function mesh_refiner(dom, varargin)
%MESH_REFINER  Interactive refinement figure for a surfacemesh.
%   MESH_REFINER(DOM) opens a figure that renders the surfacemesh DOM and shows
%   a slider that refines it interactively. MESH_REFINER(DOM, 'MaxLevel', L)
%   sets the maximum refinement level (default 3).
%
%   This holds all the wiring: it loads the prebuilt figure app, sends the mesh
%   to it (script -> figure), and refines the mesh whenever the slider in the
%   figure asks for a new level (figure -> script). The end-user script only
%   has to build a domain and call this.

maxLevel = 3;
for i = 1:2:numel(varargin) - 1
    if strcmpi(varargin{i}, 'MaxLevel')
        maxLevel = varargin{i + 1};
    end
end

% The figure app is the prebuilt single-file page, relative to the project root
% (the current working directory when a top-level script is run).
html = fileread(fullfile('app', 'dist', 'index.html'));

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

function on_refine(src, ev, dom0, maxLevel)
% Slider in the figure -> refine the base mesh to the requested level and send
% the new patches back to the figure.
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', mesh_to_data(dom, level, maxLevel));
end

function data = mesh_to_data(dom, level, maxLevel)
% Pack a surfacemesh into a plain struct the figure app can render: one flat
% (column-major) x/y/z array per patch, each an n-by-n grid. real() drops any
% all-zero imaginary part the solver may carry.
np = length(dom);
px = cell(1, np);
py = cell(1, np);
pz = cell(1, np);
for k = 1:np
    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