/***********************************************************
 * Name of program: 
 * Authors: 
 * Description: Starter code for project 4
 **********************************************************/

/* These are the included libraries.  You may need to add more. */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdint.h>
#include <unistd.h>

/* Put any symbolic constants (defines)*/
#define True 1  /* C has no booleans! */
#define False 0
#define MAX_CMD 80

/* These are globals.  You set these values once in the main function
   when the program starts. */    
uint16_t bPerSec = 0;
uint8_t  secPer = 0;
uint16_t resSec = 0;
uint8_t  numFats = 0;
uint32_t fatsz32 = 0;
int fd;
uint32_t root_addr=0;


/********************************************
 * This function displays the image's info
 *******************************************/
void print_info(){
    printf("BPB_BytesPerSec is 0x%x, %i\n",bPerSec, bPerSec);
    printf("BPB_SecPerClus is 0x%x, %i\n",secPer, secPer);
    printf("BPB_RsvdSecCnt is 0x%x, %i\n",resSec, resSec);
    printf("BPB_NumFATs is 0x%x, %i\n",numFats, numFats);
    printf("BPB_FATSz32 is 0x%x, %i\n",fatsz32, fatsz32);

    //TODO: Figure out the root address
    //printf("Root addr is 0x%x\n", root_addr);
    printf("\n");
}


/* This is the main function of your project, and it will be run
 * first before all other functions.
 */
int main(int argc, char *argv[])
{
	char cmd_line[MAX_CMD];

	/* Parse args and open our image file */
	fd = open("fat32.img", O_RDONLY);

	/* Check to see if it opened successfully */
        if(fd == -1) {
	    perror(argv[1]);
            return -1;
	}

	/* Parse boot sector and get information */

	/* Seek to byte 11 in the file */
	lseek(fd,11, SEEK_SET);

	/* Read and store BPB_BytesPerSec for 2 bytes */
	/* Note: use the & when reading into numbers.  You don't need to
         * use it if you are reading into strings. */
	read(fd, &bPerSec,2);
	bPerSec = htole16(bPerSec); // convert to little endian order

	/* Read and store BPB_SecPerClus for 1 bytes */
	read(fd, &secPer,1);

	/* Read and store BPB_RsvdSecCnt for 2 bytes */
	read(fd, &resSec,2);
	resSec = htole16(resSec);

	/* Read and store BPB_NumFATS for 1 bytes */
	read(fd, &numFats,1);

	/* Seek to byte 36 in the file */
	lseek(fd, 36, SEEK_SET);

	/* Read and store BPB_FATSz32 for 4 bytes */
	read(fd, &fatsz32,4);
	fatsz32 = htole32(fatsz32);

	/* Get root directory address */
	// TODO: You will have to do some computations and additional 
	// reads/seeks in the image file to compute the root directory
	// address.  You will also want to seek to the root directory.
        //You will want to do that here.
	// root_addr = ??


	/* Main loop.  You probably want to create a helper function
       for each command besides quit. */
	while(True) {
                /* Zero the command line, just in case */
		bzero(cmd_line, MAX_CMD);

		/* Print the prompt */
		printf("]");

		/* Get input from the user into cmd_line */
		fgets(cmd_line,MAX_CMD,stdin);

		/* Start comparing input */
		if(strncmp(cmd_line,"info",4)==0) {
			print_info();  //TODO: Finish this function!
		}

		else if(strncmp(cmd_line,"volume",6)==0) {
			printf("Not yet implemented.\n\n");
		}

		else if(strncmp(cmd_line,"stat",4)==0) {
			printf("Not yet implemented.\n\n");
		}

		else if(strncmp(cmd_line,"cd",2)==0) {
			printf("Not yet implemented.\n\n");
		}

		else if(strncmp(cmd_line,"ls",2)==0) {
			printf("Not yet implemented.\n\n");
		}

		else if(strncmp(cmd_line,"deleted",7)==0) {
			printf("Not yet implemented.\n\n");
		}

		else if(strncmp(cmd_line,"read",4)==0) {
			printf("Not yet implemented.\n\n");
		}

		else if(strncmp(cmd_line,"quit",4)==0) {
			printf("Quitting.\n\n");
 			break;
		}

		else {
			printf("Unrecognized command.\n\n");
		}

	}

	/* Close the file */
	close(fd);

	return 0; /* Success */
}