#!/usr/bin/env ruby

# this script moves given paths to another central directoriy,
# for example a versioning repository, and then links the files back to the original place.
# it uses hardlinks if possible, symlinks if necessary.

require "fileutils"

def do_cmd(cmd, run)
  if run then system cmd
  else puts cmd end
end

def move_and_link(src, repo_root, host, run)
  path = File.expand_path(src)
  return unless File.file?(path)
  rel = path.sub(%r{^/}, "")
  dest = File.join(repo_root, "data", host, rel)

  need_copy = true
  if File.exist?(dest)
    begin
      need_copy = !FileUtils.compare_file(path, dest)
    rescue
      need_copy = true
    end
  end

  if need_copy
    dir = File.dirname(dest)
    do_cmd "mkdir -p #{dir}", run unless Dir.exist?(dir)
    do_cmd "cp #{path} #{dest}", run
  end

  begin
    identical = File.identical?(path, dest)
  rescue
    identical = false
  end

  unless identical
    if File.symlink?(path)
      do_cmd "rm #{path}", run
    elsif run
      begin
        copied = File.exist?(dest) && FileUtils.compare_file(path, dest)
      rescue
        copied = false
      end
      if copied
        do_cmd "rm #{path}", run
      else
        warn "skipping removal of #{path}; backup not verified"
        return
      end
    end

    begin
      do_cmd "ln #{dest} #{path}", run
    rescue Errno::EXDEV
      do_cmd "ln -s #{dest} #{path}", run
    end
  end
end

run = ARGV.delete("-r")
abort "usage: collect-config [-r] file..." if ARGV.empty?
repo_root = "/opt/myrepo"
host = `hostname`.strip

ARGV.each do |arg|
  p = File.expand_path(arg)
  if File.directory?(p)
    Dir.glob("#{p}/**/*", File::FNM_DOTMATCH).each do |f|
      next if File.directory?(f)
      move_and_link(f, repo_root, host, run)
    end
  else
    move_and_link(p, repo_root, host, run)
  end
end