#include <stdio.h>
#include <stdbool.h>
#include <string.h>
#include <stdlib.h>
#include <ctype.h>

#define SPLIT_TO_GIVEN_SIZE     0x01    // split into SPLIT_TO_GIVEN_SIZE with given size -s
#define SPLIT_TO_GIVEN_NUMBER   0x02    // split into given number of parts -n
#define ERROR                   0xFF    // error

typedef struct
{
    char* inputFileName;
    char* outputFileTemplate;
    int commandCode;
    int parameter;
} inputStruct;

inputStruct parseInput(int argc, char *argv[]);
int stringToInt(char* str);
int getCountsOfDigits(int number);
long int sizeOfFile(FILE* fp);
char* itos(int num);
void createFileName(char* base, int fileNumber, char **pname);
int spliToGivenSize(inputStruct input, FILE* fp);

int main (int argc, char *argv[])
{

    inputStruct input = parseInput(argc, argv);
    FILE* fp;

    if(input.commandCode == ERROR)
    {
        printf("Input error\n");
        return -99;
    }
    else if(input.commandCode == SPLIT_TO_GIVEN_SIZE)
    {
        printf("given size of part: %i\n", input.parameter);

        fp = fopen(input.inputFileName, "rb");
        if(fp == NULL)
        {
            printf("No such file: %s\n", input.inputFileName);
            return -97;
        }

        spliToGivenSize(input, fp);
    }
    else if(input.commandCode == SPLIT_TO_GIVEN_NUMBER)
    {
        printf("given number of parts: %i\n", input.parameter);

        fp = fopen(input.inputFileName, "rb");
        if(fp == NULL)
        {
            printf("No such file: %s\n", input.inputFileName);
            return -97;
        }
        long int fileSize = sizeOfFile(fp);
        unsigned int numOfParts = input.parameter;
        int indexOfLastFile = 0;

        if(fileSize >= numOfParts)
            input.parameter = fileSize / numOfParts;
        else
            {
                printf("Input error\n");
                return 0;
            }

        indexOfLastFile = spliToGivenSize(input, fp);

        if(fileSize < numOfParts)
        {
            unsigned int i;
            char* name;
            FILE* nano;
            for(i = indexOfLastFile + 1; i <= numOfParts; i++)
            {
                createFileName(input.outputFileTemplate, i, &name);
                nano = fopen(name, "wb");
                putc('\n', nano);
                fclose(nano);
            }
            free(name);

            printf("%i empty files was added\n", numOfParts - indexOfLastFile);
        }
    }
    else
    {
        printf("Unknown parse error\n");
        return -98;
    }

    fclose(fp);

    return 0;
}

inputStruct parseInput(int argc, char *argv[])
{
    inputStruct input;

    input.commandCode = 0;
    input.inputFileName = '\0';
    input.outputFileTemplate = '\0';
    input.parameter = 0;

    if(argc != 6)
    {
        input.commandCode = ERROR;
        return input;
    }

    input.inputFileName = argv[1];

    char* arg2 = argv[2];
    if(strlen(arg2) != 2 || arg2[0] != '-')
    {
        input.commandCode = ERROR;
        return input;
    }
    else if(arg2[1] == 'b')
    {
        input.outputFileTemplate = argv[3];
    }
    else if(arg2[1] == 'n')
    {
        int parametr = stringToInt(argv[3]);

        if((bool)parametr)
            input.commandCode = SPLIT_TO_GIVEN_NUMBER;
        else
            input.commandCode = ERROR;

        input.parameter = parametr;
    }
    else if(arg2[1] == 's')
    {
        int parametr = stringToInt(argv[3]);

        if((bool)parametr)
            input.commandCode = SPLIT_TO_GIVEN_SIZE;
        else
            input.commandCode = ERROR;

        input.parameter = parametr;
    }
    else
    {
        input.commandCode = ERROR;
        return input;
    }

    char* arg4 = argv[4];
    if(strlen(arg4) != 2 || arg2[0] != '-')
    {
        input.commandCode = ERROR;
        return input;
    }
    else if(arg4[1] == 'b')
    {
        if(input.outputFileTemplate == '\0')
            input.outputFileTemplate = argv[5];
        else
            input.commandCode = ERROR;
    }
    else if(arg4[1] == 'n')
    {
        int parametr = stringToInt(argv[5]);

        if((bool)parametr == true)
        {
            if(input.commandCode == 0)
                input.commandCode = SPLIT_TO_GIVEN_NUMBER;
        }
        else
            input.commandCode = ERROR;

        input.parameter = parametr;
    }
    else if(arg4[1] == 's')
    {
        int parametr = stringToInt(argv[5]);

        if((bool)parametr == true)
        {
            if(input.commandCode == 0)
                input.commandCode = SPLIT_TO_GIVEN_SIZE;
        }
        else
            input.commandCode = ERROR;

        input.parameter = parametr;
    }
    else
    {
        input.commandCode = ERROR;
        return input;
    }

    return input;
}

int stringToInt(char* str)
{
    bool valid = true;

    unsigned int i;
    for(i = 0; i < strlen(str); i++)
        valid &= (bool)isdigit(str[i]);

    if(valid)
        return atoi(str);

    return 0;
}

int getCountsOfDigits(int number)
{
    int coun;
    if (number==0)
        coun = 1;
    else
        coun= 0;
    while (number != 0) {
        coun++;
        number /= 10;
    }
    return coun;
}

long int sizeOfFile(FILE* fp)
{
    long int siz;
    fseek(fp, 0, SEEK_END);
    siz = ftell(fp);
    rewind(fp);

    return siz;
}

char* itos(int num)
{
    int digits = getCountsOfDigits(num);
    char* result = malloc((digits + 1) * sizeof(char));

    if(result == NULL)
        return result;

    sprintf(result, "%d", num);
    return result;
}

void createFileName(char* base, int fileNumber, char **pname)
{
    *pname = (char*)malloc((strlen(base) + strlen("_") + strlen(itos(fileNumber)) + strlen(".txt") + 1) * sizeof(char));

    strcpy(*pname, base);
    strcat(*pname,"_");
    strcat(*pname, itos(fileNumber));
    strcat(*pname,".txt");
}

int spliToGivenSize(inputStruct input, FILE* fp)
{
    int outFileIndex = 1, n = 0;
    char box;
    int filesize = sizeOfFile(fp), del=-88;
    char* name;

    if (filesize < input.parameter)
    {
        printf("Input error\n");
        return -99;
    }

    createFileName(input.outputFileTemplate, outFileIndex, &name);
    FILE* nano = fopen(name, "wb");
    box = getc(fp);
    if (input.commandCode == SPLIT_TO_GIVEN_NUMBER)
    {
         del = filesize/input.parameter;
    }

    while(box != EOF)
    {
        putc(box, nano);
        n++;
        if(n == input.parameter)
        {
            fclose(nano);
            free(name);
            outFileIndex++;
            n = 0;
            createFileName(input.outputFileTemplate, outFileIndex, &name);
        }

        box = getc(fp);

        if(box != EOF && n == 0)
            nano = fopen(name, "wb");

        if (del>0 && outFileIndex == del+1 )
        {
            fclose(nano);
            createFileName(input.outputFileTemplate, outFileIndex, &name);
            nano = fopen(name, "wb");
            while ((box != EOF))
            {
                putc(box, nano);
                box = getc(fp);
            }
            fclose(nano);
            free(name);
            printf("%i files was created!\n", outFileIndex);
            return outFileIndex;
        }
    }
    if(n != 0)
        fclose(nano);

    printf("%i files was created!\n", outFileIndex);

    free(name);

    return outFileIndex;
}