/* 
 * echoserver.c - A sequential echo server 
 */

#include "csapp.h"
void echo(int connfd);		/* defined below */
void echo2(int connfd);         /* defined below */

int main(int argc, char **argv) 
{
    int listenfd, connfd, port, clientlen=sizeof(struct sockaddr_in);
    struct sockaddr_in clientaddr;

    if (argc != 2) {
	fprintf(stderr, "usage: %s <port>\n", argv[0]);
	exit(0);
    }
    port = atoi(argv[1]);

    listenfd = Open_listenfd(port);
    while (1) {
	connfd = Accept(listenfd, (SA *) &clientaddr, &clientlen);
	echo2(connfd);    /* Service client */
	Close(connfd);   /* Close connection with client */
    }
}

/*
 * echo - read, reverse and echo text lines until client closes connection
 * Solution to Exercise 6
 */
void echo(int connfd)
{
    size_t n;
    int i1, i2;
    char buf[MAXLINE]; 
    char tmp;
    rio_t rio;
    
    Rio_readinitb(&rio, connfd);
    while(1) {
        n =  Rio_readlineb(&rio, buf, MAXLINE);
        if(n <= 0) break;
        i1 = 0; i2 = n-2;  /* indices to first and last character */
        while (i1 <= i2)
        {
      	    tmp = buf[i1];
            buf[i1] = buf[i2];
            buf[i2] = tmp;
            i1++; i2--;
        }
        printf("server received %d bytes [%s]\n", n, buf);
        Rio_writen(connfd, buf, n);
    }
} 


/*
 * echo2 - read, concatenate and echo pairs of text lines until client closes connection
 * Solution to Exercise 7
 */
void echo2(int connfd) 
{
    size_t n1, n2; 
    char buf[2*MAXLINE];
    char buf2[MAXLINE]; 
    rio_t rio;

    Rio_readinitb(&rio, connfd);
    while(1) {
        n1 =  Rio_readlineb(&rio, buf, MAXLINE);
        if(n1 <= 0) break;
        
        /* Discard the end of line character '\n' */
        n1--;
        buf[n1] = 0;	   

        /* Inform the server that the client is ready for the next string */
        Rio_writen(connfd, "Next string, please\n", strlen("Next string, please\n"));

        n2 =  Rio_readlineb(&rio, buf2, MAXLINE);    
        if(n2 <= 0) break;

        /* Concatenate the two strings and write the result back to the client */
        strcat(buf, buf2);   
        Rio_writen(connfd, buf, n1+n2);
        printf("Server received %d bytes [%s]\n", n1+n2, buf);
    }
}