require 'rubygems'
require 'json'
require 'restclient'
require 'ostruct'
require 'ohai'
require 'erb'

## IDEAS

## firewall until ready
## ruby 1.9 compatibility
## nested configs
## user configs

class Kuzushi
  attr_accessor :config

  def self.version
  end

  def initialize(url)
    @url = url
    @base_url = File.dirname(url)
    if @url =~ /s3.amazonaws.com.*\/([^\/]*)[.](\d+)[.]tar[.]gz/
      @name = $1
      @version = $2
    end
    @configs = []
    @packages = []
    @tasks = []
  end

  def init
    @init = true
    start
  end

  def boot
    shell "mkdir -p /tmp/kuzushi/"
    shell "cd /tmp/kuzushi/ ; curl --silent '#{@url}' | tar xzv"
    @config = JSON.parse(File.read("/tmp/kuzushi/#{@name}/config.json"))
  end

  def start
#    load_config_stack(@name)
    boot
    run
  end

  def run
    process_stack
    log "----"
    @tasks.each do |t|
      log "TASK: #{t[:description]}"
      t[:blk].call
    end
    log "----"
  end

  protected

  def system
    ohai = Ohai::System.new
    ohai.all_plugins
    ohai
  end

  def http_get(url)
    RestClient.get(url)
  end

  def process_stack
    script get("before")

    process :packages
    process :local_packages
    process :gems
    process :volumes
    process :files
    process :users
    process :crontab
    process :services

    script get("after")
    script get("init") if init?
  end

  ## magic goes here
  def process(type)
    ## if the file takes no args - just call it once
    if method("process_#{type}").arity == 0
      send("process_#{type}")
    else
    ## else call it once per item
      get_array(type).each do |item|
        script item["before"]
        if item.is_a? Hash
          send("process_#{type}", OpenStruct.new(item))
        else
          send("process_#{type}", item)
        end
        script item["after"]
        script item["init"] if init?
      end
    end
  end

  def service_file(service)
    file = []
    file << "start on stopped rc RUNLEVEL=[2345]"
    file << "stop on runlevel [!2345]"
    file << "respawn" unless service.respawn == false
    if service.user
      file << "exec su -c '#{service.command}' #{service.user}"  ## TODO add shell escaping here
    else
      file << "exec #{service.command}"
    end
    file.join("\n")
  end

  def process_services(service)
    task "installing service #{service.name}" do
      put_file(service_file(service), "/etc/init/#{service.name}.conf")
      shell "service #{service.name} start"
    end
  end

  def process_packages
    @packages = get_array("packages")
    task "install packages" do
      shell "apt-get install -y #{@packages.join(" ")}" unless @packages.empty?
    end
  end

  def process_local_packages(p)
    package(p) do |file|
      task "install local package #{p}" do
        shell "dpkg -i #{file}"
      end
    end
  end

  def process_gems(gem)
    task "install gem #{gem}" do
      shell "gem install #{gem} --no-rdoc --no-ri"
    end
  end

  def process_volumes(v)
    handle_ebs    v if v.media == "ebs"
    handle_raid   v if v.media == "raid"
    set_readahead v if v.readahead
    set_scheduler v if v.scheduler
    handle_format v if v.format
    handle_mount  v if v.mount
  end

  def handle_ebs(v)
    task "wait for volume #{v.device}" do
      wait_for_volume v.device
    end
  end

  def handle_raid(r)
    task "create raid #{r.device}", :init => true do
      shell "mdadm --create #{r.device} -n #{r.drives.size} -l #{r.level} -c #{r.chunksize || 64} #{r.drives.join(" ")}"
    end
    task "assemble raid #{r.device}" do  ## assemble fails a lot with device busy - is udev to blame :(
      if not dev_exists? r.device
        shell "service stop udev"
        shell "mdadm --assemble #{r.device} #{r.drives.join(" ")}"
        shell "service start udev"
      end
    end
    add_package "mdadm"
  end

  def mount_options(m)
    o = []
    o << m.options if m.options
    o << "size=#{m.size}M" if m.size and m.media == "tmpfs"
    o << "mode=#{m.mode}" if m.mode
    o << "noatime" if o.empty?
    o.join(",")
  end

  def handle_mount(m)
    task "mount #{m.mount}" do
      unless mounted?(m.mount)
        shell "mv #{m.mount} #{m.mout}.old" if File.exists?(m.mount)
        shell "mkdir -p #{m.mount} && mount -o #{mount_options(m)} -t #{m.format || m.media} #{m.device || m.media} #{m.mount}"
        shell "chown -R #{m.user}:#{m.group} #{m.mount}" if m.user or m.group
      end
    end
  end

  def system_arch
    system.kernel["machine"]
  end

  def mounted?(mount)
    ## cant use ohai here b/c it mashes drives together with none or tmpfs devices
    mount = mount.chop if mount =~ /\/$/
    !!(File.read("/proc/mounts") =~ / #{mount} /)
  end

  def package_arch
    `dpkg --print-architecture`.chomp
  end

  def erb(data)
      @system = system
      ERB.new(data, 0, '<>').result(binding)
  end

  def process_files(f)
    file(f) do |tmp|
      task "write #{f.file}" do
        cp_file(tmp, f.file)
        shell "chmod #{f.mode} #{f.file}" if f.mode
        shell "chown #{f.user} #{f.file}" if f.user
        shell "chgrp #{f.group} #{f.file}" if f.group
      end
    end
  end

  def process_crontab(cron)
    user = cron.user || "root"
    file(cron) do |tmp|
      task "process crontab for #{user}" do
        shell "crontab -u #{user} #{tmp}"
      end
    end
  end

  def process_users(user)
    shell "useradd -m #{user}" ## this will just fail for users like 'root'
    (user.authorized_keys || []).each do |key|
      task "add authorized_key for user #{user.name}" do
        shell "su - #{user.name} -c 'mkdir -p .ssh; echo \"#{key}\" >> .ssh/authorized_keys; chmod -R 0600 .ssh'"
      end
    end
  end

  def set_readahead(v)
    task "set readahead for #{v.device}" do
      shell "blockdev --setra #{v.readahead} #{v.device}"
    end
  end

  def set_scheduler(v)
    task "set scheduler for #{v.device}" do
      shell "echo #{v.scheduler} > /sys/block/#{File.basename(v.device)}/queue/scheduler"
    end
  end

  def handle_format(v)
    return if v.format == "tmpfs"
    task "formatting #{v.device}", :init => true do
      label = "-L " + v.label rescue ""
      shell "mkfs.#{v.format} -q #{label} #{v.device}" unless v.mount && mounted?(v.mount)
    end
    add_package "xfsprogs" if v.format == "xfs"
  end

  def add_package(p)
    @packages << p unless @packages.include? p
  end

  def package(p, &block)
    fetch("/packages/#{p}_#{package_arch}.deb") do |file|
      block.call(file)
    end
  end


  def script(scripts)
    to_array(scripts).each do |s|
      if s =~ /^#!/
        inline_script(s)
      else
        external_script(s)
      end
    end
  end

  def inline_script(script)
    tmpfile(script) do |tmp|
      task "run inline script" do
        shell "#{tmp}"
      end
    end
  end

  def external_script(script)
    fetch("/scripts/#{script}") do |file|
      task "run script #{script}" do
        shell "chmod +x #{file} ; #{file}"
      end
    end
  end

  def tmpfile(content, file = "tmp_#{rand(1_000_000_000)}", &block)
    path = "/tmp/kuzushi/#{File.basename(file)}"
    put_file(content, path)
    block.call(path) if block
    path
  end

  def file(f, &blk)
    ## no magic here - move along
    if f.template
      fetch("/templates/#{f.template}", lambda { |data| erb data  }, &blk)
    elsif f.git
      git_fetch(f)
    else
      fetch("/files/#{f.source || File.basename(f.file)}", &blk) unless f.template
    end
  end

  def git_fetch(f)
    task "install packages" do
      FileUtils.mkdir_p(f.file)
      shell "cd #{f.file} && git init"
      shell "cd #{f.file} && git remote add origin #{f.git}"
      shell "cd #{f.file} && git fetch origin"
      shell "cd #{f.file} && git checkout -b master --track origin/master"
      shell "chown -R #{f.user}:#{f.group} #{f.file}" if f.user || f.group  ## is this needed?  handled above in files?
    end
  end

  ### this needs to be brought up to date - way last version - no need to read and filter...
  def fetch(file, filter = lambda { |d| d }, &block)
    begin
      tmpfile(filter.call(File.read("/tmp/kuzushi/#{@name}/#{file}")), file) do |tmp|
        block.call(tmp)
      end
    rescue Object => e
      error("error fetching file: #{file} : #{e.message}")
    end
  end

  def error(message)
    puts "ERROR :#{message}"
  end

  def get(key)
    config[key.to_s]
  end

  def get_array(key)
    to_array( get(key) )
  end

  def to_array(value)
    [ value || [] ].flatten
  end

  def wait_for_volume(vol)
    ## Maybe use ohai here instead -- FIXME
    until dev_exists? vol do
      log "waiting for volume #{vol}"
      sleep 2
    end
  end

  def shell(cmd)
    log "# #{cmd}"
    Kernel.system cmd ## FIXME - need to handle/report exceptions here
  end

  def init?
    @init ||= false
  end

  def task(description, options = {}, &blk)
    return if options[:init] and not init?
    @tasks << { :description => description, :blk => blk }
  end

  def dev_exists?(dev)
    File.exists?("/sys/block/#{File.basename(dev)}")
  end

  def cp_file(src, dest)
    FileUtils.mkdir_p(File.dirname(dest))
    FileUtils.cp(src, dest)
  end

  def put_file(data, dest)
    FileUtils.mkdir_p(File.dirname(dest))
    File.open(dest,"w") do |f|
      f.write(data)
      f.chmod(0700)
    end
  end

  def log(message)
    puts message
  end
end