#include <sys/types.h>
#include <sys/stat.h>

#include <fcntl.h>
#include <unistd.h>
#include <dirent.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>

#include "save.h"
#include "parse.h"

static unsigned int fletcher16_file(FILE *);
static int item_file_exists(char *);

static unsigned int
fletcher16_file(FILE *fp)
{
	unsigned int sum1 = 0, sum2 = 0;
	int c;

	while ((c = fgetc(fp)) != EOF) {
		sum1 += (sum1 + c) % 255;
		sum2 += (sum2 + sum1) % 255;
	}

	return (sum2 << 8) | sum1;
}

/* check if file exists already in cur/ or new/ */
static int
item_file_exists(char *filename)
{
	DIR *dp;
	struct dirent *dir;

	if ((dp = opendir("cur/"))) {
		while ((dir = readdir(dp))) {
			if (strstr(dir->d_name, filename + 4)) {
				closedir(dp);
				return 1;
			}
		}
	}
	closedir(dp);
	if ((dp = opendir("new/"))) {
		while ((dir = readdir(dp))) {
			if (strstr(dir->d_name, filename + 4)) {
				closedir(dp);
				return 1;
			}
		}
	}
	closedir(dp);

	return 0;
}

int
save_item(struct rss_item item, char *feedtitle)
{
	FILE *fp;

	static char hostname[256];
	char path[512], newpath[512], line[1024];
	unsigned int digest;

	if (gethostname(hostname, sizeof(hostname)) == -1) {
		perror("failed to get hostname, setting to localhost");
		strncpy(hostname, "localhost", sizeof(hostname));
	}
	snprintf(path, sizeof(path), "tmp/%li.rssdl-tmp.%s:2,", item.epochsec, hostname);

	fp = fopen(path, "w");
	if (!fp) {
		fprintf(stderr, "failed to open %s for writing\n", path);
		goto CLEANUP;
	}

	fprintf(fp, "From: rssdl@%s\n"
	    "Subject: [%s] %s\n"
	    "Date: %s\n"
	    "Content-Type: text/html\n"
	    "\nArticle Link: %s\n\n",
	    hostname, feedtitle, item.title, item.date, item.link);
	if (item.desc) {
		while (fgets(line, sizeof(line), item.desc) != NULL)
			fputs(line, fp);
	}

	fclose(fp);

	fp = fopen(path, "r");
	if (!fp) {
		fprintf(stderr, "failed to open %s for reading\n", path);
		goto CLEANUP;
	}

	digest = fletcher16_file(fp);
	snprintf(newpath, sizeof(newpath), "new/%li.%x.%s:2,", item.epochsec, digest, hostname);

	if (item_file_exists(newpath) == 1)
		goto CLEANUP;

	if (rename(path, newpath) == 0)
		puts(newpath);

CLEANUP:
	fclose(fp);
	unlink(path);

	return 0;
}