require 'rubygems'
require 'ruote'
require 'flexmock'
require 'spec'

# Workitem fields validation
# This participant validates the fields of the current workitem
# Especially useful to validate the initial workitem
# An input definition may include the following:
#   - name: Input name, compulsory
#   - kind: Input type, compulsory
#   - obligation: Whether input is required or optional, required by default.
#   - default: Input default value, optional.
#
# The kind of an input consists of a string corresponding to the Ruby class
# name, one of:
#   - String
#   - Fixnum
#   - Bool (note: not a ruby class per se)
#   - DateTime
#   - Array<KIND> (KIND must recursively take on the values in this list)
#   - Hash<KIND, KIND) (same note as above)
#
# The participant expects the 'fields_definitions' field to contain the
# definitions as hashes indexed by field name
#
# e.g.:
#  fields_definitions 'names'             => [ 'Array<String>', :required ],
#                     'operation'         => [ 'String', :default => 'run' ],
#                     'operation_timeout' => [ 'Fixnum', :default => 300 ],
#                     'arguments'         => [ 'Hash<String, String>', :default => {} ],
#                     'result_field'      => [ 'String', :default => '__result__' ]
#  error '${f:fields_errors}', :if => '${f:fields_errors}'
#
class FieldsValidationParticipant
  include Ruote::LocalParticipant

  # Lookup fields validations and iterate through to validate
  #
  # === Input Workitem Fields
  # fields_definitions<Hash>:: Hash of fields definition indexed by name
  #
  # === Ouput Workitem Fields
  # fields_errors<Array>:: List of error messages, empty if no error
  def consume(workitem)
    defs = workitem.fields['fields_definitions'] || {}
    errors = []

    # First validate
    defs.each { |name, val| errors += validate(name, val, workitem.lookup(name)) }
    workitem.set_field('fields_errors', errors)

    # Then set default values
    defaults = defs.select { |_, val| val.is_a?(Hash) && val.include?(:default) }
    defaults.each { |name, val| workitem.set_field(name, val[:default]) unless workitem.lookup(name) }

    reply_to_engine(workitem)
  end

  protected

  # Validate a given workitem field against its input definition
  #
  # === Argumnets
  # name<String>:: Name of field
  # definition<Array>:: Input definition
  # field<Object>:: Actual field value
  #
  # === Return
  # errors<Array>:: List of error messages or empty array if no error
  def validate(name, definition, field)
    errors = []
    if field.nil?
      if definition[1] == :required
        errors << "Missing required workitem field #{name.inspect}"
      end
    else
      errors += check_kind(field, definition[0], name)
    end
    errors
  end

  # Recursively check that the kind of given field matches given kind
  #
  # === Arguments
  # field<Object>:: Actual workitem field being checked
  # kind<String>:: Kind 'field' should match
  # name<String>:: Name of field for error message
  #
  # === Return
  # errors<Array>:: List of errors or empty array if no error
  def check_kind(field, kind, name)
    errors = []
    if kind =~ /^Array<(.*)>$/
      inner = Regexp.last_match[1]
      errors += check_kind(field, 'Array', name)
      if errors.empty?
        field.each_index do |i|
          errors += check_kind(field[i], inner, "element at index #{i} of #{name}")
        end
      end
    elsif kind =~ /^Hash<(.*), *(.*)>$/
      inner_key = Regexp.last_match[1]
      inner_val = Regexp.last_match[2]
      errors += check_kind(field, 'Hash', name)
      if errors.empty?
        field.each do |k ,v|
          errors += check_kind(k, inner_key, "key #{k.inspect} of #{name}")
          errors += check_kind(v, inner_val, "value at key #{k.inspect} of #{name}")
        end
      end
    else
      if field.class.to_s != kind
        errors << "Workitem field #{name.inspect} kind is invalid (should be " +
                  "#{kind.inspect} but is #{field.class.to_s.inspect})"
      end
    end
    errors
  end

end

config = Spec::Runner.configuration
config.mock_with :flexmock

describe Maestro::FieldsValidationParticipant do

  # Create test workitem
  def new_workitem
    workitem = Ruote::Workitem.new('fields' =>
      { 'fields_definitions' =>  { 'required_field' => [ 'String', :required ],
                                   'optional_field' => [ 'String', :optional ],
                                   'array_field'    => [ 'Array<String>', :required ],
                                   'hash_field'     => [ 'Hash<String, Fixnum>', :required ] },
        'required_field'     => 'I\'m here',
        'array_field'        => [ 'I\'m a string' ],
        'hash_field'         => { 'key' => 42 }})
  end

  before(:each) do
    @workitem = nil
    @validator = Maestro::FieldsValidationParticipant.new
    flexmock(@validator).should_receive(:reply_to_engine).and_return { |wi| @workitem = wi }
  end

  it 'should work with no definition' do
    workitem = Ruote::Workitem.new('fields' => {'a' => 'b'})
    @validator.consume(workitem)
    @workitem.should_not be_nil
    @workitem.to_h.should == workitem.to_h
  end

  it 'should validate required inputs' do
    workitem = new_workitem
    @validator.consume(workitem)
    @workitem.should_not be_nil
    @workitem.to_h.should == workitem.to_h
  end

  it 'should invalidate missing inputs' do
    workitem = new_workitem
    workitem.set_field('required_field', nil)
    @validator.consume(workitem)
    @workitem.should_not be_nil
    @workitem.lookup('fields_errors').should_not be_nil
    @workitem.lookup('fields_errors').class.should == Array
    @workitem.lookup('fields_errors').size.should == 1
    @workitem.lookup('fields_errors')[0].should =~ /^Missing required workitem field/
  end

  it 'should invalidate incorrect kinds' do
    workitem = new_workitem
    workitem.set_field('optional_field', 42)
    @validator.consume(workitem)
    @workitem.should_not be_nil
    @workitem.lookup('fields_errors').should_not be_nil
    @workitem.lookup('fields_errors').class.should == Array
    @workitem.lookup('fields_errors').size.should == 1
    @workitem.lookup('fields_errors')[0].should =~ /kind is invalid/
  end

  it 'should invalidate multiple errors' do
    workitem = new_workitem
    workitem.set_field('optional_field', 42)
    workitem.set_field('required_field', 42)
    @validator.consume(workitem)
    @workitem.should_not be_nil
    @workitem.lookup('fields_errors').should_not be_nil
    @workitem.lookup('fields_errors').class.should == Array
    @workitem.lookup('fields_errors').size.should == 2
    @workitem.lookup('fields_errors').all? { |e| e.should =~ /kind is invalid/ }
  end

  it 'should invalidate incorrect array kind' do
    workitem = new_workitem
    workitem.set_field('array_field', [ 42 ])
    @validator.consume(workitem)
    @workitem.should_not be_nil
    @workitem.lookup('fields_errors').should_not be_nil
    @workitem.lookup('fields_errors').class.should == Array
    @workitem.lookup('fields_errors').size.should == 1
    @workitem.lookup('fields_errors')[0].should =~ /kind is invalid/
  end

  it 'should invalidate incorrect hash key kind' do
    workitem = new_workitem
    workitem.set_field('hash_field', [ 42 => 42 ])
    @validator.consume(workitem)
    @workitem.should_not be_nil
    @workitem.lookup('fields_errors').should_not be_nil
    @workitem.lookup('fields_errors').class.should == Array
    @workitem.lookup('fields_errors').size.should == 1
    @workitem.lookup('fields_errors')[0].should =~ /kind is invalid/
  end

  it 'should invalidate incorrect hash value kind' do
    workitem = new_workitem
    workitem.set_field('hash_field', [ 'key' => 'not_an_int' ])
    @validator.consume(workitem)
    @workitem.should_not be_nil
    @workitem.lookup('fields_errors').should_not be_nil
    @workitem.lookup('fields_errors').class.should == Array
    @workitem.lookup('fields_errors').size.should == 1
    @workitem.lookup('fields_errors')[0].should =~ /kind is invalid/
  end
end