# frozen_string_literal: true

module Dry
  module Types
    # Homogeneous mapping. It describes a hash with unknown keys that match a certain type.
    #
    # @example
    #   type = Dry::Types['hash'].map(
    #     Dry::Types['integer'].constrained(gteq: 1, lteq: 10),
    #     Dry::Types['string']
    #   )
    #
    #   type.(1 => 'right')
    #   # => {1 => 'right'}
    #
    #   type.('1' => 'wrong')
    #   # Dry::Types::MapError: "1" violates constraints (type?(Integer, "1") AND gteq?(1, "1") AND lteq?(10, "1") failed)
    #
    #   type.(11 => 'wrong')
    #   # Dry::Types::MapError: 11 violates constraints (lteq?(10, 11) failed)
    #
    # @api public
    class Map < Nominal
      def initialize(_primitive, key_type: Types["any"], value_type: Types["any"], meta: EMPTY_HASH)
        super(_primitive, key_type: key_type, value_type: value_type, meta: meta)
      end

      # @return [Type]
      #
      # @api public
      def key_type
        options[:key_type]
      end

      # @return [Type]
      #
      # @api public
      def value_type
        options[:value_type]
      end

      # @return [String]
      #
      # @api public
      def name
        "Map"
      end

      # @param [Hash] hash
      #
      # @return [Hash]
      #
      # @api private
      def call_unsafe(hash)
        try(hash) { |failure|
          raise MapError, failure.error.message
        }.input
      end

      # @param [Hash] hash
      #
      # @return [Hash]
      #
      # @api private
      def call_safe(hash)
        try(hash) { return yield }.input
      end

      # @param [Hash] hash
      #
      # @return [Result]
      #
      # @api public
      def try(hash)
        result = coerce(hash)
        return result if result.success? || !block_given?

        yield(result)
      end

      # @param meta [Boolean] Whether to dump the meta to the AST
      #
      # @return [Array] An AST representation
      #
      # @api public
      def to_ast(meta: true)
        [:map,
         [key_type.to_ast(meta: true),
          value_type.to_ast(meta: true),
          meta ? self.meta : EMPTY_HASH]]
      end

      # @return [Boolean]
      #
      # @api public
      def constrained?
        value_type.constrained?
      end

      private

      # @api private
      def coerce(input)
        unless primitive?(input)
          return failure(
            input, CoercionError.new("#{input.inspect} must be an instance of #{primitive}")
          )
        end

        output = {}
        failures = []

        input.each do |k, v|
          res_k = key_type.try(k)
          res_v = value_type.try(v)

          if res_k.failure?
            failures << res_k.error
          elsif output.key?(res_k.input)
            failures << CoercionError.new("duplicate coerced hash key #{res_k.input.inspect}")
          elsif res_v.failure?
            failures << res_v.error
          else
            output[res_k.input] = res_v.input
          end
        end

        if failures.empty?
          success(output)
        else
          failure(input, MultipleError.new(failures))
        end
      end
    end
  end
end