#include <unistd.h>
#include <stdio.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <stdlib.h>
#include <stdbool.h>
#include <string.h>
#include <sys/stat.h>
#include <openssl/sha.h>

#include "talk.h"
#include "util.h"

#define PORT 231

#define USERSDIR "./users/"
#define PASSWORDFILE "./passwd"

static int initsocket(struct sockaddr_in address, socklen_t len){
	int s;
	if ((s = socket(AF_INET, SOCK_STREAM, 0)) == -1){
		perror("socket");
		return -1;
	}
	if ((bind(s, (struct sockaddr *)&address, len)) != 0) {
		perror("bind");
		return -1;	
	}

	listen(s, 10);
	return s;
}

static bool checkpasswd(char *username, char *password) {
	char *passwdline, *tok;
	unsigned char hash[SHA_DIGEST_LENGTH];
	FILE *f = fopen(PASSWORDFILE, "r");

	while ((passwdline = readupto(f, ':')) != NULL){
		tok = readnchars(f, 20);
		if (strcmp(passwdline, username) == 0){
			SHA1((unsigned char *)password, 30, hash);
			if (memcmp((char *)hash, tok, 20) == 0){
				free(tok);
				free(passwdline);
				return true;
			} else {
				free(tok);
				free(passwdline);
				return false;
			}
		}
		free(tok);
		free(passwdline);
	}
	return false;
}

int main(){
	struct sockaddr_in address;
	address.sin_family = AF_INET;
	address.sin_addr.s_addr = INADDR_ANY;
	address.sin_port = htons(PORT);
	socklen_t len = sizeof(address);

	int s;
	if ((s = initsocket(address, len)) < 0) return s;

	int client;
	for (;;) {
		if ((client = accept(s, (struct sockaddr *)&address, &len)) == -1){
			perror("accept");
			return 1;
		}

		int size = sizeof(packet);
		packet *buf = malloc(size);
		recv(client, buf, size, 0);

		char *userdir, *tok, *passwdline, *msg;
		unsigned char hash1[SHA_DIGEST_LENGTH], hash2[SHA_DIGEST_LENGTH];
		FILE *f, *fmsg;
		int len;

		switch (buf->type){
			case MSG:
				buf->msg = calloc(1, buf->msglen);
				recv(client, buf->msg, buf->msglen, 0);
				
				if (checkpasswd(buf->username, buf->password) == true){
					if (buf->msg == NULL || strlen(buf->msg) == 0) {
						buf->msg = "(null)";
						goto end;
					}
					userdir = malloc(80);
					snprintf(userdir, 80, "%s%s/%s", USERSDIR, buf->recipient, buf->username);
					fmsg = fopen(userdir, "a+");
					if (fmsg == NULL) goto nosuchuser;
					fprintf(fmsg, "%s\n", buf->msg);
					fclose(fmsg);
					free(userdir);
					goto end;
				} else {
					buf->type = PASSAUTHFAIL;
					goto end;	
				}

nosuchuser:
				buf->type = NOSUCHUSER;
end:
				send(client, buf, size, 0);
				break;
			case GET:
				if (checkpasswd(buf->username, buf->password) == true){
					len = 128;
					userdir = calloc(1, len);
					snprintf(userdir, len, "%s%s/%s", USERSDIR, buf->username, buf->recipient);

					f = fopen(userdir, "r");
					if (f == NULL) {
						buf->type = NEVERMSGED;
						send(client, buf, size, 0);
						break;
					}

					msg = readupto(f, EOF);
					buf->msg = msg;
					buf->msglen = strlen(msg);
					send(client, buf, size, 0);
					send(client, buf->msg, buf->msglen, 0);

					remove(userdir);	

					free(userdir);
					userdir = NULL;
				} else {
					buf->type = PASSAUTHFAIL;
				}
				send(client, buf, size, 0);
				
				break;
			case NEWUSER:
				userdir = calloc(1, strlen(USERSDIR) + strlen(buf->username));
				strcat(userdir, USERSDIR);
				strcat(userdir, buf->username);

				if (mkdir(userdir, 0777) == -1) {
					buf->type = USERMAKEERROR;
				} else {
					buf->type = NEWUSER;
					SHA1((unsigned char *)buf->password, 30, hash1);
					f = fopen(PASSWORDFILE, "a+");
					if (f == NULL) exit(1);
					fprintf(f, "%s:%s\n", buf->username, hash1);
					fclose(f);
					free(userdir);
					userdir = NULL;
				}
				send(client, buf, size, 0);
				break;
			default:
				buf->type = UNKNOWNCMD;
				send(client, buf, size, 0);
				break;
		}

		free(buf->msg);
		free(buf);

		close(client);
	}


	close(s);

	return 0;
}