# frozen_string_literal: true

module Mutant
  # Bootstrap process
  #
  # The role of the boostrap is to take the pure config and apply it against
  # the impure world to produce an environment.
  #
  # env = config interpreted against the world
  #
  # rubocop:disable Metrics/ModuleLength
  module Bootstrap
    include Adamantium, Anima.new(:config, :parser, :world)

    SEMANTICS_MESSAGE_FORMAT =
      "%<message>s. Fix your lib to follow normal ruby semantics!\n" \
      '{Module,Class}#name should return resolvable constant name as String or nil'

    CLASS_NAME_RAISED_EXCEPTION =
      '%<scope_class>s#name from: %<scope>s raised an error: %<exception>s'

    CLASS_NAME_TYPE_MISMATCH_FORMAT =
      '%<scope_class>s#name from: %<scope>s returned %<name>s'

    private_constant(*constants(false))

    # Run Bootstrap
    #
    # @param [Env] env
    #
    # @return [Either<String, Env>]
    #
    # rubocop:disable Metrics/MethodLength
    def self.call(env)
      env.record(:bootstrap) do
        env = load_hooks(env)
          .tap(&method(:infect))
          .with(matchable_scopes: matchable_scopes(env))

        matched_subjects = env.record(:subject_match) do
          Matcher.from_config(env.config.matcher).call(env)
        end

        selected_subjects = subject_select(env, matched_subjects)

        mutations = env.record(:mutation_generate) do
          selected_subjects.flat_map(&:mutations)
        end

        Integration.setup(env).fmap do |integration|
          env.with(
            integration: integration,
            mutations:   mutations,
            selector:    Selector::Expression.new(integration),
            subjects:    selected_subjects
          )
        end
      end
    end
    # rubocop:enable Metrics/MethodLength

    def self.load_hooks(env)
      env.record(__method__) do
        env.with(hooks: Hooks.load_config(env.config))
      end
    end
    private_class_method :load_hooks

    def self.subject_select(env, subjects)
      env.record(__method__) do
        start_expressions = env.config.matcher.start_expressions

        return subjects if start_expressions.empty?

        subjects.drop_while do |subject|
          start_expressions.none? do |expression|
            expression.prefix?(subject.expression)
          end
        end
      end
    end
    private_class_method :subject_select

    # rubocop:disable Metrics/AbcSize
    # rubocop:disable Metrics/MethodLength
    def self.infect(env)
      env.record(__method__) do
        config, hooks, world = env.config, env.hooks, env.world

        env.record(:hooks_env_infection_pre) do
          hooks.run(:env_infection_pre, env)
        end

        env.record(:require_target) do
          config.environment_variables.each do |key, value|
            world.environment_variables[key] = value
          end

          config.includes.each(&world.load_path.public_method(:<<))
          config.requires.each(&world.kernel.public_method(:require))
        end

        env.record(:hooks_env_infection_post) do
          hooks.run(:env_infection_post, env)
        end
      end
    end
    private_class_method :infect
    # rubocop:enable Metrics/AbcSize
    # rubocop:enable Metrics/MethodLength

    def self.matchable_scopes(env)
      env.record(__method__) do
        config = env.config

        scopes = env.world.object_space.each_object(Module).with_object([]) do |scope, aggregate|
          expression = expression(config.reporter, config.expression_parser, scope) || next
          aggregate << Scope.new(scope, expression)
        end

        scopes.sort_by { |scope| scope.expression.syntax }
      end
    end
    private_class_method :matchable_scopes

    def self.scope_name(reporter, scope)
      scope.name
    rescue => exception
      semantics_warning(
        reporter,
        CLASS_NAME_RAISED_EXCEPTION,
        exception:   exception.inspect,
        scope:       scope,
        scope_class: scope.class
      )
      nil
    end
    private_class_method :scope_name

    # rubocop:disable Metrics/MethodLength
    def self.expression(reporter, expression_parser, scope)
      name = scope_name(reporter, scope) or return

      unless name.instance_of?(String)
        semantics_warning(
          reporter,
          CLASS_NAME_TYPE_MISMATCH_FORMAT,
          name:        name,
          scope_class: scope.class,
          scope:       scope
        )
        return
      end

      expression_parser.call(name).from_right {}
    end
    private_class_method :expression
    # rubocop:enable Metrics/MethodLength

    def self.semantics_warning(reporter, format, options)
      reporter.warn(SEMANTICS_MESSAGE_FORMAT % { message: format % options })
    end
    private_class_method :semantics_warning
  end # Bootstrap
  # rubocop:enable Metrics/ModuleLength
end # Mutant