require 'base64'
require 'ably/modules/conversions'
require 'ably/modules/message_pack'

module Ably::Modules
  # Common model functionality shared across many {Ably::Models}
  module ModelCommon
    include Conversions
    include MessagePack

    # Provide a normal Hash accessor to the underlying raw message object
    #
    # @return [Object]
    def [](key)
      attributes[key]
    end

    def ==(other)
      other.kind_of?(self.class) &&
        attributes == other.attributes
    end

    # Return a JSON ready object from the underlying #attributes using Ably naming conventions for keys
    # @return [Hash]
    def as_json
      attributes.as_json.reject { |key, val| val.nil? }
    end

    # Stringify the JSON representation of this object from the underlying #attributes
    # @return [String]
    def to_json(*args)
      as_json.to_json(*args)
    end

    # Like to_json but encodes all binary fields to hex
    def to_safe_json(*args)
      as_json.
        each_with_object({}) do |(key, val), obj|
          obj[key] = to_safe_jsonable_val(val)
        end.to_json(*args)
    end

    # @!attribute [r] hash
    # @return [Integer] Compute a hash-code for this hash. Two hashes with the same content will have the same hash code
    def hash
      attributes.hash
    end

    private
    def to_safe_jsonable_val(val)
      case val
      when Array
        val.map { |array_val| to_safe_jsonable_val(array_val) }
      when Hash
        val.each_with_object({}) { |(key, hash_val), obj| obj[key] = to_safe_jsonable_val(hash_val) }
      when String
        if val.encoding == Encoding::ASCII_8BIT
          val.unpack("H*").first
        else
          val
        end
      else
        val
      end
    end

    def ensure_utf8_string_for(attribute, value)
      if value
        raise ArgumentError, "#{attribute} must be a String" unless value.kind_of?(String)
        raise ArgumentError, "#{attribute} cannot use ASCII_8BIT encoding, please use UTF_8 encoding" unless value.encoding == Encoding::UTF_8
      end
    end
  end
end