#include "station.h"

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

struct station* create_station() {
    struct station* st = (struct station*)malloc(sizeof(struct station));
    if (st == NULL) {
        return NULL;
    }

    st->tracks = (struct car**)calloc(STATION_SIZE, sizeof(struct car*));
    if (st->tracks == NULL) {
        free(st);
        return NULL;
    }

    st->track_count = STATION_SIZE;
    return st;
}

void destroy_station(struct station* station) {
    int i;

    if (station == NULL) {
        return;
    }

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

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

int select_track(struct station* station, const char* target) {
    unsigned long hash = 5381;
    const unsigned char* ptr;

    if (station == NULL || station->track_count <= 0 || target == NULL) {
        return 0;
    }

    ptr = (const unsigned char*)target;
    while (*ptr != '\0') {
        hash = ((hash << 5) + hash) + *ptr;
        ptr++;
    }

    return (int)(hash % (unsigned long)station->track_count);
}

void add_target_capacity(struct station* station, const char* target, int capacity) {
    int index;
    struct car* current;

    if (station == NULL || station->tracks == NULL || target == NULL) {
        return;
    }

    index = select_track(station, target);
    current = station->tracks[index];

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

    current = (struct car*)malloc(sizeof(struct car));
    if (current == NULL) {
        return;
    }

    strncpy(current->value, target, TARGET_SIZE - 1);
    current->value[TARGET_SIZE - 1] = '\0';
    current->capacity = capacity;
    current->next = station->tracks[index];
    station->tracks[index] = current;
}

int get_target_capacity(struct station* station, const char* target) {
    int index;
    struct car* current;

    if (station == NULL || station->tracks == NULL || target == NULL) {
        return 0;
    }

    index = select_track(station, target);
    current = station->tracks[index];

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

    return 0;
}

int count_targets(struct station* station) {
    int i;
    int count = 0;

    if (station == NULL || station->tracks == NULL) {
        return 0;
    }

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

    return count;
}

int count_capacity(struct station* station) {
    int i;
    int sum = 0;

    if (station == NULL || station->tracks == NULL) {
        return 0;
    }

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

    return sum;
}