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

#include <fcntl.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>

#include <gemtext.h>

#include "gemlog.h"

static int
find_latest_year(struct gemlog_entry **feed)
{
	int i;
	int ret;

	ret = 0;
	for (i = 0; feed[i] != NULL; i++) {
		if (feed[i]->date.tm_year > ret)
			ret = feed[i]->date.tm_year;
	}
	return ret;
}

static int
find_latest_month(struct gemlog_entry **feed, int year)
{
	int i;
	int ret;

	ret = 0;
	for (i = 0; feed[i] != NULL; i++) {
		if (feed[i]->date.tm_year == year) {
			if (feed[i]->date.tm_mon > ret)
				ret = feed[i]->date.tm_mon;
		}
	}
	return ret;
}

static int
find_latest_day(struct gemlog_entry **feed, int year, int month)
{
	int i;
	int ret;

	ret = 0;
	for (i = 0; feed[i] != NULL; i++) {
		if (feed[i]->date.tm_year == year && feed[i]->date.tm_mon == month) {
			if (feed[i]->date.tm_mday > ret)
				ret = feed[i]->date.tm_mday;
		}
	}
	return ret;
}

static int
find_latest_hour(struct gemlog_entry **feed, int year, int month, int day)
{
	int i;
	int ret;

	ret = 0;
	for (i = 0; feed[i] != NULL; i++) {
		if (feed[i]->date.tm_year == year && feed[i]->date.tm_mon == month && feed[i]->date.tm_mday == day) {
			if (feed[i]->date.tm_hour > ret)
				ret = feed[i]->date.tm_hour;
		}
	}
	return ret;
}

static int
gemlog_write_index_hour(struct gemlog_entry **feed, int fd, int year, int month, int day, int hour)
{
	int i;
	int labellen;
	char *labelbuf;
	char timestamp[11]; /* 1990-01-01\0 */
	char pathbuf[PATH_MAX+1];
	struct gemtext *out;

	labellen = 0;

	for (i = 0; feed[i] != NULL; i++) {
		if (feed[i]->date.tm_year == year
		 && feed[i]->date.tm_mon  == month
		 && feed[i]->date.tm_mday == day
		 && feed[i]->date.tm_hour == hour) {
			strftime(timestamp, sizeof(timestamp), "%F", &(feed[i]->date));
			labellen += strlen(timestamp);
			labellen += 2; /* ": " */
			labellen += strlen(feed[i]->title);
			labelbuf = malloc(labellen+1);
			if (labelbuf == NULL)
				return -1;
			strlcpy(labelbuf, timestamp, labellen+1);
			strlcat(labelbuf, ": ", labellen+1);
			strlcat(labelbuf, feed[i]->title, labellen+1);
			snprintf(pathbuf, sizeof(pathbuf), "%d/%d/%d/%d/%s", year+1900, month+1, day, hour, GEMLOG_CONTENT_FILENAME);
			out = gemtext_link_new(pathbuf, labelbuf);
			free(labelbuf);
			if (out == NULL)
				return -1;
			if (gemtext_encode_fd(out, fd) == -1) {
				gemtext_free(out);
				return -1;
			}
			gemtext_free(out);
			if (write(fd, "\n", strlen("\n")) == -1)
				return -1;
		}
	}

	return 0;
}

static int
gemlog_write_index_day(struct gemlog_entry **feed, int fd, int year, int month, int day)
{
	int hour;

	for (hour = find_latest_hour(feed, year, month, day); hour != 0; hour--) {
		if (gemlog_write_index_hour(feed, fd, year, month, day, hour) == -1)
			return -1;
	}

	return 0;
}

static int
gemlog_write_index_month(struct gemlog_entry **feed, int fd, int year, int month)
{
	int day;

	for (day = find_latest_day(feed, year, month); day != 0; day--) {
		if (gemlog_write_index_day(feed, fd, year, month, day) == -1)
			return -1;
	}

	return 0;
}

static int
gemlog_write_index_year(struct gemlog_entry **feed, int fd, int year)
{
	int month;

	for (month = find_latest_month(feed, year); month != 0; month--) {
		if (gemlog_write_index_month(feed, fd, year, month) == -1)
			return -1;
	}

	return 0;
}

int
gemlog_write_index(struct gemlog_entry **feed, const char *path)
{
	int year;
	int fd;

	fd = open(path, O_WRONLY|O_CREAT|O_TRUNC);
	if (fd == -1)
		return -1;
	if (chmod(path, 0644) == -1) {
		close(fd);
		return -1;
	}

	for (year = find_latest_year(feed); year != 0; year--) {
		if (gemlog_write_index_year(feed, fd, year) == -1) {
			close(fd);
			return -1;
		}
	}

	close(fd);
	return 0;
}