/* Protocol:
 * 	Format:
 * 		type (1 byte)
 *			next part depends on the type
 *		Client can send:
 *			1.  Report of squirrels
 *				Client sends the type (1) as a byte
 *				Then client sends the number of squirrels observed (32-bit unsigned integer, little endian)
 *			2.  Query
 *				Client sends the type (2) as a byte
 *		Server can send:
 *			3.  An acknowledgement of a report
 *				Server sends the type (3) as a byte
 *			4.  Send total number of squirrels
 *				Server sends the type (4) as a byte
 *				Then server sends the total number of squirrels recorded (32-bit unsigned little-endian integer)
 */

#include<sys/socket.h>
#include<sys/types.h>
#include<netinet/ip.h>
#include<arpa/inet.h>
#include<stdio.h>
#include<unistd.h>
#include<signal.h>

int main(int argc, char ** argv){
	struct sockaddr_in sad;
	sad.sin_port = htons(5143);
	sad.sin_addr.s_addr = INADDR_ANY;
	sad.sin_family = AF_INET;

	int skt = socket(AF_INET, SOCK_STREAM, 0); // Step 1
	if(skt == -1){
		perror("socket");
		return 1;
	}
	if( bind(skt, (struct sockaddr*)(&sad), sizeof(struct sockaddr_in)) ){ // step 2
		perror("bind");
		return 1;
	}
	if( listen(skt, 5) ){ // step 3
		perror("listen");
		return 1;
	}
	uint32_t squirrel_count = 0;
	while(1){
		int client_fd;
		struct sockaddr_in client_address;
		socklen_t address_size = sizeof(struct sockaddr_in);
		client_fd = accept(skt, (struct sockaddr *)(&client_address), &address_size); // step 4
		printf("Connection made from address %s\n", inet_ntoa(client_address.sin_addr));
		uint8_t type = 0; // Same as "unsigned char"
		ssize_t readlen = read(client_fd, &type, 1);
		if(readlen == -1)
			perror("read");
		if(readlen == 0)
			printf("readlen was 0 - client disconnect without sending a type\n");
		if(type == 1){ // A report of squirrels
			uint32_t reported_squirrels; // same as "unsigned" or "unsigned int"
			read(client_fd, &reported_squirrels, 4);
			squirrel_count += reported_squirrels;
			type = 3;
			write(client_fd, &type, 1);
			printf("New squirrel count is %d\n", squirrel_count);
		} else if(type == 2) { // A query for the total
			type = 4;
			write(client_fd, &type, 1);
			write(client_fd, &squirrel_count, 4);
		} else {
			printf("Client sent us type %d\n", type);
		}
		close(client_fd);
	}
	return 0;
}