#!/bin/bash

set -e

INSTALL_DIR="$HOME/.fnm"
RELEASE="latest"

# Parse Flags
parse_args() {
  while [[ $# -gt 0 ]]; do
    key="$1"

    case $key in
    -d | --install-dir)
      INSTALL_DIR="$2"
      shift # past argument
      shift # past value
      ;;
    -s | --skip-shell)
      SKIP_SHELL="true"
      shift # past argument
      ;;
    --force-install)
      echo "\`--force-install\`: I hope you know what you're doing." >&2
      FORCE_INSTALL="true"
      shift
      ;;
    -r | --release)
      RELEASE="$2"
      shift # past release argument
      shift # past release value
      ;;
    *)
      echo "Unrecognized argument $key"
      exit 1
      ;;
    esac
  done
}

set_filename() {
  local OS

  OS=$(uname -s)

  if [ "$OS" == "Linux" ]; then
    FILENAME="fnm-linux"
  elif [ "$OS" == "Darwin" ] && [ "$FORCE_INSTALL" == "true" ]; then
    FILENAME="fnm-macos"
  elif [ "$OS" == "Darwin" ]; then
    echo "Hey! Thanks for trying fnm."
    echo "MacOS installation works better using Homebrew."
    echo "Please consider installing using:"
    echo "    $ brew install Schniz/tap/fnm"
    echo "or run the script again with the \`--force-install\` option."
    exit 1
  else
    echo "OS $OS is not supported."
    echo "If you think that's a bug - please file an issue to https://github.com/Schniz/fnm/issues"
    exit 1
  fi
}

download_fnm() {
  if [ "$RELEASE" == "latest" ]; then
    URL=https://github.com/Schniz/fnm/releases/latest/download/$FILENAME.zip
  else
    URL=https://github.com/Schniz/fnm/releases/download/$RELEASE/$FILENAME.zip
  fi
  
  DOWNLOAD_DIR=$(mktemp -d)

  echo "Downloading $URL..."

  mkdir -p $INSTALL_DIR &>/dev/null
  curl --progress-bar -L $URL -o $DOWNLOAD_DIR/$FILENAME.zip

  if [ 0 -ne $? ]; then 
    echo "Download failed.  Check that the release/filename are correct."
    exit 1
  fi;

  unzip -q $DOWNLOAD_DIR/$FILENAME.zip -d $DOWNLOAD_DIR
  mv $DOWNLOAD_DIR/$FILENAME/fnm $INSTALL_DIR/fnm
  chmod u+x $INSTALL_DIR/fnm
}

check_dependencies() {
  echo "Checking dependencies for the installation script..."

  echo -n "Checking availability of curl... "
  if hash curl 2>/dev/null; then
    echo "OK!"
  else
    echo "Missing!"
    SHOULD_EXIT="true"
  fi

  echo -n "Checking availability of unzip... "
  if hash unzip 2>/dev/null; then
    echo "OK!"
  else
    echo "Missing!"
    SHOULD_EXIT="true"
  fi

  if [ "$SHOULD_EXIT" = "true" ]; then
    exit 1
  fi
}

ensure_containing_dir_exists() {
  local CONTAINING_DIR
  CONTAINING_DIR="$(dirname "$1")"
  if [ ! -d "$CONTAINING_DIR" ]; then
    echo " >> Creating directory $CONTAINING_DIR"
    mkdir -p "$CONTAINING_DIR"
  fi
}

setup_shell() {
  CURRENT_SHELL=$(basename $SHELL)

  if [ "$CURRENT_SHELL" == "zsh" ]; then
    CONF_FILE=$HOME/.zshrc
    ensure_containing_dir_exists "$CONF_FILE"
    echo "Installing for Zsh. Appending the following to $CONF_FILE:"
    echo ""
    echo '  # fnm'
    echo '  export PATH='"$INSTALL_DIR"':$PATH'
    echo '  eval "`fnm env --multi`"'

    echo '' >>$CONF_FILE
    echo '# fnm' >>$CONF_FILE
    echo 'export PATH='$INSTALL_DIR':$PATH' >>$CONF_FILE
    echo 'eval "`fnm env --multi`"' >>$CONF_FILE

  elif [ "$CURRENT_SHELL" == "fish" ]; then
    CONF_FILE=$HOME/.config/fish/config.fish
    ensure_containing_dir_exists "$CONF_FILE"
    echo "Installing for Fish. Appending the following to $CONF_FILE:"
    echo ""
    echo '  # fnm'
    echo '  set PATH '"$INSTALL_DIR"' $PATH'
    echo '  fnm env --multi | source'

    echo '' >>$CONF_FILE
    echo '# fnm' >>$CONF_FILE
    echo 'set PATH '"$INSTALL_DIR"' $PATH' >>$CONF_FILE
    echo 'fnm env --multi | source' >>$CONF_FILE

  elif [ "$CURRENT_SHELL" == "bash" ]; then
    if [ "$OS" == "Darwin" ]; then
      CONF_FILE=$HOME/.profile
    else
      CONF_FILE=$HOME/.bashrc
    fi
    ensure_containing_dir_exists "$CONF_FILE"
    echo "Installing for Bash. Appending the following to $CONF_FILE:"
    echo ""
    echo '  # fnm'
    echo '  export PATH='"$INSTALL_DIR"':$PATH'
    echo '  eval "`fnm env --multi`"'

    echo '' >>$CONF_FILE
    echo '# fnm' >>$CONF_FILE
    echo 'export PATH='"$INSTALL_DIR"':$PATH' >>$CONF_FILE
    echo 'eval "`fnm env --multi`"' >>$CONF_FILE

  else
    echo "Could not infer shell type. Please set up manually."
    exit 1
  fi

  echo ""
  echo "In order to apply the changes, open a new terminal or run the following command:"
  echo ""
  echo "  source $CONF_FILE"
}

parse_args "$@"
set_filename
check_dependencies
download_fnm
if [ "$SKIP_SHELL" != "true" ]; then
  setup_shell
fi