function ax = plotCryoData(tbl, tStart, tEnd)
% plotCryoData Plot cryo cell data in 3 stacked panels with shared datetime axis.
%
%   [ax] = plotCryoData(tbl, tStart, tEnd)
%   Returns struct with handles to the 3 axes for easy limit modification.
%
%   The first input may be EITHER:
%     * a table with the columns datetime, pressure_cell_hPa_,
%       temperature__C_, x_mm_, y_mm_, z_mm_, flowCryo_l_min_, OR
%     * a LabView structure produced by LabView_importData (optionally
%       combined with LabView_combine). In that case it is converted to the
%       required table on the fly (see the local function labviewToTable).

    %--- Accept a LabView timeseries structure and convert it to a table ---
    if isstruct(tbl)
        tbl = labviewToTable(tbl);
    end

    %--- Extract datetime column ---
    dt = tbl.datetime;
    
    %--- If start/stop provided, subset the table ---
    if nargin >= 3 && ~isempty(tStart) && ~isempty(tEnd)
        mask = dt >= tStart & dt <= tEnd;
        tbl = tbl(mask, :);
        dt  = dt(mask);
    end

    %--- Create tiled layout ---
    figure;
    tl = tiledlayout(4, 1);
    tl.TileSpacing = 'compact';
    tl.Padding     = 'compact';

    %--- Upper tile: pressure and temperature (spans 2 rows) ---
    ax.pressure_temp = nexttile([2 1]);
    yyaxis left;
    plot(dt, tbl.pressure_cell_hPa_, 'o', 'MarkerSize', 2, 'MarkerFaceColor', 'auto');
    ylabel('Pressure [hPa]');
    ylim padded;
    grid on;

    yyaxis right;
    plot(dt, tbl.temperature__C_, 'o', 'MarkerSize', 2, 'MarkerFaceColor', 'auto');
    ylabel('Temperature [°C]');
    ylim padded;

    title('Pressure and Temperature');
    set(gca, 'XTickLabel', []);

    %--- Middle tile: x, y, z with dual y-axes ---
    ax.xyz = nexttile;
    yyaxis left;
    plot(dt, tbl.y_mm_, 'o', 'MarkerSize', 2, 'MarkerFaceColor', 'auto', 'DisplayName', 'y'); hold on;
    ylabel('Y [mm]');
    ylim([10 15]);
    grid on;

    yyaxis right;
    plot(dt, tbl.x_mm_, 's', 'MarkerSize', 2, 'MarkerFaceColor', 'auto', 'DisplayName', 'x'); hold on;
    plot(dt, tbl.z_mm_, '^', 'MarkerSize', 2, 'MarkerFaceColor', 'auto', 'DisplayName', 'z');
    ylabel('X, Z [mm]');
    ylim([-2 2]);
    
    legend({'y', 'x', 'z'}, 'Location', 'best');
    set(gca, 'XTickLabel', []);

    %--- Lower tile: flowCryo ---
    ax.flow = nexttile;
    plot(dt, tbl.flowCryo_l_min_, 'o', 'MarkerSize', 2, 'MarkerFaceColor', 'auto');
    grid on;
    ylabel('Flow [L/min]');
    xlabel('Date & Time');
    title('Cryo Flow');

    %--- Link x-axes for all tiles ---
    linkaxes([ax.pressure_temp, ax.xyz, ax.flow], 'x');
    
    % Improve datetime formatting on x-axis
    ax.flow.XAxis.TickLabelFormat = 'dd-MMM HH:mm';
end


% =========================================================================
%  LOCAL FUNCTIONS
% =========================================================================

function tbl = labviewToTable(LabView, tsName)
%LABVIEWTOTABLE Convert a LabView cryo-log timeseries into a plotCryoData table.
%
%   Uses LabView.merge if present (created by LabView_combine); otherwise the
%   timeseries field named tsName, or the first timeseries in the structure.
%   The mapping uses the FIXED ts.Data column order that LabView_importData
%   produces for every file format:
%     [IceTemp, ResP1, ResP2, cell/Baratron1, Cooler1, Cooler2, FlowHe, ...
%      Baratron2, Baratron3, x, y, z, Tsealing]
%   so it works for old and new files alike. Channels a given file does not
%   contain (e.g. x/y/z in pre-2019 logs) are returned as NaN.

    %--- Select which timeseries to convert ---
    if nargin >= 2 && ~isempty(tsName)
        if ~isfield(LabView, tsName)
            error('plotCryoData:noSuchField', ...
                'LabView has no timeseries field "%s".', tsName);
        end
        ts = LabView.(tsName);
    elseif isfield(LabView, 'merge')
        ts = LabView.merge;                    % combined log (preferred)
    else
        fn = fieldnames(LabView);
        if isempty(fn)
            error('plotCryoData:emptyStruct', ...
                'LabView structure contains no timeseries.');
        end
        ts = LabView.(fn{1});                  % single-file case
    end

    %--- Absolute time as a datetime column ---
    try
        dt = datetime(getabstime(ts));
    catch
        dt = datetime(ts.TimeInfo.StartDate) + ...
             seconds(ts.Time * unitToSeconds(ts.TimeInfo.Units));
    end
    dt = dt(:);

    %--- Pull channels by their fixed ts.Data column index ---
    D = ts.Data;

    tbl = table( ...
        dt,            ...
        getCol(D, 4),  ...   % pressure_cell (hPa)  <- cell / Baratron-1 slot
        getCol(D, 1),  ...   % temperature  (degC)  <- ice sample
        getCol(D, 10), ...   % x (mm)
        getCol(D, 11), ...   % y (mm)
        getCol(D, 12), ...   % z (mm)
        getCol(D, 7),  ...   % flow cryo (l/min)    <- He cryoholder
        'VariableNames', {'datetime', 'pressure_cell_hPa_', 'temperature__C_', ...
                          'x_mm_', 'y_mm_', 'z_mm_', 'flowCryo_l_min_'});
end


function c = getCol(D, k)
% Return column k of D, or a NaN column if that channel is absent
% (e.g. pre-2019 logs have only 9 columns, so no x/y/z).
    if size(D, 2) >= k
        c = D(:, k);
    else
        c = nan(size(D, 1), 1);
    end
end


function s = unitToSeconds(u)
% Convert timeseries TimeInfo.Units to seconds (fallback path only).
    switch lower(u)
        case 'seconds',      s = 1;
        case 'minutes',      s = 60;
        case 'hours',        s = 3600;
        case 'days',         s = 86400;
        case 'milliseconds', s = 1e-3;
        otherwise,           s = 1;   % assume seconds
    end
end