require_relative 'helpers'

module Tickethub
  class Collection < Enumerator
    attr_accessor :cache
    attr_reader :count, :endpoint

    def initialize(endpoint, klass, params = {})
      @params = params.dup
      @endpoint = endpoint
      @klass = klass

      klass.registered_types.each do |type, options|
        define_singleton_method type do
          instance_variable_defined?("@#{type}") ? instance_variable_get("@#{type}") :
            instance_variable_set("@#{type}", Tickethub::Collection.new(@endpoint[type], options[:klass]))
        end
      end

      klass.scopes.each do |key, block|
        define_singleton_method key, &block
      end

      super() do |yielder|
        self.reload! if @cache.nil?

        @cache.each do |row|
          yielder << @klass.load(@endpoint, row)
        end

        while (@offset + @cache.length) < @count
          response = @endpoint.get @params.merge(offset: @cache.length)
          response.decoded.each do |row| @cache << row
            yielder << @klass.load(@endpoint, row)
          end
        end
      end
    end

    def reload!
      @cache = (response = @endpoint.get @params).decoded
      @count, @offset, @limit =
        response.status == 206 ? 
          response.headers.values_at(*%w(x-total-count x-offset x-limit))
            .collect { |value| value[0].to_i } : [@cache.length, 0, @cache.length]
    end

    def last
      offset(count - 1).first
    end

    def limit(value = nil)
      if value.nil?
        reload! if @limit.nil?
        return @limit
      else
        self.class.new @endpoint, @klass,
          @params.merge(limit: value)
      end
    end

    def offset(value = nil)
      if value.nil?
        reload! if @offset.nil?
        return @offset
      else
        self.class.new @endpoint, @klass,
          @params.merge(offset: value)
      end
    end

    def filter(value)
      self.class.new @endpoint, @klass,
        @params.merge(filters: (@params[:filters] || {}).merge(value))
    end

    def filters
      @params[:filters].dup
    end

    def order(value = nil)
      return @params[:order].dup if value.nil?
      order = (@params[:order] || []) + (case value
        when Symbol, String then [value.to_s]
        when Hash
          value.collect do |key, direction|
            direction.to_s == 'desc' ? "-#{key}" : key
          end
        end)

      self.class.new @endpoint, @klass,
        @params.merge(order: order)
    end

    [:get, :post, :patch, :delete].each do |key|
      define_method key do |path, params = {}, options = {}|
        endpoint = (if path.is_a? Hash
          params, options = [path, params]
          self.endpoint
        else self.endpoint[path] end)

        if (response = endpoint.send(key, @params.merge(params), options)).body.length > 2
          return response.decoded
        end
      end
    end

    def empty?
      count.zero?
    end

    def any?(&block)
      block_given?? super : ! empty?
    end

    def limit
      self.reload! if @limit.nil?
      return @limit
    end

    def count
      self.reload! if @count.nil?
      return @count
    end

    def [](*args)
      case (key = args[0])
      when Fixnum
        self.offset(key).first
      when Hash
        self.filter(key).first
      when Range
        self.offset(key.min).first(key.max)
      when String
        options = { params: args[1] || {} }.merge args[2] || {}
        @klass.load @klass.endpoint[key, @endpoint[nil, options].options]
      else
        raise ArgumentError, 'invalid search value type'
      end
    end

    def create(attributes = {})
      @klass.load @endpoint, @endpoint.post(attributes).decoded
    rescue Tickethub::ResourceInvalid => err
      @klass.load @endpoint, Tickethub::Response.new(err.response).decoded
    end

    def scope(key, params = {}, options = {})
      Tickethub::Collection.new @endpoint[key, options.merge(params: params)], @klass,
        filters: @filters, order: @order
    end
  end
end