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

#define EXPECTED_ARGUMENTS 3
#define PROGRAM_FILE 0
#define INPUT_FILE 1
#define OUTPUT_FILE 2
#define EXPECTED_INPUT 1
#define READING 1
#define ERROR_CODE 1
#define OK_CODE 0
#define MAX_STRING_LEN 256
#define SCAN_MAX_LEN 255
#define SCAN_FORMAT_LEN 16
#define IS_EQUAL 0
#define INDEX_OFFSET 1
#define BASE_TEN 10

#define TYPE_SHORT 1
#define TYPE_INTEGER 2
#define TYPE_FLOAT 3
#define TYPE_CHAR 4
#define TYPE_STRING 5

#define NEWLINE '\n'
#define VALUE_SEPARATOR ','
#define NULL_TERMINATOR '\0'
#define SENTINEL_STRING "E"

char A_NUMBER[] = "A01385066";

typedef struct NODE
{
    void        *data;
    struct NODE *next;
} NODE;

void insertNode(NODE **head, void *data)
{
    NODE *node;

    node = malloc(sizeof(NODE));
    node->data = data;
    node->next = *head;
    *head = node;
}

void freeList(NODE *head)
{
    NODE *temp;

    while (head != NULL)
    {
        temp = head;
        head = head->next;
        free(temp->data);
        free(temp);
    }
}

int compare(void *a, void *b, int type)
{
    if (type == TYPE_SHORT)
    {
        short va;
        short vb;

        va = *(short *)a;
        vb = *(short *)b;

        return (va > vb) - (va < vb);
    }

    if (type == TYPE_INTEGER)
    {
        int va;
        int vb;

        va = *(int *)a;
        vb = *(int *)b;

        return (va > vb) - (va < vb);
    }

    if (type == TYPE_FLOAT)
    {
        float va;
        float vb;

        va = *(float *)a;
        vb = *(float *)b;

        return (va > vb) - (va < vb);
    }

    if (type == TYPE_CHAR)
    {
        char va;
        char vb;

        va = *(char *)a;
        vb = *(char *)b;

        return (va > vb) - (va < vb);
    }

    return strcmp((char *)a, (char *)b);
}

NODE* split(NODE *head)
{
    NODE *fast;
    NODE *slow;
    NODE *second;

    fast = head;
    slow = head;

    while (fast != NULL && fast->next != NULL)
    {
        fast = fast->next->next;
        if (fast != NULL)
        {
            slow = slow->next;
        }
    }

    second = slow->next;
    slow->next = NULL;

    return second;
}

NODE* merge(NODE *first, NODE *second, int type)
{
    if (first == NULL)
    {
        return second;
    }

    if (second == NULL)
    {
        return first;
    }

    if (compare(first->data, second->data, type) <= IS_EQUAL)
    {
        first->next = merge(first->next, second, type);
        return first;
    }

    second->next = merge(first, second->next, type);
    return second;
}

NODE* mergeSort(NODE *head, int type)
{
    NODE *second;

    if (head == NULL || head->next == NULL)
    {
        return head;
    }

    second = split(head);
    head = mergeSort(head, type);
    second = mergeSort(second, type);

    return merge(head, second, type);
}

NODE* readFile(char *filepath, int *type, int *count)
{
    FILE  *file;
    NODE  *head;
    int    ch;
    size_t size;

    file = fopen(filepath, "r");
    if (file == NULL)
    {
        return NULL;
    }

    if (fscanf(file, "%d", type) != EXPECTED_INPUT)
    {
        fclose(file);
        return NULL;
    }

    ch = fgetc(file);
    while (ch != NEWLINE && ch != EOF)
    {
        ch = fgetc(file);
    }

    head = NULL;
    *count = 0;

    size = MAX_STRING_LEN;
    if (*type == TYPE_SHORT)
    {
        size = sizeof(short);
    }
    else if (*type == TYPE_INTEGER)
    {
        size = sizeof(int);
    }
    else if (*type == TYPE_FLOAT)
    {
        size = sizeof(float);
    }
    else if (*type == TYPE_CHAR)
    {
        size = sizeof(char);
    }

    while (READING)
    {
        char  buffer[MAX_STRING_LEN];
        char  scanFormat[SCAN_FORMAT_LEN];
        void *data;
        char *end;
        long  longValue;
        float floatValue;
        int   scanResult;

        data = malloc(size);
        if (data == NULL)
        {
            fclose(file);
            freeList(head);
            return NULL;
        }

        scanResult = snprintf(scanFormat, SCAN_FORMAT_LEN, "%%%d[^,\n]", SCAN_MAX_LEN);
        if (scanResult < 0)
        {
            free(data);
            fclose(file);
            freeList(head);
            return NULL;
        }

        if (fscanf(file, scanFormat, buffer) != EXPECTED_INPUT)
        {
            free(data);
            break;
        }

        if (strcmp(buffer, SENTINEL_STRING) == IS_EQUAL)
        {
            free(data);
            break;
        }

        if (*type == TYPE_SHORT)
        {
            longValue = strtol(buffer, &end, BASE_TEN);
            if (*end != NULL_TERMINATOR || longValue < SHRT_MIN || longValue > SHRT_MAX)
            {
                free(data);
                fclose(file);
                freeList(head);
                return NULL;
            }
            *(short *)data = (short)longValue;
        }
        else if (*type == TYPE_INTEGER)
        {
            longValue = strtol(buffer, &end, BASE_TEN);
            if (*end != NULL_TERMINATOR || longValue < INT_MIN || longValue > INT_MAX)
            {
                free(data);
                fclose(file);
                freeList(head);
                return NULL;
            }
            *(int *)data = (int)longValue;
        }
        else if (*type == TYPE_FLOAT)
        {
            floatValue = strtof(buffer, &end);
            if (*end != NULL_TERMINATOR)
            {
                free(data);
                fclose(file);
                freeList(head);
                return NULL;
            }
            *(float *)data = floatValue;
        }
        else if (*type == TYPE_CHAR)
        {
            if (strlen(buffer) != INDEX_OFFSET)
            {
                free(data);
                fclose(file);
                freeList(head);
                return NULL;
            }
            *(char *)data = buffer[0];
        }
        else
        {
            strncpy((char *)data, buffer, MAX_STRING_LEN);
            ((char *)data)[MAX_STRING_LEN - INDEX_OFFSET] = NULL_TERMINATOR;
        }

        insertNode(&head, data);
        (*count)++;

        ch = fgetc(file);
        if (ch == EOF)
        {
            break;
        }
        if (ch == NEWLINE)
        {
            continue;
        }
    }

    fclose(file);
    return head;
}

void printValue(FILE *file, void *data, int type)
{
    if (type == TYPE_SHORT)
    {
        fprintf(file, "%hd", *(short *)data);
        return;
    }

    if (type == TYPE_INTEGER)
    {
        fprintf(file, "%d", *(int *)data);
        return;
    }

    if (type == TYPE_FLOAT)
    {
        fprintf(file, "%.1f", *(float *)data);
        return;
    }

    if (type == TYPE_CHAR)
    {
        fprintf(file, "%c", *(char *)data);
        return;
    }

    fprintf(file, "%s", (char *)data);
}

void writeOutput(char *filepath, NODE *head, int type, int isError)
{
    FILE *file;

    file = fopen(filepath, "w");
    if (file == NULL)
    {
        return;
    }

    if (isError == ERROR_CODE)
    {
        fputs("Error\n", file);
        fclose(file);
        return;
    }

    while (head != NULL)
    {
        printValue(file, head->data, type);
        if (head->next != NULL)
        {
            fputc(VALUE_SEPARATOR, file);
        }
        head = head->next;
    }

    fputc(NEWLINE, file);
    fclose(file);
}

int main(int argc, char *argv[])
{
    NODE *head;
    int   type;
    int   count;

    if (argc < EXPECTED_ARGUMENTS)
    {
        printf("Usage: %s <input_file> <output_file>\n", argv[PROGRAM_FILE]);
        return 1;
    }

    head = readFile(argv[INPUT_FILE], &type, &count);

    if (head == NULL)
    {
        writeOutput(argv[OUTPUT_FILE], head, type, ERROR_CODE);
        return 1;
    }

    head = mergeSort(head, type);
    writeOutput(argv[OUTPUT_FILE], head, type, OK_CODE);
    freeList(head);

    return 0;
}