#include "gs-common.h"
#include <fcntl.h>
#include <gsocket/gsocket.h>
#include <gsocket/gs-select.h>
#include "gsocket-engine.h"
#include "gs-externs.h"


/********* FUNCTIONS ********************/

int
GS_SELECT_CTX_init(GS_SELECT_CTX *ctx, fd_set *rfd, fd_set *wfd, fd_set *r, fd_set *w, struct timeval *tv_now, int frequency)
{

	memset(ctx, 0, sizeof *ctx);
	ctx->rfd = rfd;
	ctx->wfd = wfd;
	ctx->r = r;
	ctx->w = w;

	ctx->tv_now = tv_now;

	gettimeofday(ctx->tv_now, NULL);
	GS_EVENT_MGR_init(&ctx->emgr);
	GS_EVENT_add_by_ts(&ctx->emgr, &ctx->hb, 0, frequency, NULL, NULL, 0);

	// ctx->hb_init = GS_TV_TO_USEC(ctx->tv_now);
	// ctx->hb_freq = frequency;

	int i;
	for (i = 0; i < FD_SETSIZE; i++)
	{
		ctx->mgr_r[i].func = NULL;
		ctx->mgr_w[i].func = NULL;
	}

	return 0;
}

void
gs_select_rw_save_state(GS_SELECT_CTX *ctx, int fd, char *idstr)
{
	/* Save rfd/wfd state */
	if (ctx->is_rw_state_saved[fd] == 1)
	{
		// DEBUGF_R("*** WARNING ***: RWFD already saved. SKIPPING (fd = %d, %s)\n", fd, idstr);
		return;		
	}

	DEBUGF_M("Saving state (fd = %d, %s):\n", fd, idstr);
	gs_fds_out_fd(ctx->rfd, 'r', fd);
	gs_fds_out_fd(ctx->wfd, 'w', fd);

	ctx->saved_rw_state[fd] = 0;
	ctx->is_rw_state_saved[fd] = 1;

	if (FD_ISSET(fd, ctx->rfd))
		ctx->saved_rw_state[fd] |= 0x01;
	if (FD_ISSET(fd, ctx->wfd))
		ctx->saved_rw_state[fd] |= 0x02;
}

void
gs_select_rw_restore_state(GS_SELECT_CTX *ctx, int fd, char *idstr)
{
	if (fd < 0)
		return;
	if (ctx->is_rw_state_saved[fd] == 0)
	{
		// DEBUGF("RWFD was not saved. Nothing to restore (fd = %d, %s).\n", fd, idstr);
		return;
	}

	// DEBUGF_B("Restoring RWFD state (fd = %d, %s, %d)\n", fd, idstr, ctx->is_rw_state_saved[fd]);
	/* This can happen when FD was half-closed (shutdown received):
	 * - We stopped reading (rfd not set)
	 * - Write() triggered would-block (wfd set) and then restored to 0.
	 */
	if (ctx->saved_rw_state[fd] == 0)
		DEBUGF_Y("*** NOTE ***: Restoring empty RW state (fd = %d, %s)\n", fd, idstr);
	ctx->is_rw_state_saved[fd] = 0;

	FD_CLR(fd, ctx->rfd);
	FD_CLR(fd, ctx->wfd);
	if (ctx->saved_rw_state[fd] & 0x01)
		XFD_SET(fd, ctx->rfd);
	if (ctx->saved_rw_state[fd] & 0x02)
		XFD_SET(fd, ctx->wfd);
	ctx->saved_rw_state[fd] = 0;

	if (fd > 0)
	{
		DEBUGF_M("Restored state:\n");
		gs_fds_out_fd(ctx->rfd, 'r', fd);
		gs_fds_out_fd(ctx->wfd, 'w', fd);
	}
}

void
gs_select_set_rdata_pending(GS_SELECT_CTX *ctx, int fd, int len)
{
	ctx->rdata_pending_count++;
	ctx->rdata_pending[fd] = len;
}

static void
call_item(GS_SELECT_CTX *ctx, struct _gs_sel_item *item, int fd)
{
	// int ret;

	(*item->func)(ctx, fd, item->cb_arg, item->cb_val);
	// DEBUGF("cb-func ret = %d (fd %d)\n", ret, fd);
	/* 1. Think carefully: STDIN (fd=0) may have succesfully
	 * 1024 bytes but GS_write (fd=3) failed (WANT-WRITE).
	 * - Do not set fd=0 to WANT-WRITE. Instead the GS_write()
	 *   should set that flag on itself (fd=3).
	 *
	 * 2. Think carefully: Not all GS_read/GS_write functions
	 * are called by callbacks: Reading from STDIN calls
	 * GS_write() regardless if GS_write() would block or not.
	 */ 
}

/*
 * Return 0 on timeout.
 * Return -1 on fatal error. Errno is set.
 */
int
GS_select(GS_SELECT_CTX *ctx)
{
	int n;
	struct timeval tv;
	// int ret;
	int i;


	while (1)
	{
		int max_fd = ctx->max_fd;

		/* Before calling select() to check if there is new data on I/O:
		 * - Check if there is already data in the user-land (such as from
		 *   SSL_pending() before checking I/O [kernel].
		 */
		for (i = 0; i <= max_fd; i++)
		{
			if (ctx->rdata_pending_count <= 0)
				break;
			/* Continue if there is no pending data in the input read buffer */
			if (ctx->rdata_pending[i] == 0)
				continue;
			/* Continue if the app does not want us to submit read data */
			if (!FD_ISSET(i, ctx->rfd))
				continue;
			/* HERE: Call to GS_read() needed because there is still
			 * data in the input buffer (not i/o buffer).
			 */
			DEBUGF_Y("fd=%d Pending data in SSL read input buffer (len=%d):>\n", i, ctx->rdata_pending[i]);
			ctx->rdata_pending_count--;
			call_item(ctx, &ctx->mgr_r[i], i);
		}
		/* Do it again if there are still items that
		 * have data in their input buffer...
		 */
		if (ctx->rdata_pending_count > 0)
			continue;

		memcpy(ctx->r, ctx->rfd, sizeof *ctx->r);
		memcpy(ctx->w, ctx->wfd, sizeof *ctx->w);
		
		uint64_t wait;
		wait = GS_EVENT_execute(&ctx->emgr);

		gettimeofday(ctx->tv_now, NULL);
		GS_USEC_TO_TV(&tv, wait);

		gs_fds_out_rwfd(ctx);
		n = select(max_fd + 1, ctx->r, ctx->w, NULL, &tv);
		// DEBUGF_B("max-fd = %d, *************** select = %d\n", max_fd, n);
		if (n < 0)
		{
			if (errno == EINTR)
				continue;
			return -1;
		}

		gettimeofday(ctx->tv_now, NULL);

		// gs_fds_out(ctx->r, max_fd, 'r');
		// gs_fds_out(ctx->w, max_fd, 'w');
		// int wants = 0;
		for (i = 0; i <= max_fd; i++)
		{
			/* 'n' is not reliable as a listening gsocket might handle more than 1 fd
			 * if more than 1 are readable. Only 1 listen-callback will be called
			 * but the callback may serve more than 1 fd.
			 */
			if (n <= 0)
				break;
			struct _gs_sel_item *item = NULL;
			char c;
			/* Must check r and rfd in case app deselected rfd to stop reading */
			if (FD_ISSET(i, ctx->r) && FD_ISSET(i, ctx->rfd))
			{
				// DEBUGF_B("I/O == READ (fd = %d)\n", i);
				/* GS_CALLREAD or GS_CALLDEFAULT */
				/* Find out if read-i/o was required because GS_write() set
				 * WANT_READ.
				 */
				item = &ctx->mgr_r[i];
				c = 'r';
				if (ctx->want_io_read[i])
				{
					if (ctx->blocking_func[i] & GS_CALLWRITE)
					{
						item = &ctx->mgr_w[i];
						c = 'W';
					} 
				}

				// DEBUGF_B("CTX-R: %c fd=%d\n", c, i);
				XASSERT(item->func != NULL, "%c fd = %d has no function to call\n", c, i);
				call_item(ctx, item, i);
				n--;
			}

			if (FD_ISSET(i, ctx->w) && FD_ISSET(i, ctx->wfd))
			{
				// DEBUGF_B("I/O == WRITE (fd = %d)\n", i);
				item = &ctx->mgr_w[i];
				c = 'w';
				if (ctx->want_io_write[i])
				{
					if (ctx->blocking_func[i] & GS_CALLREAD)
					{
						item = &ctx->mgr_r[i];
						c = 'R';
					}
				}

				// DEBUGF_B("call_item: %c fd=%d\n", c, i);
				XASSERT(item->func != NULL, "%c fd = %d has no function to call\n", c, i);
				call_item(ctx, item, i);
				n--;
			} /* FD_ISSET(i, ctx->w) */
		} /* for () */

		/* Time to return control to caller? */
		if (ctx->emgr.is_return_to_caller)
		{
			ctx->emgr.is_return_to_caller = 0;
			return 0;
		}
	} /* while (1) */

	ERREXIT("NOT REACHED\n");
	return -1;
}

void
GS_SELECT_del_cb(GS_SELECT_CTX *ctx, int fd)
{
	int new_max_fd = 0;

	DEBUGF_B("Removing CB for fd = %d\n", fd);
	ctx->mgr_r[fd].func = NULL;
	ctx->mgr_w[fd].func = NULL;
	ctx->mgr_r[fd].cb_arg = NULL;
	ctx->mgr_w[fd].cb_arg = NULL;
	ctx->mgr_w[fd].cb_val = 0;
	ctx->mgr_r[fd].cb_val = 0;
	FD_CLR(fd, ctx->rfd);
	FD_CLR(fd, ctx->wfd);
	FD_CLR(fd, ctx->r);
	FD_CLR(fd, ctx->w);
	ctx->blocking_func[fd] = 0;
	/* Calcualte new max-fd */
	int i;
#ifdef DEBUG
	char buf[FD_SETSIZE + 1];
	memset(buf, '-', sizeof buf);
	buf[ctx->max_fd + 1] = '\0';
	int c;
	int tracking = 0;
#endif

	for (i = 0; i <= ctx->max_fd; i++)
	{
		
		if ((ctx->mgr_r[i].func == NULL) && (ctx->mgr_w[i].func == NULL))
		{
			continue;
		}
#ifdef DEBUG
		tracking += 1;
		c = 0;
		if (ctx->mgr_r[i].func != NULL)
			c = 1;
		if (ctx->mgr_w[i].func != NULL)
			c += 2;
		if (c == 1)
			buf[i] = 'r';	// should not happen
		if (c == 2)
			buf[i] = 'w';	// should not happen.
		if (c == 3)
			buf[i] = 'X';	// both callback functions set (normal case).
#endif
		new_max_fd = i;
	}
#ifdef DEBUG
	buf[fd] = '*';	// This one being removed
	// xfprintf(gs_errfp, "%s (CB funcs, tracking=%d, max=%d)\n", buf, tracking, ctx->max_fd);
#endif

	DEBUGF("Setting MAX-FD to %d\n", new_max_fd);
	ctx->max_fd = new_max_fd;
}

void
GS_SELECT_add_cb_r(GS_SELECT_CTX *ctx, gselect_cb_t func, int fd, void *arg, int val)
{
	DEBUGF_B("Adding CB-r for fd = %d\n", fd);
	ctx->mgr_r[fd].func = (void *)func;
	ctx->mgr_r[fd].cb_arg = arg;
	ctx->mgr_r[fd].cb_val = val;
	ctx->max_fd = MAX(ctx->max_fd, fd);
	ctx->blocking_func[fd] = 0;
}

void
GS_SELECT_add_cb_w(GS_SELECT_CTX *ctx, gselect_cb_t func, int fd, void *arg, int val)
{
	DEBUGF_B("Adding CB-w for fd = %d\n", fd);
	ctx->mgr_w[fd].func = (void *)func;
	ctx->mgr_w[fd].cb_arg = arg;
	ctx->mgr_w[fd].cb_val = val;
	ctx->max_fd = MAX(ctx->max_fd, fd);
	ctx->blocking_func[fd] = 0;
}

void
GS_SELECT_add_cb(GS_SELECT_CTX *ctx, gselect_cb_t func_r, gselect_cb_t func_w, int fd, void *arg, int val)
{
	GS_SELECT_add_cb_r(ctx, func_r, fd, arg, val);
	GS_SELECT_add_cb_w(ctx, func_w, fd, arg, val);
}