class Hollerith

# File lib/hollerith.rb, line 8
def initialize configuration, main_context = {}
  @configuration = configuration 
  @main_context = main_context
  @user_context = @configuration['configuration'] || {}
  @user_defined_functions = @configuration['custom_functions'] 
end

# File lib/hollerith.rb, line 99
def evaluate_conditional conditional_statement
  return false unless conditional_statement

  evaluate_function(conditional_statement)
end

# File lib/hollerith.rb, line 105
def evaluate_function function_definition
  return unless function_definition

  runner = Hollerith::FunctionRunner.new(
    function_definition,
    @main_context,
    @user_context,
    @user_defined_functions
  )

  results = runner.evaluate

  if runner.user_context_change
    @user_context.deep_merge!(runner.user_context_change)
  end
  
  return results
end

# File lib/hollerith.rb, line 91
def evaluate_functions functions
  if functions.compact.any?
    functions.compact.each do |function|
      evaluate_function(function)
    end
  end
end

# File lib/hollerith.rb, line 33
def execute_hook_implementation definition
  if definition['before'] && definition['before']['functions']
    evaluate_functions(definition['before']['functions'])
  end

  case definition['method']
  when 'none'
    evaluate_functions(definition['functions'])
  when 'conditional'
    # TODO
    raise "Not implemented!" 
  when 'for_each'
    before_iteration_functions = definition['for_each']['before_iteration']
    each_iteration_rules = definition['for_each']['each_iteration']
    break_when = definition['for_each']['break_iteration_if']
    next_when = definition['for_each']['next_if']

    evaluate_functions(before_iteration_functions)

    get_iterator(definition['loop']) do
      next if evaluate_conditional(next_when)

      evaluate_functions(each_iteration_rules)        
      break if evaluate_conditional(break_when)
    end
  end

  if definition['finally'] && definition['finally']['functions']
    evaluate_functions(definition['finally']['functions'])
  end
end

# File lib/hollerith.rb, line 65
def get_iterator iterator_definition
  # `$$_schools as each_school`
  collection_variable, each_value_variable = iterator_definition.split(' as ')

  get_variable_from_context(collection_variable).each do |each_iteration|
    @user_context[each_value_variable] = each_iteration
    yield
  end
end

# File lib/hollerith.rb, line 75
def get_variable_from_context variable
  if variable.start_with?('$$_')
    value_to_return = @main_context[variable[3..-1].strip]   

    if value_to_return
      return value_to_return
    else
      raise ArgumentError.new(
        "Variable not found #{value_to_return} in this context"
      )
    end
  else
    raise ArgumentError.new("Invalid variable definition #{variable}")
  end
end

# File lib/hollerith.rb, line 23
def hook_should_be_run(hook_implementation)
  if hook_implementation.has_key?('run_if')
    evaluate_conditional(hook_implementation['run_if'])      
  elsif hook_implementation.has_key?('run_unless')
    !evaluate_conditional(hook_implementation['run_unless'])      
  else
    true
  end
end

# File lib/hollerith.rb, line 15
def trigger_hook hook
  @configuration[hook].each do |each_hook_implementation|
    if hook_should_be_run(each_hook_implementation)
      execute_hook_implementation(each_hook_implementation)
    end
  end
end