#include "a_station.h"

struct station* create_station() {
    struct station* s = calloc(1, sizeof(struct station));
    s->tracks = calloc(STATION_SIZE, sizeof(struct car*));
    s->track_count = STATION_SIZE;
    return s;
}

int select_track(struct station* s, const char* target) {
    unsigned long hash = 5381; //5381 это алгоритм DJB2
    int c;

    while ((c = *target++)) { // не забываем ++ чтобы идти по строке
        hash = ((hash << 5) + hash) + c; //hash << 5 сдвигает все биты числа hash на 5 позиций влево. Это тоже самое, что умножить на 2 в пятой степени
    }

    return (int)(hash % s->track_count);
}

void add_target_capacity(struct station* s, const char* target, int capacity) {
    if (!s || !target) {
        return;
    }

    int index = select_track(s, target);
    struct car* current = s->tracks[index];

    if (current == NULL) { //Этот кусок кода создаёт “поезд” на пустой колее.
        struct car* new_car = calloc(1, sizeof(struct car));
        strcpy(new_car->value, target);
        new_car->capacity = capacity;
        new_car->next = NULL;
        s->tracks[index] = new_car;
        return;
    }

    struct car* prev = NULL; //создаём указатель prev, который будет хранить предыдущий элемент списка
    while (current != NULL) {
        if (strcmp(current->value, target) == 0) {
            current->capacity += capacity;
            return;
        }
        prev = current;
        current = current->next;
    }

    struct car* new_car = calloc(1, sizeof(struct car));
    strcpy(new_car->value, target);
    new_car->capacity = capacity;
    new_car->next = NULL;
    prev->next = new_car;
}

struct car* find_target(struct station* s, const char* target) {
    if (!s || !target) return NULL;

    int index = select_track(s, target);
    struct car* current = s->tracks[index];

    while (current != NULL) {
        if (strcmp(current->value, target) == 0) {
            return current;
        }
        current = current->next;
    }

    return NULL;
}

int get_total_targets(struct station* s) {
    if (!s) return 0;

    int count = 0;
    for (int i = 0; i < s->track_count; i++) {
        struct car* current = s->tracks[i];
        while (current != NULL) {
            count++;
            current = current->next;
        }
    }
    return count;
}

int get_total_capacity(struct station* s) {
    if (!s) return 0;

    int total = 0;
    for (int i = 0; i < s->track_count; i++) {
        struct car* current = s->tracks[i];
        while (current != NULL) {
            total += current->capacity;
            current = current->next;
        }
    }
    return total;
}

void print_station(struct station* s) {
    if (!s) return;

    printf("station>>>\n");
    for (int i = 0; i < s->track_count; i++) {
        struct car* current = s->tracks[i];
        printf("[%d]: ", i);
        while (current != NULL) {
            printf("%s (%d) -> ", current->value, current->capacity);
            current = current->next;
        }
        printf("NULL\n");
    }
    printf("<<<station\n");
}

void destroy_station(struct station* s) {
    if (!s) return;

    for (int i = 0; i < s->track_count; i++) {
        struct car* current = s->tracks[i];
        while (current != NULL) {
            struct car* to_delete = current;
            current = current->next;
            free(to_delete);
        }
    }

    free(s->tracks)
    free(s);
}