#include "INET1.h"
#include <string.h>
#include <curses.h>
//#include <alloc.h>
#include <stdlib.h>
#include<unistd.h>


struct character
{
char ch;
struct character *next;
};


struct message
{
int length;
struct message * down;
struct character *next;
};

struct userpass
{
 char name[20];
 char pass[20];
}up[4];
//struct userpass abc[4];

strcpy(up[0].name,"sirish");
/*up[0].pass="sjce";
up[1].name="varun";
up[1].pass="sjce";
up[2].name="satish";
up[2].pass="sjce";
up[3].name="abhi";
up[3].pass="sjce";*/


typedef struct message MESS;
typedef struct character CHAR;


MESS *Head,*lastmess;
CHAR *lastchar;


/* this part is for the handling of the database management*/

void createdatabase()
{
FILE * f;
char ch,word[5];
int i,comp=0;
int k,z;

void addcharacter(char);
void addmessage();
void display();
int countmessage();
int sizeofeachmessage();
int sizeofdata();

Head=(MESS *)malloc(sizeof(MESS));
Head->next=NULL;
Head->down=NULL;

f=fopen("./root1","r");

lastmess=Head;


if(f==NULL)
printf("EROOR WHILE OPENING THE FILE");
else
{
while((ch=fgetc(f))!=EOF)
{
	i=0;
	printf("%c",ch);
	word[i++]=ch;

	while(ch!='\n'&&ch!=EOF)
	{
	ch=fgetc(f);
	printf("%c",ch);

	if(i<4)
	{
		word[i++]=ch;
	}
	else if (i<5)
	{
		word[i]='\0';

			if(strcmp(word,"From")==0)
			{

			if(comp==0)
			{
			printf("new mail starting");
			lastchar=NULL;
			addmessage();
			}

			if(comp==1)
			comp=0;
			else if(comp==0)
			comp=1;

			}//end of word comparison
		i=10;
		addcharacter(word[0]);
		addcharacter(word[1]);
		addcharacter(word[2]);
		addcharacter(word[3]);

	}//END OF ELSE IS IT IS NOT WORD
	else
	{
	addcharacter(ch);
	}
	}//END OF WHILE FOR END OF NEW LINE
}
}
fclose(f);
}


void addcharacter(char ch)
{
CHAR *newchar;

newchar=(CHAR *) malloc(sizeof(CHAR));

if(newchar==NULL)
printf("error in creating character\n");

newchar->ch=ch;
newchar->next=NULL;

if((lastmess->next)==NULL)
lastmess->next=newchar;
else
lastchar->next=newchar;

lastchar=newchar;
}


void addmessage()
{
MESS *newmess;
newmess=(MESS *) malloc(sizeof(MESS));
newmess->next=NULL;
newmess->down=NULL;

lastmess->down=newmess;

lastmess=newmess;
}

/*
void display(int num)
{
MESS *Mtemp;
CHAR *Ctemp;

Mtemp=Head;
int count=1;
while(count<num)
{
 count++;
	Mtemp=Mtemp->down;
}	
Ctemp=Mtemp->next;
while(Ctemp!=NULL)
	{
		strcat(buffer,Ctemp->ch);
		//printf("%c",Ctemp->ch);
		Ctemp=Ctemp->next;
	}
	
	
}
*/

int countmessage()
{
MESS * temp;
int count=0;
temp=Head;
while(temp!=NULL)
{
if(temp->next!=NULL)
count++;
temp=temp->down;
}
return(count);
}

int sizeofeachmessage(int messageno)
{
MESS * temp;
CHAR *temp1;
int count=0,i;
temp=Head;

for(i=1;i<=messageno;i++)
{
if(temp==NULL)
return(0);
else
temp=temp->down;
}

temp1=temp->next;

while(temp1!=NULL)
{
count++;
temp1=temp1->next;
}
return(count);
}

int sizeofdata()
{
int nomess,size,total=0,i;
int countmessage();
int sizeofeachmessage(int);

nomess=countmessage();

for(i=1;i<=nomess;i++)
{
size=sizeofeachmessage(i);
total+=size;
}
return(total);
}

/*end of the database management */

/*this section is to findout wheater there is list number in message*/

int findlistnumber(char buffer[])
{
int num=0;
char val[5];
int i,j;

i=5;
j=0;

if(buffer[i]=='\0')
return(0);

while(1)
{
	if(buffer[i]=='\0')
	break;
	else
	val[j++]=buffer[i++];
}

i=1;

j--;

while(j>=0)
{
num=(val[j--]-48)*i;
i=i*10;
}

return(num);

}

/*end of this section to findout wherther there is a list number*/

/*this section is for to handle the list command*/

void handleLIST(int sockfd, char buffer[])
{
int i,j,msgno,total;
char data[512];

msgno=findlistnumber(buffer);

printf("The list no is %d",msgno);

if(msgno!=0)
{
	if(msgno>countmessage())
	{
	writedata(sockfd,"-ERR SUCH MESSAGE NO DOES NOT EXIST");
	}
	else
	{
	memset((void *)data,'\0',512);

	strcpy(data,"+OK ");
	addinteger(msgno,data);
	strcat(data," ");
	addinteger(sizeofeachmessage(msgno),data);

	writedata(sockfd,data);
	}
}
else
{
	total=countmessage();

	memset((void *)data,'\0',512);

	strcpy(data,"+OK ");
	addinteger(total,data);
	strcat(data," messages (");
	addinteger(sizeofdata(),data);
	strcat(data," octets)" );

	writedata(sockfd,data);

	for(i=1;i<=total;i++)
	{
		memset((void *)data,'\0',512);

		addinteger(i,data);
		strcat(data," ");
		addinteger(sizeofeachmessage(i),data);

		writedata(sockfd,data);

	}

	writedata(sockfd,"046.");

}

}

/*end of this section which handles the list command*/

void handleRETR(int sockfd, char buffer[])
{
 int i,j,msgno,count,k;
 char data[512];
 MESS *Mtemp;
 CHAR *Ctemp;	 
 msgno=findlistnumber(buffer);
 printf("The msg  no is %d",msgno);
 if((msgno<=0)||(msgno>countmessage()))
  {
         writedata(sockfd,"-ERR SUCH MESSAGE NO DOES NOT EXIST");
  }
      else
        {
         memset((void *)data,'\0',512);
         strcpy(data,"+OK ");
         addinteger(msgno,data);
         strcat(data,"\n");
         //addinteger(sizeofeachmessage(msgno),data);
	 //MESS *Mtemp;
	 //CHAR *Ctemp;

	 Mtemp=Head;
	 count=1;
	 while(count<=msgno)
	 {
		  count++;
		          Mtemp=Mtemp->down;
	 }
	 Ctemp=Mtemp->next;
	 while(Ctemp!=NULL)
	   {
	//	strcat(data,Ctemp->ch);
                k=strlen(data);
		data[k]=Ctemp->ch;
		printf("%c",Ctemp->ch);
		Ctemp=Ctemp->next;
	   }                   
         writedata(sockfd,data);
        }
 
}

void handleDELE(int sockfd,char buffer[])
{
 int i,j,msgno,count;
 char data[512];
 MESS *Mtemp,*Ptemp;
 CHAR *Ctemp,*Dtemp;
 msgno=findlistnumber(buffer);
 printf("The msg  no is %d",msgno);
 if((msgno<=0)||(msgno>countmessage()))
  {
     writedata(sockfd,"-ERR SUCH MESSAGE NO DOES NOT EXIST");
  }
 else
   {
      memset((void *)data,'\0',512);
      strcpy(data,"+OK");
      strcat(data,"\n");
      //addinteger(sizeofeachmessage(msgno),data);
      //MESS *Mtemp;
      //CHAR *Ctemp;
       Ptemp=NULL;
       Mtemp=Head;
       count=1;
       while(count<=msgno)
         {
            count++;
	    Ptemp=Mtemp;
            Mtemp=Mtemp->down;
         }
            
           Ctemp=Mtemp->next;
	    while(Ctemp!=NULL)
	    {
	      //strcat(data,Ctemp->ch);
	      //printf("%c",Ctemp->ch);
	     Dtemp=Ctemp;
	     Ctemp=Ctemp->next;
	     free(Dtemp);
	    }
	    Ptemp->down=(Ptemp->down)->down;
	    free(Mtemp);
	    
	  writedata(sockfd,data);
   }
}

void handleupdate(int sockfd)
{
 FILE *f;
 //int i,j,msgno,count;
 char data[512],ch;
 MESS *Mtemp;
 CHAR *Ctemp;
 f=fopen("./root2","w");
 //msgno=findlistnumber(buffer);
 //printf("The msg  no is %d",msgno);
 /*if((msgno<=0)||(msgno>countmessage()))
 {
   writedata(sockfd,"-ERR SUCH MESSAGE NO DOES NOT EXIST");
 }
 else
 {
 */memset((void *)data,'\0',512);
   strcpy(data,"+OK");
   //addinteger(msgno,data);
  // strcat(data,"\n");
  //addinteger(sizeofeachmessage(msgno),data);
  //MESS *Mtemp;
  //CHAR *Ctemp;
   Mtemp=Head;
   //count=1;
   while((Mtemp)!=NULL)
   {
    Ctemp=Mtemp->next;
     while(Ctemp!=NULL)
    {
     //strcat(data,Ctemp->ch);
    //ch=Ctemp->ch;
     fprintf(f,"%c",Ctemp->ch);
     Ctemp=Ctemp->next;
    }
    Mtemp=Mtemp->down;
  } 
  fclose(f);  
   writedata(sockfd,data);

}




/* this section is for to handle the STAT command */

void handleSTAT(int newsockfd)
{
char buffer[512];

memset((void *)buffer,'\0',512);

strcpy(buffer,"+OK");
strcat(buffer," ");
addinteger(countmessage(),buffer);
strcat(buffer," ");
addinteger(sizeofdata(),buffer);

writedata(newsockfd,buffer);
}
/* end of section for to handle the list command*/

/*THIS SECTION IS FOR TO HANDLE THE NOOP COMMAND*/

void handleNOOP(int newsockfd)
{
char buffer[512];

memset((void *)buffer,'\0',512);

strcpy(buffer,"+OK");

writedata(newsockfd,buffer);

}
/*END OF SESSION TO HANDLE THE NOOP COMMAND*/



main(int argc,char * argv)
{

int i,j,k;
int sockfd,newsockfd=0,clilen,childpid;
struct sockaddr_in cli_addr,serv_addr;


if((sockfd=socket(AF_INET,SOCK_STREAM,0))<0)
	printf("error which creating socket");

bzero((char *) &serv_addr,sizeof(serv_addr));
serv_addr.sin_family =AF_INET;
serv_addr.sin_addr.s_addr=htonl(INADDR_ANY);
serv_addr.sin_port=htons(SERV_TCP_PORT);

if(bind(sockfd,(struct sockaddr *) &serv_addr,sizeof(serv_addr))<0)
	printf("error while binding");

listen(sockfd,5);



for(;;)
{
	clilen=sizeof(cli_addr);

	printf("before accept%d",newsockfd);
//	waddstr(stdscr,"before accept");
	newsockfd=accept(sockfd,(struct sockaddr *) &cli_addr,&clilen);

	printf("after accept%d",newsockfd);

	if(newsockfd<0)
		printf("error while accepting");

	if((childpid=fork())<0)
		printf("error while forking");



	else if(childpid==0)
	{
		int n=-1,i;
		char line[512],buffer[512],ptr[512],data[512],temp[512];

		close(sockfd);
		

		/*this is the initial process of making the database*/
		createdatabase();

		/*end of initial phase*/

/*this is the the first stage 1 indicating that connection has
	been established properly*/
			/*STAGE 1*/

		memset((void *)buffer,'\0',512);

		strcpy(buffer,"+OK  POP3 server ready");

		if(!(write(newsockfd,buffer,sizeof(buffer))))
		printf("eror while writing\n");

/* end of stage 1 for sending the greeting to the client that
	he has successfully connected to the server*/



			/* beging of stage 2*/
	/* This the authorization stage of the process*/


	k=0; //this is to hang on in the loop till a valid thing
			//does not happen

	while(k==0)	//this for username
	{

		readdata(newsockfd,buffer);


		memset((void *)data,'\0',512);

		strncpy(data,buffer,4);
		/*
		 writedata(1,"$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$");
		puts(data);
		writedata(1,"$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$");
                */ 

i=0;
for(j=4;j<strlen(buffer);j++)
{
	 temp[i++]=buffer[j];
}
temp[i]='\0';
if(strcmp(data,"USER")==0)
{ 
 for(i=0;i<4;i++)
  {
    if(strcmp(temp,up[i].name))
     {
       k=1;
        //strcpy(data,"+OK");
       writedata(newsockfd,"+OK");
       break;
     }
  }
}
		/*


			if(strcmp(data,"USER")==0)
			{
			//he has send the username
			writedata(newsockfd,"+OK");
			k=1;
			}
*/
			else
			{

				if(strcmp(data,"QUIT")==0)
				{
				exit(0);
				}
				else
				{
				writedata(newsockfd,"-ERR NO MESSAGE");
				}

			}
} //END OF WHILE LOOP FOR USERNAME

	k=0; //this is to hang on in the loop till a valid thing
			//does not happen

	while(k==0)     //this loop is for password
	{

		readdata(newsockfd,buffer);


		memset((void *)data,'\0',512);

		strncpy(data,buffer,4);
	/*	writedata(1,"$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$");
		puts(data);
		writedata(1,"$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$");



			if(strcmp(data,"PASS")==0)
			{
			//he has send the username
			writedata(newsockfd,"+OK username is valid");
			k=1;
			}
	*/		
	
	i=0;
	for(j=4;j<strlen(buffer);j++)
	{
		 temp[i++]=buffer[j];
	}
	temp[i]='\0';
	if(strcmp(data,"PASS")==0)
	{
	 for(i=0;i<4;i++)
	  {
	    if(strcmp(temp,up[i].pass))
	      {
	           k=1;
	        //strcpy(data,"+OK");
	       writedata(newsockfd,"+OK");
	       break;
	      }
	   }
	}
			else
			{

				if(strcmp(data,"QUIT")==0)
				{
				exit(0);
				}
				else
				{
				writedata(newsockfd,"-ERR NO MESSAGE");
				}

			}
}//END OF WHILE LOOP FOR PASSWORD

	/* end of the stage 2 for the authorization */
			/*end of AUTHORIZATION*/
i=0;		
for(j=4;j<strlen(buffer);j++)
{
 temp[i++]=buffer[j];
} 
temp[i]='\0';
if(strcmp(data,"USER")==0)
{
 for(i=0;i<4;i++)
 { 
  if(strcmp(temp,up[i].name))
   {
	k=1;
       //strcpy(data,"+OK");
       writedata(newsockfd,"+OK");
       break;
   }
 }
} 


//if(strcmp(data,"PASS")==0)
//{

	
	

		/* BEGING OF THE NEXT PHASE i.e TRANSACTION */
			/*STAGE 3*/


		
for(;;)
{
		readdata(newsockfd,buffer); //reading the request from the the client


		memset((void *)data,'\0',512);

		strncpy(data,buffer,4);

			if(strcmp(data,"STAT")==0)
			{
			//SENDING RESPOND FOR stat
			handleSTAT(newsockfd);
			}
			else if(strcmp(data,"NOOP")==0)
			{
			handleNOOP(newsockfd);
			}
			else if(strcmp(data,"LIST")==0)
			{
			handleLIST(newsockfd,buffer);
			}
                        else if(strcmp(data,"RETR")==0)
			{
			handleRETR(newsockfd,buffer);
			} 
                        else if(strcmp(data,"DELE")==0)
			{
			handleDELE(newsockfd,buffer);
		        }	
                        else if(strcmp(data,"UPDT")==0)
		        {
			handleupdate(newsockfd);
		        }
}


	/*END OF THE TRANSACTION PHASE*/
		/*STAGE 3*/


/* this is for testing wheather it is reading or not  */
/*
		printf("The value of n is %d",n);

		strncpy(temp,line,4);

		if(i==1)
		strcpy(ptr,"+OK received1");


		if(i==2)
		strcpy(ptr,"+OK received2");

		write(newsockfd,ptr,512);

		if(strcmp(temp,"USER")==0)
		{
		printf("username is given");
		}
		else if(strcmp(temp,"QUIT")==0)
		{
		printf("he is wishing to quit the terminal");
		}
		else
		{
		printf("it has read %s",temp);
		}

		i++;


/*This is indiacate the end of testing of wheather server is
		reading */



		exit(0);
	}

	close(newsockfd);


}

}