require 'dry/validation/schema/dsl'

module Dry
  module Validation
    class Schema
      class Value < DSL
        attr_reader :type, :schema_class, :schema, :type_map

        def initialize(options = {})
          super
          @type = options.fetch(:type, :key)
          @schema_class = options.fetch(:schema_class, ::Class.new(Schema))
          @options = options.merge(type: @type, schema_class: @schema_class)
          @type_map = parent && parent.root? ? parent.type_map : {}
        end

        def predicates(mod)
          @registry = options[:registry] = schema_class.predicates(mod)
        end

        def input(*predicates)
          schema_class.config.input = predicates
          self
        end

        def key(name, &block)
          warn 'key is deprecated - use required instead.'

          required(name, &block)
        end

        def required(name, type_spec = nil, &block)
          rule = define(name, Key, &block)

          if type_spec
            type_map[name] = type_spec
          end

          rule
        end

        def schema(other = nil, &block)
          @schema = Schema.create_class(self, other, &block)
          type_map.update(@schema.type_map)
          hash?.and(@schema)
        end

        def each(*predicates, &block)
          left = array?

          right =
            if predicates.size > 0
              create_rule([:each, infer_predicates(predicates, new).to_ast])
            else
              val = Value[
                name, registry: registry, schema_class: schema_class.clone
              ].instance_eval(&block)

              if val.type_map?
                if root?
                  @type_map = [val.type_map]
                else
                  type_map[name] = [val.type_map]
                end
              end

              create_rule([:each, val.to_ast])
            end

          rule = left.and(right)

          add_rule(rule) if root?

          rule
        end

        def when(*predicates, &block)
          left = infer_predicates(predicates, Check[path, type: type, registry: registry])

          right = Value.new(type: type, registry: registry)
          right.instance_eval(&block)

          add_check(left.then(create_rule(right.to_ast)))

          self
        end

        def rule(id = nil, **options, &block)
          if id
            val = Value[id, registry: registry]
            res = val.instance_exec(&block)
          else
            id, deps = options.to_a.first
            val = Value[id, registry: registry]
            res = val.instance_exec(*deps.map { |name| val.value(name) }, &block)
          end

          add_check(val.with(rules: [res.with(deps: deps || [])]))
        end

        def confirmation
          conf = :"#{name}_confirmation"

          parent.optional(conf).maybe

          rule(conf => [conf, name]) { |left, right| left.eql?(right) }
        end

        def value(name)
          check(name, registry: registry, rules: rules)
        end

        def check(name, options = {})
          Check[name, options.merge(type: type)]
        end

        def configure(&block)
          schema_class.class_eval(&block)
          @registry = schema_class.registry
          self
        end

        def root?
          name.nil?
        end

        def type_map?
          ! type_map.empty?
        end

        def schema?
          ! @schema.nil?
        end

        def class
          Value
        end

        def new
          self.class.new(registry: registry, schema_class: schema_class.clone)
        end

        def key?(name)
          create_rule([:val, registry[:key?].curry(name).to_ast])
        end

        def predicate(name, *args)
          registry.ensure_valid_predicate(name, args, schema_class)
          registry[name].curry(*args)
        end

        def node(input, *args)
          if input.is_a?(::Symbol)
            [type, [name, predicate(input, *args).to_ast]]
          elsif input.respond_to?(:rule)
            [type, [name, [:type, input]]]
          elsif input.is_a?(::Class) && input < ::Dry::Types::Struct
            [type, [name, [:schema, Schema.create_class(self, input)]]]
          elsif input.is_a?(Schema)
            [type, [name, schema(input).to_ast]]
          else
            [type, [name, input.to_ast]]
          end
        end

        def dyn_arg?(name)
          schema_class.instance_methods.include?(name)
        end

        private

        def infer_predicates(predicates, infer_on = self)
          predicates.map { |predicate|
            name, *args = ::Kernel.Array(predicate).first

            if name.is_a?(Schema)
              infer_on.schema(name)
            else
              infer_on.__send__(name, *args)
            end
          }.reduce(:and)
        end

        def method_missing(meth, *args, &block)
          return schema_class.instance_method(meth) if dyn_arg?(meth)

          val_rule = create_rule([:val, predicate(meth, *args).to_ast])

          if block
            val = new.instance_eval(&block)

            type_map.update(val.type_map) if val.type_map?

            new_rule = create_rule([:and, [val_rule.to_ast, val.to_ast]])

            add_rule(new_rule)
          else
            val_rule
          end
        end
      end
    end
  end
end