#!/bin/sh
#
# USAGE
#   #1: curl -L git.io/omf | sh
#   #2: curl -L git.io/omf > install && chmod +x install && ./install
#   #3: OMF_CONFIG=~/.omf curl -L git.io/omf | sh
#
# ENV
#   XDG_DATA_HOME       Base directory (~/.local/share)
#   XDG_CONFIG_HOME     Base configuration directory (~/.config)
#
#   ↑ See XDG Base Directory Specification
#   → https://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html
#
#   OMF_PATH          Oh My Fish directory
#   OMF_CONFIG        Oh My Fish configuration
#
#   OMF_REPO_URI      Source git repository
#   OMF_REPO_BRANCH   Source repository default branch (master)
#
# FUNCTIONS
#   die
#   is_installed
#   omf_create_fish_config <path/to/fish.config>
#   omf_install

test -z ${XDG_DATA_HOME+_}    && XDG_DATA_HOME="${HOME}/.local/share"
test -z ${XDG_CONFIG_HOME+_}  && XDG_CONFIG_HOME="${HOME}/.config"

test -z ${OMF_PATH+_}         && OMF_PATH="${XDG_DATA_HOME}/omf"
test -z ${OMF_CONFIG+_}       && OMF_CONFIG="${XDG_CONFIG_HOME}/omf"

test -z ${OMF_REPO_URI+_}     && OMF_REPO_URI="https://github.com/fish-shell/oh-my-fish"
test -z ${OMF_REPO_BRANCH+_}  && OMF_REPO_BRANCH="master"

die() {
  echo "$1" && exit 1
}

is_installed() {
  type "$1" >/dev/null 2>&1
}

omf_create_fish_config() {
  local fish_config_file=$1
  mkdir -p $(dirname "${fish_config_file}")
  touch "${fish_config_file}"
}

omf_install() {
  echo "Resolving Oh My Fish path → ${OMF_PATH}"
  test -d "${OMF_PATH}" && die "Existing installation detected, aborting"
  local git_uri="$(echo ${OMF_REPO_URI} | sed 's/\.git//').git"

  echo "Cloning Oh My Fish → ${git_uri}"
  if ! git clone -q --depth 1 -b "${OMF_REPO_BRANCH}" "${git_uri}" "${OMF_PATH}"; then
    echo "Is 'git' installed?"
    die "Could not clone the repository → ${OMF_PATH}:${OMF_REPO_BRANCH}"
  fi

  pushd ${OMF_PATH} >/dev/null 2>&1

  local git_rev=$(git rev-parse HEAD) >/dev/null 2>&1
  local git_upstream=$(git config remote.upstream.url)

  if [ -z "${git_upstream}" ]; then
    git remote add upstream ${git_uri}
  else
    git remote set-url upstream ${git_uri}
  fi

  echo "Oh My Fish revision id → ${git_rev}"
  popd >/dev/null 2>&1
  test -z ${FISH_CONFIG+_} && FISH_CONFIG="${XDG_CONFIG_HOME}/fish"

  local fish_config_file="${FISH_CONFIG}/config.fish"

  if [ -e "${FISH_CONFIG}/config.fish" ]; then
    local timestamp=$(date +%s)
    local fish_config_bk="${FISH_CONFIG}/config.${timestamp}.copy"

    echo "Found existing 'fish' configuration → ${fish_config_file}"
    echo "Writing back-up copy → ${fish_config_bk}"

    cp "${fish_config_file}" "${fish_config_bk}" >/dev/null 2>&1
    test $? -ne 0 && die "Writing back-up copy failed, error code → ${?}"
  else
    omf_create_fish_config $fish_config_file
  fi

  echo "Adding Oh My Fish bootstrap → ${fish_config_file}"
  touch ${fish_config_file} >/dev/null 2>&1
  test ! -w ${fish_config_file} && die "Fish configuration file is not writable, aborting."

  sed "s|{{OMF_PATH}}|$(echo "${OMF_PATH}" | sed -e "s|$HOME|\$HOME|")|;\
       s|{{OMF_CONFIG}}|$(echo "${OMF_CONFIG}" | sed -e "s|$HOME|\$HOME|")|" \
    "${OMF_PATH}/templates/config.fish" > "${fish_config_file}"

  if [ ! -d "${OMF_CONFIG}" ]; then
    echo "Writing Oh My Fish configuration → ${OMF_CONFIG}"
    mkdir -p "${OMF_CONFIG}"
    test -f "${OMF_CONFIG}/bundle"    || echo "theme default" > "${OMF_CONFIG}/bundle"
    test -f "${OMF_CONFIG}/theme"     || echo default > "${OMF_CONFIG}/theme"
    test -f "${OMF_CONFIG}/revision"  || echo ${git_rev} > "${OMF_CONFIG}/revision"
  else
    fish -c "omf install"
  fi
}

echo "Installing Oh My Fish..."
! is_installed "fish" && die "Please install fish to continue → http://fishshell.com/"
if omf_install; then
  echo "Oh My Fish successfully installed."
  cd $HOME
  # Do not swap process if running in a CI environment.
  [ -z ${CI+_} ] || exit 0 && exec "fish" < /dev/tty
else
  die "Oh My Fish couldn't install, but you can complain here → git.io/omf-issues"
fi