#!/usr/bin/env ruby

require 'fileutils'
require 'aws'

# Change these values according to your configuration
gmail_account = 'foo@gmail.com'   # Gmail gmail_account that should be synced
s3_bucket     = 'gmvault-backup'  # S3 bucket that the backups should be stored in
password      = 'secret'          # The password used to encrypt the files

# Configure AWS
AWS.config \
  access_key_id:     ENV['AWS_ACCESS_KEY_ID'],
  secret_access_key: ENV['AWS_SECRET_ACCESS_KEY']

# Load bucket
s3_bucket = AWS::S3.new.buckets[s3_bucket]

# Helper method to execute commands
def execute(command)
  system(command).tap do |result|
    puts %(Error running command "#{command}") unless result
  end
end

# Save start time before running Gmvault so we know which files have changed
start = Time.now

# Do a quick sync (only last two months) and redirect STDOUT to /dev/null
command = "gmvault sync --type quick #{gmail_account} > /dev/null"
# Quit if sync fails
exit unless execute(command)

gmvault_folder = File.join(Dir.home, 'gmvault-db')
db_folders     = Dir[File.join(gmvault_folder, 'db', '*')]

# Create "backup" folder inside Gmvault folder which will store the backup files
FileUtils.mkdir_p File.join(gmvault_folder, 'backup')

# Pick only folders that have been changed during sync
db_folders_to_upload = db_folders.sort.select do |db_folder|
  File.mtime(db_folder) > start
end

# Compress, encrypt and upload each folder
db_folders_to_upload.each do |db_folder|
  backup_filename           = [db_folder.split('/').last, 'tar.gz'].join('.')
  backup_file               = File.join(gmvault_folder, 'backup', backup_filename)
  encrypted_backup_filename = [backup_filename, 'gpg'].join('.')
  encrypted_backup_file     = [backup_file, 'gpg'].join('.')

  commands = [
    # Compress db folder (e.g. ~/gmvault-db/db/2012-06) into single file (e.g. ~/gmvault-db/backup/2012-06.tar.gz)
    "tar cvzfP #{backup_file} #{db_folder} > /dev/null",

    # Encrypt the created file with the password
    "echo '#{password}' | gpg --symmetric --batch --yes --passphrase-fd 0 --output #{encrypted_backup_file} #{backup_file}"
  ]

  # Skip to next folder if any command fails
  next unless commands.all?(&method(:execute))

  # Upload to S3
  s3_bucket.objects[encrypted_backup_filename].write(file: encrypted_backup_file)
end