly_token)
    except BaseException:
        return False

    user = user_or_session.get("user_id")
    session_key = user_or_session.get("user_session")
    remote_ip = user_or_session.get("remote_ip_addr")

    if user:
        try:
            user = User.objects.get(id=user)
        except BaseException:
            return False

    if not (user or session_key):
        return False

    if action in ["like", "dislike", "watch", "report"]:
        if not pre_save_action(
            media=media,
            user=user,
            session_key=session_key,
            action=action,
            remote_ip=remote_ip,
        ):
            return False

    if action == "watch":
        if user:
            MediaAction.objects.filter(user=user, media=media, action="watch").delete()
        else:
            MediaAction.objects.filter(session_key=session_key, media=media, action="watch").delete()
    if action == "rate":
        try:
            score = extra_info.get("score")
            rating_category = extra_info.get("category_id")
        except BaseException:
            # TODO: better error handling?
            return False
        try:
            rating = Rating.objects.filter(user=user, media=media, rating_category_id=rating_category).first()
            if rating:
                rating.score = score
                rating.save(update_fields=["score"])
            else:
                rating = Rating.objects.create(
                    user=user,
                    media=media,
                    rating_category_id=rating_category,
                    score=score,
                )
        except Exception:
            # TODO: more specific handling, for errors in score, or
            # rating_category?
            return False

    ma = MediaAction(
        user=user,
        session_key=session_key,
        media=media,
        action=action,
        extra_info=extra_info,
        remote_ip=remote_ip,
    )
    ma.save()

    if action == "watch":
        media.views += 1
        media.save(update_fields=["views"])
    elif action == "report":
        media.reported_times += 1

        if media.reported_times >= settings.REPORTED_TIMES_THRESHOLD:
            media.state = "private"
        media.save(update_fields=["reported_times", "state"])

        notify_users(
            friendly_token=media.friendly_token,
            action="media_reported",
            extra=extra_info,
        )
    elif action == "like":
        media.likes += 1
        media.save(update_fields=["likes"])
    elif action == "dislike":
        media.dislikes += 1
        media.save(update_fields=["dislikes"])

    return True

@task(name="save_voice_action", queue="short_tasks")
def save_voice_action(user_or_session, friendly_token=None, action="watch", extra_info=None, uid=None):
    """Short task that saves a voice action"""

    if action not in VALID_VOICE_ACTIONS:
        return False

    try:
        media = Media.objects.get(friendly_token=friendly_token)
    except BaseException:
        return False

    try:
        voice = Voice.objects.get(uid=uid)
    except BaseException:
        return False

    user = user_or_session.get("user_id")
    session_key = user_or_session.get("user_session")
    remote_ip = user_or_session.get("remote_ip_addr")

    if user:
        try:
            user = User.objects.get(id=user)
        except BaseException:
            return False

    if not (user or session_key):
        return False

    # Check if user has alread done like/likeundo once. Avoid spam. And more.
    if action in ["like", "likeundo", "watch", "report"]:
        if not pre_save_action__voice(
            media=media,
            user=user,
            session_key=session_key,
            action=action,
            remote_ip=remote_ip,
            voice=voice
        ):
            return False

    # TODO: Exactly why the previous `watch` actions are deleted?
    if action == "watch":
        if user:
            VoiceAction.objects.filter(user=user, voice=voice, action="watch").delete()
        else:
            VoiceAction.objects.filter(session_key=session_key, voice=voice, action="watch").delete()

    # Check whether `filter` result is empty or not, by `.first()`
    # https://stackoverflow.com/a/50453580/3405291

    # In the case of `like` action, delete previous `likeundo` actions.
    if action == "like":
        if user:
            va = VoiceAction.objects.filter(user=user, voice=voice, action="likeundo").first()
            if va:
                VoiceAction.objects.filter(user=user, voice=voice, action="likeundo").delete()
        else:
            va = VoiceAction.objects.filter(session_key=session_key, voice=voice, action="likeundo").first()
            if va:
                VoiceAction.objects.filter(session_key=session_key, voice=voice, action="likeundo").delete()

    # In the case of `likeundo` action, delete previous `like` actions.
    if action == "likeundo":
        if user:
            va = VoiceAction.objects.filter(user=user, voice=voice, action="like").first()
            if va:
                VoiceAction.objects.filter(user=user, voice=voice, action="like").delete()
        else:
            va = VoiceAction.objects.filter(session_key=session_key, voice=voice, action="like").first()
            if va:
                VoiceAction.objects.filter(session_key=session_key, voice=voice, action="like").delete()

    # There is no `rate` action for voice. So, it's skipped.

    va = VoiceAction(
        user=user,
        session_key=session_key,
        media=media,
        action=action,
        extra_info=extra_info,
        remote_ip=remote_ip,
        voice=voice,
    )
    va.save()

    if action == "watch":
        voice.views += 1
        voice.save(update_fields=["views"])
    elif action == "report":
        voice.reported_times += 1
        if voice.reported_times >= settings.REPORTED_TIMES_THRESHOLD:
            # Delete voice?
            voice.delete()
        voice.save(update_fields=["reported_times"])
        # TODO: notify_users
        # There is a code for notification. That might be helpful.
    elif action == "like":
        voice.likes += 1
        voice.save(update_fields=["likes"])
    elif action == "likeundo":
        voice.likes -= 1
        voice.save(update_fields=["likes"])

    return True

### Let's make this method a regular method, not a celery_short task.
### Since we have to return the path of the resulted video as HTTP response.
### Combining video with voices by FFMPEG should be quite fast. Just copy audio channels.
###
#@task(name="video_with_voices", queue="short_tasks")
def video_with_voices(user_or_session, friendly_token=None, voicesUid=None):
    #"""Short task that combines a video with some voices"""

    try:
        media = Media.objects.get(friendly_token=friendly_token)
    except BaseException:
        return False

    # Only video is acceptable.
    if media.media_type != "video":
       return False

    voices = []

    for uid in voicesUid:
        # Double-check voice existence.
        try:
            voice = Voice.objects.get(uid=uid)
        except BaseException:
            return False
        voices.append(voice)

    # To download a video combined with some voices,
    # we require a valid user or session.
    # We have to check remote_ip to avoid spam.
    user = user_or_session.get("user_id")
    session_key = user_or_session.get("user_session")
    remote_ip = user_or_session.get("remote_ip_addr")

    if user:
        try:
            user = User.objects.get(id=user)
        except BaseException:
            return False

    if not (user or session_key):
        return False

    # Avoid spam and more.
    if not pre_save_action__videowithvoices(
        media=media,
        user=user,
        session_key=session_key,
        action="getvideowithvoices",
        remote_ip=remote_ip,
    ):
        return False

    va = VoiceAction(
        user=user,
        session_key=session_key,
        media=media,
        action="getvideowithvoices",
        remote_ip=remote_ip,
        # Voice is not really needed for this action, but pass voice just to avoid this database error:
        # ERROR:  null value in column "voice_id" of relation "actions_voiceaction" violates not-null constraint
        voice=voice,
    )
    va.save()

    # Combine video with the voices.
    cwd = os.path.dirname(os.path.realpath(media.media_file.path))
    video_name = media.media_file.path.split("/")[-1]
    random_prefix = produce_friendly_token()
    result_file_name = "{0}_{1}".format(random_prefix, video_name)
    result_file_name = "combineVideoWithSomeVoices_{0}".format(result_file_name)
    result_file_name += ".mkv"

    # To add a new audio track into an existing video with audio, use:
    # https://stackoverflow.com/a/70001304/3405291
    cmd = [
        settings.FFMPEG_COMMAND,
        "-i",
        media.media_file.path,
    ]

    for voice in voices:
        cmd.append("-i")
        cmd.append(voice.voice_file.path)

    # To combine voices.
    cmd.append("-filter_complex")

    voiceCounter = 1
    arg = ""
    for voice in voices:
        arg += "[{0}:a] ".format(voiceCounter)
        voiceCounter += 1
    arg += "amix=inputs={0}:duration=longest:dropout_transition=0".format(len(voices))

    cmd.append(arg)
    cmd.append("-c:v")
    cmd.append("copy")
    # The -an option disables audio recording for the output file,
    # which means that the original audio track from the input video
    # will not be included in the output file.
    # The video stream is still copied over using -c:v copy,
    # and the combined audio track is created using the amix filter as before.
    cmd.append("-an")
    cmd.append(result_file_name)

    ret = run_command(cmd, cwd=cwd)

    # You can double-check result file by this command:
    # /usr/local/bin/docker-compose exec web ls -lhrtc /tmp/

    # You can copy result file from docker container to host by a command like:
    # docker cp <containerId>:/tmp/<result_file_name> /home/m3/Downloads/

    result_file_path = os.path.join(cwd, result_file_name)
    result_file_url = url_from_path(result_file_path)

    return {"result_file_url": result_file_url, "ffmpeg_return": ret}

@task(name="get_list_of_popular_media", queue="long_tasks")
def get_list_of_popular_media():
    """Experimental task for preparing media listing
    for index page / recommended section
    calculate and return the top 50 popular media, based on two rules
    X = the top 25 videos that have the most views during the last week
    Y = the most recent 25 videos that have been liked over the last 6 months
    """

    valid_media_x = {}
    valid_media_y = {}
    basic_query = Q(listable=True)
    media_x = Media.objects.filter(basic_query).values("friendly_token")

    period_x = datetime.now() - timedelta(days=7)
    period_y = datetime.now() - timedelta(days=30 * 6)

    for media in media_x:
        ft = media["friendly_token"]
        num = MediaAction.objects.filter(action_date__gte=period_x, action="watch", media__friendly_token=ft).count()
        if num:
            valid_media_x[ft] = num
        num = MediaAction.objects.filter(action_date__gte=period_y, action="like", media__friendly_token=ft).count()
        if num:
            valid_media_y[ft] = num

    x = sorted(valid_media_x.items(), key=lambda kv: kv[1], reverse=True)[:25]
    y = sorted(valid_media_y.items(), key=lambda kv: kv[1], reverse=True)[:25]

    media_ids = [a[0] for a in x]
    media_ids.extend([a[0] for a in y])
    media_ids = list(set(media_ids))
    cache.set("popular_media_ids", media_ids, 60 * 60 * 12)
    logger.info("saved popular media ids")

    return True


@task(name="update_listings_thumbnails", queue="long_tasks")
def update_listings_thumbnails():
    """Populate listings_thumbnail field for models"""

    # Categories
    used_media = []
    saved = 0
    qs = Category.objects.filter().order_by("-media_count")
    for object in qs:
        media = Media.objects.exclude(friendly_token__in=used_media).filter(category=object, state="public", is_reviewed=True).order_by("-views").first()
        if media:
            object.listings_thumbnail = media.thumbnail_url
            object.save(update_fields=["listings_thumbnail"])
            used_media.append(media.friendly_token)
            saved += 1
    logger.info("updated {} categories".format(saved))

    # Tags
    used_media = []
    saved = 0
    qs = Tag.objects.filter().order_by("-media_count")
    for object in qs:
        media = Media.objects.exclude(friendly_token__in=used_media).filter(tags=object, state="public", is_reviewed=True).order_by("-views").first()
        if media:
            object.listings_thumbnail = media.thumbnail_url
            object.save(update_fields=["listings_thumbnail"])
            used_media.append(media.friendly_token)
            saved += 1
    logger.info("updated {} tags".format(saved))

    return True


@task_revoked.connect
def task_sent_handler(sender=None, headers=None, body=None, **kwargs):
    # For encode_media tasks that are revoked,
    # ffmpeg command won't be stopped, since
    # it got started by a subprocess.
    # Need to stop that process
    # Also, removing the Encoding object,
    # since the task that would prepare it was killed
    # Maybe add a killed state for Encoding objects
    try:
        uid = kwargs["request"].task_id
        if uid:
            encoding = Encoding.objects.get(task_id=uid)
            encoding.delete()
            logger.info("deleted the Encoding object")
            if encoding.temp_file:
                kill_ffmpeg_process(encoding.temp_file)

    except BaseException:
        pass

    return True


def kill_ffmpeg_process(filepath):
    # this is not ideal, ffmpeg pid could be linked to the Encoding object
    cmd = "ps aux|grep 'ffmpeg'|grep %s|grep -v grep |awk '{print $2}'" % filepath
    result = subprocess.run(cmd, stdout=subprocess.PIPE, shell=True)
    pid = result.stdout.decode("utf-8").strip()
    if pid:
        cmd = "kill -9 %s" % pid
        result = subprocess.run(cmd, stdout=subprocess.PIPE, shell=True)
    return result


@task(name="remove_media_file", base=Task, queue="long_tasks")
def remove_media_file(media_file=None):
    rm_file(media_file)
    return True


# TODO LIST
# 1 chunks are deleted from original server when file is fully encoded.
# however need to enter this logic in cases of fail as well
# 2 script to delete chunks in fail status
# (and check for their encdings, and delete them as well, along with
# all chunks)
# 3 beat task, remove chunks