module Stripe
  class StripeObject
    include Enumerable

    @@permanent_attributes = Set.new([:id])

    # The default :id method is deprecated and isn't useful to us
    if method_defined?(:id)
      undef :id
    end

    def initialize(id=nil, opts={})
      # parameter overloading!
      if id.kind_of?(Hash)
        @retrieve_params = id.dup
        @retrieve_params.delete(:id)
        id = id[:id]
      else
        @retrieve_params = {}
      end

      @opts = opts
      @values = {}
      # This really belongs in APIResource, but not putting it there allows us
      # to have a unified inspect method
      @unsaved_values = Set.new
      @transient_values = Set.new
      @values[:id] = id if id
    end

    def self.construct_from(values, opts={})
      self.new(values[:id]).refresh_from(values, opts)
    end

    def to_s(*args)
      JSON.pretty_generate(@values)
    end

    def inspect
      id_string = (self.respond_to?(:id) && !self.id.nil?) ? " id=#{self.id}" : ""
      "#<#{self.class}:0x#{self.object_id.to_s(16)}#{id_string}> JSON: " + JSON.pretty_generate(@values)
    end

    def refresh_from(values, opts, partial=false)
      @opts = opts
      @original_values = Marshal.load(Marshal.dump(values)) # deep copy
      removed = partial ? Set.new : Set.new(@values.keys - values.keys)
      added = Set.new(values.keys - @values.keys)
      # Wipe old state before setting new.  This is useful for e.g. updating a
      # customer, where there is no persistent card parameter.  Mark those values
      # which don't persist as transient

      instance_eval do
        remove_accessors(removed)
        add_accessors(added)
      end
      removed.each do |k|
        @values.delete(k)
        @transient_values.add(k)
        @unsaved_values.delete(k)
      end
      values.each do |k, v|
        @values[k] = Util.convert_to_stripe_object(v, @opts)
        @transient_values.delete(k)
        @unsaved_values.delete(k)
      end

      return self
    end

    def [](k)
      @values[k.to_sym]
    end

    def []=(k, v)
      send(:"#{k}=", v)
    end

    def keys
      @values.keys
    end

    def values
      @values.values
    end

    def to_json(*a)
      JSON.generate(@values)
    end

    def as_json(*a)
      @values.as_json(*a)
    end

    def to_hash
      @values.inject({}) do |acc, (key, value)|
        acc[key] = value.respond_to?(:to_hash) ? value.to_hash : value
        acc
      end
    end

    def each(&blk)
      @values.each(&blk)
    end

    def _dump(level)
      Marshal.dump([@values, @opts])
    end

    def self._load(args)
      values, opts = Marshal.load(args)
      construct_from(values, opts)
    end

    if RUBY_VERSION < '1.9.2'
      def respond_to?(symbol)
        @values.has_key?(symbol) || super
      end
    end

    def serialize_nested_object(key)
      new_value = @values[key]
      if new_value.is_a?(APIResource)
        return {}
      end

      if @unsaved_values.include?(key)
        # the object has been reassigned
        # e.g. as object.key = {foo => bar}
        update = new_value
        new_keys = update.keys.map(&:to_sym)

        # remove keys at the server, but not known locally
        if @original_values.include?(key)
          keys_to_unset = @original_values[key].keys - new_keys
          keys_to_unset.each {|key| update[key] = ''}
        end

        update
      else
        # can be serialized normally
        self.class.serialize_params(new_value)
      end
    end

    def self.serialize_params(obj, original_value=nil)
      case obj
      when nil
        ''
      when StripeObject
        unsaved_keys = obj.instance_variable_get(:@unsaved_values)
        obj_values = obj.instance_variable_get(:@values)
        update_hash = {}

        unsaved_keys.each do |k|
          update_hash[k] = serialize_params(obj_values[k])
        end

        obj_values.each do |k, v|
          if v.is_a?(StripeObject) || v.is_a?(Hash)
            update_hash[k] = obj.serialize_nested_object(k)
          elsif v.is_a?(Array)
            original_value = obj.instance_variable_get(:@original_values)[k]
            if original_value && original_value.length > v.length
              # url params provide no mechanism for deleting an item in an array,
              # just overwriting the whole array or adding new items. So let's not
              # allow deleting without a full overwrite until we have a solution.
              raise ArgumentError.new(
                "You cannot delete an item from an array, you must instead set a new array"
              )
            end
            update_hash[k] = serialize_params(v, original_value)
          end
        end

        update_hash
      when Array
        update_hash = {}
        obj.each_with_index do |value, index|
          update = serialize_params(value)
          if update != {} && (!original_value || update != original_value[index])
            update_hash[index] = update
          end
        end

        if update_hash == {}
          nil
        else
          update_hash
        end
      else
        obj
      end
    end

    protected

    def metaclass
      class << self; self; end
    end

    def remove_accessors(keys)
      metaclass.instance_eval do
        keys.each do |k|
          next if @@permanent_attributes.include?(k)
          k_eq = :"#{k}="
          remove_method(k) if method_defined?(k)
          remove_method(k_eq) if method_defined?(k_eq)
        end
      end
    end

    def add_accessors(keys)
      metaclass.instance_eval do
        keys.each do |k|
          next if @@permanent_attributes.include?(k)
          k_eq = :"#{k}="
          define_method(k) { @values[k] }
          define_method(k_eq) do |v|
            if v == ""
              raise ArgumentError.new(
                "You cannot set #{k} to an empty string." \
                "We interpret empty strings as nil in requests." \
                "You may set #{self}.#{k} = nil to delete the property.")
            end
            @values[k] = v
            @unsaved_values.add(k)
          end
        end
      end
    end

    def method_missing(name, *args)
      # TODO: only allow setting in updateable classes.
      if name.to_s.end_with?('=')
        attr = name.to_s[0...-1].to_sym
        add_accessors([attr])
        begin
          mth = method(name)
        rescue NameError
          raise NoMethodError.new("Cannot set #{attr} on this object. HINT: you can't set: #{@@permanent_attributes.to_a.join(', ')}")
        end
        return mth.call(args[0])
      else
        return @values[name] if @values.has_key?(name)
      end

      begin
        super
      rescue NoMethodError => e
        if @transient_values.include?(name)
          raise NoMethodError.new(e.message + ".  HINT: The '#{name}' attribute was set in the past, however.  It was then wiped when refreshing the object with the result returned by Stripe's API, probably as a result of a save().  The attributes currently available on this object are: #{@values.keys.join(', ')}")
        else
          raise
        end
      end
    end

    def respond_to_missing?(symbol, include_private = false)
      @values && @values.has_key?(symbol) || super
    end
  end
end