#!/usr/bin/env python3
"""A captured thumbnail has to be a picture of something.

Run against a locally running backend:

    backend/main.py &
    .venv/bin/python tests/smoke_poster_black.py

Two ways a card ends up a black box rather than a picture, both of which the
capture used to keep for the life of the item -- the only test a frame had to
pass was being a few hundred bytes long:

  * the frame at the mark is black. A video that opens on a fade, or whose
    length nobody will say (so there is no quarter mark to seek to and the
    opening frame is all there is), hands over exactly that.
  * the element decoded nothing. Drawing one that has not presented a frame
    gives an untouched canvas, which is a pure black JPEG about 1.6 KB long.

The fixture is black for its first three and a half seconds -- past the quarter
mark a capture aims for -- and flat orange after, so the picture on the card
says whether anything looked at what it was keeping.
"""
import json
import os
import re
import sys
from playwright.sync_api import sync_playwright

CLIP = os.path.join(os.path.dirname(__file__), "fixtures", "dark.mp4")

BASE = "http://127.0.0.1:5000/"
SERVER = "https://fixture.test"
CHANNEL = "clips"
CACHE_KEY = "posterCache"

STATUS = {
    "online": True,
    "channels": [{
        "id": CHANNEL,
        "name": "Fixture Clips",
        "description": "A channel that only exists for this test.",
        "options": [],
    }],
}

# Saved with the thumbnail it had at the time, and with nothing known about how
# long it is -- which is the state the item this test comes from is in.
SEED = """([server, channel]) => {
    localStorage.setItem('config', JSON.stringify({ servers: [{ [server]: {} }] }));
    localStorage.setItem('preferences', JSON.stringify({ [server]: { channelId: channel } }));
    localStorage.removeItem('session');
    localStorage.removeItem('posterCache');
    Object.keys(localStorage).forEach((k) => {
        if (k.indexOf('posterCache:') === 0) localStorage.removeItem(k);
    });
    localStorage.setItem('favorites', JSON.stringify([{
        key: 'vid-0',
        id: 'vid-0',
        url: 'https://fixture.test/v0.mp4',
        title: 'kept clip 0',
        thumb: 'https://pictures.fixture.test/gone/0.jpg',
        channel: channel,
        uploader: '',
        duration: 0,
        isLive: false,
        favoriteDate: new Date().toISOString()
    }]));
}"""

CAPTURED = """(id) => {
    const card = document.querySelector(`.video-card[data-video-id="${id}"]`);
    if (!card) return false;
    const img = card.querySelector('.video-thumb img');
    return (img.getAttribute('src') || '').indexOf('data:image/jpeg') === 0;
}"""

# What the card is showing, measured: the brightest sample in it and the
# average, which is all it takes to tell a picture from a black box.
LIGHT = """(id) => new Promise((resolve) => {
    const card = document.querySelector(`.video-card[data-video-id="${id}"]`);
    const img = card ? card.querySelector('.video-thumb img') : null;
    const src = img ? (img.getAttribute('src') || '') : '';
    if (!src) { resolve(null); return; }
    const probe = new Image();
    probe.onload = () => {
        const canvas = document.createElement('canvas');
        canvas.width = probe.naturalWidth;
        canvas.height = probe.naturalHeight;
        const ctx = canvas.getContext('2d');
        ctx.drawImage(probe, 0, 0);
        const px = ctx.getImageData(0, 0, canvas.width, canvas.height).data;
        let sum = 0, brightest = 0;
        for (let i = 0; i < px.length; i += 4) {
            const value = Math.max(px[i], px[i + 1], px[i + 2]);
            sum += value;
            if (value > brightest) brightest = value;
        }
        resolve({ brightest, mean: Math.round(sum / (px.length / 4)),
                  bytes: src.length, w: canvas.width, h: canvas.height });
    };
    probe.onerror = () => resolve(null);
    probe.src = src;
})"""

CACHE = """() => JSON.parse(localStorage.getItem('posterCache') || '[]')"""

FORGET = """() => {
    localStorage.removeItem('posterCache');
    Object.keys(localStorage).forEach((k) => {
        if (k.indexOf('posterCache:') === 0) localStorage.removeItem(k);
    });
}"""

# The item this test comes from has no duration: the extractor reports none and
# the favorite kept a zero. Where the browser can't supply one either, there is
# no quarter mark to seek to -- and the frame the element decodes on its own is
# the opening one, which is the frame this clip is black for.
NO_DURATION = """
Object.defineProperty(HTMLVideoElement.prototype, 'duration', {
    configurable: true,
    get: function() { return NaN; }
});
"""

# What the version before this kept: an untouched canvas, JPEG'd. Written over
# the picture in the cache, with the "this was looked at" marker taken off the
# index entry, which is exactly the state those sessions left behind.
POISON = """() => {
    const canvas = document.createElement('canvas');
    canvas.width = 360;
    canvas.height = 203;
    const black = canvas.toDataURL('image/jpeg', 0.72);
    const index = JSON.parse(localStorage.getItem('posterCache') || '[]');
    index.forEach((entry) => {
        delete entry.v;
        entry.n = black.length;
        localStorage.setItem(`posterCache:${entry.k}`, black);
    });
    localStorage.setItem('posterCache', JSON.stringify(index));
    return { black: black, entries: index.length };
}"""


class Checks:
    def __init__(self):
        self.failed = 0

    def ok(self, label, condition, detail=""):
        mark = "PASS" if condition else "FAIL"
        if not condition:
            self.failed += 1
        print(f"  [{mark}] {label}" + (f" -- {detail}" if detail and not condition else ""))


def items():
    return [{"id": "vid-0", "title": "clip 0",
             "url": "https://fixture.test/v0.mp4",
             "thumb": "https://pictures.fixture.test/gone/0.jpg",
             "channel": CHANNEL, "duration": 0, "isLive": False, "tags": []}]


def main():
    c = Checks()
    streamed = []

    with sync_playwright() as p:
        browser = p.chromium.launch(args=[
            "--no-sandbox", "--disable-dev-shm-usage", "--disable-gpu",
            "--autoplay-policy=no-user-gesture-required",
            "--renderer-process-limit=1", "--js-flags=--max-old-space-size=512",
        ])
        page = browser.new_page(viewport={"width": 1180, "height": 920})
        crashes = []
        page.on("pageerror", lambda e: crashes.append(str(e)))

        page.route("**/api/status", lambda route: route.fulfill(
            status=200, content_type="application/json", body=json.dumps(STATUS)))
        page.route("**/api/videos", lambda route: route.fulfill(
            status=200, content_type="application/json",
            body=json.dumps({"items": items(), "pageInfo": {"hasNextPage": False}})))
        page.route(re.compile(r"pictures\.fixture\.test"),
                   lambda route: route.fulfill(status=404, body=""))
        page.route(re.compile(r"/api/image"),
                   lambda route: route.fulfill(status=404, body=""))
        page.route(re.compile(r"/api/poster"), lambda route: route.fulfill(
            status=200, content_type="application/json", body=json.dumps({"thumb": ""})))

        # Byte ranges and all: a response a browser cannot seek in is one it
        # will not take a frame out of the middle of.
        def stream(route):
            streamed.append(route.request.url)
            body = open(CLIP, "rb").read()
            span = re.match(r"bytes=(\d+)-(\d*)", route.request.headers.get("range") or "")
            if span:
                start = int(span.group(1))
                end = int(span.group(2)) if span.group(2) else len(body) - 1
                chunk = body[start:end + 1]
                route.fulfill(status=206, body=chunk, headers={
                    "Content-Type": "video/mp4",
                    "Accept-Ranges": "bytes",
                    "Content-Range": f"bytes {start}-{end}/{len(body)}",
                    "Content-Length": str(len(chunk)),
                })
                return
            route.fulfill(status=200, body=body, headers={
                "Content-Type": "video/mp4",
                "Accept-Ranges": "bytes",
                "Content-Length": str(len(body)),
            })
        page.route(re.compile(r"/api/stream"), stream)

        page.goto(BASE, wait_until="domcontentloaded")
        page.evaluate(SEED, [SERVER, CHANNEL])
        page.goto(BASE, wait_until="load")
        page.wait_for_selector(".video-card", timeout=30000)

        print("\nthe quarter mark of this clip is black")
        page.wait_for_function(CAPTURED, arg="vid-0", timeout=60000)
        shot = page.evaluate(LIGHT, "vid-0")
        c.ok("the card ended up with a captured picture", shot is not None, str(shot))
        c.ok("and it is not a black box",
             shot and shot["brightest"] > 40, str(shot))
        c.ok("it is the orange the clip shows past its lead-in",
             shot and shot["mean"] > 60, str(shot))
        c.ok("at card width, so it is a thumbnail and not a frame of video",
             shot and shot["w"] == 360, str(shot))

        print("\nand the picture it kept says it was looked at")
        cached = page.evaluate(CACHE)
        c.ok("one picture is in the cache", len(cached) == 1, str(cached))
        c.ok("marked as checked", cached and cached[0].get("v") == 1, str(cached))

        print("\na black picture kept by an earlier version is replaced")
        poisoned = page.evaluate(POISON)
        c.ok("the cache now holds what that version would have kept",
             poisoned["entries"] == 1, str(poisoned["entries"]))
        streamed.clear()
        page.goto(BASE, wait_until="load")
        page.wait_for_selector(".video-card", timeout=30000)
        # A flat frame weighs about what a blank one does -- both are a single
        # colour -- so what says the card moved on is the picture itself.
        page.wait_for_function(
            """([id, black]) => {
                const card = document.querySelector(`.video-card[data-video-id="${id}"]`);
                const img = card && card.querySelector('.video-thumb img');
                const src = img ? (img.getAttribute('src') || '') : '';
                // The listed picture is on the card while the ladder walks
                // down it, so what counts is a captured picture that is not
                // the one that was there.
                return src.indexOf('data:image/jpeg') === 0 && src !== black;
            }""", arg=["vid-0", poisoned["black"]], timeout=60000)
        healed = page.evaluate(LIGHT, "vid-0")
        c.ok("the card shows a picture again", healed is not None, str(healed))
        c.ok("not the black one it was given", healed and healed["brightest"] > 40, str(healed))
        c.ok("taken from the video, which was fetched for it",
             any("/api/stream" in url for url in streamed), str(streamed[:2]))
        kept = page.evaluate(CACHE)
        c.ok("and the replacement is what is kept now",
             len(kept) == 1 and kept[0].get("v") == 1, str(kept))

        print("\nand it is not measured a second time")
        streamed.clear()
        page.goto(BASE, wait_until="load")
        page.wait_for_selector(".video-card", timeout=30000)
        page.wait_for_timeout(2000)
        again = page.evaluate(LIGHT, "vid-0")
        c.ok("the kept picture is on the card straight away",
             again and again["brightest"] > 40, str(again))
        c.ok("without going back to the video", streamed == [], str(streamed))

        print("\nand a clip nobody will say the length of is not left on frame one")
        page.evaluate(FORGET)
        page.add_init_script(NO_DURATION)
        streamed.clear()
        page.goto(BASE, wait_until="load")
        page.wait_for_selector(".video-card", timeout=30000)
        c.ok("the browser gives no length to go by",
             page.evaluate("() => String(document.createElement('video').duration)") == 'NaN')
        page.wait_for_function(CAPTURED, arg="vid-0", timeout=60000)
        blind = page.evaluate(LIGHT, "vid-0")
        c.ok("a frame came out of the video anyway", blind is not None, str(blind))
        c.ok("and it is not the black one it opens on",
             blind and blind["brightest"] > 40, str(blind))

        c.ok("nothing threw along the way", not crashes, str(crashes[:2]))
        browser.close()

    print(f"\n{'OK' if not c.failed else 'FAILED'}: {c.failed} check(s) failed")
    return 1 if c.failed else 0


sys.exit(main())