Implement plugins control of nnn + plugins (#364)

* Implement plugins control of nnn + plugins

* Refactor plugins control code and fix getplugs to recognize hidden files

* Fix bug when going to dir on non-current context from plugin

* Fix some plugins to work on openbsd and freebsd

* Renamings

* Switch to -R flag in cp instead of -r; BSDs complain

* Change braces of function location

* Rewrite plugin creation in README and add new plugins to the table

* Update the fzcd script to include fzy or fzf

* Change plugin name resolve-link-dir -> lncd

* Fixing plugins README table

* Remove some cd plugins but add them as examples to plugins README

4 files changed, 136 insertions, 18 deletions

diff --git a/plugins/.nnn-plugin-helper b/plugins/.nnn-plugin-helper
new file mode 100644
index 0000000..ec66a29
--- /dev/null
+++ b/plugins/.nnn-plugin-helper
@@ -0,0 +1,33 @@
+#!/usr/bin/env sh
+
+# Description: Helper script for plugins
+#
+# Shell: POSIX compliant
+# Author: Anna Arad
+
+selection=${XDG_CONFIG_HOME:-$HOME/.config}/nnn/.selection
+
+## Ask nnn to switch to directory $1 in context $2.
+## If $2 is not provided, the function asks explicitly.
+nnn_cd () {
+    dir=$1
+
+    if [ -z "$NNN_PIPE" ]; then
+        echo "No pipe file found" 1>&2
+        return
+    fi
+
+    if [ -n "$2" ]; then
+        context=$2
+    else
+        echo -n "Choose context 1-4 (blank for current): "
+        read context
+    fi
+
+    echo -n ${context:-0}$dir > $NNN_PIPE
+}
+
+cmd_exists () {
+	which "$1" > /dev/null 2>&1
+	echo $?
+}
diff --git a/plugins/README.md b/plugins/README.md
index 85550ca..9d48ec3 100644
--- a/plugins/README.md
+++ b/plugins/README.md
@@ -14,6 +14,7 @@ The currently available plugins are listed below.
 | checksum | sh | md5sum,<br>sha256sum | Create and verify checksums |
 | drag-file | sh | [dragon](https://github.com/mwh/dragon) | Drag and drop files from nnn |
 | drop-file | sh | [dragon](https://github.com/mwh/dragon) | Drag and drop files into nnn |
+| fzcd | sh | fzy/fzf<br>(optional fd) | Change to the directory of a file/directory selected by fzy/fzf |
 | fzy-open | sh | fzy, xdg-open | Fuzzy find a file in dir subtree and edit or xdg-open |
 | getplugs | sh | curl | Update plugins |
 | gutenread | sh | curl, unzip, w3m<br>[epr](https://github.com/wustho/epr) (optional)| Browse, download, read from Project Gutenberg |
@@ -67,28 +68,68 @@ With this, plugin `fzy-open` can be run with the keybind <kbd>:o</kbd>, `mocplay
 
 **Method 2:** Use the _pick plugin_ shortcut to visit the plugin directory and execute a plugin. Repeating the same shortcut cancels the operation and puts you back in the original directory.
 
-## File access from plugins
+## Create your own plugins
+
+Plugins are a powerful yet easy way to extend the capabilities of `nnn`.
 
-Plugins can access:
-- all files in the directory (`nnn` switches to the dir where the plugin is to be run so the dir is `$PWD` for the plugin)
-- the current file under the cursor (the file name is passed as the first argument to a plugin)
-- the traversed path where plugin is invoked (this is the second argument to the plugin; for all practical purposes this is the same as `$PWD` except paths with symlinks)
-- the current selection (by reading the file `.selection` in config dir, see the plugin `ndiff`)
+Plugins are scripts that can be written in any scripting language. However, POSIX-compliant shell scripts runnable in `sh` are preferred.
 
 Each script has a _Description_ section which provides more details on what the script does, if applicable.
 
-## Create your own plugins
+The plugins reside in `${XDG_CONFIG_HOME:-$HOME/.config}/nnn/plugins`.
+
+When `nnn` executes a plugin, it does the following:
+- Change to the directory where the plugin is to be run (`$PWD` pointing to the active directory)
+- Passes two arguments to the script:
+    1. The hovered file's name
+    2. The working directory (might differ from `$PWD` in case of symlinked paths; non-canonical)
+- Sets the environment variable `NNN_PIPE` used to control `nnn` active directory.
+
+Plugins can also access the current selections by reading the `.selections` file in the config directory (See the `ndiff` plugin for example).
 
-Plugins are scripts and all scripting languages should work. However, POSIX-compliant shell scripts runnable in `sh` are preferred. If that's too rudimentary for your use case, use Python, Perl or Ruby.
+#### Controlling `nnn`'s active directory
+`nnn` provides a mechanism for plugins to control its active directory.
+The way to do so is by writing to the pipe pointed by the environment variable `NNN_PIPE`.
+The plugin should write a single string in the format `<number><path>` without a newline at the end. For example, `1/etc`.
+The number indicates the context to change the active directory of (0 is used to indicate the current context).
 
-You can create your own plugins by putting them in `${XDG_CONFIG_HOME:-$HOME/.config}/nnn/plugins`.
+For convenience, we provided a helper script named `.nnn-plugin-helper` and a function named `nnn_cd` to ease this process. `nnn_cd` receives the path to change to as the first argument, and the context as an optional second argument.
+If a context is not provided, it is asked for explicitly.
+Usage examples can be found in the Examples section below.
 
-For example, you could create a executable shell script `git-changes`:
+#### Examples
+There are many plugins provided by `nnn` which can be used as examples. Here are a few simple selected examples.
 
+- Show the git log of changes to the particular file along with the code for a quick and easy review.
+   ```sh
     #!/usr/bin/env sh
-    git log -p -- "$@"
+    git log -p -- "$1"
+    ```
+    
+- Change to directory in clipboard using helper script
+    ```sh
+    #!/usr/bin/env sh
+    . $(dirname $0/.nnn-plugin-helper)
+
+    nnn_cd "$(xsel -ob)"
+    ```
 
-And then trigger it by hitting the pick plugin key and selecting `git-changes` which will conveniently show the git log of changes to the particular file along with the code for a quick and easy review.
+- Change direcory to the location of a link using helper script with specific context (current)
+    ```sh
+    #!/usr/bin/env sh
+    . $(dirname $0/.nnn-plugin-helper)
+
+    nnn_cd "$(dirname $(readlink -fn $1))" 0
+    ```
+    
+- Change to arbitrary directory without helper script
+    ```sh
+    #!/usr/bin/env sh
+    echo -n "cd to: "
+    read dir
+    
+    echo -n "0$dir" > $NNN_PIPE
+    ```
 
 ## Contributing plugins
 
diff --git a/plugins/fzcd b/plugins/fzcd
new file mode 100755
index 0000000..443ac2d
--- /dev/null
+++ b/plugins/fzcd
@@ -0,0 +1,32 @@
+#!/usr/bin/env sh
+
+# Description: Run fzf and go to the directory of the file selected
+#
+# Shell: POSIX compliant
+# Author: Anna Arad
+
+. $(dirname $0)/.nnn-plugin-helper
+
+if [ "$(cmd_exists fzy)" -eq "0" ]; then
+	if [ "$(cmd_exists fd)" -eq "0" ]; then
+		fd=fd
+	elif [ "$(cmd_exists fdfind)" -eq "0" ]; then
+		fd=fdfind
+	else
+		fd=find
+	fi
+
+	sel=$($fd | fzy)
+elif [ "$(cmd_exists fzf)" -eq "0" ]; then
+	sel=$(fzf --print0)
+else
+	exit 1
+fi
+
+if [ "$?" -eq "0" ]; then
+	case "$(file -bi "$sel")" in
+		*directory*) ;;
+		*) sel=$(dirname $sel) ;;
+	esac
+	nnn_cd "$PWD/$sel"
+fi
diff --git a/plugins/getplugs b/plugins/getplugs
index e144be3..42d5400 100755
--- a/plugins/getplugs
+++ b/plugins/getplugs
@@ -8,15 +8,27 @@
 CONFIG_DIR=${XDG_CONFIG_HOME:-$HOME/.config}/nnn/
 PLUGIN_DIR=${XDG_CONFIG_HOME:-$HOME/.config}/nnn/plugins
 
+is_cmd_exists () {
+    which "$1" > /dev/null 2>&1
+    echo $?
+}
+
+if [ "$(is_cmd_exists sudo)" == "0" ]; then
+    sucmd=sudo
+elif [ "$(is_cmd_exists doas)" == "0" ]; then
+    sucmd=doas
+else
+    sucmd=: # noop
+fi
+
 # backup any earlier plugins
 if [ -d $PLUGIN_DIR ]; then
-    tar -C $CONFIG_DIR -cf $CONFIG_DIR"plugins-$(date '+%Y%m%d%H%M').tar.bz2" plugins/
+    tar -C $CONFIG_DIR -czf $CONFIG_DIR"plugins-$(date '+%Y%m%d%H%M').tar.gz" plugins/
 fi
 
-mkdir -p $PLUGIN_DIR
-cd $PLUGIN_DIR
+cd $CONFIG_DIR
 curl -Ls -O https://github.com/jarun/nnn/archive/master.tar.gz
-tar -xf master.tar.gz
-cp -vf nnn-master/plugins/* .
-sudo mv -vf nnn-master/misc/nlaunch/nlaunch /usr/local/bin/
+tar -zxf master.tar.gz
+cp -vRf nnn-master/plugins .
+$sucmd mv -vf nnn-master/misc/nlaunch/nlaunch /usr/local/bin/
 rm -rf nnn-master/ master.tar.gz README.md