#define _GNU_SOURCE // sigaction
#include <stdio.h>
#include <stdbool.h>
#include <string.h>
#include <signal.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <dlfcn.h>
#include <errno.h>
#include "http.h"
#include "memory.h"
#include "plugin.h"
#include "util.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;
	}
}


typedef struct Plugin{
	char *name;
	Handler handler;
	struct Plugin *next;
} Plugin;

Plugin *pluginlist=NULL,*pluginlist_last=NULL;

static void plugin_register_callback(const char *name,Handler handler){
	if(pluginlist==NULL){
		pluginlist=pluginlist_last=malloc(1,Plugin);
		pluginlist->name=copy_str(name);
		pluginlist->handler=handler;
		pluginlist->next=NULL;
	} else {
		Plugin *newplugin=malloc(1,Plugin);
		newplugin->name=copy_str(name);
		newplugin->handler=handler;
		newplugin->next=NULL;
		pluginlist_last->next=newplugin;
		pluginlist_last=newplugin;
	}
	printf("Registered plugin '%s' (handler %p)\n",name,handler);
}

typedef void (*register_function)(register_callback_t callback);

static void load_plugin(const char *name){
	void *lib=dlopen(name,RTLD_NOW|RTLD_LOCAL);
	if(lib==NULL){
		fprintf(stderr,"dlopen(%s): %s\n",name,dlerror());
		exit(1);
	}
	register_function regfunc=(register_function)dlsym(lib,"plugin_register_yourself");
	if(regfunc==NULL){
		fprintf(stderr,"Cannot find plugin_register_yourself symbol in library '%s'\n",name);
		exit(1);
	}
	regfunc(&plugin_register_callback);
}


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

	for(Plugin *pl=pluginlist;pl!=NULL;pl=pl->next){
		switch(pl->handler(sock,headers)){
			case HR_HANDLED:
				printf("Request handled by %s\n",pl->name);
				break;

			case HR_NEXT:
				continue;

			case HR_ERROR:
				printf("Request handler '%s' threw error\n",pl->name);
				break;
		}
		break;
	}
}


int main(int argc,char **argv){
	if(argc==1){
		printf("Loading no plugin files\n");
	} else {
		for(int i=1;i<argc;i++){
			load_plugin(argv[i]);
		}
	}

	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;
	}

	struct sigaction sa;
	sa.sa_handler=signal_handler;
	sigemptyset(&sa.sa_mask);
	sa.sa_flags=SA_RESTART;
	if(sigaction(SIGCHLD,&sa,NULL)<0){
		perror("sigaction");
		return 1;
	}

	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);
	}
}