# core/views.py
import os
import sys
import subprocess
import logging
import re
import redis

from django.conf import settings
from django.http import StreamingHttpResponse, HttpResponseServerError
from django.shortcuts import render

from apps.channels.models import Channel, Stream
from apps.m3u.models import M3UAccountProfile
from core.models import StreamProfile, CoreSettings

# Import the persistent lock (the “real” lock)
from dispatcharr.persistent_lock import PersistentLock

# Configure logging to output to the console.
logging.basicConfig(stream=sys.stdout, level=logging.DEBUG)
logger = logging.getLogger(__name__)


def settings_view(request):
    """
    Renders the settings page.
    """
    return render(request, 'settings.html')


def stream_view(request, channel_uuid):
    """
    Streams the first available stream for the given channel.
    It uses the channel’s assigned StreamProfile.
    A persistent Redis lock is used to prevent concurrent streaming on the same channel.
    """
    try:
        redis_host = getattr(settings, "REDIS_HOST", "localhost")
        redis_client = redis.Redis(host=settings.REDIS_HOST, port=6379, db=int(getattr(settings, "REDIS_DB", "0")))

        # Retrieve the channel by the provided stream_id.
        channel = Channel.objects.get(uuid=channel_uuid)
        logger.debug("Channel retrieved: ID=%s, Name=%s", channel.id, channel.name)

        # Ensure the channel has at least one stream.
        if not channel.streams.exists():
            logger.error("No streams found for channel ID=%s", channel.id)
            return HttpResponseServerError("No stream found for this channel.")

        active_stream = None
        m3u_account = None
        active_profile = None
        lock_key = None
        persistent_lock = None

        streams = channel.streams.all().order_by('channelstream__order')
        logger.debug(f'Found {len(streams)} streams for channel {channel.channel_number}')
        for stream in streams:
            # Get the first available stream.
            logger.debug("Checking stream: ID=%s, Name=%s", stream.id, stream.name)

            # Retrieve the M3U account associated with the stream.
            m3u_account = stream.m3u_account
            logger.debug("Stream M3U account ID=%s, Name=%s", m3u_account.id, m3u_account.name)

            # Use the custom URL if available; otherwise, use the standard URL.
            input_url = stream.url
            logger.debug("Input URL: %s", input_url)

            # Determine which profile we can use.
            m3u_profiles = m3u_account.profiles.all()
            default_profile = next((obj for obj in m3u_profiles if obj.is_default), None)
            profiles = [obj for obj in m3u_profiles if not obj.is_default]

            # -- Loop through profiles and pick the first active one --
            for profile in [default_profile] + profiles:
                logger.debug(f'Checking profile {profile.name}...')
                if not profile.is_active:
                    logger.debug('Profile is not active, skipping.')
                    continue

                logger.debug(f'Profile has a max streams of {profile.max_streams}, checking if any are available')
                stream_index = 0
                max_streams = profile.max_streams
                if max_streams == 0:
                    max_streams = 999999 # maybe a better way than just hardcoding a high number...
                while stream_index < max_streams:
                    stream_index += 1

                    lock_key = f"lock:{profile.id}:{stream_index}"
                    persistent_lock = PersistentLock(redis_client, lock_key, lock_timeout=120)
                    logger.debug(f'Attempting to acquire lock: {lock_key}')

                    if not persistent_lock.acquire():
                        logger.error(f"Could not acquire persistent lock for profile {profile.id} index {stream_index}, currently in use.")
                        persistent_lock = None
                        continue

                    break

                if persistent_lock is not None:
                    logger.debug(f'Successfully acquired lock: {lock_key}')
                    active_profile = M3UAccountProfile.objects.get(id=profile.id)
                    break

            if active_profile is None or persistent_lock is None:
                logger.exception("No available profiles for the stream")
                continue

            logger.debug(f"Found available stream profile: stream={stream.name}, profile={profile.name}")
            break

        if not active_profile:
            logger.exception("No available streams for this channel")
            return HttpResponseServerError("No available streams for this channel")

        logger.debug(f"Using M3U profile ID={active_profile.id} (ignoring viewer count limits)")
        # Prepare the pattern replacement.
        logger.debug("Executing the following pattern replacement:")
        logger.debug(f"  search: {active_profile.search_pattern}")
        safe_replace_pattern = re.sub(r'\$(\d+)', r'\\\1', active_profile.replace_pattern)
        logger.debug(f"  replace: {active_profile.replace_pattern}")
        logger.debug(f"  safe replace: {safe_replace_pattern}")
        stream_url = re.sub(active_profile.search_pattern, safe_replace_pattern, input_url)
        logger.debug(f"Generated stream url: {stream_url}")

        # Get the stream profile set on the channel.
        stream_profile = channel.stream_profile
        if not stream_profile:
            logger.error("No stream profile set for channel ID=%s, using default", channel.id)
            stream_profile = StreamProfile.objects.get(id=CoreSettings.objects.get(key="default-stream-profile").value)

        logger.debug("Stream profile used: %s", stream_profile.name)

        # Determine the user agent to use.
        user_agent = stream_profile.user_agent or getattr(settings, "DEFAULT_USER_AGENT", "Mozilla/5.0")
        logger.debug("User agent: %s", user_agent)

        # Substitute placeholders in the parameters template.
        parameters = stream_profile.parameters.format(userAgent=user_agent, streamUrl=stream_url)
        logger.debug("Formatted parameters: %s", parameters)

        # Build the final command.
        cmd = [stream_profile.command] + parameters.split()
        logger.debug("Executing command: %s", cmd)

        try:
            # Start the streaming process.
            process = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
        except Exception as e:
            persistent_lock.release()  # Ensure the lock is released on error.
            logger.exception("Error starting stream for channel ID=%s", stream_id)
            return HttpResponseServerError(f"Error starting stream: {e}")

    except Exception as e:
        logger.exception("Error preparing stream for channel ID=%s", stream_id)
        return HttpResponseServerError(f"Error preparing stream: {e}")

    def stream_generator(proc, s, persistent_lock):
        try:
            while True:
                chunk = proc.stdout.read(8192)
                if not chunk:
                    break
                yield chunk
        finally:
            try:
                proc.terminate()
                logger.debug("Streaming process terminated for stream ID=%s", s.id)
            except Exception as e:
                logger.error("Error terminating process for stream ID=%s: %s", s.id, e)
            persistent_lock.release()
            logger.debug("Persistent lock released for channel ID=%s", channel.id)

        return StreamingHttpResponse(
            stream_generator(process, stream, persistent_lock),
            content_type="video/MP2T"
        )
