#define _GNU_SOURCE
#include <stdio.h>
#include <stdbool.h>
#include <stdarg.h>
#include <string.h>
#include <signal.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <errno.h>
#include "http.h"
#include "memory.h"


#define PORT 8080


int num_threads=0;


static void signal_handler(int sig){
	if(sig==SIGCHLD){
		int saved_errno=errno;
		while(true){
			int status;
			pid_t pid=waitpid(-1,&status,WNOHANG);
			if(pid<=0){
				break;
			}
			if(WIFEXITED(status)){
				num_threads--;
			}
		}
		errno=saved_errno;
	}
}


// Returns -1 on error, 0 on success
static int sendall(int sock,const char *buf,ssize_t len){
	if(len==-1){
		len=strlen(buf);
	}

	ssize_t sent=0;
	while(sent<len){
		ssize_t ret=send(sock,buf+sent,len-sent,0);
		if(ret<0){
			if(errno==EINTR){
				continue;
			} else {
				return -1;
			}
		}
		sent+=ret;
	}

	return 0;
}

__attribute__((format (printf, 2, 3)))
static int sendallf(int sock,const char *format,...){
	va_list ap;
	va_start(ap,format);
	char *buf;
	int len=vasprintf(&buf,format,ap);
	va_end(ap);
	if(len<0){
		return -1;
	}
	int ret=sendall(sock,buf,len);
	free(buf);
	return ret;
}

static void connection_handler(int sock){
	Headers *headers=http_get_headers(sock);
	if(headers==NULL){
		return;
	}

	sendall(sock,"HTTP/1.1 200 OK\r\n"
	             "Content-Type: text/plain; charset=UTF-8\r\n"
	             "Server: cserver\r\n"
	             "\r\n",-1);

	sendallf(sock,"Method: %s\n",headers->method);
	sendallf(sock,"URL: %s\n",headers->url);
	sendallf(sock,"Version: %s\n",headers->version);
	for(int i=0;i<headers->nheaders;i++){
		sendallf(sock,"Header '%s': '%s'\n",headers->headers[i][0],headers->headers[i][1]);
	}
}


int main(void){
	int sock=socket(PF_INET,SOCK_STREAM,0);
	if(sock<0){
		perror("socket");
		return 1;
	}

	int one=1;
	if(setsockopt(sock,SOL_SOCKET,SO_REUSEADDR,&one,sizeof(int))<0){
		perror("setsockopt");
		return 1;
	}

	struct sockaddr_in sin;
	sin.sin_family=AF_INET;
	sin.sin_addr.s_addr=htonl(INADDR_ANY);
	sin.sin_port=htons(PORT);

	if(bind(sock,(struct sockaddr*)&sin,sizeof(sin))<0){
		close(sock);
		perror("bind");
		return 1;
	}

	if(listen(sock,8)<0){
		perror("listen");
		return 1;
	}

	signal(SIGCHLD,signal_handler);

	printf("Listening on port %d\n",PORT);

	while(true){
		struct sockaddr_storage client_addr;
		socklen_t client_addr_sz=sizeof(client_addr);
		int clientsock=accept(sock,(struct sockaddr*)&client_addr,&client_addr_sz);
		if(clientsock<0){
			perror("accept");
			continue;
		}

		char str[INET_ADDRSTRLEN];
		inet_ntop(client_addr.ss_family,&((struct sockaddr_in*)&client_addr)->sin_addr,
		          str,sizeof(str));

		pid_t pid=fork();
		if(pid==0){
			close(sock);
			connection_handler(clientsock);
			close(clientsock);
			exit(0);
		}
		if(pid<0){
			perror("fork");
			return 1;
		}
		num_threads++;
		printf("Accept from %s; child pid %d, %d thread%s\n",str,pid,num_threads,
		       num_threads==1?"":"s");
		close(clientsock);
	}
}