classdef Fiber_test < IMDDTestCase
    methods (Test, TestTags = {'unit', 'fast', 'optical', 'fiber'})
        function zeroLengthPropagationLeavesSignalUnchanged(testCase)
            fiber = Fiber("fsimu", 64e9, "fiber_length", 0, "alpha", 0, "D", 0, ...
                "Dslope", 0, "lambda0", 1310, "gamma", 0);
            inputSig = makeOpticalsignal([1 + 1i; -2 + 0.5i; 0.25 - 0.75i], 64e9, 1310e-9);

            outputSig = fiber.process_(inputSig);

            testCase.verifyClass(outputSig, 'Opticalsignal');
            testCase.verifyEqual(outputSig.signal, inputSig.signal, "AbsTol", 1e-12);
            testCase.verifyEqual(outputSig.lambda, inputSig.lambda);
            testCase.verifyEqual(outputSig.fs, inputSig.fs);
        end

        function attenuationOnlyMatchesAnalyticalFieldScaling(testCase)
            fs = 32e9;
            lambda = 1310e-9;
            fiberLengthKm = 2.5;
            alphaDbPerKm = 0.2;
            inputSignal = [1 + 2i; -0.5 + 0.25i; 0.75 - 1.25i; 2 - 1i];
            fiber = Fiber("fsimu", fs, "fiber_length", fiberLengthKm, "alpha", alphaDbPerKm, ...
                "D", 0, "Dslope", 0, "lambda0", 1310, "gamma", 0);
            inputSig = makeOpticalsignal(inputSignal, fs, lambda);

            outputSig = fiber.process_(inputSig);

            alphaLin = alphaDbPerKm / 10 * log(10) / 1e3;
            expected = inputSignal .* exp(-alphaLin / 2 * fiber.fiber_length);

            testCase.verifyEqual(outputSig.signal, expected, "AbsTol", 1e-12);
        end

        function linearOnlyPropagationPreservesShapeAndEnergyWhenLossless(testCase)
            fs = 64e9;
            lambda = 1310e-9;
            inputSignal = [1 + 0.5i; -1i; 0.75; 2 - 0.25i];
            fiber = Fiber("fsimu", fs, "fiber_length", 0.3, "alpha", 0, ...
                "D", 0, "Dslope", 0, "lambda0", 1310, "gamma", 0);
            inputSig = makeOpticalsignal(inputSignal, fs, lambda);

            outputSig = fiber.process_(inputSig);

            testCase.verifySize(outputSig.signal, size(inputSignal));
            testCase.verifyEqual(outputSig.signal, inputSignal, "AbsTol", 1e-12);
            testCase.verifyEqual(norm(outputSig.signal), norm(inputSignal), "AbsTol", 1e-12);
        end

        function processAddsLogbookEntryAndReturnsOpticalsignal(testCase)
            fs = 32e9;
            lambda = 1310e-9;
            fiber = Fiber("fsimu", fs, "fiber_length", 0, "alpha", 0, "D", 0, ...
                "Dslope", 0, "lambda0", 1310, "gamma", 0);
            inputSig = makeOpticalsignal([1; -1; 2], fs, lambda);

            outputSig = fiber.process(inputSig);

            testCase.verifyClass(outputSig, 'Opticalsignal');
            testCase.verifyEqual(outputSig.signal, inputSig.signal, "AbsTol", 1e-12);
            testCase.verifyEqual(height(outputSig.logbook), height(inputSig.logbook) + 1);
            testCase.verifyEqual(string(outputSig.logbook.Description(end)), "Fiber ");
        end
    end
end

function sig = makeOpticalsignal(values, fs, lambda)
    sig = Opticalsignal(values, ...
        "fs", fs, ...
        "logbook", emptyLogbook(), ...
        "lambda", lambda, ...
        "nase", 0, ...
        "polrot", 0);
end

function lb = emptyLogbook()
    SignalType = [];
    TimeStamp = [];
    Length = [];
    SignalPower = [];
    Nase = [];
    SignalCopy = [];
    ModifierName = [];
    ModifierCopy = {};
    Description = [];

    lb = table(SignalType, TimeStamp, Length, SignalPower, Nase, SignalCopy, ModifierName, ModifierCopy, Description);
end