"""Shared isolated HTTP sessions; callers attach hooks before navigating to url."""
import argparse
from contextlib import contextmanager
import os
from pathlib import Path
import sys
from urllib.parse import quote

from server import DIST, isolated_server

GPU_ARGS = ['--use-angle=vulkan', '--enable-features=Vulkan,VulkanFromANGLE', '--enable-gpu',
            '--ignore-gpu-blocklist', '--enable-gpu-rasterization', '--enable-unsafe-webgpu']
SOFT_ARGS = ['--use-gl=angle', '--use-angle=swiftshader', '--enable-unsafe-swiftshader']
DEFAULT_GPU = 'real'


def gpu_option(parser):
    parser.add_argument('--gpu', choices=['real', 'soft'],
                        default=os.environ.get('DEEPGRAIN_GPU', DEFAULT_GPU))


def consume_gpu_option():
    """Keep the older scripts' positional arguments."""
    parser = argparse.ArgumentParser(add_help=False)
    gpu_option(parser)
    options, remaining = parser.parse_known_args()
    os.environ['DEEPGRAIN_GPU'] = options.gpu
    sys.argv[1:] = remaining
    return options.gpu


@contextmanager
def launch(*, gpu=None, browser_name='chromium', viewport=None, page_path=None, args=()):
    from playwright.sync_api import sync_playwright
    gpu = gpu or os.environ.get('DEEPGRAIN_GPU', DEFAULT_GPU)
    if gpu not in ('real', 'soft'):
        raise ValueError('GPU must be real or soft')
    path = Path(page_path).resolve() if page_path else DIST / 'index.html'
    with isolated_server(path.parent) as base, sync_playwright() as p:
        flags = (GPU_ARGS if gpu == 'real' else SOFT_ARGS) if browser_name == 'chromium' else []
        browser = getattr(p, browser_name).launch(args=[*flags, *args])
        try:
            context = browser.new_context(viewport=viewport or {'width': 1280, 'height': 760})
            page = context.new_page()
            if gpu == 'soft':
                page.add_init_script('window.__allowSoftwareGL = true;')
            yield browser, page, base + '/' + quote(path.name)
        finally:
            browser.close()


def installed(browser_name):
    from playwright.sync_api import sync_playwright
    with sync_playwright() as p:
        return Path(getattr(p, browser_name).executable_path).is_file()


def capabilities(page):
    page.wait_for_function('CAPS.ready')
    return page.evaluate("""() => {
      const gl = document.createElement('canvas').getContext('webgl2');
      const dbg = gl && gl.getExtension('WEBGL_debug_renderer_info');
      return { isolated: CAPS.isolated, webgpu: CAPS.webgpu, adapterInfo: CAPS.adapterInfo,
        renderer: gl ? gl.getParameter(dbg ? dbg.UNMASKED_RENDERER_WEBGL : gl.RENDERER) : null };
    }""")