#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
#include <errno.h>
#include <stdlib.h>
#include <aio.h>
#include <time.h>


//////////////////////////////////////////////////
///                                            ///
///  Run using either one of these forms:      ///
///                                            ///
///  ./async read filename                     ///
///  ./async write filename                    ///
///                                            ///
///  write makes a copy of the file            ///
///                                            ///
///                                            ///
///  Erman Haskan (2010510036)                 ///
///  2013 - DEU                                ///
///                                            ///
//////////////////////////////////////////////////


#define BUF_SIZE 1024

int main(int argc , char *argv[])
{
    if(argc!=3)
    {
        printf("Need exactly 2 arguments\n");
        exit(1);
    }

    int write;

    if(strncmp(argv[1],"read",4)==0) // READ OPERATION
    {
        write=0;
    }
    else if(strncmp(argv[1],"write",5)==0) // READ + WRITE OPERATION
    {
        write=1;
    }
    else
    {
        printf("Invalid arguments\n");
        exit(1);
    }

    char* fileName=argv[2];

    FILE * fp = fopen(fileName, "r");
    fseek(fp, 0L, SEEK_END);
    int num=ftell(fp)/BUF_SIZE; // NUMBER OF READ/WRITE CYCLES
    fclose(fp);

    char buf[BUF_SIZE];
    int fd,fd2,i;
    struct aiocb aiocb;
    struct aiocb aiocb2;


    if ((fd= open(fileName, O_RDWR | O_EXCL, S_IRUSR | S_IWUSR)) == -1)
    {
        printf(" Error at open(): %s\n", strerror(errno));
        exit(1);
    }

    memset(&aiocb, 0, sizeof(struct aiocb));
    aiocb.aio_fildes = fd;
    aiocb.aio_buf = buf;
    aiocb.aio_nbytes = BUF_SIZE;
    aiocb.aio_lio_opcode = LIO_READ;

    if(write)
    {
        char writeFile[100];
        sprintf (writeFile, "%s Copy", fileName);
        fd2 = open(writeFile, O_CREAT | O_RDWR | O_EXCL, S_IRUSR | S_IWUSR);
        memset(&aiocb2, 0, sizeof(struct aiocb));
        aiocb2.aio_fildes = fd2;
        aiocb2.aio_nbytes = BUF_SIZE;
        aiocb2.aio_buf=buf;
    }


    /////////////////////////////////////////////////// READ/WRITE OPERATION START

    clock_t start=clock();

    for(i=0;i<num;i++)
    {
        aiocb.aio_offset = i*BUF_SIZE;
        if (aio_read(&aiocb) == -1)
        {
            printf("AIO READ ERROR");
            exit(2);
        }
        while (aio_error(&aiocb) == EINPROGRESS);
        aio_return(&aiocb);

        if(write)
        {
            aiocb2.aio_offset = i*BUF_SIZE;
            if (aio_write(&aiocb2) == -1)
            {
                printf("AIO WRITE ERROR");
                exit(2);
            }
            while (aio_error(&aiocb2) == EINPROGRESS);
            aio_return(&aiocb2);
        }
    }

    clock_t end=clock();

    ////////////////////////////////////////////////// READ/WRITE OPERATION END


    printf("%f\n",(float)(end-start) / CLOCKS_PER_SEC);

    close(fd);

    if(write)
    {
        close(fd2);
        printf ("WRITE DONE\n");
    }
    else
    {
        printf ("READ DONE\n");
    }

    return 0;
}