# typed: strict
# frozen_string_literal: true

class Hash
  # Returns a new hash with `self` and `other_hash` merged recursively.
  #
  # ### Examples
  #
  # ```ruby
  # h1 = { a: true, b: { c: [1, 2, 3] } }
  # h2 = { a: false, b: { x: [3, 4, 5] } }
  #
  # h1.deep_merge(h2) # => { a: false, b: { c: [1, 2, 3], x: [3, 4, 5] } }
  # ```
  #
  # Like with Hash#merge in the standard library, a block can be provided
  # to merge values:
  #
  # ```ruby
  # h1 = { a: 100, b: 200, c: { c1: 100 } }
  # h2 = { b: 250, c: { c1: 200 } }
  # h1.deep_merge(h2) { |key, this_val, other_val| this_val + other_val }
  # # => { a: 100, b: 450, c: { c1: 300 } }
  # ```
  def deep_merge(other_hash, &block)
    dup.deep_merge!(other_hash, &block)
  end

  # Same as {#deep_merge}, but modifies `self`.
  def deep_merge!(other_hash, &block)
    merge!(other_hash) do |key, this_val, other_val|
      if T.unsafe(this_val).is_a?(Hash) && other_val.is_a?(Hash)
        T.unsafe(this_val).deep_merge(other_val, &block)
      elsif block
        yield(key, this_val, other_val)
      else
        other_val
      end
    end
  end
end
