function refine_demo
%REFINE_DEMO  Interactive surfacefun mesh refinement via a uihtml figure.
%
%   Runs in the numbl IDE and via `numbl run --plot`. Shows a cubed-sphere
%   surfacemesh rendered with numbl's surface renderer (duplicated into the
%   bundled web app). Drag the "Refinement level" slider in the figure: the
%   page sends the level to this script, which refines the base mesh with
%   surfacefun and sends the new patches back — the figure re-renders without
%   losing the camera orientation.
%
%   The web app is prebuilt into app/dist/index.html (cd app && npm run build).

mip load --install flatironinstitute/flatironinstitute/surfacefun

here = fileparts(mfilename('fullpath'));
html = fileread(fullfile(here, 'app', 'dist', 'index.html'));

maxLevel = 3;            % slider range 0..maxLevel
n = 8;                   % Chebyshev order per patch
dom0 = surfacemesh.sphere(n);   % base cubed sphere (6 patches)

data0 = meshToData(dom0, 0, maxLevel);

fig = figure;
gl = uigridlayout(fig, [1 1], 'Padding', [0 0 0 0], ...
                  'RowHeight', {'1x'}, 'ColumnWidth', {'1x'});
uihtml(gl, 'HTMLSource', html, 'Data', data0, ...
       'HTMLEventReceivedFcn', @(src, ev) onRefine(src, ev, dom0, maxLevel));
end

function onRefine(src, ev, dom0, maxLevel)
% Refine the base mesh to the requested absolute level and send it back.
if ~strcmp(ev.HTMLEventName, 'refine')
    return
end
level = max(0, min(maxLevel, round(ev.HTMLEventData)));
if level == 0
    dom = dom0;
else
    dom = refine(dom0, level);
end
sendEventToHTMLSource(src, 'mesh', meshToData(dom, level, maxLevel));
fprintf('refined to level %d: %d patches\n', level, length(dom));
end

function data = meshToData(dom, level, maxLevel)
% Pack a surfacemesh into a plain struct the web app can render: one flat
% (column-major) x/y/z array per patch, each an n-by-n grid.
np = length(dom);
px = cell(1, np);
py = cell(1, np);
pz = cell(1, np);
for k = 1:np
    % real() drops any (all-zero) imaginary part the solver/JIT may carry;
    % the geometry is real and jsonencode (numbl and MATLAB) rejects complex.
    px{k} = real(dom.x{k}(:).');
    py{k} = real(dom.y{k}(:).');
    pz{k} = real(dom.z{k}(:).');
end
data = struct();
data.n = size(dom.x{1}, 1);
data.x = px;
data.y = py;
data.z = pz;
data.npatches = np;
data.level = level;
data.maxLevel = maxLevel;
end