#    Copyright 2013 Mirantis, Inc.
#
#    Licensed under the Apache License, Version 2.0 (the "License"); you may
#    not use this file except in compliance with the License. You may obtain
#    a copy of the License at
#
#         http://www.apache.org/licenses/LICENSE-2.0
#
#    Unless required by applicable law or agreed to in writing, software
#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
#    License for the specific language governing permissions and limitations
#    under the License.


require "json"
require "base64"
require 'fileutils'

module MCollective
  module Agent
    class Erase_node < RPC::Agent

      # Look at https://github.com/torvalds/linux/blob/master/Documentation/devices.txt
      # Please also update the device codes here
      # https://github.com/stackforge/fuel-web/blob/master/bin/agent#L43
      STORAGE_CODES = [3, 8, 65, 66, 67, 68, 69, 70, 71, 104, 105, 106, 107, 108, 109, 110, 111, 202, 252, 253]

      action "erase_node" do
        erase_node
      end

      action "reboot_node" do
        reboot
      end

      private

      def erase_node
        request_reboot = request.data[:reboot]
        dry_run = request.data[:dry_run]
        error_msg = []
        reply[:status] = 0  # Shell exitcode behaviour

        prevent_discover unless dry_run

        tempfile_storage='/mnt/tempfiles'

        begin
          File.open('/proc/sys/kernel/panic','w') { |file| file.write("5\n") }
          #Enable sysrq trigger for further hard reboot
          File.open('/proc/sys/kernel/sysrq','w') { |file| file.write("1\n") }
          get_boot_devices.each do |dev|
            erase_data(dev[:name])
            erase_data(dev[:name], 1, dev[:size], '512')
          end unless dry_run

          reply[:erased] = true
        rescue Exception => e
          reply[:erased] = false
          reply[:status] += 1
          msg = "MBR can't be erased. Reason: #{e.message};"
          Log.error(msg)
          error_msg << msg
        end

        begin
          reboot if !dry_run && request_reboot
          reply[:rebooted] = request_reboot
        rescue Exception => e
          reply[:rebooted] = false
          reply[:status] += 1
          msg = "Can't reboot node. Reason: #{e.message};"
          Log.error(msg)
          error_msg << "Can't reboot node. Reason: #{e.message};"
        end

        unless error_msg.empty?
          reply[:error_msg] = error_msg.join(' ')
        end
      end

      def get_boot_devices
        raise "Path /sys/block does not exist" unless File.exists?("/sys/block")
        Dir["/sys/block/*"].inject([]) do |blocks, block_device_dir|
          basename_dir = File.basename(block_device_dir)
          dev_name = basename_dir.gsub(/!/, '/')
          major = `udevadm info --query=property --name=#{dev_name} | grep MAJOR`.strip.split(/\=/)[-1]
          if File.exists?("/sys/block/#{basename_dir}/removable")
            removable = File.open("/sys/block/#{basename_dir}/removable") { |f| f.read_nonblock(1024).strip }
          end
          if File.exists?("/sys/block/#{basename_dir}/size")
            size = File.open("/sys/block/#{basename_dir}/size") { |f| f.read_nonblock(1024).strip }
          else
            size = 0
            debug_msg("Can not define device size. File /sys/block/#{basename_dir}/size not found.")
          end

          if STORAGE_CODES.include?(major.to_i) && removable =~ /^0$/
            blocks << {:name => dev_name, :size => size}
          end
          blocks
        end
      end

      def reboot
        pid = fork do
          #Use sysrq trigger: Umount->Sync->reBoot
          debug_msg("Run node rebooting command using 'SB' to sysrq-trigger")
          sleep 5
          # turning panic on oops and setting panic timeout to 10
          File.open('/proc/sys/kernel/panic_on_oops', 'w') {|file| file.write("1\n")}
          File.open('/proc/sys/kernel/panic','w') {|file| file.write("10\n")}
          ['b'].each do |req|
            File.open('/proc/sysrq-trigger','w') do |file|
              file.write("#{req}\n")
            end
          end
        end
        Process.detach(pid)
      end

      def erase_data(dev, length=1, offset=0, bs='1M')
        cmd = "dd if=/dev/zero of=/dev/#{dev} bs=#{bs} count=#{length} seek=#{offset} oflag=direct"
        status = system(cmd)
        debug_msg("Run device erasing command '#{cmd}' returned '#{status}'")

        status
      end

      # Prevent discover by agent while node rebooting
      def prevent_discover
        lock_path = '/var/run/nodiscover'
        debug_msg("Create file for discovery preventing #{lock_path}")
        FileUtils.touch(lock_path)
      end

      # In case of node erasing we can lose all
      # debug messages, lets send them to orchestrator
      def debug_msg(msg)
        reply[:debug_msg] = [] unless reply[:debug_msg]
        Log.debug(msg)
        reply[:debug_msg] << msg
      end

    end
  end
end