#!/usr/bin/env bash
# He wrote this in BASH because he hates himself, apparently :(
USAGE="Usage: ./configure [-g|--global] [-u|--uninstall] [-f|--force]"
set -ue

# === Configure Install === #
INSTALL_PATH_HOME="$HOME/.local/bin"
INSTALL_PATH_GLOBAL="/usr/local/bin"
SCRIPT_PERM=555
ALIASES_PERM=444
# ========================= #

# NOTE: since this last changed in 2015 its a really good unique identifier...
# NOTE: (to avoid uninstalling other programs called g)
G_IDENTIFIER="I'm writing this in BASH because I hate myself, apparently."

# Filters filenames based on if the file contains the G_IDENTIFIER
is_this_g() {
  while read -r LOC; do
    if [[ -d "$LOC" ]]; then
      LOC="$LOC/g"
    fi
    grep -lF "$G_IDENTIFIER" "$LOC" 2>/dev/null
  done <&0
}

# Finds absolute paths to all installed g binaries
# (or the extremely rare case there are multiple)
find_installed() {
  (echo -e "$INSTALL_PATH_HOME\n$INSTALL_PATH_GLOBAL" && which -a g 2>/dev/null) \
    | is_this_g
  exit 0
}

# Escapes all / \ & characters in sed patterns
escape_pattern() {
  <<< "$1" sed -e 's/[\/&]/\\&/g'
}

install_g() {
  local LOC=$1
  local FORCE=$2
  mkdir -p "$LOC"

  FOUND=$(find_installed)
  if [[ -n "$FOUND" && -z "$FORCE" ]]; then
    echo "Failed: g already exists at:" $FOUND >&2
    echo "   1. Run \`./configure --uninstall\` to remove, OR" >&2
    echo "   2. Use \`--force\` to overwrite" >&2
    exit 2
  fi
  
  install -m "$SCRIPT_PERM" bin/g "$LOC/g"
  install -m "$ALIASES_PERM" bin/g_aliases "$LOC/g_aliases"
  # Format config strings for `g_aliases`
  local G_BIN_DIR=$(escape_pattern "$LOC")
  sed -i -e "s/AUTO_G_BIN_DIR/$G_BIN_DIR/g" "$LOC/g_aliases"
  
  echo "Installed bin/g -> $LOC/g"
  echo "Installed bin/g_aliases -> $LOC/g_aliases"
  echo -e "\n[+] To use the aliases, add this to your ~/.bashrc or ~/.bash_aliases:"
  echo "### source $LOC/g_aliases"
}

uninstall_g() {
  local FOUND=""
  while read -r LOC; do
    local FOUND="1"
    LOC=$(dirname "$LOC")
    rm "$LOC/g" "$LOC/g_aliases"
    rmdir "$LOC"
    echo "Removed: $LOC/g"
    echo "Removed: $LOC/g_aliases"
  done < <(find_installed | uniq -u)

  if [[ -z "$FOUND" ]]; then
    echo "Failed: g was not found to be installed" >&2
    exit 2
  fi

  echo -e "\nAliases are still bound!\nUse \`source ~/.bashrc\` or \`exec \`$SHELL\`"
}

INSTALL_PATH="$INSTALL_PATH_HOME"
FORCE=
for OPT in "$@"; do
  case $OPT in
    -g|--global)
      INSTALL_PATH="$INSTALL_PATH_GLOBAL"
      ;;
    -u|--uninstall)
      uninstall_g
      exit 0 # non-zero will already propagate from `set -e`
      ;;
    -f|--force)
      FORCE="1"
      ;;
    *)
      echo -e "Unknown option $OPT\n$USAGE" >&2
      exit 1
      ;;
  esac
done
install_g "$INSTALL_PATH" "$FORCE"