# frozen_string_literal: true

require 'bolt/pal/yaml_plan/parameter'
require 'bolt/pal/yaml_plan/step'

module Bolt
  class PAL
    class YamlPlan
      PLAN_KEYS = Set['parameters', 'steps', 'return', 'version', 'description']
      VAR_NAME_PATTERN = /\A[a-z_][a-z0-9_]*\z/.freeze

      attr_reader :name, :parameters, :steps, :return, :description

      def initialize(name, plan)
        # Top-level plan keys aren't allowed to be Puppet code, so force them
        # all to strings.
        plan = Bolt::Util.walk_keys(plan) { |key| stringify(key) }
        @name = name.freeze
        @description = stringify(plan['description']) if plan['description']

        params_hash = stringify(plan.fetch('parameters', {}))
        # Ensure params is a hash
        unless params_hash.is_a?(Hash)
          raise Bolt::Error.new("Plan parameters must be a Hash", "bolt/invalid-plan")
        end

        # Munge parameters into an array of Parameter objects, which is what
        # the Puppet API expects
        @parameters = params_hash.map do |param, definition|
          Parameter.new(param, definition)
        end.freeze

        # Validate top level plan keys
        top_level_keys = plan.keys.to_set
        unless PLAN_KEYS.superset?(top_level_keys)
          invalid_keys = top_level_keys - PLAN_KEYS
          raise Bolt::Error.new("Plan contains illegal key(s) #{invalid_keys.to_a.inspect}",
                                "bolt/invalid-plan")
        end

        unless plan['steps'].is_a?(Array)
          raise Bolt::Error.new("Plan must specify an array of steps", "bolt/invalid-plan")
        end

        used_names = Set.new(@parameters.map(&:name))

        @steps = plan['steps'].each_with_index.map do |step, index|
          # Step keys also aren't allowed to be code and neither is the value of "name"
          stringified_step = Bolt::Util.walk_keys(step) { |key| stringify(key) }
          stringified_step['name'] = stringify(stringified_step['name']) if stringified_step.key?('name')

          step = Step.create(stringified_step, index + 1)
          duplicate_check(used_names, stringified_step['name'], index + 1)
          used_names << stringified_step['name'] if stringified_step['name']
          step
        end.freeze
        @return = plan['return']
      end

      def duplicate_check(used_names, name, step_number)
        if used_names.include?(name)
          error_message = "Duplicate step name or parameter detected: #{name.inspect}"
          err = Step.step_error(error_message, name, step_number)
          raise Bolt::Error.new(err, "bolt/invalid-plan")
        end
      end

      def body
        self
      end

      def return_type
        Puppet::Pops::Types::TypeParser.singleton.parse('Boltlib::PlanResult')
      end

      # Turn all "potential" strings in the object into actual strings.
      # Because we interpret bare strings as potential Puppet code, even in
      # places where Puppet code isn't allowed (like some hash keys), we need
      # to be able to force them back into regular strings, as if we had
      # parsed them normally.
      def stringify(value)
        case value
        when Array
          value.map { |element| stringify(element) }
        when Hash
          value.each_with_object({}) do |(k, v), o|
            o[stringify(k)] = stringify(v)
          end
        when EvaluableString
          value.value
        else
          value
        end
      end

      # This class wraps a value parsed from YAML which may be Puppet code.
      # That includes double-quoted strings and string literals, each of which
      # subclasses this parent class in order to implement its own evaluation
      # logic.
      class EvaluableString
        attr_reader :value

        def initialize(value)
          @value = value
        end

        def ==(other)
          self.class == other.class && @value == other.value
        end
      end

      # This class represents a double-quoted YAML string, which is interpreted
      # as though it were a double-quoted Puppet string (with associated
      # variable interpolations)
      class DoubleQuotedString < EvaluableString
        def evaluate(scope, evaluator)
          # "inspect" allows us to get back a double-quoted string literal with
          # special characters escaped. This is based on the assumption that
          # YAML, Ruby and Puppet all support similar escape sequences.
          parse_result = evaluator.parse_string(@value.inspect)

          scope.with_local_scope({}) do
            evaluator.evaluate(scope, parse_result)
          end
        end
      end

      # This represents a literal snippet of Puppet code
      class CodeLiteral < EvaluableString
        def evaluate(scope, evaluator)
          parse_result = evaluator.parse_string(@value)

          scope.with_local_scope({}) do
            evaluator.evaluate(scope, parse_result)
          end
        end
      end

      # This class stores a bare YAML string, which is fuzzily interpreted as
      # either Puppet code or a literal string, depending on whether it starts
      # with a variable reference.
      class BareString < EvaluableString
        def evaluate(scope, evaluator)
          if @value.start_with?('$')
            # Try to parse the string as Puppet code. If it's invalid code,
            # return the original string.
            parse_result = evaluator.parse_string(@value)
            scope.with_local_scope({}) do
              evaluator.evaluate(scope, parse_result)
            end
          else
            @value
          end
        end
      end
    end
  end
end