#!/usr/bin/env python3
import aioboto3
import aiohttp
import asyncio
import cv2
import hashlib
import io
import json
import numpy as np
import os
import pymongo
import signal
import sys
import botocore.exceptions
from datetime import datetime, timedelta
from jpeg2dct.numpy import loads
from math import inf
from motor.motor_asyncio import AsyncIOMotorClient
from prometheus_client import Counter, Gauge, Histogram
from pymongo import ReturnDocument
from sanic import Sanic, response
from sanic_json_logging import setup_json_logging
from sanic.log import logger
from sanic_prometheus import monitor
from sanic.response import stream
from time import time
from urllib.parse import urlparse

_, target = sys.argv

# Override basic auth password from env var
basic_auth_password = os.getenv("BASIC_AUTH_PASSWORD")
if basic_auth_password:
    o = urlparse(target)
    netloc = o.netloc
    username = ""
    if "@" in netloc:
        username, netloc = o.netloc.split("@", 1)
        if ":" in username:
            username, _ = username.split(":")
    target = o._replace(netloc="%s:%s@%s" % (username, basic_auth_password, netloc)).geturl()

AWS_ACCESS_KEY_ID = os.environ["AWS_ACCESS_KEY_ID"]
AWS_SECRET_ACCESS_KEY = os.environ["AWS_SECRET_ACCESS_KEY"]

S3_ENDPOINT_URL = os.environ["S3_ENDPOINT_URL"]
S3_BUCKET_NAME = os.getenv("S3_BUCKET_NAME", "camdetect")
MONGO_URI = os.getenv("MONGO_URI", "mongodb://127.0.0.1:27017/default")
MONGO_COLLECTION = os.getenv("MONGO_COLLECTION", "eventlog")
SOURCE_NAME = os.environ["SOURCE_NAME"]
SLIDE_WINDOW = 4
DCT_BLOCK_SIZE = 8
UPLOAD_FRAMESKIP = 3
CLOCK_SKEW_TOLERANCE = timedelta(seconds=3)

# Percentage of blocks active to consider movement in whole frame
THRESHOLD_RATIO = int(os.getenv("THRESHOLD_RATIO", "5"))

# Days to keep events
TTL_DAYS = int(os.getenv("TTL_DAYS", "3"))

CHUNK_BOUNDARY = b"\n--frame\nContent-Type: image/jpeg\n\n"

hist_active_blocks_ratio = Histogram(
    "camtiler_active_blocks_ratio",
    "Ratio of active DCT blocks",
    ["roi"],
    buckets=(0.01, 0.02, 0.05, 0.1, 0.5, inf))
hist_processing_latency = Histogram(
    "camtiler_frame_processing_latency_seconds",
    "Frame processing latency",
    buckets=(0.01, 0.05, 0.1, 0.5, 1, inf))
hist_upload_latency = Histogram(
    "camtiler_frame_upload_latency_seconds",
    "Frame processing latency",
    buckets=(0.1, 0.5, 1, 5, 10, inf))
counter_events = Counter(
    "camtiler_events",
    "Count of successfully processed events")
counter_frames = Counter(
    "camtiler_frames",
    "Count of frames",
    ["stage"])
counter_dropped_frames = Counter(
    "camtiler_dropped_frames",
    "Frames that were dropped due to one of queues being full",
    ["stage"])
counter_discarded_bytes = Counter(
    "camtiler_discarded_bytes",
    "Bytes that were not not handled or part of actual JPEG frames")
counter_receive_bytes = Counter(
    "counter_receive_bytes",
    "Bytes received over HTTP stream")
counter_transmit_bytes = Counter(
    "camtiler_transmit_bytes",
    "Bytes transmitted over HTTP streams")
counter_receive_frames = Counter(
    "camtiler_receive_frames",
    "Frames received from upstream")
counter_transmit_frames = Counter(
    "camtiler_transmit_frames",
    "Frames transmitted to downstream consumers")
counter_emitted_events = Counter(
    "camtiler_emitted_events",
    "Events emitted")
counter_receive_chunks = Counter(
    "camtiler_receive_chunks",
    "HTTP chunks received")
counter_errors = Counter(
    "camtiler_errors",
    "Upstream connection errors",
    ["stage", "exception"])
gauge_last_frame = Gauge(
    "camtiler_last_frame_timestamp_seconds",
    "Timestamp of last frame",
    ["stage"])
gauge_queue_frames = Gauge(
    "camtiler_queue_frames",
    "Numer of frames in a queue",
    ["stage"])
gauge_build_info = Gauge(
    "docker_build_info",
    "Build info",
    ["git_commit", "git_commit_timestamp"])

gauge_build_info.labels(
    os.getenv("GIT_COMMIT", "null"),
    os.getenv("GIT_COMMIT_TIMESTAMP", "null")).set(1)

# Reset some gauges
gauge_queue_frames.labels("download").set(0)
gauge_queue_frames.labels("hold").set(0)
gauge_queue_frames.labels("upload").set(0)
counter_frames.labels("motion").inc(0)
counter_frames.labels("downloaded").inc(0)

assert SLIDE_WINDOW <= 8  # This is 256 frames which should be enough


async def upload(bucket, blob: bytes, thumb: bytes, event_id):
    """
    Upload single frame to S3 bucket
    """

    # Generate S3 path based on the JPEG blob SHA512 digest
    fp = hashlib.sha512(blob).hexdigest()
    path = "%s/%s.jpg" % (fp[:4], fp[4:])

    try:
        await bucket.upload_fileobj(io.BytesIO(thumb), "thumb/%s" % path)
        await bucket.upload_fileobj(io.BytesIO(blob), path)
    except (botocore.exceptions.ClientError, botocore.exceptions.BotoCoreError) as e:
        j = "%s.%s" % (e.__class__.__module__, e.__class__.__name__)
        counter_errors.labels("upload", j).inc()

    # Add screenshot path to the event
    app.ctx.coll.update_one({
        "_id": event_id
    }, {
        "$addToSet": {
            "screenshots": path,
        }
    })

    counter_frames.labels("stored").inc()
    now = datetime.utcnow()
    gauge_last_frame.labels("upload").set(now.timestamp())
    # TODO: Handle 16MB maximum document size


async def uploader(queue):
    """
    Uploader task grabs JPEG blobs from upload queue and uploads them to S3
    """
    session = aioboto3.Session()
    async with session.resource("s3",
                                aws_access_key_id=AWS_ACCESS_KEY_ID,
                                aws_secret_access_key=AWS_SECRET_ACCESS_KEY,
                                endpoint_url=S3_ENDPOINT_URL) as s3:
        bucket = await s3.Bucket(S3_BUCKET_NAME)
        while True:
            dt, blob, thumb, event_id = await queue.get()
            gauge_queue_frames.labels("upload").set(queue.qsize())
            await upload(bucket, blob, thumb, event_id)
            counter_frames.labels("uploaded").inc()
            hist_upload_latency.observe(
                (datetime.utcnow() - dt).total_seconds())


class ReferenceFrame():
    """
    ReferenceFrame keeps last 2 ^ size frames to infer the background scene
    compared to which motion is detected

    This is pretty much what background subtractor does in OpenCV,
    only difference is that we want have better performance instead of
    accuracy
    """
    class NotEnoughFrames(Exception):
        pass

    def __init__(self, size=SLIDE_WINDOW):
        self.y = []
        self.cumulative = None
        self.size = size

    def put(self, y):
        if self.cumulative is None:
            self.cumulative = np.copy(y)
        else:
            self.cumulative += y
        self.y.append(y)
        if len(self.y) > 2 ** self.size:
            self.cumulative -= self.y[0]
            self.y = self.y[1:]

    def get(self):
        if len(self.y) == 2 ** self.size:
            return self.cumulative >> SLIDE_WINDOW
        else:
            raise self.NotEnoughFrames()


async def motion_detector(reference_frame, download_queue, upload_queue):
    """
    Motion detector grabs JPEG blobs and Y channel coefficients
    from download queue, performs motion detection and pushes relevant
    JPEG blobs to upload queue going to S3
    """
    event_id = None
    differing_blocks = []
    uploads_skipped = 0

    # Hold queue keeps frames that we have before motion event start timestamp
    hold_queue = asyncio.Queue(2 ** SLIDE_WINDOW)

    while True:
        dt, blob, dct, thumb = await download_queue.get()
        gauge_queue_frames.labels("download").set(download_queue.qsize())
        app.ctx.last_frame, app.ctx.dct = blob, dct

        # Signal /bypass and /debug handlers about new frame
        app.ctx.event_frame.set()
        app.ctx.event_frame.clear()

        # Separate most significant luma value for each DCT (8x8 pixel) block
        y = np.int16(dct[0][:, :, 0])

        reference_frame.put(y)
        try:
            app.ctx.mask = cv2.inRange(cv2.absdiff(y,
                                       reference_frame.get()), 50, 65535)
        except ReferenceFrame.NotEnoughFrames:
            app.ctx.mask = None
            motion_detected = False
        else:
            # Implement dumb Kalman filter
            active_blocks = np.count_nonzero(app.ctx.mask)
            differing_blocks.append(active_blocks)
            differing_blocks[:] = differing_blocks[-10:]
            total_blocks = app.ctx.mask.shape[0] * app.ctx.mask.shape[1]
            threshold_blocks = THRESHOLD_RATIO * total_blocks / 100
            average_blocks = sum(differing_blocks) / len(differing_blocks)
            hist_active_blocks_ratio.labels("main").observe(active_blocks / total_blocks)
            motion_detected = average_blocks > threshold_blocks

        now = datetime.utcnow()
        gauge_last_frame.labels("processed").set(now.timestamp())
        hist_processing_latency.observe((now - dt).total_seconds())

        # Propagate SIGUSR1 signal handler
        if app.ctx.manual_trigger:
            logger.info("Manually triggering event via SIGUSR1")
            motion_detected = True
            app.ctx.manual_trigger = False

        # Handle event start
        if motion_detected and not event_id:
            result = await app.ctx.coll.find_one_and_update({
                "@timestamp": {
                    "$lte": dt + CLOCK_SKEW_TOLERANCE,
                    "$gte": dt - CLOCK_SKEW_TOLERANCE,
                },
                "source": SOURCE_NAME,
            }, {
                "$setOnInsert": {
                    "@timestamp": dt,
                    "source": SOURCE_NAME,
                    "event": "motion-detected",
                    "started": dt,
                    "finished": dt + timedelta(minutes=2),
                    "component": "camdetect",
                    "screenshots": [],
                    "action": "event",
                }
            }, upsert=True, return_document=ReturnDocument.AFTER)
            app.ctx.event_id = event_id = result["_id"]

        # Handle buffering frames prior event start
        if hold_queue.full():
            await hold_queue.get()
        hold_queue.put_nowait((blob, thumb))
        gauge_queue_frames.labels("hold").set(hold_queue.qsize())

        # Handle image upload
        if motion_detected and event_id:
            counter_frames.labels("motion").inc()
            while True:
                if not uploads_skipped:
                    uploads_skipped = UPLOAD_FRAMESKIP
                else:
                    uploads_skipped -= 1
                    continue

                # Drain queue of frames prior event start
                try:
                    blob, thumb = hold_queue.get_nowait()
                except asyncio.QueueEmpty:
                    break

                try:
                    # Push JPEG blob into upload queue
                    upload_queue.put_nowait((dt, blob, thumb, event_id))
                except asyncio.QueueFull:
                    counter_dropped_frames.labels("upload").inc()
                gauge_queue_frames.labels("upload").set(upload_queue.qsize())

        # Handle event end
        if not motion_detected and event_id:
            app.ctx.coll.update_one({
                "_id": event_id
            }, {
                "$set": {
                    "finished": dt,
                }
            })
            app.ctx.event_id = event_id = None
            counter_events.inc()


def generate_thumbnail(dct):
    """
    This is highly efficient and highly inaccurate function to generate
    thumbnail based purely on JPEG coefficients
    """
    y, cr, cb = dct

    # Determine aspect ratio and minimum dimension for cropping
    ar = y.shape[0] < y.shape[1]
    dm = (y.shape[0] if ar else y.shape[1]) & 0xfffffff8

    # Determine cropping slices to make it square
    jl = ((y.shape[1] >> 1) - (dm >> 1) if ar else 0)
    jt = (0 if ar else (y.shape[0] >> 1) - (dm >> 1))
    jr = jl + dm
    jb = jt + dm

    # Do the actual crop
    ty = y[jt:jb, jl:jr, 0]
    tb = cb[jt >> 1:jb >> 1, jl >> 1:jr >> 1, 0]
    tr = cr[jt >> 1:jb >> 1, jl >> 1:jr >> 1, 0]

    # Upsample chroma, dummy convert first coeff and stack all channels
    m = np.dstack((
        np.array((ty >> 3) + 127, dtype=np.uint8),
        np.array(
            (tb.repeat(2, 1).repeat(2, 0) >> 3) + 127, dtype=np.uint8)[:dm],
        np.array(
            (tr.repeat(2, 1).repeat(2, 0) >> 3) + 127, dtype=np.uint8)[:dm]))
    _, jpeg = cv2.imencode(".jpg",
                           cv2.cvtColor(m, cv2.COLOR_YCrCb2BGR),
                           (cv2.IMWRITE_JPEG_QUALITY, 80))
    return jpeg


async def download(resp, queue):
    """
    This coroutine iterates over HTTP connection chunks
    assembling the original JPEG blobs and decodes the
    DCT coefficients of the frames
    """
    buf = b""
    logger.info("Upstream connection opened with status: %d", resp.status)
    async for data, end_of_http_chunk in resp.content.iter_chunks():
        counter_receive_bytes.inc(len(data))
        if end_of_http_chunk:
            counter_receive_chunks.inc()
        if buf:
            # seek end
            marker = data.find(b"\xff\xd9")
            if marker < 0:
                buf += data
                continue
            else:
                # Assemble JPEG blob
                blob = buf + data[:marker + 2]

                # Parse DCT coefficients
                try:
                    dct = loads(blob)
                except RuntimeError:
                    counter_frames.labels("corrupted").inc()
                else:
                    now = datetime.utcnow()
                    gauge_last_frame.labels("download").set(now.timestamp())
                    try:
                        queue.put_nowait((
                            now,
                            blob,
                            dct,
                            generate_thumbnail(dct)))
                    except asyncio.QueueFull:
                        counter_dropped_frames.labels("download").inc()
                    else:
                        counter_frames.labels("downloaded").inc()
                    gauge_queue_frames.labels("download").set(queue.qsize())
                data = data[marker + 2:]
                buf = b""
                counter_receive_frames.inc()

        # seek begin
        marker = data.rfind(b"\xff\xd8")
        if marker >= 0:
            buf = data[marker:]
        else:
            counter_discarded_bytes.inc(len(data))


async def downloader(queue: asyncio.Queue):
    """
    Downloader task connects to MJPEG source and
    pushes the JPEG frames to download queue
    """
    while True:
        to = aiohttp.ClientTimeout(connect=5, sock_read=2)
        async with aiohttp.ClientSession(timeout=to) as session:
            logger.info("Opening connection to %s", target)
            try:
                async with session.get(target) as resp:
                    await download(resp, queue)
            except (aiohttp.ClientError, asyncio.exceptions.TimeoutError) as e:
                j = "%s.%s" % (e.__class__.__module__, e.__class__.__name__)
                logger.info("Caught exception %s", j)
                counter_errors.labels("download", j).inc()
        await asyncio.sleep(1)

app = Sanic("camdetect")
setup_json_logging(app)


@app.route("/bypass")
async def bypass_stream_wrapper(request):
    # Desired frame interval, by default 500ms
    interval = float(request.args.get("interval", 500)) / 1000.0

    async def stream_camera(response):
        ts = 0
        while True:
            while True:
                await app.ctx.event_frame.wait()
                if time() > ts + interval:
                    break
            ts = time()
            data = CHUNK_BOUNDARY + app.ctx.last_frame
            await response.write(data)
            counter_transmit_bytes.inc(len(data))
            counter_transmit_frames.inc()
    return response.stream(
        stream_camera,
        content_type="multipart/x-mixed-replace; boundary=frame")


@app.route("/debug")
async def stream_wrapper(request):
    async def stream_camera(response):
        while True:
            await app.ctx.event_frame.wait()

            # Parse JPEG blob
            arr = np.frombuffer(app.ctx.last_frame, dtype=np.uint8)
            img = cv2.imdecode(arr, cv2.IMREAD_UNCHANGED)

            # Highlight green or red channel depending on whether
            # motion event is in progress or not
            channel = 2 if app.ctx.event_id else 1
            if app.ctx.mask is not None:
                for y in range(0, app.ctx.mask.shape[0]):
                    for x in range(0, app.ctx.mask.shape[1]):
                        if app.ctx.mask[y][x] > 0:
                            img[y * DCT_BLOCK_SIZE:(y + 1) * DCT_BLOCK_SIZE,
                                x * DCT_BLOCK_SIZE:(x + 1) * DCT_BLOCK_SIZE,
                                channel] = 255

            # Compress modified frame as JPEG frame
            _, jpeg = cv2.imencode(".jpg", img, (cv2.IMWRITE_JPEG_QUALITY, 80))
            data = CHUNK_BOUNDARY + jpeg.tobytes()
            await response.write(data)
            counter_transmit_bytes.inc(len(data))
            counter_transmit_frames.inc()

    # Transmit as chunked MJPEG stream
    return response.stream(
        stream_camera,
        content_type="multipart/x-mixed-replace; boundary=frame"
    )


@app.route("/readyz")
async def ready_check(request):
    logger.info("Testing if Mongo is accessible")
    try:
        async for i in app.ctx.coll.find().limit(1):
            break
    except pymongo.errors.ServerSelectionTimeoutError:
        return response.text("MongoDB server selection timeout", status=503)

    session = aioboto3.Session()
    logger.info("Testing if S3 is writable")
    async with session.resource("s3",
                                aws_access_key_id=AWS_ACCESS_KEY_ID,
                                aws_secret_access_key=AWS_SECRET_ACCESS_KEY,
                                endpoint_url=S3_ENDPOINT_URL) as s3:
        bucket = await s3.Bucket(S3_BUCKET_NAME)
        await bucket.upload_fileobj(io.BytesIO(b"test"), "test")
    return response.text("OK")

    print("Checking if there are any frames received")
    if app.ctx.mask is None:
        return response.text("Not enough frames", status=503)


@app.route("/healthz")
async def health_check(request):
    if app.ctx.mask is None:
        return response.text("Not enough frames", status=503)


@app.route("/event")
async def wrapper_stream_event(request):
    async def stream_event(response):
        while True:
            await app.ctx.event_frame.wait()
            if app.ctx.mask is not None:
                continue
            s = "data: " + json.dumps(app.ctx.mask.tolist()) + "\r\n\r\n"
            await response.write(s.encode())
            counter_emitted_events.inc()
    return stream(stream_event, content_type="text/event-stream")


def handler(signum, frame):
    # SIGUSR1 handler for manually triggering an event
    app.ctx.manual_trigger = True


@app.listener("before_server_start")
async def setup_db(app, loop):
    app.ctx.mask = None
    app.ctx.db = AsyncIOMotorClient(MONGO_URI).get_default_database()
    app.ctx.coll = app.ctx.db[MONGO_COLLECTION]
    app.ctx.coll.create_index(
        "@timestamp", expireAfterSeconds=TTL_DAYS * 60 * 60 * 24)
    app.ctx.coll.create_index([
        ("source", pymongo.ASCENDING),
        ("@timestamp", pymongo.ASCENDING)], unique=True)
    app.ctx.last_frame = None
    app.ctx.event_frame = asyncio.Event()
    app.ctx.event_id = None
    app.ctx.manual_trigger = False
    signal.signal(signal.SIGUSR1, handler)

    # Set up processing pipeline
    download_queue = asyncio.Queue(50)
    upload_queue = asyncio.Queue(50)
    asyncio.create_task(uploader(
        upload_queue))
    asyncio.create_task(downloader(
        download_queue))
    asyncio.create_task(motion_detector(
        ReferenceFrame(),
        download_queue,
        upload_queue))


monitor(app).expose_endpoint()

app.run(host="0.0.0.0",
        port=5000,
        debug=bool(os.getenv("DEBUG", 0)))