"""WebGPU pixel parity, rare-cell selection, world replacement, resize and device loss."""
import pathlib, sys
sys.path.insert(0, str(pathlib.Path(__file__).resolve().parent.parent / 'tools'))
from use_venv import ensure_playwright; ensure_playwright()
from browser import launch, consume_gpu_option
gpu_mode = consume_gpu_option()
root = pathlib.Path(__file__).resolve().parent.parent
with launch(viewport={'width': 960, 'height': 600}) as (browser, pg, url):
    errors = []
    pg.on('pageerror', lambda e: errors.append(str(e)))
    pg.on('console', lambda m: errors.append(m.text) if m.type == 'error' else None)
    pg.add_init_script('requestAnimationFrame = () => 0;')
    pg.goto(url); pg.evaluate('CAPS_CHECK')
    if gpu_mode == 'soft' and not pg.evaluate('CAPS.webgpu'):
        print('SKIP WebGPU parity: software browser has no WebGPU adapter')
        sys.exit(0)
    assert pg.evaluate('GPU.ok'), pg.evaluate('GPU.error')
    pg.evaluate('generateWorld(424242, 640, 384, null); enterGame(); GAME.paused=true;')
    pg.evaluate('() => {' + (root / 'tools/scenes/t88-renderer.js').read_text() + '}')
    result = pg.evaluate("""() => {
      SET.look='pixel'; SET.zoom=6; SET.glow='off'; SET.lighting='off';
      resizeRender(); bot.x=CAM[0]-bot.w/2; bot.y=CAM[1]-bot.h/2; snapCamera(); R.frame=1000;
      const results=[];
      for(const rain of [0,0.7])for(const lit of [false,true])for(const lens of [false,true])for(const palette of ['inferno','ironbow','gray'])for(const fogOn of [false,true]) {
        SET.lighting=lit?'full':'off'; SET.glow=lit?'low':'off';
        R.lens=lens; SET.thermalPalette=palette; SET.fog=fogOn;
        R.rain=rain; SET.renderer='legacy';drawWorld(); const a=worldPixelContext().getImageData(0,0,960,600).data;
        R.rain=rain; SET.renderer='webgpu';drawWorld(); const b=worldPixelContext().getImageData(0,0,960,600).data;
        let max=0, sum=0, bad=0;
        for(let i=0;i<a.length;i+=4) {let d=0;for(let j=0;j<3;j++){const e=Math.abs(a[i+j]-b[i+j]);sum+=e;d=Math.max(d,e);}max=Math.max(max,d);bad+=d>8;}
        results.push({rain,lit,lens,palette,fogOn,max,mean:sum/(960*600*3),bad});
      }
      R.lens=false;
      return results;
    }""")
    for r in result:
        assert r['bad'] == 0, r
    print('PASS plain cells, built geometry, ghosts, rain and all thermal palettes match legacy within 8', len(result), 'configurations; max', max(r['max'] for r in result))
    assert pg.evaluate('GPU.overrideCount > 0 && GPU.overrideCount < R.bw*R.bh*0.25')
    alpha = pg.evaluate('[R.gpuOn,GPU.ok,GPU.error,R.ctx.getImageData(10,10,1,1).data[3],worldPixelContext().getImageData(10,10,1,1).data[3],R.canvas.width,R.canvas.height]')
    assert alpha[3:5] == [0,255], alpha
    print('PASS most visible grains use GPU colouring; pixel reads include the opaque GPU world')
    glow = pg.evaluate("""() => {
      SET.fog=false; SET.lighting='off'; SET.glow='high'; R.lens=false;
      spawnBar(BARFE,CAM[0]-30,CAM[1]+15,0,0,20);
      const x=CAM[0]-64,y=CAM[1]-36;
      setCell(y*W+x,MAGMA,1450,F_NAT);
      flyers.push({x,y,m:COAL,rain:false});
      SET.renderer='legacy';drawWorld();const a=worldPixelContext().getImageData(0,0,960,600).data;
      SET.renderer='webgpu';drawWorld();const b=worldPixelContext().getImageData(0,0,960,600).data;
      let max=0;for(let i=0;i<a.length;i++)if((i&3)!==3)max=Math.max(max,Math.abs(a[i]-b[i]));return max;
    }""")
    assert glow <= 8, f'Objects must retain the hot grain glow beneath them: max error {glow}'
    print('PASS bars and flying grains preserve the glow behind them', glow)
    # Fresh arrays, same dimensions: catches stale world/static textures after a load.
    pg.evaluate('generateWorld(777, 640, 384, null); buildSky(); SET.renderer="webgpu"; SET.zoom=2; resizeRender(); snapCamera(); drawWorld();')
    assert pg.evaluate('GPU.world===mat && GPU.colourTex.width===R.bw && GPU.ok')
    parity = pg.evaluate("""() => {
      const a=worldPixelContext().getImageData(0,0,960,600).data;
      SET.renderer='legacy';drawWorld();const b=worldPixelContext().getImageData(0,0,960,600).data;
      SET.renderer='webgpu'; let max=0,nonblack=0;
      for(let i=0;i<a.length;i+=4){nonblack+=a[i]+a[i+1]+a[i+2]>0;for(let j=0;j<3;j++)max=Math.max(max,Math.abs(a[i+j]-b[i+j]));}
      return {max,nonblack};
    }""")
    assert parity['max'] <= 8 and parity['nonblack'] > 1000, parity
    print('PASS world replacement and zoom reallocate textures and draw the new world', parity)
    pg.evaluate('SET.look="smooth"; drawWorld();')
    assert pg.evaluate('!R.gpuOn && R.smoothOn && GPU.canvas.hidden')
    print('PASS smooth keeps the legacy path')
    pg.evaluate('SET.look="pixel"; SET.renderer="webgpu"; PERF_MARKS=true; drawWorld();')
    pg.wait_for_function('!GPU.timingBusy')
    assert pg.evaluate('!GPU.queries || GPU.gpuMs>=0')
    assert pg.evaluate('perfMarks.override>=0 && perfMarks.upload>=0')
    print('PASS separate override/upload clocks and optional GPU timestamps')
    pg.evaluate('() => {' + (root / 'tools/scenes/t88-light.js').read_text() + '}')
    # Draw GPU first with no CPU grid and forbid accidental CPU lighting calls.
    pg.evaluate("""() => {
      window.savedComputeLight=computeLight;
      computeLight=()=>{throw Error('CPU light called in WebGPU');};
      R.lr=R.lg=R.lb=R.latt=R.lightPx=null; R.lw=R.lh=0;
      SET.renderer='webgpu';SET.look='pixel';SET.zoom=6;SET.lighting='full';SET.lightEvery=1;
      resizeRender();bot.x=CAM[0]-bot.w/2;bot.y=CAM[1]-bot.h/2;snapCamera();drawWorld();
      computeLight=savedComputeLight;
    }""")
    for mode in ['full', 'fast']:
        for case in ['lamp', 'opening', 'magma', 'fire']:
            parity = pg.evaluate("""([mode,kind]) => {
              lightScene(kind);SET.lighting=mode;SET.lightEvery=1;R.frame=1000;R.rain=0;
              SET.renderer='legacy';drawWorld();const a=worldPixelContext().getImageData(0,0,960,600).data;
              R.rain=0;SET.renderer='webgpu';drawWorld();const b=worldPixelContext().getImageData(0,0,960,600).data;
              let max=0,bad=0,sum=0;
              for(let i=0;i<a.length;i+=4){let d=0;for(let j=0;j<3;j++){const e=Math.abs(a[i+j]-b[i+j]);sum+=e;d=Math.max(d,e);}max=Math.max(max,d);bad+=d>8;}
              return {mode,kind,max,bad,mean:sum/(960*600*3)};
            }""", [mode,case])
            assert parity['bad'] == 0, parity
            print('PASS light scene', parity)
    cadence = pg.evaluate("""() => {
      SET.lightEvery=3;R.frame=1002;drawWorld();const old=GPU.lightFrame,origin=R.lx0;
      bot.lamp=!bot.lamp;R.camX+=4;R.frame=1003;drawWorld();
      const held=GPU.lightFrame===old && R.lx0===origin;
      R.frame=1005;drawWorld();const updated=GPU.lightFrame===1005 && R.lx0!==origin;
      SET.lightEvery=1;return {held,updated};
    }""")
    assert all(cadence.values()), cadence
    print('PASS GPU-only lighting, both resolutions and lightEvery cadence')
    assert pg.evaluate('!GPU.queries || GPU.lightMs>=0')
    pg.evaluate('GPU.device.destroy()')
    pg.wait_for_function('!GPU.ok')
    assert pg.evaluate('SET.renderer==="legacy"')
    pg.evaluate('drawWorld()')
    print('PASS device loss restores the legacy renderer')
    assert not errors, errors
    print('PASS no page or WebGPU validation errors')