Include actions for fish when installing

Fish has to be configured to use nvm.
Basically 2 actions have to be taken (like with bash and others):
1. Introduce the nvm function
2. Execute the nvm function once the shell is loaded to have access to nodejs
   The first session with fish might take a while to start,
   if nvm doesn't have its default env (stable nodejs + default alias)

install.sh

@@ -1,5 +1,15 @@
 #!/bin/bash
 
+# Get this script after dereferincing all symlinks
+# !! Doesn't check for circular symlinks !!
+SOURCE="${BASH_SOURCE[0]}"
+while [ -h "$SOURCE" ]; do # resolve $SOURCE until the file is no longer a symlink
+  DIR="$( cd -P "$( dirname "$SOURCE" )" && pwd )"
+  SOURCE="$(readlink "$SOURCE")"
+  [[ $SOURCE != /* ]] && SOURCE="$DIR/$SOURCE" # if $SOURCE was a relative symlink, we need to resolve it relative to the path where the symlink file was located
+done
+DIR="$( cd -P "$( dirname "$SOURCE" )" && pwd )"
+
 set -e
 
 nvm_has() {
@@ -135,6 +145,24 @@ nvm_do_install() {
     fi
   fi
 
+  # Actions for fish shell
+  if (which fish > /dev/null); then
+    echo "=> fish found, copying nvm function"
+    FISH_CONFIG_DIR=$HOME/.config/fish
+    FISH_FUNCTIONS_DIR=$FISH_CONFIG_DIR/functions
+
+    mkdir -p $FISH_FUNCTIONS_DIR
+    cp $NVM_DIR/nvm.fish $FISH_FUNCTIONS_DIR
+
+    # Apply nvm in fish configuration
+    FISH_CONFIG_STRING="nvm > /dev/null ^&1"
+    FISH_CONFIG_FILE=$FISH_CONFIG_DIR/config.fish
+    if ! grep -q "$FISH_CONFIG_STRING" $FISH_CONFIG_FILE 2> /dev/null ; then
+      echo "=> appending nvm to fish configuration"
+      echo $FISH_CONFIG_STRING >> $FISH_CONFIG_DIR/config.fish
+    fi
+  fi
+
   echo "=> Close and reopen your terminal to start using nvm"
   nvm_reset
 }