/**
 * client.c: 	client program which talks to the stasher.c RAM file servers
 *		and allows user to send commands for processing.
 *
 * author:	Bon Adriel Aseniero
 *		base code provided by TA, Ali Abedi		
 */

#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h> 

#define MAX_BUFFER_SIZE	1048576

/** 
 * Prints an error message and exits
 * char *msg	a pointer to the char array containing the error message
 */
void error( char *msg )
{
	perror( msg );
	exit( 0 );
}

/**
 * Checks if the given command is valid or not
 * returns 1 if valid otherwise 0
 */
int isValidCommand( char *cmd )
{
	int flag = 0;

	if ( 	strncmp( cmd, "LIST", 4 ) 	== 0 || 
		strncmp( cmd, "DONE", 4 ) 	== 0 || 
		strncmp( cmd, "EXIT", 4 ) 	== 0 ||
		strncmp( cmd, "STASH", 5 )	== 0 ||
		strncmp( cmd, "VIEW", 4 )	== 0 ||
		strncmp( cmd, "REMOVE", 6 )	== 0 )
		flag = 1;
	
	return flag;		
}

int main( int argc, char *argv[] )
{
	int sockfd, portno, n;
	struct sockaddr_in serv_addr;
	struct hostent *server;

	// checking hostname provided
	char buffer[MAX_BUFFER_SIZE];
	if ( argc < 3 ) 
	{
		fprintf( stderr, "usage %s hostname port\n", argv[0] );
		exit( 0 );
	}

	// some socket programming provided by TA
	portno = atoi( argv[2] );
	sockfd = socket( AF_INET, SOCK_STREAM, 0 );
	if ( sockfd < 0 ) 
		error( "ERROR opening socket" );
	server = gethostbyname( argv[1] );
	if ( server == NULL ) 
	{
		fprintf( stderr, "ERROR, no such host\n" );
		exit( 0 );
	}

	bzero( (char *) &serv_addr, sizeof( serv_addr ) );
	serv_addr.sin_family = AF_INET;
	bcopy( (char *) server->h_addr, 
		(char *) &serv_addr.sin_addr.s_addr,
		server->h_length);
	serv_addr.sin_port = htons( portno );
	if ( connect( sockfd, &serv_addr, sizeof( serv_addr ) ) < 0 ) 
		error( "ERROR connecting" );

	// While loop ensuring the user can send as much commands as he/she
	// wants until he/she disconnects using the commands DONE or EXIT
	while( 1 )
	{
		// Display prompt
		printf( "Please enter one of the following the commands:\n" );
		printf( "\tSTASH  <file_name>\t[stores a file into the RAM server]\n" );
		printf( "\tLIST\t\t\t[lists all files in the server]\n" );
		printf( "\tVIEW   <file_name>\t[shows the contents of the specified file]\n" );
		printf( "\tREMOVE <file_name>\t[deletes the specified file from server]\n" );
		printf( "\tDONE\t\t\t[closes session but keeps the server running]\n" );
		printf( "\tEXIT\t\t\t[closes session and server]\n:" );
      		
		bzero( buffer, MAX_BUFFER_SIZE );				// set string buffer
		fgets( buffer, MAX_BUFFER_SIZE-1, stdin );			// from user input

		if ( isValidCommand( buffer ) )
		{
			n = write( sockfd, buffer, strlen( buffer ) );		// send the command to the server
			if ( n < 0 ) 
				error( "ERROR writing to socket" );
		
			// If the user uses the EXIT or DONE command, then quit the while loop
			if ( strncmp( buffer, "EXIT", 4 ) == 0 || strncmp( buffer, "DONE", 4 ) == 0 )
				break;

			bzero( buffer, MAX_BUFFER_SIZE );			// clear buffer
			n = read( sockfd, buffer, MAX_BUFFER_SIZE-1 );		// read server response
			if ( n < 0 ) 
				error( "ERROR reading from socket" );

			printf( "%s\n", buffer );				// display server response
		}
		else
			printf( "Invalid Command: %s\n", buffer );
	}
	
	return 0;
}