// Copyright (2019-2024) Paul Scherrer Institute

#include "CPUSpotFinder.h"

template <int N>
void FindSpots(StrongPixelSet& set,
               int big_column, int big_row,
               const SpotFindingSettings& settings,
               const int16_t* image) {
    uint64_t sum = 0;
    uint64_t sum2 = 0;
    uint64_t valid_count = 0;

    for (int y = 0; y < N; y++) {
        for (int x = 0; x < N; x++) {
            size_t coord = (big_row * N + y) * RAW_MODULE_COLS + big_column * N + x;
            if ((image[coord] != INT16_MIN) || (image[coord] != INT16_MAX)) {
                sum += image[coord];
                sum2 += image[coord] * image[coord];
                valid_count++;
            }
        }
    }

    int64_t variance = valid_count * sum2 - sum * sum;
    float threshold = variance * settings.signal_to_noise_threshold * settings.signal_to_noise_threshold;

    for (int y = 0; y < N; y++) {
        for (int x = 0; x < N; x++) {
            size_t coord = (big_row * N + y) * RAW_MODULE_COLS + big_column * N + x;

            bool strong_pixel = true;

            if ((settings.photon_count_threshold < 0)
                && (settings.signal_to_noise_threshold <= 0))
                strong_pixel = false;

            if ((settings.photon_count_threshold >= 0)
                && (image[coord] < settings.photon_count_threshold)) {
                strong_pixel = false;
            }

            if (settings.signal_to_noise_threshold > 0) {
                int64_t in_minus_mean = image[coord] * valid_count - sum;
                if ((in_minus_mean * in_minus_mean <= threshold)
                    || (in_minus_mean <= 0)
                    || (valid_count < N * N / 2))
                    strong_pixel = false;
            }

            if (strong_pixel)
                set.AddStrongPixel(big_column * N + x, big_row * N + y, image[coord]);
        }
    }
}

void FindSpots(StrongPixelSet& set,
               const SpotFindingSettings& settings,
               const int16_t* image) {
    for (int i = 0; i < RAW_MODULE_LINES / 32; i++) {
        for (int j = 0; j < RAW_MODULE_COLS / 32; j++)
            FindSpots<32>(set, j, i, settings, image);
    }
}