class Dry::Schema::Path

def self.[](spec)
  call(spec)
end

def self.call(spec)
  case spec
  when Symbol, Array
    new(Array[*spec])
  when String
    new(spec.split(DOT).map(&:to_sym))
  when Hash
    new(keys_from_hash(spec))
  when Path
    spec
  else
    raise ArgumentError, "+spec+ must be either a Symbol, Array, Hash or a Path"
  end
end

def self.keys_from_hash(hash)
  hash.inject([]) { |a, (k, v)|
    v.is_a?(Hash) ? a.concat([k, *keys_from_hash(v)]) : a.concat([k, v])
  }
end

def &(other)
  unless same_root?(other)
    raise ArgumentError, "#{other.inspect} doesn't have the same root #{inspect}"
  end
  self.class.new(
    key_matches(other, :select).compact.reject { |value| value.equal?(false) }
  )
end

def <=>(other)
  raise ArgumentError, "Can't compare paths from different branches" unless same_root?(other)
  return 0 if keys.eql?(other.keys)
  res = key_matches(other).compact.reject { |value| value.equal?(false) }
  res.size < count ? 1 : -1
end

def each(&block)
  keys.each(&block)
end

def include?(other)
  if !same_root?(other)
    false
  elsif index?
    if other.index?
      last.equal?(other.last)
    else
      without_index.include?(other)
    end
  elsif other.index? && key_matches(other, :select).size < 2
    false
  else
    self >= other && !other.key_matches(self).include?(nil)
  end
end

def index(key)
  keys.index(key)
end

def index?
  last.is_a?(Integer)
end

def initialize(keys)
  @keys = keys
end

def key_matches(other, meth = :map)
  public_send(meth) { |key| (idx = other.index(key)) && keys[idx].equal?(key) }
end

def last
  keys.last
end

def same_root?(other)
  root.equal?(other.root)
end

def to_h(value = EMPTY_ARRAY.dup)
  curr_idx = 0
  last_idx = keys.size - 1
  hash = EMPTY_HASH.dup
  node = hash
  while curr_idx <= last_idx
    node =
      node[keys[curr_idx]] =
        if curr_idx == last_idx
          value.is_a?(Array) ? value : [value]
        else
          EMPTY_HASH.dup
        end
    curr_idx += 1
  end
  hash
end

def without_index
  self.class.new(to_a[0..-2])
end