/* SPDX-License-Identifier: GPL-2.0 */
#include <stdio.h>
#include <ctype.h>
#include <string.h>
#include <stdbool.h>
#include <sys/inotify.h>
#include <dirent.h>
#include <errno.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <inttypes.h>

#include "minecproxy.h"
#include "uring.h"
#include "shared/config-parser.h"
#include "server.h"
#include "server-config.h"
#include "config.h"

void server_cfg_async_dns_update(struct server_config *scfg)
{
	struct server *server = container_of(scfg, struct server, scfg);

	scfg_async_dns_update(scfg);

	if (list_empty(&server->scfg.dnslookups)) {
		uring_task_put(&server->task);
		server_commit(server);
	}
}

static void server_reading_done(struct server *server)
{
	if (!list_empty(&server->scfg.dnslookups)) {
		uring_task_get(&server->task);
		scfg_async_dns_start(&server->scfg);
		return;
	}

	server_commit(server);
}

static void server_prop_read_cb(struct uring_task *task, int res)
{
	struct server *server = container_of(task, struct server, task);
	const char *error;
	unsigned lineno;

	assert_return(task);
	assert_task_alive(DBG_CFG, task);

	if (res <= 0) {
		error("error reading prop file for %s: %s", server->scfg.name,
		      strerror(-res));
		uring_task_close_fd(&server->task);
		server_reading_done(server);
		return;
	}

	debug(DBG_CFG, "%s: parsing cfg (%i bytes)", server->scfg.name, res);
	uring_task_close_fd(&server->task);
	
	sprop_parse(&server->scfg, server->tbuf.buf, &lineno, &error);

	server_reading_done(server);
}

static void server_prop_open_cb(struct uring_task *task, int res)
{
	struct server *server = container_of(task, struct server, task);

	assert_return(task);
	assert_task_alive(DBG_CFG, task);

	if (res < 0) {
		debug(DBG_CFG, "open prop(%s) failed: %s", server->scfg.name,
		      strerror(-res));
		server_reading_done(server);
		return;
	}

	debug(DBG_CFG, "reading server prop %s (fd %i)", server->scfg.name, res);
	uring_task_set_fd(&server->task, res);
	uring_tbuf_read_until_eof(&server->task, server_prop_read_cb);
}

static void server_cfg_read_cb(struct uring_task *task, int res)
{
	struct server *server = container_of(task, struct server, task);
	const char *error;
	unsigned lineno;
	_cleanup_free_ char *sprop = NULL;

	assert_return(task);
	assert_task_alive(DBG_CFG, task);

	if (res <= 0) {
		error("error reading config file for %s: %s", server->scfg.name,
		      strerror(-res));
		server_delete(server);
	}

	debug(DBG_CFG, "%s: parsing cfg (%i bytes)", server->scfg.name, res);
	uring_task_close_fd(&server->task);
	
	if (!scfg_parse(&server->scfg, server->tbuf.buf, true,
			&lineno, &error)) {
		error("%s: failed to parse config file, line %u: %s",
		      server->scfg.name, lineno, error);
		server_delete(server);
		return;
	}

	sprop = xstrcat(server->scfg.name, "/" MC_SERVER_PROPERTIES, NULL);
	if (!sprop) {
		error("%s: xstrcat %m", server->scfg.name);
		server_delete(server);
		return;
	}

	uring_openat(&server->task, dirfd(cfg->data_dir), sprop,
		     server_prop_open_cb);
}

static void server_cfg_open_cb(struct uring_task *task, int res)
{
	struct server *server = container_of(task, struct server, task);

	assert_return(task);
	assert_task_alive(DBG_CFG, task);

	if (res < 0) {
		error("open cfg(%s) failed: %s", server->scfg.name, strerror(-res));
		server_delete(server);
		return;
	}

	debug(DBG_CFG, "reading server cfg %s (fd %i)", server->scfg.name, res);
	uring_task_set_fd(&server->task, res);
	uring_tbuf_read_until_eof(&server->task, server_cfg_read_cb);
}

struct server_cfg_monitor {
	struct uring_task task;
	char buf[4096] _alignas_(struct inotify_event);
};

static void scfgm_free(struct uring_task *task)
{
	struct server_cfg_monitor *scfgm =
		container_of(task, struct server_cfg_monitor, task);

	assert_return(task);

	debug(DBG_CFG, "called");
	xfree(scfgm);
	cfg->server_cfg_monitor = NULL;
}

static void inotify_event_dump(const struct inotify_event *event)
{
	assert_return(event);

	debug(DBG_CFG, "inotify event:");
	debug(DBG_CFG, " * WD     : %i", event->wd);
	debug(DBG_CFG, " * Cookie : %" PRIu32, event->cookie);
	debug(DBG_CFG, " * Length : %" PRIu32, event->len);
	debug(DBG_CFG, " * Name   : %s", event->name);
	debug(DBG_CFG, " * Mask   : %" PRIu32, event->mask);
	if (event->mask & IN_ACCESS)
		debug(DBG_CFG, "\tIN_ACCESS");
	else if (event->mask & IN_MODIFY)
		debug(DBG_CFG, "\tIN_MODIFY");
	else if (event->mask & IN_ATTRIB)
		debug(DBG_CFG, "\tIN_ATTRIB");
	else if (event->mask & IN_CLOSE_WRITE)
		debug(DBG_CFG, "\tIN_CLOSE_WRITE");
	else if (event->mask & IN_CLOSE_NOWRITE)
		debug(DBG_CFG, "\tIN_CLOSE_NOWRITE");
	else if (event->mask & IN_OPEN)
		debug(DBG_CFG, "\tIN_OPEN");
	else if (event->mask & IN_MOVED_FROM)
		debug(DBG_CFG, "\tIN_MOVED_FROM");
	else if (event->mask & IN_MOVED_TO)
		debug(DBG_CFG, "\tIN_MOVED_TO");
	else if (event->mask & IN_CREATE)
		debug(DBG_CFG, "\tIN_CREATE");
	else if (event->mask & IN_DELETE)
		debug(DBG_CFG, "\tIN_DELETE");
	else if (event->mask & IN_DELETE_SELF)
		debug(DBG_CFG, "\tIN_DELETE_SELF");
	else if (event->mask & IN_MOVE_SELF)
		debug(DBG_CFG, "\tIN_MOVE_SELF");
	else if (event->mask & IN_UNMOUNT)
		debug(DBG_CFG, "\tIN_UNMOUNT");
	else if (event->mask & IN_Q_OVERFLOW)
		debug(DBG_CFG, "\tIN_Q_OVERFLOW");
	else if (event->mask & IN_IGNORED)
		debug(DBG_CFG, "\tIN_IGNORED");
}

static void inotify_cb(struct uring_task *task, int res)
{
	struct server_cfg_monitor *scfgm =
		container_of(task, struct server_cfg_monitor, task);
	const struct inotify_event *event;
	char *ptr;
	struct server *server;

	assert_return(task);
	assert_task_alive(DBG_CFG, task);

	if (res <= 0) {
		error("inotify_read: %i", res);
		return;
	}

	for (ptr = scfgm->buf; ptr < scfgm->buf + res;
	     ptr += sizeof(struct inotify_event) + event->len) {
		event = (const struct inotify_event *)ptr;

		if (debug_enabled(DBG_CFG))
			inotify_event_dump(event);

		if (event->mask &
		    (IN_IGNORED | IN_MOVE_SELF | IN_DELETE_SELF | IN_UNMOUNT))
			die("configuration directory gone, exiting");

		if (event->mask & IN_Q_OVERFLOW) {
			error("inotify queue overflow");
			continue;
		}

		if (!config_valid_server_filename(NULL, event->name))
			continue;

		if (event->mask & (IN_MOVED_FROM | IN_DELETE))
			server_delete_by_filename(event->name);
		else if (event->mask &
			 (IN_MOVED_TO | IN_CREATE | IN_CLOSE_WRITE)) {
			server = server_new(event->name);
			verbose("New server config file detected: %s",
				event->name);
			uring_openat(&server->task, dirfd(cfg->cfg_dir),
				     event->name, server_cfg_open_cb);
		} else
			error("inotify: unknown event: 0x%08x", event->mask);
	}

	uring_read(&scfgm->task, scfgm->buf, sizeof(scfgm->buf), inotify_cb);
}

void server_cfg_monitor_refdump()
{
	assert_return_silent(cfg->server_cfg_monitor);

	uring_task_refdump(&cfg->server_cfg_monitor->task);
}

void server_cfg_monitor_delete()
{
	assert_return(cfg->server_cfg_monitor);

	debug(DBG_CFG, "closing fd %i", cfg->server_cfg_monitor->task.fd);
	uring_task_destroy(&cfg->server_cfg_monitor->task);
	cfg->server_cfg_monitor = NULL;
}

void server_cfg_monitor_init()
{
	int ifd;
	int iwd;
	struct server_cfg_monitor *scfgm;
	struct dirent *dent;
	struct server *server;

	assert_return(!cfg->server_cfg_monitor && cfg->cfg_dir);

	scfgm = zmalloc(sizeof(*scfgm));
	if (!scfgm)
		die("malloc: %m");

	ifd = inotify_init1(IN_CLOEXEC);
	if (ifd < 0)
		die("inotify_init1: %m");

	/* ln = IN_CREATE, cp/vi/mv = IN_CREATE, IN_OPEN, IN_CLOSE_WRITE */
	iwd = inotify_add_watch(
		ifd, cfg->cfg_real_path,
		IN_CLOSE_WRITE | IN_DELETE | IN_CREATE | IN_DELETE_SELF |
			IN_MOVE_SELF | IN_MOVED_TO | IN_MOVED_FROM |
			IN_DONT_FOLLOW | IN_EXCL_UNLINK | IN_ONLYDIR);
	if (iwd < 0)
		die("inotify_add_watch: %m");

	uring_task_init(&scfgm->task, "server-config-monitor", uring_parent(),
			scfgm_free);
	uring_task_set_fd(&scfgm->task, ifd);
	cfg->server_cfg_monitor = scfgm;
	uring_read(&scfgm->task, scfgm->buf, sizeof(scfgm->buf), inotify_cb);

	while ((dent = readdir(cfg->cfg_dir)) != NULL) {
		if (!config_valid_server_filename(dent, NULL))
			continue;

		server = server_new(dent->d_name);
		if (server)
			uring_openat(&server->task, dirfd(cfg->cfg_dir),
				     server->scfg.filename, server_cfg_open_cb);
	}
}