text: /* $OpenBSD$ */
  
  /*
   * Copyright (c) 2015 Nicholas Marriott <nicholas.marriott@gmail.com>
   *
   * Permission to use, copy, modify, and distribute this software for any
   * purpose with or without fee is hereby granted, provided that the above
   * copyright notice and this permission notice appear in all copies.
   *
   * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
   * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
   * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
   * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
   * WHATSOEVER RESULTING FROM LOSS OF MIND, USE, DATA OR PROFITS, WHETHER
   * IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
   * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
   */
  
  #include <sys/types.h>
  
  #include <fnmatch.h>
  #include <limits.h>
  #include <stdlib.h>
  #include <string.h>
  #include <unistd.h>
  
  #include "tmux.h"
  
  static struct session *cmd_find_try_TMUX(struct client *, struct window *);
  static int	cmd_find_client_better(struct client *, struct client *);
  static struct client *cmd_find_best_client(struct client **, u_int);
  static int	cmd_find_session_better(struct session *, struct session *,
  		    int);
  static struct session *cmd_find_best_session(struct session **, u_int, int);
  static int	cmd_find_best_session_with_window(struct cmd_find_state *);
  static int	cmd_find_best_winlink_with_window(struct cmd_find_state *);
  
  static int	cmd_find_current_session_with_client(struct cmd_find_state *);
  static int	cmd_find_current_session(struct cmd_find_state *);
  static struct client *cmd_find_current_client(struct cmdq_item *);
  
  static const char *cmd_find_map_table(const char *[][2], const char *);
  
  static int	cmd_find_get_session(struct cmd_find_state *, const char *);
  static int	cmd_find_get_window(struct cmd_find_state *, const char *, int);
  static int	cmd_find_get_window_with_session(struct cmd_find_state *,
  		    const char *);
  static int	cmd_find_get_pane(struct cmd_find_state *, const char *, int);
  static int	cmd_find_get_pane_with_session(struct cmd_find_state *,
  		    const char *);
  static int	cmd_find_get_pane_with_window(struct cmd_find_state *,
  		    const char *);
  
  static const char *cmd_find_session_table[][2] = {
  	{ NULL, NULL }
  };
  static const char *cmd_find_window_table[][2] = {
  	{ "{start}", "^" },
  	{ "{last}", "!" },
  	{ "{end}", "$" },
  	{ "{next}", "+" },
  	{ "{previous}", "-" },
  	{ NULL, NULL }
  };
  static const char *cmd_find_pane_table[][2] = {
  	{ "{last}", "!" },
  	{ "{next}", "+" },
  	{ "{previous}", "-" },
  	{ "{top}", "top" },
  	{ "{bottom}", "bottom" },
  	{ "{left}", "left" },
  	{ "{right}", "right" },
  	{ "{top-left}", "top-left" },
  	{ "{top-right}", "top-right" },
  	{ "{bottom-left}", "bottom-left" },
  	{ "{bottom-right}", "bottom-right" },
  	{ "{up-of}", "{up-of}" },
  	{ "{down-of}", "{down-of}" },
  	{ "{left-of}", "{left-of}" },
  	{ "{right-of}", "{right-of}" },
  	{ NULL, NULL }
  };
  
  /* Get session from TMUX if present. */
  static struct session *
  cmd_find_try_TMUX(struct client *c, struct window *w)
  {
  	struct environ_entry	*envent;
  	char			 tmp[256];
  	long long		 pid;
  	u_int			 session;
  	struct session		*s;
  
  	envent = environ_find(c->environ, "TMUX");
  	if (envent == NULL)
  		return (NULL);
  
  	if (sscanf(envent->value, "%255[^,],%lld,%d", tmp, &pid, &session) != 3)
  		return (NULL);
  	if (pid != getpid())
  		return (NULL);
  	log_debug("client %p TMUX is %s (session @%u)", c, envent->value,
  	    session);
  
  	s = session_find_by_id(session);
  	if (s == NULL || (w != NULL && !session_has(s, w)))
  		return (NULL);
  	return (s);
  }
  
  /* Is this client better? */
  static int
  cmd_find_client_better(struct client *c, struct client *than)
  {
  	if (than == NULL)
  		return (1);
  	return (timercmp(&c->activity_time, &than->activity_time, >));
  }
  
  /* Find best client from a list, or all if list is NULL. */
  static struct client *
  cmd_find_best_client(struct client **clist, u_int csize)
  {
  	struct client	*c_loop, *c;
  	u_int		 i;
  
  	c = NULL;
  	if (clist != NULL) {
  		for (i = 0; i < csize; i++) {
  			if (clist[i]->session == NULL)
  				continue;
  			if (cmd_find_client_better(clist[i], c))
  				c = clist[i];
  		}
  	} else {
  		TAILQ_FOREACH(c_loop, &clients, entry) {
  			if (c_loop->session == NULL)
  				continue;
  			if (cmd_find_client_better(c_loop, c))
  				c = c_loop;
  		}
  	}
  	return (c);
  }
  
  /* Is this session better? */
  static int
  cmd_find_session_better(struct session *s, struct session *than, int flags)
  {
  	int	attached;
  
  	if (than == NULL)
  		return (1);
  	if (flags & CMD_FIND_PREFER_UNATTACHED) {
  		attached = (~than->flags & SESSION_UNATTACHED);
  		if (attached && (s->flags & SESSION_UNATTACHED))
  			return (1);
  		else if (!attached && (~s->flags & SESSION_UNATTACHED))
  			return (0);
  	}
  	return (timercmp(&s->activity_time, &than->activity_time, >));
  }
  
  /* Find best session from a list, or all if list is NULL. */
  static struct session *
  cmd_find_best_session(struct session **slist, u_int ssize, int flags)
  {
  	struct session	 *s_loop, *s;
  	u_int		  i;
  
  	s = NULL;
  	if (slist != NULL) {
  		for (i = 0; i < ssize; i++) {
  			if (cmd_find_session_better(slist[i], s, flags))
  				s = slist[i];
  		}
  	} else {
  		RB_FOREACH(s_loop, sessions, &sessions) {
  			if (cmd_find_session_better(s_loop, s, flags))
  				s = s_loop;
  		}
  	}
  	return (s);
  }
  
  /* Find best session and winlink for window. */
  static int
  cmd_find_best_session_with_window(struct cmd_find_state *fs)
  {
  	struct session	**slist = NULL;
  	u_int		  ssize;
  	struct session	 *s;
  
  	if (fs->item != NULL && fs->item->client != NULL) {
  		fs->s = cmd_find_try_TMUX(fs->item->client, fs->w);
  		if (fs->s != NULL)
  			return (cmd_find_best_winlink_with_window(fs));
  	}
  
  	ssize = 0;
  	RB_FOREACH(s, sessions, &sessions) {
  		if (!session_has(s, fs->w))
  			continue;
  		slist = xreallocarray(slist, ssize + 1, sizeof *slist);
  		slist[ssize++] = s;
  	}
  	if (ssize == 0)
  		goto fail;
  	fs->s = cmd_find_best_session(slist, ssize, fs->flags);
  	if (fs->s == NULL)
  		goto fail;
  	free(slist);
  	return (cmd_find_best_winlink_with_window(fs));
  
  fail:
  	free(slist);
  	return (-1);
  }
  
  /*
   * Find the best winlink for a window (the current if it contains the pane,
   * otherwise the first).
   */
  static int
  cmd_find_best_winlink_with_window(struct cmd_find_state *fs)
  {
  	struct winlink	 *wl, *wl_loop;
  
  	wl = NULL;
  	if (fs->s->curw != NULL && fs->s->curw->window == fs->w)
  		wl = fs->s->curw;
  	else {
  		RB_FOREACH(wl_loop, winlinks, &fs->s->windows) {
  			if (wl_loop->window == fs->w) {
  				wl = wl_loop;
  				break;
  			}
  		}
  	}
  	if (wl == NULL)
  		return (-1);
  	fs->wl = wl;
  	fs->idx = fs->wl->idx;
  	return (0);
  }
  
  /* Find current session when we have an unattached client. */
  static int
  cmd_find_current_session_with_client(struct cmd_find_state *fs)
  {
  	struct window_pane	*wp;
  
  	/*
  	 * If this is running in a pane, we can use that to limit the list of
  	 * sessions to those containing that pane (we still use the current
  	 * window in the best session).
  	 */
  	if (fs->item != NULL) {
  		RB_FOREACH(wp, window_pane_tree, &all_window_panes) {
  			if (strcmp(wp->tty, fs->item->client->ttyname) == 0)
  				break;
  		}
  	} else
  		wp = NULL;
  
  	/* Not running in a pane. We know nothing. Find the best session. */
  	if (wp == NULL)
  		goto unknown_pane;
  
  	/* Find the best session and winlink containing this pane. */
  	fs->w = wp->window;
  	if (cmd_find_best_session_with_window(fs) != 0) {
  		if (wp != NULL) {
  			/*
  			 * The window may have been destroyed but the pane
  			 * still on all_window_panes due to something else
  			 * holding a reference.
  			 */
  			goto unknown_pane;
  		}
  		return (-1);
  	}
  
  	/* Use the current window and pane from this session. */
  	fs->wl = fs->s->curw;
  	fs->idx = fs->wl->idx;
  	fs->w = fs->wl->window;
  	fs->wp = fs->w->active;
  
  	return (0);
  
  unknown_pane:
  	fs->s = NULL;
  	if (fs->item != NULL)
  		fs->s = cmd_find_try_TMUX(fs->item->client, NULL);
  	if (fs->s == NULL)
  		fs->s = cmd_find_best_session(NULL, 0, fs->flags);
  	if (fs->s == NULL)
  		return (-1);
  	fs->wl = fs->s->curw;
  	fs->idx = fs->wl->idx;
  	fs->w = fs->wl->window;
  	fs->wp = fs->w->active;
  
  	return (0);
  }
  
  /*
   * Work out the best current state. If this function succeeds, the state is
   * guaranteed to be completely filled in.
   */
  static int
  cmd_find_current_session(struct cmd_find_state *fs)
  {
  	/* If we know the current client, use it. */
  	if (fs->item != NULL && fs->item->client != NULL) {
  		log_debug("%s: have client %p%s", __func__, fs->item->client,
  		    fs->item->client->session == NULL ? "" : " (with session)");
  		if (fs->item->client->session == NULL)
  			return (cmd_find_current_session_with_client(fs));
  		fs->s = fs->item->client->session;
  		fs->wl = fs->s->curw;
  		fs->idx = fs->wl->idx;
  		fs->w = fs->wl->window;
  		fs->wp = fs->w->active;
  		return (0);
  	}
  
  	/* We know nothing, find the best session and client. */
  	fs->s = cmd_find_best_session(NULL, 0, fs->flags);
  	if (fs->s == NULL)
  		return (-1);
  	fs->wl = fs->s->curw;
  	fs->idx = fs->wl->idx;
  	fs->w = fs->wl->window;
  	fs->wp = fs->w->active;
  
  	return (0);
  }
  
  /* Work out the best current client. */
  static struct client *
  cmd_find_current_client(struct cmdq_item *item)
  {
  	struct cmd_find_state	 current;
  	struct session		*s;
  	struct client		*c, **clist = NULL;
  	u_int		 	 csize;
  
  	/* If the queue client has a session, use it. */
  	if (item->client != NULL && item->client->session != NULL) {
  		log_debug("%s: using item %p client %p", __func__, item,
  		    item->client);
  		return (item->client);
  	}
  
  	/* Otherwise find the current session. */
  	cmd_find_clear_state(&current, item, 0);
  	if (cmd_find_current_session(&current) != 0)
  		return (NULL);
  
  	/* If it is attached, find the best of it's clients. */
  	s = current.s;
  	log_debug("%s: current session $%u %s", __func__, s->id, s->name);
  	if (~s->flags & SESSION_UNATTACHED) {
  		csize = 0;
  		TAILQ_FOREACH(c, &clients, entry) {
  			if (c->session != s)
  				continue;
  			clist = xreallocarray(clist, csize + 1, sizeof *clist);
  			clist[csize++] = c;
  		}
  		if (csize != 0) {
  			c = cmd_find_best_client(clist, csize);
  			if (c != NULL) {
  				free(clist);
  				return (c);
  			}
  		}
  		free(clist);
  	}
  
  	/* Otherwise pick best of all clients. */
  	return (cmd_find_best_client(NULL, 0));
  }
  
  /* Maps string in table. */
  static const char *
  cmd_find_map_table(const char *table[][2], const char *s)
  {
  	u_int	i;
  
  	for (i = 0; table[i][0] != NULL; i++) {
  		if (strcmp(s, table[i][0]) == 0)
  			return (table[i][1]);
  	}
  	return (s);
  }
  
  /* Find session from string. Fills in s. */
  static int
  cmd_find_get_session(struct cmd_find_state *fs, const char *session)
  {
  	struct session	*s, *s_loop;
  	struct client	*c;
  
  	log_debug("%s: %s", __func__, session);
  
  	/* Check for session ids starting with $. */
  	if (*session == '$') {
  		fs->s = session_find_by_id_str(session);
  		if (fs->s == NULL)
  			return (-1);
  		return (0);
  	}
  
  	/* Look for exactly this session. */
  	fs->s = session_find(session);
  	if (fs->s != NULL)
  		return (0);
  
  	/* Look for as a client. */
  	c = cmd_find_client(NULL, session, 1);
  	if (c != NULL && c->session != NULL) {
  		fs->s = c->session;
  		return (0);
  	}
  
  	/* Stop now if exact only. */
  	if (fs->flags & CMD_FIND_EXACT_SESSION)
  		return (-1);
  
  	/* Otherwise look for prefix. */
  	s = NULL;
  	RB_FOREACH(s_loop, sessions, &sessions) {
  		if (strncmp(session, s_loop->name, strlen(session)) == 0) {
  			if (s != NULL)
  				return (-1);
  			s = s_loop;
  		}
  	}
  	if (s != NULL) {
  		fs->s = s;
  		return (0);
  	}
  
  	/* Then as a pattern. */
  	s = NULL;
  	RB_FOREACH(s_loop, sessions, &sessions) {
  		if (fnmatch(session, s_loop->name, 0) == 0) {
  			if (s != NULL)
  				return (-1);
  			s = s_loop;
  		}
  	}
  	if (s != NULL) {
  		fs->s = s;
  		return (0);
  	}
  
  	return (-1);
  }
  
  /* Find window from string. Fills in s, wl, w. */
  static int
  cmd_find_get_window(struct cmd_find_state *fs, const char *window, int only)
  {
  	log_debug("%s: %s", __func__, window);
  
  	/* Check for window ids starting with @. */
  	if (*window == '@') {
  		fs->w = window_find_by_id_str(window);
  		if (fs->w == NULL)
  			return (-1);
  		return (cmd_find_best_session_with_window(fs));
  	}
  
  	/* Not a window id, so use the current session. */
  	fs->s = fs->current->s;
  
  	/* We now only need to find the winlink in this session. */
  	if (cmd_find_get_window_with_session(fs, window) == 0)
  		return (0);
  
  	/* Otherwise try as a session itself. */
  	if (!only && cmd_find_get_session(fs, window) == 0) {
  		fs->wl = fs->s->curw;
  		fs->w = fs->wl->window;
  		if (~fs->flags & CMD_FIND_WINDOW_INDEX)
  			fs->idx = fs->wl->idx;
  		return (0);
  	}
  
  	return (-1);
  }
  
  /*
   * Find window from string, assuming it is in given session. Needs s, fills in
   * wl and w.
   */
  static int
  cmd_find_get_window_with_session(struct cmd_find_state *fs, const char *window)
  {
  	struct winlink	*wl;
  	const char	*errstr;
  	int		 idx, n, exact;
  	struct session	*s;
  
  	log_debug("%s: %s", __func__, window);
  	exact = (fs->flags & CMD_FIND_EXACT_WINDOW);
  
  	/*
  	 * Start with the current window as the default. So if only an index is
  	 * found, the window will be the current.
  	 */
  	fs->wl = fs->s->curw;
  	fs->w = fs->wl->window;
  
  	/* Check for window ids starting with @. */
  	if (*window == '@') {
  		fs->w = window_find_by_id_str(window);
  		if (fs->w == NULL || !session_has(fs->s, fs->w))
  			return (-1);
  		return (cmd_find_best_winlink_with_window(fs));
  	}
  
  	/* Try as an offset. */
  	if (!exact && (window[0] == '+' || window[0] == '-')) {
  		if (window[1] != '\0')
  			n = strtonum(window + 1, 1, INT_MAX, NULL);
  		else
  			n = 1;
  		s = fs->s;
  		if (fs->flags & CMD_FIND_WINDOW_INDEX) {
  			if (window[0] == '+') {
  				if (INT_MAX - s->curw->idx < n)
  					return (-1);
  				fs->idx = s->curw->idx + n;
  			} else {
  				if (n < s->curw->idx)
  					return (-1);
  				fs->idx = s->curw->idx - n;
  			}
  			return (0);
  		}
  		if (window[0] == '+')
  			fs->wl = winlink_next_by_number(s->curw, s, n);
  		else
  			fs->wl = winlink_previous_by_number(s->curw, s, n);
  		if (fs->wl != NULL) {
  			fs->idx = fs->wl->idx;
  			fs->w = fs->wl->window;
  			return (0);
  		}
  	}
  
  	/* Try special characters. */
  	if (!exact) {
  		if (strcmp(window, "!") == 0) {
  			fs->wl = TAILQ_FIRST(&fs->s->lastw);
  			if (fs->wl == NULL)
  				return (-1);
  			fs->idx = fs->wl->idx;
  			fs->w = fs->wl->window;
  			return (0);
  		} else if (strcmp(window, "^") == 0) {
  			fs->wl = RB_MIN(winlinks, &fs->s->windows);
  			if (fs->wl == NULL)
  				return (-1);
  			fs->idx = fs->wl->idx;
  			fs->w = fs->wl->window;
  			return (0);
  		} else if (strcmp(window, "$") == 0) {
  			fs->wl = RB_MAX(winlinks, &fs->s->windows);
  			if (fs->wl == NULL)
  				return (-1);
  			fs->idx = fs->wl->idx;
  			fs->w = fs->wl->window;
  			return (0);
  		}
  	}
  
  	/* First see if this is a valid window index in this session. */
  	if (window[0] != '+' && window[0] != '-') {
  		idx = strtonum(window, 0, INT_MAX, &errstr);
  		if (errstr == NULL) {
  			if (fs->flags & CMD_FIND_WINDOW_INDEX) {
  				fs->idx = idx;
  				return (0);
  			}
  			fs->wl = winlink_find_by_index(&fs->s->windows, idx);
  			if (fs->wl != NULL) {
  				fs->w = fs->wl->window;
  				return (0);
  			}
  		}
  	}
  
  	/* Look for exact matches, error if more than one. */
  	fs->wl = NULL;
  	RB_FOREACH(wl, winlinks, &fs->s->windows) {
  		if (strcmp(window, wl->window->name) == 0) {
  			if (fs->wl != NULL)
  				return (-1);
  			fs->wl = wl;
  		}
  	}
  	if (fs->wl != NULL) {
  		fs->idx = fs->wl->idx;
  		fs->w = fs->wl->window;
  		return (0);
  	}
  
  	/* Stop now if exact only. */
  	if (exact)
  		return (-1);
  
  	/* Try as the start of a window name, error if multiple. */
  	fs->wl = NULL;
  	RB_FOREACH(wl, winlinks, &fs->s->windows) {
  		if (strncmp(window, wl->window->name, strlen(window)) == 0) {
  			if (fs->wl != NULL)
  				return (-1);
  			fs->wl = wl;
  		}
  	}
  	if (fs->wl != NULL) {
  		fs->idx = fs->wl->idx;
  		fs->w = fs->wl->window;
  		return (0);
  	}
  
  	/* Now look for pattern matches, again error if multiple. */
  	fs->wl = NULL;
  	RB_FOREACH(wl, winlinks, &fs->s->windows) {
  		if (fnmatch(window, wl->window->name, 0) == 0) {
  			if (fs->wl != NULL)
  				return (-1);
  			fs->wl = wl;
  		}
  	}
  	if (fs->wl != NULL) {
  		fs->idx = fs->wl->idx;
  		fs->w = fs->wl->window;
  		return (0);
  	}
  
  	return (-1);
  }
  
  /* Find pane from string. Fills in s, wl, w, wp. */
  static int
  cmd_find_get_pane(struct cmd_find_state *fs, const char *pane, int only)
  {
  	log_debug("%s: %s", __func__, pane);
  
  	/* Check for pane ids starting with %. */
  	if (*pane == '%') {
  		fs->wp = window_pane_find_by_id_str(pane);
  		if (fs->wp == NULL || window_pane_outside(fs->wp))
  			return (-1);
  		fs->w = fs->wp->window;
  		return (cmd_find_best_session_with_window(fs));
  	}
  
  	/* Not a pane id, so try the current session and window. */
  	fs->s = fs->current->s;
  	fs->wl = fs->current->wl;
  	fs->idx = fs->current->idx;
  	fs->w = fs->current->w;
  
  	/* We now only need to find the pane in this window. */
  	if (cmd_find_get_pane_with_window(fs, pane) == 0)
  		return (0);
  
  	/* Otherwise try as a window itself (this will also try as session). */
  	if (!only && cmd_find_get_window(fs, pane, 0) == 0) {
  		fs->wp = fs->w->active;
  		return (0);
  	}
  
  	return (-1);
  }
  
  /*
   * Find pane from string, assuming it is in given session. Needs s, fills in wl
   * and w and wp.
   */
  static int
  cmd_find_get_pane_with_session(struct cmd_find_state *fs, const char *pane)
  {
  	log_debug("%s: %s", __func__, pane);
  
  	/* Check for pane ids starting with %. */
  	if (*pane == '%') {
  		fs->wp = window_pane_find_by_id_str(pane);
  		if (fs->wp == NULL || window_pane_outside(fs->wp))
  			return (-1);
  		fs->w = fs->wp->window;
  		return (cmd_find_best_winlink_with_window(fs));
  	}
  
  	/* Otherwise use the current window. */
  	fs->wl = fs->s->curw;
  	fs->idx = fs->wl->idx;
  	fs->w = fs->wl->window;
  
  	/* Now we just need to look up the pane. */
  	return (cmd_find_get_pane_with_window(fs, pane));
  }
  
  /*
   * Find pane from string, assuming it is in the given window. Needs w, fills in
   * wp.
   */
  static int
  cmd_find_get_pane_with_window(struct cmd_find_state *fs, const char *pane)
  {
  	const char		*errstr;
  	int			 idx;
  	struct window_pane	*wp;
  	u_int			 n;
  
  	log_debug("%s: %s", __func__, pane);
  
  	/* Check for pane ids starting with %. */
  	if (*pane == '%') {
  		fs->wp = window_pane_find_by_id_str(pane);
  		if (fs->wp == NULL || window_pane_outside(fs->wp))
  			return (-1);
  		if (fs->wp->window != fs->w)
  			return (-1);
  		return (0);
  	}
  
  	/* Try special characters. */
  	if (strcmp(pane, "!") == 0) {
  		if (fs->w->last == NULL)
  			return (-1);
  		fs->wp = fs->w->last;
  		if (fs->wp == NULL || window_pane_outside(fs->wp))
  			return (-1);
  		return (0);
  	} else if (strcmp(pane, "{up-of}") == 0) {
  		fs->wp = window_pane_find_up(fs->w->active);
  		if (fs->wp == NULL || window_pane_outside(fs->wp))
  			return (-1);
  		return (0);
  	} else if (strcmp(pane, "{down-of}") == 0) {
  		fs->wp = window_pane_find_down(fs->w->active);
  		if (fs->wp == NULL || window_pane_outside(fs->wp))
  			return (-1);
  		return (0);
  	} else if (strcmp(pane, "{left-of}") == 0) {
  		fs->wp = window_pane_find_left(fs->w->active);
  		if (fs->wp == NULL || window_pane_outside(fs->wp))
  			return (-1);
  		return (0);
  	} else if (strcmp(pane, "{right-of}") == 0) {
  		fs->wp = window_pane_find_right(fs->w->active);
  		if (fs->wp == NULL || window_pane_outside(fs->wp))
  			return (-1);
  		return (0);
  	}
  
  	/* Try as an offset. */
  	if (pane[0] == '+' || pane[0] == '-') {
  		if (pane[1] != '\0')
  			n = strtonum(pane + 1, 1, INT_MAX, NULL);
  		else
  			n = 1;
  		wp = fs->w->active;
  		if (pane[0] == '+')
  			fs->wp = window_pane_next_by_number(fs->w, wp, n);
  		else
  			fs->wp = window_pane_previous_by_number(fs->w, wp, n);
  		if (fs->wp != NULL && !window_pane_outside(fs->wp))
  			return (0);
  	}
  
  	/* Get pane by index. */
  	idx = strtonum(pane, 0, INT_MAX, &errstr);
  	if (errstr == NULL) {
  		fs->wp = window_pane_at_index(fs->w, idx);
  		if (fs->wp != NULL && !window_pane_outside(fs->wp))
  			return (0);
  	}
  
  	/* Try as a description. */
  	fs->wp = window_find_string(fs->w, pane);
  	if (fs->wp != NULL && !window_pane_outside(fs->wp))
  		return (0);
  
  	return (-1);
  }
  
  /* Clear state. */
  void
  cmd_find_clear_state(struct cmd_find_state *fs, struct cmdq_item *item,
      int flags)
  {
  	memset(fs, 0, sizeof *fs);
  
  	fs->item = item;
  	fs->flags = flags;
  
  	fs->idx = -1;
  }
  
  /* Check if state is empty/ */
  int
  cmd_find_empty_state(struct cmd_find_state *fs)
  {
  	if (fs->s == NULL && fs->wl == NULL && fs->w == NULL && fs->wp == NULL)
  		return (1);
  	return (0);
  }
  
  /* Check if a state if valid. */
  int
  cmd_find_valid_state(struct cmd_find_state *fs)
  {
  	struct winlink	*wl;
  
  	if (fs->s == NULL || fs->wl == NULL || fs->w == NULL || fs->wp == NULL)
  		return (0);
  
  	if (!session_alive(fs->s))
  		return (0);
  
  	RB_FOREACH(wl, winlinks, &fs->s->windows) {
  		if (wl->window == fs->w && wl == fs->wl)
  			break;
  	}
  	if (wl == NULL)
  		return (0);
  
  	if (fs->w != fs->wl->window)
  		return (0);
  
  	if (!window_has_pane(fs->w, fs->wp))
  		return (0);
  	return (!window_pane_outside(fs->wp));
  }
  
  /* Copy a state. */
  void
  cmd_find_copy_state(struct cmd_find_state *dst, struct cmd_find_state *src)
  {
  	dst->s = src->s;
  	dst->wl = src->wl;
  	dst->idx = src->idx;
  	dst->w = src->w;
  	dst->wp = src->wp;
  }
  
  /* Log the result. */
  void
  cmd_find_log_state(const char *prefix, struct cmd_find_state *fs)
  {
  	if (fs->s != NULL)
  		log_debug("%s: s=$%u", prefix, fs->s->id);
  	else
  		log_debug("%s: s=none", prefix);
  	if (fs->wl != NULL) {
  		log_debug("%s: wl=%u %d w=@%u %s", prefix, fs->wl->idx,
  		    fs->wl->window == fs->w, fs->w->id, fs->w->name);
  	} else
  		log_debug("%s: wl=none", prefix);
  	if (fs->wp != NULL)
  		log_debug("%s: wp=%%%u", prefix, fs->wp->id);
  	else
  		log_debug("%s: wp=none", prefix);
  	if (fs->idx != -1)
  		log_debug("%s: idx=%d", prefix, fs->idx);
  	else
  		log_debug("%s: idx=none", prefix);
  }
  
  /* Find state from a session. */
  int
  cmd_find_from_session(struct cmd_find_state *fs, struct session *s)
  {
  	cmd_find_clear_state(fs, NULL, 0);
  
  	fs->s = s;
  	fs->wl = fs->s->curw;
  	fs->w = fs->wl->window;
  	fs->wp = fs->w->active;
  
  	cmd_find_log_state(__func__, fs);
  	return (0);
  }
  
  /* Find state from a winlink. */
  int
  cmd_find_from_winlink(struct cmd_find_state *fs, struct session *s,
      struct winlink *wl)
  {
  	cmd_find_clear_state(fs, NULL, 0);
  
  	fs->s = s;
  	fs->wl = wl;
  	fs->w = wl->window;
  	fs->wp = wl->window->active;
  
  	cmd_find_log_state(__func__, fs);
  	return (0);
  }
  
  /* Find state from a session and window. */
  int
  cmd_find_from_session_window(struct cmd_find_state *fs, struct session *s,
      struct window *w)
  {
  	cmd_find_clear_state(fs, NULL, 0);
  
  	fs->s = s;
  	fs->w = w;
  	if (cmd_find_best_winlink_with_window(fs) != 0)
  		return (-1);
  	fs->wp = fs->w->active;
  
  	cmd_find_log_state(__func__, fs);
  	return (0);
  }
  
  /* Find state from a window. */
  int
  cmd_find_from_window(struct cmd_find_state *fs, struct window *w)
  {
  	cmd_find_clear_state(fs, NULL, 0);
  
  	fs->w = w;
  	if (cmd_find_best_session_with_window(fs) != 0)
  		return (-1);
  	if (cmd_find_best_winlink_with_window(fs) != 0)
  		return (-1);
  	fs->wp = fs->w->active;
  
  	cmd_find_log_state(__func__, fs);
  	return (0);
  }
  
  /* Find state from a pane. */
  int
  cmd_find_from_pane(struct cmd_find_state *fs, struct window_pane *wp)
  {
  	if (cmd_find_from_window(fs, wp->window) != 0)
  		return (-1);
  	if (window_pane_outside(wp))
  		return (-1);
  	fs->wp = wp;
  
  	cmd_find_log_state(__func__, fs);
  	return (0);
  }
  
  /* Find current state. */
  int
  cmd_find_current(struct cmd_find_state *fs, struct cmdq_item *item, int flags)
  {
  	cmd_find_clear_state(fs, item, flags);
  	if (cmd_find_current_session(fs) != 0) {
  		if (~flags & CMD_FIND_QUIET)
  			cmdq_error(item, "no current session");
  		return (-1);
  	}
  	return (0);
  }
  
  /*
   * Split target into pieces and resolve for the given type. Fills in the given
   * state. Returns 0 on success or -1 on error.
   */
  int
  cmd_find_target(struct cmd_find_state *fs, struct cmd_find_state *current,
      struct cmdq_item *item, const char *target, enum cmd_find_type type,
      int flags)
  {
  	struct mouse_event	*m;
  	char			*colon, *period, *copy = NULL;
  	const char		*session, *window, *pane;
  	int			 window_only = 0, pane_only = 0;
  
  	/* Log the arguments. */
  	if (target == NULL)
  		log_debug("%s: target none, type %d", __func__, type);
  	else
  		log_debug("%s: target %s, type %d", __func__, target, type);
  	log_debug("%s: item %p, flags %#x", __func__, item, flags);
  
  	/* Clear new state. */
  	cmd_find_clear_state(fs, item, flags);
  
  	/* Find current state. */
  	if (server_check_marked() && (flags & CMD_FIND_DEFAULT_MARKED)) {
  		fs->current = &marked_pane;
  		log_debug("%s: current is marked pane", __func__);
  	} else if (cmd_find_valid_state(&item->current)) {
  		fs->current = &item->current;
  		log_debug("%s: current is from queue", __func__);
  	} else {
  		fs->current = current;
  		log_debug("%s: current is from argument", __func__);
  	}
  	if (!cmd_find_empty_state(fs->current) &&
  	    !cmd_find_valid_state(fs->current))
  		fatalx("invalid current find state");
  
  	/* An empty or NULL target is the current. */
  	if (target == NULL || *target == '\0')
  		goto current;
  
  	/* Mouse target is a plain = or {mouse}. */
  	if (strcmp(target, "=") == 0 || strcmp(target, "{mouse}") == 0) {
  		m = &item->mouse;
  		switch (type) {
  		case CMD_FIND_PANE:
  			fs->wp = cmd_mouse_pane(m, &fs->s, &fs->wl);
  			if (fs->wp != NULL && !window_pane_outside(fs->wp))
  				fs->w = fs->wl->window;
  			break;
  		case CMD_FIND_WINDOW:
  		case CMD_FIND_SESSION:
  			fs->wl = cmd_mouse_window(m, &fs->s);
  			if (fs->wl != NULL) {
  				fs->w = fs->wl->window;
  				fs->wp = fs->w->active;
  			}
  			break;
  		}
  		if (fs->wp == NULL) {
  			if (~flags & CMD_FIND_QUIET)
  				cmdq_error(item, "no mouse target");
  			goto error;
  		}
  		goto found;
  	}
  
  	/* Marked target is a plain ~ or {marked}. */
  	if (strcmp(target, "~") == 0 || strcmp(target, "{marked}") == 0) {
  		if (!server_check_marked()) {
  			if (~flags & CMD_FIND_QUIET)
  				cmdq_error(item, "no marked target");
  			goto error;
  		}
  		cmd_find_copy_state(fs, &marked_pane);
  		goto found;
  	}
  
  	/* Find separators if they exist. */
  	copy = xstrdup(target);
  	colon = strchr(copy, ':');
  	if (colon != NULL)
  		*colon++ = '\0';
  	if (colon == NULL)
  		period = strchr(copy, '.');
  	else
  		period = strchr(colon, '.');
  	if (period != NULL)
  		*period++ = '\0';
  
  	/* Set session, window and pane parts. */
  	session = window = pane = NULL;
  	if (colon != NULL && period != NULL) {
  		session = copy;
  		window = colon;
  		window_only = 1;
  		pane = period;
  		pane_only = 1;
  	} else if (colon != NULL && period == NULL) {
  		session = copy;
  		window = colon;
  		window_only = 1;
  	} else if (colon == NULL && period != NULL) {
  		window = copy;
  		pane = period;
  		pane_only = 1;
  	} else {
  		if (*copy == '$')
  			session = copy;
  		else if (*copy == '@')
  			window = copy;
  		else if (*copy == '%')
  			pane = copy;
  		else {
  			switch (type) {
  			case CMD_FIND_SESSION:
  				session = copy;
  				break;
  			case CMD_FIND_WINDOW:
  				window = copy;
  				break;
  			case CMD_FIND_PANE:
  				pane = copy;
  				break;
  			}
  		}
  	}
  
  	/* Set exact match flags. */
  	if (session != NULL && *session == '=') {
  		session++;
  		fs->flags |= CMD_FIND_EXACT_SESSION;
  	}
  	if (window != NULL && *window == '=') {
  		window++;
  		fs->flags |= CMD_FIND_EXACT_WINDOW;
  	}
  
  	/* Empty is the same as NULL. */
  	if (session != NULL && *session == '\0')
  		session = NULL;
  	if (window != NULL && *window == '\0')
  		window = NULL;
  	if (pane != NULL && *pane == '\0')
  		pane = NULL;
  
  	/* Map though conversion table. */
  	if (session != NULL)
  		session = cmd_find_map_table(cmd_find_session_table, session);
  	if (window != NULL)
  		window = cmd_find_map_table(cmd_find_window_table, window);
  	if (pane != NULL)
  		pane = cmd_find_map_table(cmd_find_pane_table, pane);
  
  	log_debug("target %s (flags %#x): session=%s, window=%s, pane=%s",
  	    target, flags, session == NULL ? "none" : session,
  	    window == NULL ? "none" : window, pane == NULL ? "none" : pane);
  
  	/* No pane is allowed if want an index. */
  	if (pane != NULL && (flags & CMD_FIND_WINDOW_INDEX)) {
  		if (~flags & CMD_FIND_QUIET)
  			cmdq_error(item, "can't specify pane here");
  		goto error;
  	}
  
  	/* If the session isn't NULL, look it up. */
  	if (session != NULL) {
  		/* This will fill in session. */
  		if (cmd_find_get_session(fs, session) != 0)
  			goto no_session;
  
  		/* If window and pane are NULL, use that session's current. */
  		if (window == NULL && pane == NULL) {
  			fs->wl = fs->s->curw;
  			fs->idx = -1;
  			fs->w = fs->wl->window;
  			fs->wp = fs->w->active;
  			goto found;
  		}
  
  		/* If window is present but pane not, find window in session. */
  		if (window != NULL && pane == NULL) {
  			/* This will fill in winlink and window. */
  			if (cmd_find_get_window_with_session(fs, window) != 0)
  				goto no_window;
  			fs->wp = fs->wl->window->active;
  			goto found;
  		}
  
  		/* If pane is present but window not, find pane. */
  		if (window == NULL && pane != NULL) {
  			/* This will fill in winlink and window and pane. */
  			if (cmd_find_get_pane_with_session(fs, pane) != 0)
  				goto no_pane;
  			goto found;
  		}
  
  		/*
  		 * If window and pane are present, find both in session. This
  		 * will fill in winlink and window.
  		 */
  		if (cmd_find_get_window_with_session(fs, window) != 0)
  			goto no_window;
  		/* This will fill in pane. */
  		if (cmd_find_get_pane_with_window(fs, pane) != 0)
  			goto no_pane;
  		goto found;
  	}
  
  	/* No session. If window and pane, try them. */
  	if (window != NULL && pane != NULL) {
  		/* This will fill in session, winlink and window. */
  		if (cmd_find_get_window(fs, window, window_only) != 0)
  			goto no_window;
  		/* This will fill in pane. */
  		if (cmd_find_get_pane_with_window(fs, pane) != 0)
  			goto no_pane;
  		goto found;
  	}
  
  	/* If just window is present, try it. */
  	if (window != NULL && pane == NULL) {
  		/* This will fill in session, winlink and window. */
  		if (cmd_find_get_window(fs, window, window_only) != 0)
  			goto no_window;
  		fs->wp = fs->wl->window->active;
  		goto found;
  	}
  
  	/* If just pane is present, try it. */
  	if (window == NULL && pane != NULL) {
  		/* This will fill in session, winlink, window and pane. */
  		if (cmd_find_get_pane(fs, pane, pane_only) != 0)
  			goto no_pane;
  		goto found;
  	}
  
  current:
  	/* Use the current session. */
  	cmd_find_copy_state(fs, fs->current);
  	if (flags & CMD_FIND_WINDOW_INDEX)
  		fs->idx = -1;
  	goto found;
  
  error:
  	fs->current = NULL;
  	log_debug("%s: error", __func__);
  
  	free(copy);
  	return (-1);
  
  found:
  	fs->current = NULL;
  	cmd_find_log_state(__func__, fs);
  
  	free(copy);
  	return (0);
  
  no_session:
  	if (~flags & CMD_FIND_QUIET)
  		cmdq_error(item, "can't find session %s", session);
  	goto error;
  
  no_window:
  	if (~flags & CMD_FIND_QUIET)
  		cmdq_error(item, "can't find window %s", window);
  	goto error;
  
  no_pane:
  	if (~flags & CMD_FIND_QUIET)
  		cmdq_error(item, "can't find pane %s", pane);
  	goto error;
  }
  
  /* Find the target client or report an error and return NULL. */
  struct client *
  cmd_find_client(struct cmdq_item *item, const char *target, int quiet)
  {
  	struct client	*c;
  	char		*copy;
  	size_t		 size;
  
  	/* A NULL argument means the current client. */
  	if (item != NULL && target == NULL) {
  		c = cmd_find_current_client(item);
  		if (c == NULL && !quiet)
  			cmdq_error(item, "no current client");
  		log_debug("%s: no target, return %p", __func__, c);
  		return (c);
  	}
  	copy = xstrdup(target);
  
  	/* Trim a single trailing colon if any. */
  	size = strlen(copy);
  	if (size != 0 && copy[size - 1] == ':')
  		copy[size - 1] = '\0';
  
  	/* Check name and path of each client. */
  	TAILQ_FOREACH(c, &clients, entry) {
  		if (c->session == NULL)
  			continue;
  		if (strcmp(copy, c->name) == 0)
  			break;
  
  		if (*c->ttyname == '\0')
  			continue;
  		if (strcmp(copy, c->ttyname) == 0)
  			break;
  		if (strncmp(c->ttyname, _PATH_DEV, (sizeof _PATH_DEV) - 1) != 0)
  			continue;
  		if (strcmp(copy, c->ttyname + (sizeof _PATH_DEV) - 1) == 0)
  			break;
  	}
  
  	/* If no client found, report an error. */
  	if (c == NULL && !quiet)
  		cmdq_error(item, "can't find client %s", copy);
  
  	free(copy);
  	log_debug("%s: target %s, return %p", __func__, target, c);
  	return (c);
  }
  