"""
The sign-in page with the welcome text beside it, measured in a browser.

Two columns on a desktop, one on a phone with the form first, and nothing wider
than the screen at any width. The text is the English catalogue's, at its real
length: a fixture shorter than the real copy measures the fixture.

The markup is `LoginPage` and `WelcomePitch` as `auth-page.js` renders them,
inside the shell `app.js` puts every page in. What is under test is the
stylesheet, which is served as it ships.
"""

import json
import re
import shutil
import subprocess
import textwrap
from pathlib import Path

import pytest

HARNESS = Path(__file__).parent / "harness" / "layout_probe.py"
STATIC = Path(__file__).resolve().parents[1] / "src" / "meshbay_hub" / "static"

pytestmark = pytest.mark.skipif(
    shutil.which("google-chrome") is None or not (STATIC / "style.css").exists(),
    reason="Chrome or the SPA stylesheet is not available")


def _en(key: str) -> str:
    source = (STATIC / "locales" / "en.js").read_text(encoding="utf-8")
    m = re.search(rf"^\s*'{re.escape(key)}': '([^']*)',$", source, re.M)
    assert m, f"{key} is missing from en.js"
    return m.group(1)


def _items(*keys: str) -> str:
    return "".join(f"<li><span>{_en(k)}</span></li>" for k in keys)


def _page() -> str:
    li = _items
    return textwrap.dedent(f"""
      <nav class="nav"><div class="nav-left"><a class="nav-brand" href="#/">MeshBay</a></div>
        <div class="nav-right"><button class="nav-btn">Login</button></div></nav>
      <div class="layout"><main class="main"><div class="page-center"><div class="welcome">
        <div class="card login-card"><h2>Login</h2>
          <form><input type="text" placeholder="Username" />
            <input type="password" placeholder="Password" /><button>Login</button></form>
          <div class="login-footer">No account? <a href="#/register">Register</a></div>
          <div class="login-footer"><a href="#/reset">Forgot your passphrase?</a></div>
        </div>
        <section class="welcome-pitch">
          <h1 class="welcome-title">{_en('welcome.title')}</h1>
          <p class="welcome-lead">{_en('welcome.lead')}</p>
          <ul class="welcome-apps">{li('welcome.app_chat', 'welcome.app_photos',
              'welcome.app_media', 'welcome.app_video', 'welcome.app_music')}</ul>
          <p>{_en('welcome.groups')}</p>
          <p class="welcome-e2e"><span>{_en('welcome.e2e')}</span></p>
          <h2 class="welcome-h">{_en('welcome.uses_title')}</h2>
          <ul class="welcome-uses">{li('welcome.use_chat', 'welcome.use_photos',
              'welcome.use_media', 'welcome.use_apps')}</ul>
          <div class="welcome-hub"><h2 class="welcome-h">{_en('welcome.hub_title')}</h2>
            <p>{_en('welcome.hub_body')}</p>
            <p class="welcome-hub-never">{_en('welcome.hub_never')}</p>
            <ul class="welcome-never">{li('welcome.never_transit', 'welcome.never_stored',
                'welcome.never_e2e')}</ul>
            <p class="welcome-hub-free">{_en('welcome.hub_free')}</p></div>
          <div class="welcome-links"><a class="welcome-cta" href="#">{_en('welcome.download')}</a>
            <a class="welcome-legal" href="#">{_en('welcome.legal')}</a></div>
        </section>
      </div></div></main></div>
    """)


PHONES = [320, 360, 412]
DESKTOPS = [1100, 1440]
WIDTHS = PHONES + [768] + DESKTOPS
SELECTORS = [".welcome", ".login-card", ".welcome-pitch"]


@pytest.fixture(scope="module")
def measured(tmp_path_factory):
    fragment = tmp_path_factory.mktemp("welcome") / "fragment.html"
    fragment.write_text(_page(), encoding="utf-8")
    proc = subprocess.run(
        ["python3", str(HARNESS), ",".join(str(w) for w in WIDTHS),
         str(fragment), *SELECTORS],
        capture_output=True, text=True, timeout=180)
    assert proc.returncode == 0, f"probe failed: {proc.stdout}{proc.stderr}"
    out = json.loads(proc.stdout)
    assert "error" not in out, f"no measurement: {out}"
    for w in WIDTHS:
        assert out[str(w)]["viewport"]["w"] == w
    return out


def _box(measured, width, selector):
    box = measured[str(width)]["boxes"][selector]
    assert box is not None, f"{selector} did not render at {width} px"
    return box


@pytest.mark.parametrize("width", WIDTHS)
def test_nothing_is_wider_than_the_screen(measured, width):
    """A document wider than the screen unpins every sticky header on Android."""
    assert measured[str(width)]["docScrollW"] <= width, (
        f"the page is {measured[str(width)]['docScrollW']} px wide on a {width} px screen")
    for sel in SELECTORS:
        box = _box(measured, width, sel)
        assert box["offLeft"] == 0 and box["offRight"] == 0, f"{sel} hangs off at {width} px"


@pytest.mark.parametrize("width", PHONES + [768])
def test_a_narrow_screen_shows_the_form_first(measured, width):
    card, pitch = _box(measured, width, ".login-card"), _box(measured, width, ".welcome-pitch")
    assert pitch["top"] >= card["top"] + card["height"], (
        f"at {width} px the welcome text is not below the sign-in form")


@pytest.mark.parametrize("width", DESKTOPS)
def test_a_desktop_puts_the_form_right_of_the_text(measured, width):
    """Text on the left, the form on the right with room between them, and
    the form up by the title rather than centred on a column far taller."""
    card, pitch = _box(measured, width, ".login-card"), _box(measured, width, ".welcome-pitch")
    gap = card["left"] - (pitch["left"] + pitch["width"])
    assert gap >= 80, f"at {width} px the form is {gap} px right of the text"
    assert pitch["width"] >= 480, f"the text column is {pitch['width']} px at {width} px"
    assert 0 <= card["top"] - pitch["top"] <= 80, (
        f"at {width} px the form starts {card['top'] - pitch['top']} px below the text")


def test_the_pair_is_centred_in_the_window(measured):
    """Signed out there is no sidebar, and `.main` is capped at 960 px — so
    before `.page-center` lifted the cap, a centred form sat centred in the
    left 960 px of the window: x=290 in 1440."""
    # Against the document's width, not the window's: the probe's frame is
    # shorter than the page, so a vertical scrollbar takes its share.
    box = _box(measured, 1440, ".welcome")
    middle = measured["1440"]["docScrollW"] / 2
    centre = box["left"] + box["width"] / 2
    assert abs(centre - middle) <= 2, f"the page is centred on x={centre}, not {middle}"