#! /usr/bin/env bash
shopt -s extglob
[ -n "$TMUXIFIER_DEBUG" ] && set -x

# Load internal utility functions.
source "$TMUXIFIER/lib/util.sh"

# Provide tmuxifier help
if calling-help "$@"; then
  echo "usage: tmuxifier tmux-version [target-version]

Outputs current Tmux version. If given optional target-version it outputs one
of three possible characters indicating if the current Tmux version number is
equal to, less than, or greater than the [target-version].

The three possible outputs are \"=\", \"<\", and \">\"."
  exit
fi

# The vercomp() function is shamelessly ripped/borrowed from the following
# StackOverflow answer: http://stackoverflow.com/a/4025065/42146
vercomp () {
  if [[ $1 == $2 ]]; then return 0; fi

  local IFS=.
  local i ver1=($1) ver2=($2)

  # fill empty fields in ver1 with zeros
  for ((i=${#ver1[@]}; i<${#ver2[@]}; i++)); do ver1[i]=0; done

  for ((i=0; i<${#ver1[@]}; i++)); do
    # fill empty fields in ver2 with zeros
    if [[ -z ${ver2[i]} ]]; then ver2[i]=0; fi

    if ((10#${ver1[i]} > 10#${ver2[i]})); then
      return 1
    elif ((10#${ver1[i]} < 10#${ver2[i]})); then
      return 2
    fi
  done
  return 0
}

version=$(tmux -V)
version=${version/tmux /}

if [ -n "$1" ]; then
  # Fix for "1.9a" version comparison, as vercomp() can only deal with
  # purely numeric version numbers.
  version=${version//+([a-zA-Z])/}

  vercomp "$version" "$1"
  case $? in
    0) echo '=';;
    1) echo '>';;
    2) echo '<';;
  esac
else
  echo "$version"
fi