Add preview path caching to prevent redundant I/O

2 files changed, 44 insertions, 9 deletions

diff --git a/src/fm.c b/src/fm.c
index 92526c3..c863cad 100644
--- a/src/fm.c
+++ b/src/fm.c
@@ -22,6 +22,7 @@
 static magic_t g_magic_ctx = NULL;
 static char *const utils[] = {"vi", "xdg-open"};
 static char *const envs[] = {"SHELL", "EDITOR", "SF"};
+static char last_preview_path[PATH_MAX] = "";
 bool need_redraw = true;
 
 /* Function forward declarations */
@@ -201,6 +202,12 @@ detect_file_type(const char *filepath)
 	return desc ? strdup(desc) : strdup("unknown");
 }
 
+static bool
+is_previewed_path(const char *path)
+{
+	return (strcmp(last_preview_path, path) == 0);
+}
+
 void
 fm_draw_file_stream(window *w, FILE *fp)
 {
@@ -220,30 +227,57 @@ fm_preview_file(window *w, const char *path)
 	if (!w || !path)
 		return false;
 
-	wclear(w->win);
-
-	char *file_type = detect_file_type(path);
-
-	if (strstr(file_type, "text") == NULL) {
-		mvwprintw(w->win, 0, 0, "%s", file_type);
-		free(file_type);
+	if (is_previewed_path(path))
 		return false;
-	}
 
+	wclear(w->win);
+	char *file_type = detect_file_type(path);
 	FILE *fp = fopen(path, "r");
 	if (!fp) {
 		mvwprintw(w->win, 0, 0, "<Cannot open file>");
 		free(file_type);
 		return false;
+	} else if (strstr(file_type, "text")) {
+		fm_draw_file_stream(w, fp);
+	} else {
+		mvwprintw(w->win, 0, 0, "%s", file_type);
 	}
 
-	fm_draw_file_stream(w, fp);
+	snprintf(last_preview_path, sizeof(last_preview_path), "%s", path);
 
 	fclose(fp);
 	free(file_type);
 	return true;
 }
 
+bool
+fm_preview_dir(fm_info *info, const char *path)
+{
+	if (!info)
+		return false;
+
+	if (is_previewed_path(path))
+		return false;
+
+	window *right = info->windows[FM_PANE_RIGHT];
+	int right_height = info->windows[FM_PANE_RIGHT]->height;
+
+	wclear(right->win);
+
+	file_list *new_list = info->next;
+	new_list = fm_getdir(new_list, path);
+	if (new_list) {
+		info->next = new_list;
+		fm_draw_entries(right, new_list, -1, 0, right_height);
+	} else {
+		return false;
+	}
+
+	snprintf(last_preview_path, sizeof(last_preview_path), "%s", path);
+
+	return true;
+}
+
 void
 fm_draw_entries(window *window, file_list *list, size_t cursor, int top,
 		int bottom)
diff --git a/src/fm.h b/src/fm.h
index 493d1f9..9293bfe 100644
--- a/src/fm.h
+++ b/src/fm.h
@@ -60,6 +60,7 @@ void fm_draw_file_stream(window *w, FILE *fp);
 void fm_cd_up(fm_info *i);
 void fm_cd_down(fm_info *i);
 bool fm_preview_file(window *w, const char *path);
+bool fm_preview_dir(fm_info *info, const char *path);
 int open_with_editor(char **argv);
 void magic_init(void);
 void magic_cleanup(void);