function Scpe_sig = preprocessSignal(Scpe_sig, Symbols, fsym, options)
% PREPROCESSSIGNAL Performs standard preprocessing on a signal
%
% Inputs:
%   Scpe_sig - Input signal
%   Symbols - Reference symbols for synchronization
%   fsym - Symbol frequency
%
% Outputs:
%   Scpe_sig - Preprocessed signal

arguments
    Scpe_sig
    Symbols
    fsym
    options.mode string = "auto"
    options.tx_pulseformer = []
    options.debug_plots (1,1) logical = false
    options.apply_gaussian_filter (1,1) logical = true
    options.gaussian_cutoff_factor (1,1) double = 0.52
end

preprocessMode = resolvePreprocessMode(options.mode, options.tx_pulseformer, Symbols);
targetFs = 2 * fsym;

switch preprocessMode
    case "matched_filter"
        matchedPulseformer = buildMatchedPulseformer(options.tx_pulseformer, Symbols, fsym, targetFs);
        Scpe_sig = matchedPulseformer.process(Scpe_sig);
    case "resample"
        Scpe_sig = Scpe_sig.resample("fs_out", targetFs);
    otherwise
        error('preprocessSignal:InvalidMode', 'Unsupported preprocessing mode "%s".', preprocessMode);
end

[Scpe_sig, Scpe_cell] = Scpe_sig.tsynch("reference", Symbols, "fs_ref", fsym, "debug_plots", options.debug_plots);
 % Scpe_sig = Scpe_cell{1};

% Apply Gaussian filter
if options.apply_gaussian_filter
    Scpe_sig = Filter('filtdegree', 8, "f_cutoff", Symbols.fs.*options.gaussian_cutoff_factor, ...
        "fs", Scpe_sig.fs, "filterType", filtertypes.gaussian, ...
        "active", true).process(Scpe_sig);
end

%Remove DC offset
Scpe_sig = Scpe_sig - mean(Scpe_sig.signal);

end

function preprocessMode = resolvePreprocessMode(requestedMode, txPulseformer, Symbols)
    requestedMode = string(requestedMode);
    if requestedMode ~= "auto"
        preprocessMode = requestedMode;
        return
    end

    pulseformer = txPulseformer;
    if isempty(pulseformer)
        pulseformer = findSignalPulseformer(Symbols);
    end

    if isRootRaisedCosinePulseformer(pulseformer)
        preprocessMode = "matched_filter";
    else
        preprocessMode = "resample";
    end
end

function tf = isRootRaisedCosinePulseformer(pulseformer)
    tf = false;
    if isempty(pulseformer)
        return
    end

    pulseValue = readPulseformerField(pulseformer, 'pulse', []);
    if isempty(pulseValue)
        return
    end

    pulseValue = normalizePulseValue(pulseValue);
    tf = pulseValue == pulseform.rrc;
end

function matchedPulseformer = buildMatchedPulseformer(txPulseformer, Symbols, fsym, targetFs)
    pulseformerMeta = txPulseformer;
    if isempty(pulseformerMeta)
        pulseformerMeta = findSignalPulseformer(Symbols);
    end

    pulseValue = normalizePulseValue(readPulseformerField(pulseformerMeta, 'pulse', pulseform.rrc));
    alphaValue = readPulseformerField(pulseformerMeta, 'alpha', 0.05);
    pulseLengthValue = readPulseformerField(pulseformerMeta, 'pulselength', 16);

    if isempty(alphaValue)
        alphaValue = 0.05;
    end

    matchedPulseformer = Pulseformer( ...
        "fsym", fsym, ...
        "fdac", targetFs, ...
        "pulse", pulseValue, ...
        "pulselength", pulseLengthValue, ...
        "alpha", alphaValue, ...
        "matched", 1);
end

function value = readPulseformerField(pulseformerMeta, fieldName, defaultValue)
    value = defaultValue;
    if isempty(pulseformerMeta)
        return
    end

    if isstruct(pulseformerMeta) && isfield(pulseformerMeta, fieldName)
        candidate = pulseformerMeta.(fieldName);
        if ~isempty(candidate)
            value = candidate;
        end
        return
    end

    if isobject(pulseformerMeta) && isprop(pulseformerMeta, fieldName)
        candidate = pulseformerMeta.(fieldName);
        if ~isempty(candidate)
            value = candidate;
        end
    end
end

function pulseValue = normalizePulseValue(rawValue)
    if isa(rawValue, 'pulseform')
        pulseValue = rawValue;
        return
    end

    if iscell(rawValue)
        rawValue = rawValue{1};
    end

    if isstring(rawValue) || ischar(rawValue)
        pulseValue = pulseform.(char(string(rawValue)));
        return
    end

    pulseValue = pulseform(rawValue);
end