/* SPDX-License-Identifier: ISC */
#include "init.h"

/* service configurations */
static service_list_t cfg;

/* service run time data, sorted by target and topological order */
static svc_run_data_t *rt_data = NULL;
static size_t rt_count = 0;

/* maps a target to range in rt_data */
static size_t queue_start[TGT_MAX];
static size_t queue_count[TGT_MAX];

/* current state */
static size_t queue_idx = 0;
static int target = TGT_BOOT;
static size_t singleshot = 0;

/*****************************************************************************/

static const char *status_str[] = {
	[STATE_OFF] = NULL,
	[STATE_QUEUED] = NULL,
	[STATE_RUNNING] ="\033[22;33m UP \033[0m",
	[STATE_COMPLETED] = "\033[22;32mDONE\033[0m",
	[STATE_FAILED] ="\033[22;31mFAIL\033[0m",
};

static void print_status(const char *msg, int type)
{
	printf("[%s] %s\n", status_str[type], msg);
	fflush(stdout);
}

static void respawn(svc_run_data_t *rt)
{
	if (rt->svc->rspwn_limit > 0) {
		rt->rspwn_count += 1;

		if (rt->rspwn_count >= rt->svc->rspwn_limit)
			goto fail;
	}

	rt->pid = runsvc(rt->svc);
	if (rt->pid == -1)
		goto fail;

	rt->state = STATE_RUNNING;
	return;
fail:
	rt->state = STATE_FAILED;
	print_status(rt->svc->desc, rt->state);
	return;
}

static void check_target_completion(void)
{
	if (singleshot > 0 || queue_idx < queue_count[target])
		return;

	switch (target) {
	case TGT_BOOT:
		break;
	case TGT_SHUTDOWN:
		for (;;)
			reboot(RB_POWER_OFF);
		break;
	case TGT_REBOOT:
		for (;;)
			reboot(RB_AUTOBOOT);
		break;
	}
}

void supervisor_handle_exited(pid_t pid, int status)
{
	svc_run_data_t *rt;
	service_t *svc;
	size_t i;

	for (i = 0; i < rt_count; ++i) {
		if (rt_data[i].pid == pid)
			break;
	}

	if (i >= rt_count)
		return;

	rt = rt_data + i;
	svc = rt->svc;
	rt->status = status;
	rt->pid = -1;

	if (svc->type == SVC_RESPAWN) {
		if (target != TGT_REBOOT && target != TGT_SHUTDOWN)
			respawn(rt);
	} else {
		if (rt->status == EXIT_SUCCESS) {
			rt->state = STATE_COMPLETED;
		} else {
			rt->state = STATE_FAILED;
		}

		print_status(svc->desc, rt->state);

		if (svc->type == SVC_ONCE)
			singleshot -= 1;

		check_target_completion();
	}
}

void supervisor_set_target(int next)
{
	if (target == TGT_REBOOT || target == TGT_SHUTDOWN || next == target)
		return;

	if (queue_idx < queue_count[target]) {
		if (next != TGT_REBOOT && next != TGT_SHUTDOWN)
			return;
	}

	target = next;
	queue_idx = 0;
}

void supervisor_init(void)
{
	int status = STATE_FAILED;
	service_t *it;
	size_t i, j;

	if (svcscan(SVCDIR, &cfg))
		goto out;

	/* allocate run time data */
	rt_count = 0;

	for (i = 0; i < TGT_MAX; ++i) {
		for (it = cfg.targets[i]; it != NULL; it = it->next)
			++rt_count;
	}

	rt_data = calloc(rt_count, sizeof(rt_data[0]));
	if (rt_data == NULL) {
		rt_count = 0;
		goto out;
	}

	/* map runtime data to services */
	j = 0;

	for (i = 0; i < TGT_MAX; ++i) {
		queue_start[i] = j;

		for (it = cfg.targets[i]; it != NULL; it = it->next) {
			rt_data[j].svc = it;
			rt_data[j].state = STATE_OFF;
			rt_data[j].pid = -1;
			++j;
		}

		queue_count[i] = j - queue_start[i];
	}

	/* initialize state */
	status = STATE_COMPLETED;

	for (i = 0; i < queue_count[target]; ++i)
		rt_data[queue_start[target] + i].state = STATE_QUEUED;
out:
	print_status("reading configuration from " SVCDIR, status);
}

static pid_t wait_for_process(int *status)
{
	pid_t pid = wait(status);

	if (pid == -1 || !WIFEXITED(*status)) {
		*status = EXIT_FAILURE;
	} else {
		*status = WEXITSTATUS(*status);
	}
	return pid;
}

void supervisor_process_queues(void)
{
	svc_run_data_t *rt;
	service_t *svc;
	size_t count;
	int status;
	pid_t pid;

	count = queue_count[target];

	if (queue_idx >= count) {
		pid = wait_for_process(&status);
		supervisor_handle_exited(pid, status);
		return;
	}

	rt = rt_data + queue_start[target] + queue_idx++;
	svc = rt->svc;

	if (svc->flags & SVC_FLAG_HAS_EXEC) {
		rt->pid = runsvc(rt->svc);

		if (rt->pid == -1) {
			rt->state = STATE_FAILED;
			print_status(svc->desc, rt->state);
		} else {
			rt->state = STATE_RUNNING;
			print_status(svc->desc, rt->state);

			switch (svc->type) {
			case SVC_WAIT:
				for (;;) {
					pid = wait_for_process(&status);
					if (pid == rt->pid)
						break;
					supervisor_handle_exited(pid, status);
				}

				rt->state = status == EXIT_SUCCESS ?
					STATE_COMPLETED : STATE_FAILED;
				print_status(svc->desc, rt->state);
				break;
			case SVC_ONCE:
				singleshot += 1;
				break;
			}
		}
	} else {
		rt->status = EXIT_SUCCESS;
		rt->state = STATE_COMPLETED;
		print_status(svc->desc, rt->state);
	}

	check_target_completion();
}