#include "usg_common.h"
#include "usg_typedef.h"
#include <sys/file.h>
#include <fcntl.h>

int open_file(char *filename) {
	int fd = open(filename, O_CREAT | O_APPEND | O_RDWR , FILE_MODE);
	return fd;
}

void write_to_file_with_no_lock(int fd, int start, int end) {
	int i;
	char buf[1024];
	for(i = start;  i< end; i++) {
		sprintf(buf, "%d\n", i);
		if (write(fd,  buf,  strlen(buf)) == -1) {
			 err_exit(errno, "write_to_file");
		}

	}

}

void write_to_file_with_lock(int fd, int start, int end) {
	int i;
	char buf[1024];
	for(i = start; i< end; i++) {
		sprintf(buf, "%d\n", i);

		if (flock(fd , LOCK_EX) == -1) {
			err_exit(errno, "LOCK_EX");
		}
		if (write(fd,  buf,  strlen(buf)) == -1) {
			 err_exit(errno, "write_to_file");
		}
		if (flock(fd, LOCK_UN) == -1)
			err_exit(errno, "LOCK_UN");

	}

}


void write_to_file(int fd, int start, int end) {
	
	write_to_file_with_no_lock(fd, start, end);
	//write_to_file_with_lock(fd, start, end);
}

void read_from_file(int fd) {
	lseek(fd, 0, SEEK_SET);
	char buf[1024];
	while(read( fd,   buf,  1024) > 0) {
		printf("%s", buf);
	}

}

int main() {
	int fd = open_file("test.txt");
	int status, i = 0, processors = 4, scale = 100;
	pid_t productors[processors], consumers[processors];
	pid_t pid;

	fd = open_file("stand.txt");
	write_to_file_with_no_lock(fd, 0,  processors * scale);
	read_from_file(fd);

	for ( i = 0; i < processors; i++) {
		if ((productors[i] = fork()) == 0)     /* Child runs user job */
		{
		   fd = open_file("test.txt");
		   int start = i * scale, end = i * scale + scale;
		   printf("======start=%d, end=%d\n", start, end);
		   write_to_file(fd, start, end);
		   sleep(1);
		   exit(0);
		}
	}


	// for ( i = 0; i < processors; i++) {
	// 	if ((consumers[i] = fork()) == 0)     /* Child runs user job */
	// 	{
			    
	// 	   // char cmd[1000];
	// 	   // char  *argv[] = {"productor", start, end, NULL };
	// 	    const char *cmd = "./consumer  >> c.txt";
	// 		if (execl("/bin/bash", "bash", "-c", cmd, 0) < 0)
	// 	    {
	// 	        err_exit(errno, "consumers execve");
	// 	    }
	// 	}
	// }

	while ((pid = waitpid(-1, &status, 0)) > 0) {
		if(WIFEXITED(status)) {
			//fprintf(stderr, "child %d terminated normally with exit status=%d\n", pid, WEXITSTATUS(status));
		}else
			fprintf(stderr, "child %d terminated abnormally\n", pid);
	}

	if (errno != ECHILD)
		perror("waitpid error");

	close(fd);
}