refactor(emacs): remove dependency on `require_tool.sh` and clean up code style

plugins/emacs/emacs.plugin.zsh

@@ -9,9 +9,12 @@
 # - You can share opened buffered across opened frames.
 # - Configuration changes made at runtime are applied to all frames.
 
+# Require emacs version to be minimum 24
+autoload -Uz is-at-least
+is-at-least 24 "${${(Az)"$(emacsclient --version 2>/dev/null)"}[2]}" || return 0
 
-if "$ZSH/tools/require_tool.sh" emacsclient 24 2>/dev/null ; then
+# Path to custom emacsclient launcher
-    export EMACS_PLUGIN_LAUNCHER="$ZSH/plugins/emacs/emacsclient.sh"
+export EMACS_PLUGIN_LAUNCHER="${0:A:h}/emacsclient.sh"
 
 # set EDITOR if not already defined.
 export EDITOR="${EDITOR:-${EMACS_PLUGIN_LAUNCHER}}"
@@ -41,25 +44,20 @@ if "$ZSH/tools/require_tool.sh" emacsclient 24 2>/dev/null ; then
 # opened in the current buffer.
 function efile {
   local cmd="(buffer-file-name (window-buffer))"
-        "$EMACS_PLUGIN_LAUNCHER" --eval "$cmd" | tr -d \"
+  local file="$("$EMACS_PLUGIN_LAUNCHER" --eval "$cmd" | tr -d \")"
+
+  if [[ -z "$file" ]]; then
+    echo "Can't deduce current buffer filename." >&2
+    return 1
+  fi
+
+  echo "$file"
 }
 
 # Write to standard output the directory of the file
 # opened in the the current buffer
 function ecd {
-        local cmd="(let ((buf-name (buffer-file-name (window-buffer))))
+  local file
-                     (if buf-name (file-name-directory buf-name)))"
+  file="$(efile)" || return $?
-
+  echo "${file:h}"
-        local dir="$($EMACS_PLUGIN_LAUNCHER --eval $cmd | tr -d \")"
-        if [ -n "$dir" ] ;then
-            echo "$dir"
-        else
-            echo "can not deduce current buffer filename." >/dev/stderr
-            return 1
-        fi
 }
-fi
-
-## Local Variables:
-## mode: sh
-## End: