function [Bits, Symbols, Scpe_cell, found_sync] = loadAndSyncRunSignals(dataTable, options)
%LOADANDSYNCRUNSIGNALS Load and synchronize signal files for one run.
%
% Inputs:
%   dataTable - one-row table with run metadata and signal file paths
%   options   - struct with storage_path, start_occurence and max_occurences
%
% Outputs:
%   Bits       - transmitted bit reference
%   Symbols    - transmitted symbol reference
%   Scpe_cell  - synchronized received signal occurrences
%   found_sync - true when a valid synchronization was found

found_sync = 0;
tempLocalStorage = 1;
Scpe_cell = {};
loaded_from_cache = false;

storage_dir = fullfile(prefdir, 'temp_sync_data');

if tempLocalStorage == 1
    local_filename = fullfile(storage_dir, sprintf('sync_data_run_%s.mat', num2str(dataTable.run_id)));
    if exist(local_filename, 'file')
        try
            cacheData = load(local_filename, 'Bits', 'Symbols', 'Scpe_cell');
            if isValidSyncCache(cacheData)
                Bits = cacheData.Bits;
                Symbols = cacheData.Symbols;
                Scpe_cell = cacheData.Scpe_cell;
                found_sync = 1;
                loaded_from_cache = true;
            else
                warning('loadAndSyncRunSignals:InvalidSyncCache', ...
                    'Ignoring incomplete sync cache file "%s".', local_filename);
                safeDelete(local_filename);
            end
        catch
            safeDelete(local_filename);
            found_sync = 0;
        end
    end
end

if ~found_sync
    Bits = load(composeStoragePath(options.storage_path, dataTable.tx_bits_path));
    Bits = Bits.Bits;

    M = double(dataTable.pam_level);
    fsym = dataTable.symbolrate;
    Symbols_mapped = PAMmapper(M,0).map(Bits);
    Symbols_mapped.fs = fsym;

    Symbols = load(composeStoragePath(options.storage_path, dataTable.tx_symbols_path));
    Symbols = Symbols.Symbols;

    found_sync = 0;
    try
        Scpe_load = load(composeStoragePath(options.storage_path, dataTable.rx_sync_path));
        Scpe_cell = Scpe_load.S;
        [~,~,~,found_sync] = Scpe_cell{1}.tsynch("reference", Symbols, ...
            "fs_ref", fsym, ...
            "debug_plots", 0);
    catch
        % Continue with raw data if pre-synchronized data is unavailable.
    end
end

if ~found_sync
    try
        Scpe_sig_raw = load(composeStoragePath(options.storage_path, dataTable.rx_raw_path));
        Scpe_sig_raw = Scpe_sig_raw.Scpe_sig_raw;
        Scpe_sig_resampled = Scpe_sig_raw.resample("fs_in", Scpe_sig_raw.fs, "fs_out", 2*fsym);
        [~, Scpe_cell, ~, found_sync] = Scpe_sig_resampled.tsynch("reference", Symbols, ...
            "fs_ref", fsym, ...
            "debug_plots", 0);
    catch
        % Continue to mapped-symbol fallback if raw data sync fails.
    end
end

if ~found_sync && exist('Scpe_sig_raw', 'var')
    if length(Symbols_mapped.signal) ~= sum(Symbols_mapped.signal == Symbols.signal)
        [~, Scpe_cell, ~, found_sync] = Scpe_sig_raw.tsynch("reference", Symbols_mapped, ...
            "fs_ref", fsym, ...
            "debug_plots", 0);
    end
end

if tempLocalStorage == 1 && found_sync && ~loaded_from_cache
    if ~exist(storage_dir, 'dir')
        mkdir(storage_dir);
    end

    max_local_files = 10;
    files = dir(fullfile(storage_dir, 'sync_data_run_*.mat'));
    if length(files) >= max_local_files
        [~, fileOrder] = sort([files.datenum]);
        delete(fullfile(storage_dir, files(fileOrder(1)).name));
    end

    writeSyncCache(local_filename, Bits, Symbols, Scpe_cell);
end

if found_sync
    Scpe_cell = selectSyncedOccurrences(Scpe_cell, options);
else
    warning('Could not synchronize the received signal with the stored symbols!');
end

end

function path = composeStoragePath(storagePath, relativePath)
relativePath = firstValue(relativePath);
path = char(string(storagePath) + string(relativePath));
if ismac
    path = strrep(path,'\','/');
else
    path = strrep(path,'/','\');
end
end

function value = firstValue(value)
if iscell(value)
    value = value{1};
elseif ~ischar(value) && ~isscalar(value)
    value = value(1);
end
end

function Scpe_cell = selectSyncedOccurrences(Scpe_cell, options)
available_occurences = length(Scpe_cell);
start_occurence = floor(getOption(options, 'start_occurence', 1));
max_occurences = floor(getOption(options, 'max_occurences', available_occurences));

if available_occurences < 1
    warning('loadAndSyncRunSignals:NoSyncedOccurrences', ...
        'Synchronization reported success, but no synced occurrences are available.');
    return
end

if start_occurence < 1
    error('loadAndSyncRunSignals:InvalidStartOccurrence', ...
        'start_occurence must be >= 1.');
end

if max_occurences < 1
    Scpe_cell = Scpe_cell(1:0);
    return
end

if start_occurence > available_occurences
    warning('loadAndSyncRunSignals:StartOccurrenceTooHigh', ...
        ['Requested start_occurence %d, but only %d synced occurrences are available. ', ...
        'Processing the last occurrence only.'], ...
        start_occurence, available_occurences);
    Scpe_cell = Scpe_cell(available_occurences);
    return
end

stop_occurence = min(available_occurences, start_occurence + max_occurences - 1);
Scpe_cell = Scpe_cell(start_occurence:stop_occurence);
end

function value = getOption(options, name, defaultValue)
if isfield(options, name)
    value = options.(name);
else
    value = defaultValue;
end
end

function valid = isValidSyncCache(cacheData)
valid = isfield(cacheData, 'Bits') && ...
    isfield(cacheData, 'Symbols') && ...
    isfield(cacheData, 'Scpe_cell') && ...
    iscell(cacheData.Scpe_cell) && ...
    ~isempty(cacheData.Scpe_cell);
end

function writeSyncCache(local_filename, Bits, Symbols, Scpe_cell)
cache_dir = fileparts(local_filename);
temp_filename = [tempname(cache_dir), '.mat'];

try
    save(temp_filename, 'Bits', 'Symbols', 'Scpe_cell');
    movefile(temp_filename, local_filename, 'f');
catch ME
    safeDelete(temp_filename);
    rethrow(ME);
end
end

function safeDelete(filename)
if exist(filename, 'file')
    try
        delete(filename);
    catch
        % Another parallel worker may already have removed or replaced it.
    end
end
end