/* See LICENSE file for copyright and license details. */
#include "common.h"

/* TODO Add support for comments (indent the next line in the file with a tab) */

USAGE("");


struct entry {
	struct entry *next;
	struct entry *prev;
	struct entry *in;
	struct entry *out;
	struct entry *flat_next;
	char status;
	char text[];
};


static struct entry *
load(const char *path)
{
	struct entry *entry, *ret = NULL, *tail = NULL, *parent = NULL;
	FILE *fp;
	char *line = NULL;
	size_t size = 0, lineno = 0, indent = 0, i;
	ssize_t len;

	fp = fopen(path, "r");
	if (!fp) {
		if (errno == ENOENT)
			return NULL;
		eprintf("fopen %s \"r\":", path);
	}

	while ((len = getdelim(&line, &size, '\n', fp)) >= 0) {
		lineno += 1;
		if (len && line[len - 1] == '\n')
			line[--len] = '\0';
		for (i = 0; line[i] == ' '; i++);
		if (i == (size_t)len)
			eprintf("line %zu in %s is malformatted 1\n", lineno, path);
		if (i > indent + (size_t)!!ret)
			eprintf("line %zu in %s is malformatted 2 %zu > %zu + %i\n", lineno, path, i, indent, !!ret);
		entry = ecalloc(1, offsetof(struct entry, text) + (size_t)len - i);
		if (!ret)
			ret = entry;
		else
			tail->flat_next = entry;
		entry->status = line[i];
		if (entry->status != '_' && /* unmarked, displayed as [ ] */
		    entry->status != 'X' && /* done */
		    entry->status != '-' && /* not now */
		    entry->status != '/' && /* partially done */
		    entry->status != '!' && /* important */
		    entry->status != '?')   /* maybe */
			eprintf("line %zu in %s is malformatted\n", lineno, path);
		stpcpy(entry->text, &line[i + 1]);
		if (i == indent) {
			entry->prev = tail;
			if (tail)
				tail->next = entry;
			entry->out = parent;
		} else if (i > indent) {
			indent += 1;
			entry->out = tail;
			tail->in = entry;
			parent = entry->out;
		} else {
			while (--indent > i)
				parent = parent->out;
			entry->prev = parent;
			parent->next = entry;
			parent = parent->out;
			entry->out = parent;
		}
		tail = entry;
	}

	if (ferror(fp))
		eprintf("getdelim %s:", path);

	fclose(fp);
	free(line);
	return ret;
}


static struct entry *
get_next(struct entry *entry, size_t *indentp)
{
	if (entry->in) {
		++*indentp;
		return entry->in;
	}
	if (entry->next)
		return entry->next;
	while (entry->out) {
		entry = entry->out;
		--*indentp;
		if (entry->next)
			return entry->next;
	}
	return NULL;
}


static int
save(const char *path, const char *tmppath, struct entry *head)
{
#define SPACES "                "

	int fd, saved_errno;
	size_t indent = 0, n, off;
	ssize_t r;

	fd = open(tmppath, O_WRONLY | O_CREAT | O_TRUNC, 0666);
	if (fd < 0)
		return -1;

	for (; head; head = get_next(head, &indent)) {
		for (n = indent; n; n -= (size_t)r) {
			r = write(fd, SPACES, indent < sizeof(SPACES) - 1 ? indent : sizeof(SPACES) - 1);
			if (r < 0)
				goto fail;
		}
		if (write(fd, &head->status, 1) < 1)
			goto fail;
		n = strlen(head->text);
		for (off = 0; off < n; off += (size_t)r) {
			r = write(fd, &head->text[off], n - off);
			if (r < 0)
				goto fail;
		}
		if (write(fd, &(char){'\n'}, 1) < 1)
			goto fail;
	}

	if (fsync(fd)) {
	fail:
		saved_errno = errno;
		close(fd);
		errno = saved_errno;
		return -1;
	}
	if (close(fd) || rename(tmppath, path))
		return -1;

	return 0;

#undef SPACES
}


static char *
get_path(void)
{
	struct passwd *user;
	size_t homelen;
	char *ret;

	errno = 0;
	user = getpwuid(getuid());
	if (!user)
		eprintf("getpwuid: %s\n", errno ? strerror(errno) : "user does not exist");
	if (!user->pw_dir || !*user->pw_dir)
		eprintf("user does not have a home directory\n");
	if (access(user->pw_dir, R_OK | W_OK | X_OK))
		eprintf("access %s R_OK|W_OK|X_OK:", user->pw_dir);

	homelen = strlen(user->pw_dir);
	if (homelen && user->pw_dir[homelen - 1] == '/')
		homelen -= 1;

	ret = emalloc(homelen + sizeof("/.var/lib/pdatools/checklist"));
	memcpy(ret, user->pw_dir, homelen);
	memcpy(&ret[homelen], "/.var/lib/pdatools/checklist", sizeof("/.var/lib/pdatools/checklist"));
	return ret;
}


int
main(int argc, char *argv[])
{
	char *path, *tmppath;
	struct entry *head, *node;
	size_t indent;

	NOFLAGS(argc);

	path = get_path();
	tmppath = emalloc(strlen(path) + 2);
	stpcpy(stpcpy(tmppath, path), "~");
	head = load(path);

	/* TODO */
	indent = 0;
	for (node = head; node; node = get_next(node, &indent))
		printf("%*.s[%c] %s\n", (int)indent * 2, "", node->status, node->text);

	for (node = NULL; free(node), head; node = head, head = head->flat_next);
	free(path);
	free(tmppath);
	return 0;
}