#pragma once

#ifdef __cplusplus
extern "C" {
#endif
#ifdef __cplusplus
}
#endif

int qsort_doubles_comparator_nonnan(const void* a, const void* b);
int qsort_doubles_comparator(const void* a, const void* b);

// @brief Calculates difference and approximate derivative for 1-dimensional data
// Caller needs to supply memory for output and understand that output_length = input_length - 1
PROTOTYPING_API Native_Error* Basic_Difference2 (ArrayView<f64> input, ArrayView<f64>& output);

PROTOTYPING_API Native_Error* Basic_Mean2 (ArrayView<f64> input, f64* mean);

PROTOTYPING_API Native_Error* Basic_QuickSortInPlace (ArrayView<f64> input);

PROTOTYPING_API Native_Error* Basic_Median2 (ArrayView<f64> unsorted_input, f64* median);

PROTOTYPING_API Native_Error* Basic_RescaleInPlace (ArrayView<f64> input, double min, double max);

PROTOTYPING_API Native_Error* Basic_Min2 (ArrayView<f64> input, f64* min_out);

PROTOTYPING_API Native_Error* Basic_Max2 (ArrayView<f64> input, f64* max_out);

double Basic_Max (double input1, double input2);

bool Basic_Is_Positive_Real (f32 input);
bool Basic_Is_Positive_Real (f64 input);

PROTOTYPING_API Native_Error* Basic_Standard_Deviation2 (ArrayView<f64> input, f64* stddev);

PROTOTYPING_API Native_Error* Basic_Variance2 (ArrayView<f64> input, f64* variance);

PROTOTYPING_API Native_Error* Basic_Root_Mean_Squared2 (ArrayView<f64> input, f64* rms);

// Sorts an array from largest to smallest, returning the indices of the sorted array
PROTOTYPING_API Native_Error* Basic_IndexSort2 (ArrayView<f64> input, ArrayView<s64> output);

PROTOTYPING_API Native_Error* Basic_Count_Non_Nan2 (ArrayView<f64> input, s64* non_nan_count);

PROTOTYPING_API Native_Error* Basic_Calculate_Percentile_New (ArrayView<f64> input, f64 percentile, f64* percentile_value_out);

// Does not include sort, because sorting is slow, and we may need to call this multiple 
// times with the same sorted input. 
PROTOTYPING_API Native_Error* Basic_CalculatePercentileNoSort (ArrayView<f64> input, f64 percentile, f64* percentile_value_out);

PROTOTYPING_API Native_Error* Basic_ReverseArrayInPlace (ArrayView<f64> input);
// Native_Error* Basic_Reverse_Array (double* input, int input_length);
// Native_Error* Basic_Reverse_Array (int* input, int input_length);

// Switches from row-order to column-order or vice-versa. #NOTE: you must know what the order
// and dimensions of the data are to begin with!!
PROTOTYPING_API Native_Error* Basic_2DArrayInvertMemoryOrder (ArrayView<f64> input, s64 first_dimension, s64 second_dimension, ArrayView<f64> output);

// In-place replacement of outliers (using interquartile method, with threshold of 1.5) with nearest values.
PROTOTYPING_API Native_Error* Basic_Replace_Outliers2 (ArrayView<f64> input, f64 outlier_threshold=1.5);

PROTOTYPING_API Native_Error* Basic_Replace_Values_Beyond_Threshold2 (ArrayView<f64> input, f64 low_threshold, f64 high_threshold, f64 replacement_value);

PROTOTYPING_API Native_Error* Basic_Roots_To_Polynomials2 (ArrayView<f64> roots, ArrayView<f64> polynomials);

// #TODO: Basic_Find (returns indices of non-zero elements).
// Need to make this generic, maybe using templates?
// PROTOTYPING_API ArrayView<s32> Basic_Find(ArrayView<f64> x, void* condition);

// Add parameters for peak prominence, height, etc.
// PROTOTYPING_API Native_Error* Basic_Find_Peaks (double* input, int input_length, int* peak_indices, int* peak_count);

struct Complex {
    f64 real; f64 imag;
    
    Complex() { real = 0; imag = 0; }
    Complex(f64 _real) { real = _real; imag = 0; }
    Complex(f64 _real, f64 _imag) { real = _real; imag = _imag; }
    
    Complex operator+(const Complex& other) const {
        return Complex(real + other.real, imag + other.imag);
    }

    Complex operator-(const Complex& other) const {
        return Complex(real - other.real, imag - other.imag);
    }

    Complex operator*(const Complex& other) const {
        return Complex(
            real * other.real - imag * other.imag,
            real * other.imag + imag * other.real
        );
    }

    Complex operator/(const Complex& other) const {
        f64 denom = other.real * other.real + other.imag * other.imag;
        return Complex(
            (real * other.real + imag * other.imag) / denom,
            (imag * other.real - real * other.imag) / denom
        );
    }

    Complex& operator+=(const Complex& other) {
        real += other.real;
        imag += other.imag;
        return *this;
    }

    Complex& operator-=(const Complex& other) {
        real -= other.real;
        imag -= other.imag;
        return *this;
    }

    Complex& operator*=(const Complex& other) {
        f64 r = real * other.real - imag * other.imag;
        f64 i = real * other.imag + imag * other.real;
        real = r;
        imag = i;
        return *this;
    }

    Complex& operator/=(const Complex& other) {
        f64 denom = other.real * other.real + other.imag * other.imag;
        f64 r = (real * other.real + imag * other.imag) / denom;
        f64 i = (imag * other.real - real * other.imag) / denom;
        real = r;
        imag = i;
        return *this;
    }

    bool operator==(const Complex& other) const {
        return real == other.real && imag == other.imag;
    }

    bool operator!=(const Complex& other) const {
        return !(*this == other);
    }
};

struct Complex32 { f32 real; f32 imag; };

Complex exponential (Complex cx);
Complex conjugate (Complex cx);
f64 fabs (Complex cx);