Track changes to a skeleton Rails app since a given version

rails_default_diff.sh

#!/usr/bin/env zsh
# -------------------------------------------------------------------------------- #
# 1304046900 Track changes to a skeleton Rails app since a given `base_version`
# -------------------------------------------------------------------------------- #
## Changelog
# - Update 7/7/2012: 
#   * rewrote to use Bundler instead of RubyGems
#   * attempting to switch to a master branch for which no commit existing was causing a pathspec error
#   * simplified rails new commands by running them on the current path (after changing directory to tmp/skeleton_check of course).
#   * renamed `old_version` variable to `base_version` for clarity
#   * added `new_version` variable in case you don't want to upgrade to the latest stable Rails, empty by default
#
## Requirements
# * RubyGems installed (http://rubygems.org/pages/download)
# * Bundler installed (gem install bundler)
#
## Usage
# Place this script anywhere and run ./rails_default_diff.sh
#
## Configuration
# Insert the base version of Rails you want to upgrade from below.
base_version="3.1.4"
new_version="" # use the same format as base_version
#
# ================================================================================ #
# ================================================================================ #

## No Touching!
### Don't modify anything below this line unless you know what you're doing

# Exit script in case anything fails
set -e

print "$(tput setaf 2)# Creating skeleton Rails $base_version app $(tput sgr0)"
mkdir -p tmp/skeleton_check
cd tmp/skeleton_check
git init
bundle init # creates a Gemfile with rubygems as the source
echo "gem 'rails', '$base_version'" >> Gemfile # appends to the end of Gemfile
bundle
bundle exec rails new . -f
git add -A .
git commit -m "# Install $base_version"
git checkout -b $base_version # creates and checks out a new branch

print "$(tput setaf 2)# Removing all the things $(tput sgr0)"

# recursively removes all files and folders within the current path (tmp/skeleton_check)
rm -rf * 

print "$(tput setaf 2)# Updating Rails to latest version $(tput sgr0)"
# creating a new blank Gemfile
bundle init 

# if a new_version was set, use that
if [ "$new_version" ]; then
  print "$(tput setaf 2)# Upgrading to Rails $new_version $(tput sgr0)"
  # appending a requirement for the new_version at the bottom of the Gemfile
  echo "gem 'rails', '$new_version'" >> Gemfile 

# if a new_version wasn't set, use the latest version of Rails
else
  print "$(tput setaf 2)# Using latest version of Rails (oooh, danger!) $(tput sgr0)"
  echo "gem 'rails'" >> Gemfile
fi
bundle

print "$(tput setaf 2)# Creating new Rails app on top of old one $(tput sgr0)"
bundle exec rails new . -f
git add -A .
git checkout master
git commit -m "Install latest Rails"

if output=$(git diff --exit-code --name-status $base_version HEAD); then
  print "No changes"
else

  # Group name statuses
  #
  while read -r flag file; do
    case $flag in
      (M*) modified+=($file) ;;
      (A*) added+=($file) ;;
      (D*) deleted+=($file) ;;
    esac
  done <<< $output

  # Display groups
  #
  if [[ -n $modified ]]; then
    print -f "M %s\n" $modified
    echo
  fi
  if [[ -n $added ]]; then
    print -f "A %s\n" $added
    echo
  fi
  if [[ -n $deleted ]]; then
    print -f "D %s\n" $deleted
    echo
  fi

  print -n "$(tput setaf 2)# Show full git-diff of modified files? $(tput sgr0) (Y/n)"
  if read -q; then
    # running a diff on all the modified files and ouputting the result to the system $EDITOR
    git diff $base_version HEAD $modified | ruby -pe 'puts "\n#########" if /^diff/ && $. > 1' | $EDITOR
    echo
  fi

  print "$(tput setaf 2)# Current version: $(rails -v) $(tput sgr0)"
fi

# going back to the original path where the script was being executed from
cd ../../
# cleaning up our mess
rm -rf tmp/skeleton_check