/*
 *  Author : WangBoJing , email : 1989wangbojing@gmail.com
 * 
 *  Copyright Statement:
 *  --------------------
 *  This software is protected by Copyright and the information contained
 *  herein is confidential. The software may not be copied and the information
 *  contained herein may not be used or disclosed except with the written
 *  permission of Author. (C) 2017
 * 
 *

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  *   **     *    ***********    *****    *****  **                   ****
  *   **     *        **           **      **    **                 **    **
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  *     **   *        **            **     *     **                *        **
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 *
 */




#include <arpa/inet.h>

#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>

#include <sys/types.h>
#include <sys/sysinfo.h>
#include <sys/syscall.h>

#include <sys/ipc.h>
#include <sys/shm.h>
#include <sys/sem.h>

#include <errno.h>

#include <fcntl.h>
#include <sys/epoll.h>
#include <sys/poll.h>

#define __USE_GNU

#include <sched.h>
#include <string.h>
#include <pthread.h>

#include <ctype.h>

#include "nty_coroutine.h"


#define MAX_CLIENT_NUM			1000000
#define TOTALFDS			16


typedef struct _shm_area {
	int totalfds[TOTALFDS];
	char cpu_lb[TOTALFDS];
	//mtx : default 0
	// 1 : lock -- del epoll
	// 2 : lock -- del complete
	// 3 : unlock -- add
	// 0 : unlock -- add complete
	int accept_mtx;
} shm_area;

static shm_area *global_shmaddr = NULL;
static int global_shmid = -1;

int cpu_size = 0;
int accept_disable = 1000;
int enable_accept = 1;
pid_t self_id = 0;



unsigned long cmpxchg(void *addr, unsigned long _old, unsigned long _new, int size) {
	unsigned long prev;
	volatile unsigned int *_ptr = (volatile unsigned int *)(addr);

	switch (size) {
		case 1: {
			__asm__ volatile (
		        "lock; cmpxchgb %b1, %2"
		        : "=a" (prev)
		        : "r" (_new), "m" (*_ptr), "0" (_old)
		        : "memory");
			break;
		}
		case 2: {
			__asm__ volatile (
		        "lock; cmpxchgw %w1, %2"
		        : "=a" (prev)
		        : "r" (_new), "m" (*_ptr), "0" (_old)
		        : "memory");
			break;
		}
		case 4: {
			__asm__ volatile (
		        "lock; cmpxchg %1, %2"
		        : "=a" (prev)
		        : "r" (_new), "m" (*_ptr), "0" (_old)
		        : "memory");
			break;
		}
	}

	return prev;
}


int atomic_add(volatile int *value, int add)
{
    __asm__ volatile (

         "lock;"
    "    addl  %0, %1;   "

    : "+r" (add) : "m" (*value) : "cc", "memory");

    return add;
}

int atomic_sub(volatile int *value, int sub)
{
    __asm__ volatile (

         "lock;"
    "    subl  %0, %1;   "

    : "+r" (sub) : "m" (*value) : "cc", "memory");

    return sub;
}


#define ISspace(x) isspace((int)(x))

#define SERVER_STRING "Server: ntyco_httpd/0.1.0\r\n"
#define STDIN   0
#define STDOUT  1
#define STDERR  2

#define ENABLE_NTYCO	0

#if ENABLE_NTYCO

#define socket 	nty_socket 
#define accept 	nty_accept 
#define recv(a, b, c, d) 	nty_recv(a, b, c, d)
#define send(a, b, c, d) 	nty_send(a, b, c, d) 

#define MAX_BUFFER_LENGTH	1024



#endif

#define INC_COUNTFD  do {				\
	atomic_add(&global_shmaddr->totalfds[self_id % cpu_size], 1);	\
} while (0)


#define DEC_COUNTFD  do {				\
	atomic_sub(&global_shmaddr->totalfds[self_id % cpu_size], 1);	\
} while (0)

int get_countfd(void) {	
	return global_shmaddr->totalfds[self_id % cpu_size];	
}

int max_countfd(void) {

	int count = -1;
	int i = 0;

	for (i = 0;i < cpu_size;i ++) {
		if (count < global_shmaddr->totalfds[i]) {
			count = global_shmaddr->totalfds[i];
		}
	}
	return count;
}

int min_countfd(void) {

	int count = 0xffffffff;
	int i = 0;

	for (i = 0;i < cpu_size;i ++) {
		if (count > global_shmaddr->totalfds[i]) {
			count = global_shmaddr->totalfds[i];
		}
	}
	return count;
}

int compare_out_countfd(void) {

	int current = get_countfd();
	int min = min_countfd();

	if ((current * 7 / 8) > min) {
		return 1;
	} else {
		return 0;
	}
}

int compare_in_countfd(void) {

	int current = get_countfd();
	int max = max_countfd();

	if ((current * 8 / 7) < max) {
		return 1;
	} else {
		return 0;
	}
}

void print_countfds(void) {

	int i = 0;
	for (i = 0;i < cpu_size;i ++) {
		printf("%5d : %5d ", i, global_shmaddr->totalfds[i]);
	}
	printf("\n");
}

void lock_accept(void) {
	
	global_shmaddr->cpu_lb[self_id % cpu_size] = 1;

	int count = 0xffffffff;
	int i = 0;

	for (i = 0;i < cpu_size;i ++) {
		if (count > global_shmaddr->totalfds[i]) {
			count = global_shmaddr->totalfds[i];
		}
	}

	for (i = 0;i < cpu_size;i ++) {
		if (count == global_shmaddr->totalfds[i]) {
			global_shmaddr->cpu_lb[i] = 3;
		}
	}
	
}

char read_accept(void) {
	return global_shmaddr->cpu_lb[self_id % cpu_size];
}

void write_accept(char state) { //0, 1, 2, 3		
	global_shmaddr->cpu_lb[self_id % cpu_size] = state;
}

int lock(void) {

	return cmpxchg(&global_shmaddr->accept_mtx, 0, 1, 4); //zero:success, non-zero:failed

}

void unlock(void) {

	global_shmaddr->accept_mtx = 0;

}


void accept_request(void *arg);
void bad_request(int);
void cat(int);
void cannot_execute(int);
void error_die(const char *);
void execute_cgi(int, const char *, const char *, const char *);
int get_line(int, char *, int);
void headers(int);
void not_found(int);
void serve_file(int);
int startup(u_short *);
void unimplemented(int);


void accept_request(void* arg)
{
    int client = *(int*)arg;
	
    char buf[1024];
    size_t numchars;
    char method[16];
    char url[32];
    char path[64];
    size_t i, j;
    struct stat st;
    int cgi = 0;      /* becomes true if server decides this is a CGI
                       * program */
    char *query_string = NULL;

	while (1) {
		
		numchars = nty_recv(client, buf, sizeof(buf), 0);
		if (numchars > 0) {
			serve_file(client);
		} else if (numchars == 0) {	
			nty_close(client);
			DEC_COUNTFD;
			break;
		} else if (numchars == -1) {
			if (errno == EAGAIN) {
				continue;
			} 
			nty_close(client);
			DEC_COUNTFD;
			break;
		}
	}

}


#define HTML_PAGE       "<!DOCTYPE html> \
<html> \
<head> \
<title>Welcome to nginx!</title> \
<style> \
    body { \
        width: 35em;\
        margin: 0 auto;\
        font-family: Tahoma, Verdana, Arial, sans-serif;\
    }\
</style>\
</head>\
<body>\
<h1>Welcome to nginx!</h1>\
<p>If you see this page, the nginx web server is successfully installed and\
working. Further configuration is required.</p>\
\
<p>For online documentation and support please refer to\
<a href=\"http://nginx.org/\">nginx.org</a>.<br/>\
Commercial support is available at\
<a href=\"http://nginx.com/\">nginx.com</a>.</p>\
\
<p><em>Thank you for using nginx.</em></p>\
</body>\
</html>"


void error_die(const char *sc)
{
    printf("%s\n", sc);
    exit(1);
}

void headers(int client)
{
    char buf[1024] = {0};
	char content[128] = {0};

	sprintf(buf, "HTTP/1.0 200 OK\r\n");
	strcat(buf, SERVER_STRING);
	strcat(buf, "Content-Type: text/html\r\n");
#if 0
	strcat(buf, "Transfer-Encoding: chunked\r\n");
#else 
	sprintf(content, "Content-Length: %ld\r\n", strlen(HTML_PAGE));
	strcat(buf, content);
#endif 
	strcat(buf, "\r\n");

    strcat(buf, HTML_PAGE);
	
	int ret = nty_send(client, buf, strlen(buf), 0);
    if (ret == -1) {
        printf("send : errno : %d\n", errno);
    } else {
        //printf("headers send ret : %d\n", ret);
    }
    

}

void serve_file(int client)
{
    headers(client);
}

#define MAX_EPOLLSIZE		10240

void server(void *arg) {

	int fd = *(int *)arg;
	
	while (1) {

		struct sockaddr_in client_addr;
		memset(&client_addr, 0, sizeof(struct sockaddr_in));
		socklen_t client_len = sizeof(client_addr);

		if (lock()) {
			nty_coroutine_sleep(0);
			continue;
		}
		
		int clientfd = nty_accept(fd, (struct sockaddr*)&client_addr, &client_len);
		unlock();

		if (clientfd < 0) {
			return ;
		}

		INC_COUNTFD;

		nty_coroutine *read_co;
		int *client_sock = (int *)malloc(sizeof(int));
		*client_sock = clientfd;
		nty_coroutine_create(&read_co, accept_request, client_sock);

		print_countfds();
	}

}

int process_bind(int fd) {

	int num = sysconf(_SC_NPROCESSORS_CONF);

	self_id = syscall(__NR_gettid);
	//printf("selfid --> %d\n", self_id);

	cpu_set_t mask;

	CPU_ZERO(&mask);
	CPU_SET(self_id % num, &mask);

	sched_setaffinity(0, sizeof(mask), &mask);

	nty_coroutine *co = NULL;
	nty_coroutine_create(&co, server, &fd);

	nty_schedule_run();
}

int init_shmvalue(int num) {
	
	global_shmid = shmget(IPC_PRIVATE, sizeof(shm_area), IPC_CREAT|0600);
	if (global_shmid < 0) {
		perror("shmget failed\n");
		return -1;
	}
	global_shmaddr = (shm_area*)shmat(global_shmid, NULL, 0);
	if (global_shmaddr == (shm_area*)-1) {
		perror("shmat addr error");
		return -1;
	}
	memset(global_shmaddr->totalfds, 0, TOTALFDS * sizeof(int));
	memset(global_shmaddr->cpu_lb, 0, TOTALFDS * sizeof(char));
	global_shmaddr->accept_mtx = 0;
}


int main(int argc, char *argv[]) {

    short port = 9001;
	struct sockaddr_in client_name;
	socklen_t  client_name_len = sizeof(client_name);

	int fd = nty_socket(AF_INET, SOCK_STREAM, 0);
	if (fd < 0) return -1;

	struct sockaddr_in local, remote;
	local.sin_family = AF_INET;
	local.sin_port = htons(port);
	local.sin_addr.s_addr = INADDR_ANY;
	bind(fd, (struct sockaddr*)&local, sizeof(struct sockaddr_in));

	listen(fd, 5);

	int num = sysconf(_SC_NPROCESSORS_CONF);
	cpu_size = num;
	init_shmvalue(num);
	
	int i = 0;
	pid_t pid = 0;
	for(i = 0;i < num;i ++) {
		pid = fork();
		if(pid <= (pid_t) 0)
		{
		   usleep(1);
		   break;
		}
  	}

	if (pid > 0) {
		printf("ntyco_httpd server running ...\n");
		getchar();
	} else if (pid == 0) {
		process_bind(fd);
	}

}