#include "./lib/worker.h"
#include "lib/common.h"
#include "math.h"

const long double RUNGE_SIMPSON_CONST = 1.0L / 15;

typedef long double (*func_value_t)(long double);

typedef struct func_t {
    func_value_t value;
    func_value_t derivative;
    int id;
} func_t;

long double func_value(long double x) {
    return x * x * x * x * x * x - 15 * x * x * x * x * x + 134567 * x * x * x - 3486 * x * x + 100;
}

long double func_der(long double x) { return 6 * x * x * x * x * x - 75 * x * x * x * x + 403701 * x * x - 6972 * x; }

long double func_value_x(long double x) { return x; }
long double func_der_x(long double x) {
    x = x * 2;
    return 1;
}

func_t func = {func_value, func_der, 1};
// func_t func = {func_value_x, func_der_x, 1};

long double calculate_integral(func_t f, long double a, long double b, long double eps) {
    int n = 2;
    long double delta = (b - a) / n, x = 0;

    // integral value = (sum_by_1 + 2 * sum_by_2 + 4 * sum_by_4) * delta / 3
    long double sum_by_1 = 0, sum_by_2 = 0, sum_by_4 = 0;

    sum_by_1 += f.value(a);
    sum_by_1 += f.value(b);

    x = a + delta;
    for (int i = 1; i < n; i += 2) {
        sum_by_4 += f.value(x);
        x += 2 * delta;
    }

    x = a + 2 * delta;
    for (int i = 2; i < n; i += 2) {
        sum_by_2 += f.value(x);
        x += 2 * delta;
    }

    long double prev_sum = (sum_by_1 + 2 * sum_by_2 + 4 * sum_by_4) * delta / 3;
    long double sum = prev_sum;

    do {
        prev_sum = sum;
        sum_by_2 += sum_by_4;
        sum_by_4 = 0;

        n *= 2;
        delta = (b - a) / n;

        x = a + delta;
        for (int i = 1; i < n; i += 2) {
            sum_by_4 += f.value(x);
            x += 2 * delta;
        }

        sum = (sum_by_1 + 2 * sum_by_2 + 4 * sum_by_4) * delta / 3;
    } while ((fabsl(prev_sum - sum) - eps / RUNGE_SIMPSON_CONST) > 0);

    return sum;
}

void worker_func(const char* task, size_t task_size, char** resp, size_t* resp_size) {
    long double* args = (long double*) task;
    task_size = task_size * 2;

    long double res = calculate_integral(func, args[0], args[1], args[2]);
    printf("task %Lf %Lf -> %Lf\n", args[0], args[1], res);

    *resp = calloc(1, sizeof(long double));
    *((long double*) *resp) = res;
    *resp_size = sizeof(long double);
}

int32_t main() {
    worker_init("127.0.0.1", "33554", 1, worker_func);
    configure_timeout(10);
    worker_exec();
}