fzf: add support for debian packages (#8001)

plugins/fzf/fzf.plugin.zsh

-test -d "${FZF_BASE}" && fzf_base="${FZF_BASE}"
+function setup_using_base_dir() {
+	# Declare all variables local not no mess with outside env in any way
+	local fzf_base
+	local fzf_shell
+	local fzfdirs
+	local dir
 
-if [[ -z "${fzf_base}" ]]; then
+    test -d "${FZF_BASE}" && fzf_base="${FZF_BASE}"
+
+    if [[ -z "${fzf_base}" ]]; then
         fzfdirs=(
           "${HOME}/.fzf"
           "/usr/local/opt/fzf"
@@ -20,10 +27,9 @@ if [[ -z "${fzf_base}" ]]; then
                 fi
             fi
         fi
-fi
-
-if [[ -n "${fzf_base}" ]]; then
+    fi
 
+    if [[ -d "${fzf_base}" ]]; then
         # Fix fzf shell directory for Archlinux package
         if [[ ! -d "${fzf_base}/shell" ]] && [[ -f /etc/arch-release ]]; then
           fzf_shell="${fzf_base}"
@@ -31,27 +37,59 @@ if [[ -n "${fzf_base}" ]]; then
           fzf_shell="${fzf_base}/shell"
         fi
 
-  # Setup fzf
-  # ---------
+        # Setup fzf binary path
         if ! (( ${+commands[fzf]} )) && [[ ! "$PATH" == *$fzf_base/bin* ]]; then
           export PATH="$PATH:$fzf_base/bin"
         fi
 
         # Auto-completion
-  # ---------------
         if [[ ! "$DISABLE_FZF_AUTO_COMPLETION" == "true" ]]; then
           [[ $- == *i* ]] && source "${fzf_shell}/completion.zsh" 2> /dev/null
         fi
 
         # Key bindings
-  # ------------
         if [[ ! "$DISABLE_FZF_KEY_BINDINGS" == "true" ]]; then
           source "${fzf_shell}/key-bindings.zsh"
         fi
+    else
+        return 1
+    fi
+}
+
+
+function setup_using_debian_package() {
+    dpkg -s fzf &> /dev/null
+    if (( $? )); then
+        # Either not a debian based distro, or no fzf installed. In any case skip ahead
+        return 1
+    fi
+
+    # NOTE: There is no need to configure PATH for debian package, all binaries
+    # are installed to /usr/bin by default
+
+    local completions="/usr/share/zsh/vendor-completions/_fzf"
+    local key_bindings="/usr/share/doc/fzf/examples/key-bindings.zsh"
+
+    # Auto-completion
+    if [[ $- == *i* ]] && [[ ! "$DISABLE_FZF_AUTO_COMPLETION" == "true" ]]; then
+         source $completions 2> /dev/null
+    fi
+
+    # Key bindings
+    if [[ ! "$DISABLE_FZF_KEY_BINDINGS" == "true" ]]; then
+        source $key_bindings
+    fi
 
-else
+    return 0
+}
+
+function indicate_error() {
     print "[oh-my-zsh] fzf plugin: Cannot find fzf installation directory.\n"\
           "Please add \`export FZF_BASE=/path/to/fzf/install/dir\` to your .zshrc" >&2
-fi
+}
+
+# Check for debian package first, because it easy to short cut
+# Indicate to user that fzf installation not found if nothing worked
+setup_using_debian_package || setup_using_base_dir || indicate_error
 
-unset fzf_base fzf_shell dir fzfdirs
+unset -f setup_using_debian_package setup_using_base_dir indicate_error