#!/usr/bin/env bash
#
# Usage: get-scala-revision [dir]
# Figures out current scala revision of a git clone.
# If no dir is given, current working dir is used.
#
# Example build version string:
#   v2.10.0-M1-0098-g6f1c486d0b-2012-02-01
#

[[ $# -eq 0 ]] || cd "$1"

ensure_tag () {
  # v2.10.0-M1
  fallback=58cb15c40d
  [[ -n $(git tag -l v2.10.0-M1) ]] || {
    git tag -a -m "generated by get-scala-revision" v2.10.0-M1 $fallback
  }
}
ensure_tag

# the closest tag, obtained separately because we have to
# reconstruct the string around the padded distance.
tag=$(git describe --match 'v2*' --abbrev=0)

# the full string - padding correctness depends on abbrev=10.
described=$(git describe --match 'v2*' --abbrev=10)
suffix="${described##${tag}-}"
counter=$(echo $suffix | cut -d - -f 1)
hash=$(echo $suffix | cut -d - -f 2)

# 016 is rocket-surgically-calibrated to pad the distance from the
# tag to the current commit into a 4-digit number - since maven
# will be treating this as a string, the ide depends on
# 10 being greater than 9 (thus 0010 and 00009.)
printf "%s-%04d-%10s-%s\n" "$tag" "$counter" "$hash" $(date "+%Y-%m-%d")