#include "c_Test.h"
#include "c_FFT.h"

TEST_CASE(test_fft_forward_and_inverse_precision) {
    c_size_t N = 8;
    c_FFT_t fft;
    c_err_t err = c_FFT_Init(&fft, N, NULL);
    ASSERT_INT_EQ(C_SUCCESS, err);

    /* Allocate and initialize a test complex input signal (e.g., a simple square pulse) */
    c_Complex_t signal[8] = {
        {1.0, 0.0}, {1.0, 0.0}, {1.0, 0.0}, {1.0, 0.0},
        {0.0, 0.0}, {0.0, 0.0}, {0.0, 0.0}, {0.0, 0.0}
    };

    /* Backup the original signal vector values for accuracy verification tests later */
    double original_real[8];
    for (c_size_t i = 0; i < N; ++i) original_real[i] = signal[i].real;

    /* 1. Execute Forward Fourier Transformation */
    err = c_FFT_Execute(&fft, signal, C_FALSE);
    ASSERT_INT_EQ(C_SUCCESS, err);

    /* The DC component (index 0) must equal the sum of all elements = 4.0 */
    ASSERT_DOUBLE_EQ_MSG(4.0, signal[0].real, "Forward FFT DC component calculation wrong");

    /* 2. Execute Inverse Fourier Transformation to reconstruct the original signal */
    err = c_FFT_Execute(&fft, signal, C_TRUE);
    ASSERT_INT_EQ(C_SUCCESS, err);

    /* Confirm that the output matches the original input wave precisely within allowed errors */
    for (c_size_t i = 0; i < N; ++i) {
        ASSERT_DOUBLE_EQ_MSG(original_real[i], signal[i].real, "FFT-IFFT signal precision mismatch");
        ASSERT_DOUBLE_EQ_MSG(0.0, signal[i].imag, "Residual imaginary noise caught in reconstructed signal");
    }

    c_FFT_Destroy(&fft);
}

int main(void) {
    TEST_START(FastFourierTransform_Engine_Suite);
    RUN_TEST(test_fft_forward_and_inverse_precision);
    TEST_REPORT();
    RETURN_TEST_STATUS;
}