#
# Author:: Adam Edwards (<adamed@opscode.com>)
# Copyright:: Copyright 2013-2016, Chef Software Inc.
# License:: Apache License, Version 2.0
#
# 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 "chef/platform/query_helpers"
require "chef/provider/windows_script"

class Chef
  class Provider
    class PowershellScript < Chef::Provider::WindowsScript

      provides :powershell_script, os: "windows"

      def initialize (new_resource, run_context)
        super(new_resource, run_context, ".ps1")
        add_exit_status_wrapper
      end

      def action_run
        validate_script_syntax!
        super
      end

      def command
        basepath = is_forced_32bit ? wow64_directory : run_context.node.kernel.os_info.system_directory

        # Powershell.exe is always in "v1.0" folder (for backwards compatibility)
        interpreter_path = Chef::Util::PathHelper.join(basepath, "WindowsPowerShell", "v1.0", interpreter)

        # Must use -File rather than -Command to launch the script
        # file created by the base class that contains the script
        # code -- otherwise, powershell.exe does not propagate the
        # error status of a failed Windows process that ran at the
        # end of the script, it gets changed to '1'.
        #
        # Nano only supports -Command
        cmd = "\"#{interpreter_path}\" #{flags}"
        if Chef::Platform.windows_nano_server?
          cmd << " -Command \". '#{script_file.path}'\""
        else
          cmd << " -File \"#{script_file.path}\""
        end
        cmd
      end

      def flags
        interpreter_flags = [*default_interpreter_flags].join(" ")

        if ! (@new_resource.flags.nil?)
          interpreter_flags = [@new_resource.flags, interpreter_flags].join(" ")
        end

        interpreter_flags
      end

      protected

      # Process exit codes are strange with PowerShell and require
      # special handling to cover common use cases.
      def add_exit_status_wrapper
        self.code = wrapper_script
        Chef::Log.debug("powershell_script provider called with script code:\n\n#{@new_resource.code}\n")
        Chef::Log.debug("powershell_script provider will execute transformed code:\n\n#{self.code}\n")
      end

      def validate_script_syntax!
        interpreter_arguments = default_interpreter_flags.join(" ")
        Tempfile.open(["chef_powershell_script-user-code", ".ps1"]) do | user_script_file |
          # Wrap the user's code in a PowerShell script block so that
          # it isn't executed. However, syntactically invalid script
          # in that block will still trigger a syntax error which is
          # exactly what we want here -- verify the syntax without
          # actually running the script.
          user_code_wrapped_in_powershell_script_block = <<-EOH
{
  #{@new_resource.code}
}
EOH
          user_script_file.puts user_code_wrapped_in_powershell_script_block

          # A .close or explicit .flush required to ensure the file is
          # written to the file system at this point, which is required since
          # the intent is to execute the code just written to it.
          user_script_file.close
          validation_command = "\"#{interpreter}\" #{interpreter_arguments} -Command \". '#{user_script_file.path}'\""

          # Note that other script providers like bash allow syntax errors
          # to be suppressed by setting 'returns' to a value that the
          # interpreter would return as a status code in the syntax
          # error case. We explicitly don't do this here -- syntax
          # errors will not be suppressed, since doing so could make
          # it harder for users to detect / debug invalid scripts.

          # Therefore, the only return value for a syntactically valid
          # script is 0. If an exception is raised by shellout, this
          # means a non-zero return and thus a syntactically invalid script.

          with_os_architecture(node, architecture: new_resource.architecture) do
            shell_out!(validation_command, {returns: [0]})
          end
        end
      end

      def default_interpreter_flags
        return [] if Chef::Platform.windows_nano_server?

        # Execution policy 'Bypass' is preferable since it doesn't require
        # user input confirmation for files such as PowerShell modules
        # downloaded from the Internet. However, 'Bypass' is not supported
        # prior to PowerShell 3.0, so the fallback is 'Unrestricted'
        execution_policy = Chef::Platform.supports_powershell_execution_bypass?(run_context.node) ? "Bypass" : "Unrestricted"

        [
          "-NoLogo",
          "-NonInteractive",
          "-NoProfile",
          "-ExecutionPolicy #{execution_policy}",
          # Powershell will hang if STDIN is redirected
          # http://connect.microsoft.com/PowerShell/feedback/details/572313/powershell-exe-can-hang-if-stdin-is-redirected
          "-InputFormat None",
        ]
      end

      # A wrapper script is used to launch user-supplied script while
      # still obtaining useful process exit codes. Unless you
      # explicitly call exit in Powershell, the powershell.exe
      # interpreter returns only 0 for success or 1 for failure. Since
      # we'd like to get specific exit codes from executable tools run
      # with Powershell, we do some work using the automatic variables
      # $? and $LASTEXITCODE to return the process exit code of the
      # last process run in the script if it is the last command
      # executed, otherwise 0 or 1 based on whether $? is set to true
      # (success, where we return 0) or false (where we return 1).
      def wrapper_script
<<-EOH
# Chef Client wrapper for powershell_script resources

# LASTEXITCODE can be uninitialized -- make it explictly 0
# to avoid incorrect detection of failure (non-zero) codes
$global:LASTEXITCODE = 0

# Catch any exceptions -- without this, exceptions will result
# In a zero return code instead of the desired non-zero code
# that indicates a failure
trap [Exception] {write-error ($_.Exception.Message);exit 1}

# Variable state that should not be accessible to the user code
new-variable -name interpolatedexitcode -visibility private -value $#{@new_resource.convert_boolean_return}
new-variable -name chefscriptresult -visibility private

# Initialize a variable we use to capture $? inside a block
$global:lastcmdlet = $null

# Execute the user's code in a script block --
$chefscriptresult =
{
 #{@new_resource.code}

 # This assignment doesn't affect the block's return value
 $global:lastcmdlet = $?
}.invokereturnasis()

# Assume failure status of 1 -- success cases
# will have to override this
$exitstatus = 1

# If convert_boolean_return is enabled, the block's return value
# gets precedence in determining our exit status
if ($interpolatedexitcode -and $chefscriptresult -ne $null -and $chefscriptresult.gettype().name -eq 'boolean')
{
  $exitstatus = [int32](!$chefscriptresult)
}
elseif ($lastcmdlet)
{
  # Otherwise, a successful cmdlet execution defines the status
  $exitstatus = 0
}
elseif ( $LASTEXITCODE -ne $null -and $LASTEXITCODE -ne 0 )
{
  # If the cmdlet status is failed, allow the Win32 status
  # in $LASTEXITCODE to define exit status. This handles the case
  # where no cmdlets, only Win32 processes have run since $?
  # will be set to $false whenever a Win32 process returns a non-zero
  # status.
  $exitstatus = $LASTEXITCODE
}

# Print STDOUT for the script execution
Write-Output $chefscriptresult

# If this script is launched with -File, the process exit
# status of PowerShell.exe will be $exitstatus. If it was
# launched with -Command, it will be 0 if $exitstatus was 0,
# 1 (i.e. failed) otherwise.
exit $exitstatus
EOH
      end

    end
  end
end