#!/usr/bin/env ruby

require 'rubygems'
require 'trollop'
require "sup"; Redwood::check_library_version_against "0.10.2"

STATE_BACKUP_FN = "/tmp/sup-state.txt"
SOURCE_BACKUP_FN = "sources.yaml-before-xapian-upgrade"
BIN_DIR = File.dirname __FILE__

$opts = Trollop::options do
  version "sup-convert-ferret-index (sup #{Redwood::VERSION})"
  banner <<EOS
Convert an Sup Ferret index to a Xapian index.

This will be a very slow process, but it will be lossless.

If you interrupt it, nothing bad will happen. However, you will have to
restart it from scratch.

Usage:
  sup-convert-ferret-index

Options:
EOS
  opt :verbose, "Be verbose", :short => "-v"
  opt :dry_run, "Don't actually do anything, just print out what would happen.", :short => "-n"
  opt :force, "Force overwrite of an old Xapian index"
  opt :version, "Show version information", :short => :none
end

def build_cmd cmd
  (ENV["RUBY_INVOCATION"] ? ENV["RUBY_INVOCATION"] + " " : "") + File.join(BIN_DIR, cmd)
end

def run cmd
  puts cmd
  unless $opts[:dry_run]
    startt = Time.now
    system cmd or abort
    printf "(completed in %.1fs)\n", (Time.now - startt)
  end
  puts
end

begin
  require 'xapian'
rescue LoadError
  Trollop::die "you don't have the xapian gem installed, so this script won't do much for you--`gem install xapian` (or xapian-full) first"
end

Redwood::start
index = Redwood::Index.init
Trollop::die "you appear to already have a Xapian index--delete #{File.join(Redwood::BASE_DIR, "xapian")} or use --force if you really want to do this" unless Redwood::Index.is_a_deprecated_ferret_index? || $opts[:force]

puts "## Step one: back up all message state to #{STATE_BACKUP_FN}"
run "#{build_cmd 'sup-dump'} --index ferret > #{STATE_BACKUP_FN}"
puts "## message state saved to #{STATE_BACKUP_FN}"

source_backup_fn = File.join Redwood::BASE_DIR, SOURCE_BACKUP_FN
puts "## Step two: back up sources.yaml file to #{source_backup_fn}"
run "cp #{Redwood::SOURCE_FN} #{source_backup_fn}"

puts "## Step three: build the Xapian index"
run "#{build_cmd 'sup-sync'} --all --all-sources --index xapian --restore #{STATE_BACKUP_FN} #{$opts[:verbose] ? '--verbose' : ''}"
puts "## xapian index successfully built!"

puts <<EOS

Congratulations, your index has been upgraded to the Xapian backend.
From now on, running sup should detect this index automatically.

If you want to revert to the Ferret index:
1. overwrite #{Redwood::SOURCE_FN} with #{source_backup_fn}
2. use sup --index ferret, OR delete your #{Redwood::BASE_DIR}/xapian directory"
Note that the Ferret index will not be supported as of the next Sup release, so
you probably shouldn't do this.

If you are happy with Xapian and want to reclaim precious hard drive space:
1. rm #{source_backup_fn}
2. rm -r #{Redwood::BASE_DIR}/ferret

Happy supping!
EOS