#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>

#define BUFFER_SIZE 1024

#define degToRad(angleInDegrees) ((angleInDegrees) * M_PI / 180.0)
#define radToDeg(angleInRadians) ((angleInRadians) * 180.0 / M_PI)

double getDistance(double lat1, double lon1, double lat2, double lon2)
{
    double a = (sin((lat2 - lat1) / 2) * sin((lat2 - lat1) / 2)) + cos(lat1) * cos(lat2) * (sin((lon2 - lon1) / 2) * sin((lon2 - lon1) / 2));
    return 6371. * 2. * atan2(sqrt(a), sqrt(1 - a));
}

int main(int argc, char *argv[]) {
    FILE* input = fopen(argv[1], "r");
    FILE *output = fopen(argv[4], "w");
    char line[BUFFER_SIZE];

    double input_lat;
    double input_lon;
    int total = 0;

    while (fgets(line, BUFFER_SIZE, input))
    {
        char* tmp = strdup(line);
        int i = 0;
        const char* tok;

        const char* city;
        double lat;
        double lon;

        for (tok = strtok(line, ";");
             tok && *tok;
             tok = strtok(NULL, ";\n"))
        {
            switch(i) {
                case 0:
                    city = tok;
                    break;
                case 2:
                    lat = degToRad(strtod(tok, NULL));
                    break;
                case 3:
                    lon = degToRad(strtod(tok, NULL));
                    break;
            }
            i++;
        }
        if(strcmp(city, argv[2]) == 0) {
            input_lon = lon;
            input_lat = lat;
        }

        free(tmp);
    }

    fseek(input, 0, SEEK_SET);

    while (fgets(line, BUFFER_SIZE, input))
    {
        char* tmp = strdup(line);
        int i = 0;
        const char* tok;

        const char* city;
        int population;
        double lat;
        double lon;

        for (tok = strtok(line, ";");
             tok && *tok;
             tok = strtok(NULL, ";\n"))
        {
            switch(i) {
                case 0:
                    city = tok;
                    break;
                case 1:
                    population = strtol(tok, NULL, 10);
                    break;
                case 2:
                    lat = degToRad(strtod(tok, NULL));
                    break;
                case 3:
                    lon = degToRad(strtod(tok, NULL));
                    break;
            }
            i++;
        }

        double distance = getDistance(input_lat, input_lon, lat, lon);

        if(distance <= strtod(argv[3], NULL)) {
            fprintf(output, "%s %d %.2f km\n", city, population, distance);
            total += population;
        }

        free(tmp);
    }

    printf("total population: %d", total);

    fclose(input);
    fclose(output);
    return 0;
}