# Description: Adds preview pipe to enable closing and re-opening the preview
#              pane when running an undetached editor. If you are using vim
#              you might experience incorrectly resized window. Consider adding
#              the following to your vimrc:
#              autocmd VimEnter * :silent exec "!kill -s WINCH $PPID"
#
# Authors: Luuk van Baal

diff --git a/src/nnn.c b/src/nnn.c
index 0388b23c..66d3316a 100644
--- a/src/nnn.c
+++ b/src/nnn.c
@@ -390,7 +390,8 @@ typedef struct {
 	uint_t uidgid     : 1;  /* Show owner and group info */
 	uint_t usebsdtar  : 1;  /* Use bsdtar as default archive utility */
 	uint_t xprompt    : 1;  /* Use native prompt instead of readline prompt */
-	uint_t reserved   : 4;  /* Adjust when adding/removing a field */
+	uint_t previewer  : 1;  /* Run state of previewer */
+	uint_t reserved   : 3;  /* Adjust when adding/removing a field */
 } runstate;
 
 /* Contexts or workspaces */
@@ -516,6 +517,9 @@ alignas(max_align_t) static char g_tmpfpath[TMP_LEN_MAX];
 /* Buffer to store plugins control pipe location */
 alignas(max_align_t) static char g_pipepath[TMP_LEN_MAX];
 
+/* Buffer to store preview plugins control pipe location */
+static char g_ppipepath[TMP_LEN_MAX] __attribute__ ((aligned));
+
 /* Non-persistent runtime states */
 static runstate g_state;
 
@@ -696,12 +700,13 @@ static const char * const messages[] = {
 #define NNN_FCOLORS 5
 #define NNNLVL      6
 #define NNN_PIPE    7
-#define NNN_MCLICK  8
-#define NNN_SEL     9
-#define NNN_ARCHIVE 10
-#define NNN_ORDER   11
-#define NNN_HELP    12 /* strings end here */
-#define NNN_TRASH   13 /* flags begin here */
+#define NNN_PPIPE   8
+#define NNN_MCLICK  9
+#define NNN_SEL     10
+#define NNN_ARCHIVE 11
+#define NNN_ORDER   12
+#define NNN_HELP    13 /* strings end here */
+#define NNN_TRASH   14 /* flags begin here */
 
 static const char * const env_cfg[] = {
 	"NNN_OPTS",
@@ -712,6 +717,7 @@ static const char * const env_cfg[] = {
 	"NNN_FCOLORS",
 	"NNNLVL",
 	"NNN_PIPE",
+	"NNN_PPIPE",
 	"NNN_MCLICK",
 	"NNN_SEL",
 	"NNN_ARCHIVE",
@@ -850,7 +856,7 @@ static int set_sort_flags(int r);
 static void statusbar(char *path);
 static bool get_output(char *file, char *arg1, char *arg2, int fdout, bool page);
 #ifndef NOFIFO
-static void notify_fifo(bool force);
+static void notify_fifo(bool force, bool closepreview);
 #endif
 
 /* Functions */
@@ -3140,7 +3146,7 @@ try_quit:
 			} else {
 #ifndef NOFIFO
 				if (!g_state.fifomode)
-					notify_fifo(TRUE); /* Send hovered path to NNN_FIFO */
+					notify_fifo(TRUE, FALSE); /* Send hovered path to NNN_FIFO */
 #endif
 				escaped = TRUE;
 				settimeout();
@@ -5258,15 +5264,20 @@ static void run_cmd_as_plugin(const char *file, uchar_t flags)
 
 static bool plctrl_init(void)
 {
-	size_t len;
+	size_t len, lenbuf;
+	pid_t pid = getpid();
 
 	/* g_tmpfpath is used to generate tmp file names */
 	g_tmpfpath[tmpfplen - 1] = '\0';
-	len = xstrsncpy(g_pipepath, g_tmpfpath, TMP_LEN_MAX);
+	len = lenbuf = xstrsncpy(g_pipepath, g_tmpfpath, TMP_LEN_MAX);
 	g_pipepath[len - 1] = '/';
-	len = xstrsncpy(g_pipepath + len, "nnn-pipe.", TMP_LEN_MAX - len) + len;
-	xstrsncpy(g_pipepath + len - 1, xitoa(getpid()), TMP_LEN_MAX - len);
+	xstrsncpy(g_ppipepath, g_pipepath, TMP_LEN_MAX);
+	len += xstrsncpy(g_pipepath + len, "nnn-pipe.", TMP_LEN_MAX - len);
+	xstrsncpy(g_pipepath + len - 1, xitoa(pid), TMP_LEN_MAX - len);
+	len = xstrsncpy(g_ppipepath + lenbuf, "nnn-ppipe.", TMP_LEN_MAX - lenbuf) + lenbuf;
+	xstrsncpy(g_ppipepath + len - 1, xitoa(pid), TMP_LEN_MAX - len);
 	setenv(env_cfg[NNN_PIPE], g_pipepath, TRUE);
+	setenv(env_cfg[NNN_PPIPE], g_ppipepath, TRUE);
 
 	return EXIT_SUCCESS;
 }
@@ -5295,6 +5306,21 @@ static ssize_t read_nointr(int fd, void *buf, size_t count)
 	return len;
 }
 
+void *previewpipe(void *arg __attribute__ ((unused)))
+{
+	int fd, buf;
+
+	mkfifo(g_ppipepath, 0600);
+	fd = open(g_ppipepath, O_RDONLY);
+
+	if (read(fd, &buf, 1) == 1)
+		g_state.previewer = buf;
+
+	close(fd);
+	unlink(g_ppipepath);
+	return NULL;
+}
+
 static char *readpipe(int fd, char *ctxnum, char **path)
 {
 	char ctx, *nextpath = NULL;
@@ -5979,7 +6005,7 @@ static void populate(char *path, char *lastname)
 }
 
 #ifndef NOFIFO
-static void notify_fifo(bool force)
+static void notify_fifo(bool force, bool closepreview)
 {
 	if (!fifopath)
 		return;
@@ -5995,6 +6021,12 @@ static void notify_fifo(bool force)
 		}
 	}
 
+	if (closepreview) {
+		if (write(fifofd, "close\n", 6) != 6)
+			xerror();
+		return;
+	}
+
 	static struct entry lastentry;
 
 	if (!force && !memcmp(&lastentry, &pdents[cur], sizeof(struct entry))) // NOLINT
@@ -6027,7 +6059,7 @@ static void send_to_explorer(int *presel)
 		if (fd > 1)
 			close(fd);
 	} else
-		notify_fifo(TRUE); /* Send opened path to NNN_FIFO */
+		notify_fifo(TRUE, FALSE); /* Send opened path to NNN_FIFO */
 }
 #endif
 
@@ -6060,7 +6092,7 @@ static void move_cursor(int target, int ignore_scrolloff)
 
 #ifndef NOFIFO
 	if (!g_state.fifomode)
-		notify_fifo(FALSE); /* Send hovered path to NNN_FIFO */
+		notify_fifo(FALSE, FALSE); /* Send hovered path to NNN_FIFO */
 #endif
 }
 
@@ -6733,7 +6765,7 @@ static bool browse(char *ipath, const char *session, int pkey)
 	pEntry pent;
 	enum action sel;
 	struct stat sb;
-	int r = -1, presel, selstartid = 0, selendid = 0;
+	int r = -1, presel, selstartid = 0, selendid = 0, previewkey = 0;
 	const uchar_t opener_flags = (cfg.cliopener ? F_CLI : (F_NOTRACE | F_NOSTDIN | F_NOWAIT));
 	bool watch = FALSE, cd = TRUE;
 	ino_t inode = 0;
@@ -6991,7 +7023,7 @@ nochange:
 					move_cursor(r, 1);
 #ifndef NOFIFO
 				else if ((event.bstate == BUTTON1_PRESSED) && !g_state.fifomode)
-					notify_fifo(TRUE); /* Send clicked path to NNN_FIFO */
+					notify_fifo(TRUE, FALSE); /* Send clicked path to NNN_FIFO */
 #endif
 				/* Handle right click selection */
 				if (event.bstate == BUTTON3_PRESSED) {
@@ -7153,7 +7185,14 @@ nochange:
 			    && strstr(g_buf, "text")
 #endif
 			) {
+				if (g_state.previewer)
+					notify_fifo(FALSE, TRUE);
 				spawn(editor, newpath, NULL, NULL, F_CLI);
+				if (g_state.previewer) {
+					pkey = previewkey;
+					goto run_plugin;
+				}
+
 				if (cfg.filtermode) {
 					presel = FILTER;
 					clearfilter();
@@ -7471,8 +7510,14 @@ nochange:
 				copycurname();
 				goto nochange;
 			case SEL_EDIT:
+				if (g_state.previewer)
+					notify_fifo(FALSE, TRUE);
 				if (!(g_state.picker || g_state.fifomode))
 					spawn(editor, newpath, NULL, NULL, F_CLI);
+				if (g_state.previewer) {
+					pkey = previewkey;
+					goto run_plugin;
+				}
 				continue;
 			default: /* SEL_LOCK */
 				lock_terminal();
@@ -7860,6 +7905,7 @@ nochange:
 			cd = FALSE;
 			goto begin;
 		}
+run_plugin:
 		case SEL_PLUGIN:
 			/* Check if directory is accessible */
 			if (!xdiraccess(plgpath)) {
@@ -7885,6 +7931,12 @@ nochange:
 					goto nochange;
 				}
 
+				if (xstrcmp(tmp, "preview-tui") == 0) {
+					previewkey = r;
+					pthread_t tid;
+					pthread_create(&tid, NULL, previewpipe, NULL);
+				}
+
 				if (tmp[0] == '-' && tmp[1]) {
 					++tmp;
 					r = FALSE; /* Do not refresh dir after completion */
@@ -7943,7 +7995,13 @@ nochange:
 		case SEL_SHELL: // fallthrough
 		case SEL_LAUNCH: // fallthrough
 		case SEL_PROMPT:
+			if (g_state.previewer)
+				notify_fifo(FALSE, TRUE);
 			r = handle_cmd(sel, newpath);
+			if (g_state.previewer) {
+				pkey = previewkey;
+				goto run_plugin;
+			}
 
 			/* Continue in type-to-nav mode, if enabled */
 			if (cfg.filtermode)
@@ -8492,8 +8550,10 @@ static void cleanup(void)
 	if (g_state.autofifo)
 		unlink(fifopath);
 #endif
-	if (g_state.pluginit)
+	if (g_state.pluginit){
 		unlink(g_pipepath);
+		unlink(g_ppipepath);
+	}
 #ifdef DEBUG
 	disabledbg();
 #endif
@@ -9020,7 +9080,7 @@ int main(int argc, char *argv[])
 
 #ifndef NOFIFO
 	if (!g_state.fifomode)
-		notify_fifo(FALSE);
+		notify_fifo(FALSE, TRUE);
 	if (fifofd != -1)
 		close(fifofd);
 #endif