#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>
#include<stdlib.h>
#include<sys/stat.h>
#include<fcntl.h>

#include<thread>
using namespace std;

/* Google AI wrote this */
long getFileSize(const char *filename) {
	struct stat st;
	if (stat(filename, &st) == 0) {
		return st.st_size; // Returns the file size in bytes
	} else {
		perror("Error getting file size"); // Prints error if stat fails
		return -1; // Indicates an error
	}
}

/* Client should send a length of filename, then filename */

void handle_client(int client_fd, struct sockaddr_in client_address){
	int64_t file_size;
	int file_fd;
	char *file_space, *filename;
	printf("Connection made from address %s\n", inet_ntoa(client_address.sin_addr));
	uint16_t filename_length;
	if(2 != recv(client_fd, &filename_length, 2, MSG_WAITALL))
		goto exit;

	filename = (char*)malloc(filename_length + 1);
	filename[filename_length] = 0;
	if(filename_length != recv(client_fd, filename, filename_length, MSG_WAITALL))
		goto exit;

	printf("Opening file \"%s\" for client on fd %d\n", filename, client_fd);
	file_fd = open(filename, O_RDONLY);
	if(file_fd < 0){
		perror("open");
		file_size = -1;
		write(client_fd, &file_size, 8);
		goto exit;
	}

	file_size = getFileSize(filename);

	file_space = (char*)malloc(file_size); // 10 megs
	if(file_size != read(file_fd, file_space, file_size)){
		printf("Error reading file %s\n", filename);
		goto exit;
	}
	free(file_space);
	free(filename);
	close(file_fd);
	// Send file size first
	write(client_fd, &file_size, 8);
	// Then send actual file
	write(client_fd, file_space, file_size);

exit:

	close(client_fd);
}

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;
	}	
	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

		thread client_thread(handle_client, client_fd, client_address);
		client_thread.detach();
	}

	return 0;
}