Overhaul availability

Resolves #1501
  - Availability methods all work as expected
  - Adds counter cache on equipment models for current overdue reservations
  - Reservation factory trait :past allows for creation of past
    reservations without skipping validations
  - New reservation model methods for counting reservations, attribute
    checking, and checking for overlapping

app/controllers/application_controller.rb

@@ -246,8 +246,7 @@ def prepare_catalog_index_vars(eq_models = nil)
       # build the hash using class methods that use 0 queries
       @availability_hash[em.id] =
         [EquipmentItem.for_eq_model(em.id, eq_items)\
-        - Reservation.number_overdue_for_eq_model(em.id, source_reservations)\
-        - em.num_reserved(cart.start_date, cart.due_date, source_reservations)\
+        - em.num_busy(cart.start_date, cart.due_date, source_reservations)\
         - cart.items[em.id].to_i, 0].max
 
       # have requirements as part of equipment model itself

app/controllers/equipment_models_controller.rb

@@ -205,31 +205,16 @@ def calendar_name_method
     :reserver
   end
 
-  def calculate_availability # rubocop:disable all
+  def calculate_availability
     # get start and end dates
     @start_date = Time.zone.today.beginning_of_week(:sunday)
     @end_date = (Time.zone.today + 1.month).end_of_week(:sunday)
 
-    reservations =
-      (Reservation.for_eq_model(@equipment_model.id).active
-        .overlaps_with_date_range(@start_date, @end_date) + \
-      Reservation.for_eq_model(@equipment_model).overdue).uniq
     max_avail = @equipment_model.equipment_items.active.count
 
     @avail_data = []
     (@start_date..@end_date).map do |date|
-      count = 0
-      # also hack-y, we need to fix these methods
-      reservations.each do |res|
-        if res.overdue && res.checked_out?
-          count += 1
-        elsif res.start_date <= date && res.due_date >= date
-          count += 1
-        end
-      end
-
-      availability = max_avail - count
-
+      availability = @equipment_model.num_available_on(date)
       # set up colors
       if date < Time.zone.today
         color = '#888'

app/decorators/equipment_item_decorator.rb

@@ -16,7 +16,7 @@ def make_deactivate_btn
       res = object.current_reservation
       overbooked_dates = []
       (Time.zone.today..Time.zone.today + 7.days).each do |date|
-        overbooked_dates << date.to_s(:short) if em.available_count(date) <= 0
+        overbooked_dates << date.to_s(:short) if em.num_available_on(date) <= 0
       end
       onclick_str = "handleDeactivation(this, #{res ? res.id : 'null'}, "\
         "#{overbooked_dates});"

app/models/cart.rb

@@ -31,6 +31,16 @@ def get_items # rubocop:disable AccessorMethodName
     full_hash
   end
 
+  def get_categories # rubocop:disable AccessorMethodName
+    cat_hash = {}
+    ems = EquipmentModel.where(id: items.keys).includes(:category)
+    items.each_with_index do |(_em_id, q), index|
+      cat_hash[ems[index].category] ||= 0
+      cat_hash[ems[index].category] += q
+    end
+    cat_hash
+  end
+
   # Adds equipment model id to items hash
   def add_item(equipment_model, _quantity = nil)
     return if equipment_model.nil?

app/models/cart_validations.rb

@@ -105,49 +105,57 @@ def check_cookie_limit
     errors
   end
 
-  def check_max_items(count_hash, relevant, count_method)
-    # generic method for making sure the count_hash doesn't
-    # contain more than the item max when taking into account
-    # the relevant reservations
-
-    errors = []
-    count_hash.each do |item, q|
-      max = item.maximum_per_user
-
-      start_date.upto(due_date) do |d|
-        unless Reservation.send(count_method, d, item.id, relevant) + q > max
-          next
-        end
-        errors << "Only #{max} #{item.name.pluralize(max)} "\
-          'can be reserved at a time.'
-      end
-    end
-    errors
-  end
-
   def check_max_ems
     # check to make sure that the cart's EMs + the current resever's
     # EMs doesn't exceed any limits
+    # 1 query
+
+    # get reserver's active reservations
+    source = Reservation.active.for_reserver(reserver_id)
 
-    count_hash = get_items
-    relevant = Reservation.for_reserver(reserver_id).active
-               .includes(:equipment_model).all
-    check_max_items(count_hash, relevant, :number_for_model_on_date)
+    errors = []
+    get_items.each do |model, number_in_cart|
+      # get highest number of items reserved in date range of cart
+      valid = Reservation.number_for_date_range(source, start_date..due_date,
+                                                equipment_model_id: model.id,
+                                                overdue: false).max
+      valid ||= 0
+      # count overdue reservations for this eq model
+      overdue = source.count { |r| r.equipment_model == model && r.overdue }
+
+      next unless valid + overdue + number_in_cart > model.maximum_per_user
+
+      max = model.maximum_per_user
+      errors << "Only #{max} #{model.name.pluralize(max)} "\
+        'can be reserved at a time.'
+    end
+    errors
   end
 
   def check_max_cat
     # same but for categories. we need to build the counts of the
     # categories ourselves though
+    # 2 queries
+
+    cat_hash = get_categories
 
-    cat_hash = {}
-    ems = EquipmentModel.where(id: items.keys).includes(:category)
-    items.each_with_index do |(_em_id, q), index|
-      cat_hash[ems[index].category] ||= 0
-      cat_hash[ems[index].category] += q
+    source = Reservation.for_reserver(reserver_id).with_categories.active
+
+    # split overdue and non overdue reservations
+    overdue, source = source.partition(&:overdue)
+
+    errors = []
+    cat_hash.each do |cat, q|
+      max = cat.maximum_per_user
+      s = source.select { |r| r.equipment_model.category == cat }
+      s = Reservation.number_for_date_range(s, start_date..due_date).max
+      s ||= 0
+      o = overdue.count { |r| r.equipment_model.category == cat }
+      next unless s + o + q > max
+      errors << "Only #{max} #{cat.name.pluralize(max)} "\
+        'can be reserved at a time.'
     end
-    relevant = Reservation.for_reserver(reserver_id).active
-               .with_categories.all
-    check_max_items(cat_hash, relevant, :number_for_category_on_date)
+    errors
   end
 
   def check_availability(model = EquipmentModel.find(items.keys.first),
@@ -174,8 +182,7 @@ def check_availability(model = EquipmentModel.find(items.keys.first),
     # 2 queries
 
     errors = []
-    max_available = model.num_available_from_source(start_date, due_date,
-                                                    source_res)
+    max_available = model.num_available(start_date, due_date, source_res)
     return errors unless max_available < quantity
     if max_available == 0
       error = "No #{model.name.pluralize} are"

app/models/equipment_model.rb

@@ -164,70 +164,53 @@ def document_attributes=(document_attributes)
     end
   end
 
-  def num_reserved(start_date, due_date, source_reservations)
-    # get the number reserved in the source reservations
-    # uses 0 queries, you need to specify the max number of
-    # items yourself
-    max_reserved = 0
-    start_date.upto(due_date) do |d|
-      reserved = Reservation.number_for_model_on_date(d, id,
-                                                      source_reservations)
-      max_reserved = reserved if reserved > max_reserved
-    end
-    max_reserved
+  def num_busy(start_date, due_date, source)
+    # get the number busy (not able to be reserved) in the source reservations
+    # uses 0 queries
+    max = Reservation.number_for_date_range(source, start_date..due_date,
+                                            equipment_model_id: id,
+                                            overdue: false).max
+    max ||= 0
+    max + overdue_count
   end
 
-  def num_available_from_source(start_date, due_date, source_reservations)
+  def num_available(start_date, due_date, source = nil)
     # get the number available in the given date range
-    # take an array of reservations instead of using a database call
-    # for database query optimization purposes
-    # 2 queries to calculate max_num
-    max_num = equipment_items.active.count - number_overdue
-    available = max_num - num_reserved(start_date, due_date,
-                                       source_reservations)
-    available < 0 ? 0 : available
-  end
-
-  def num_available(start_date, due_date)
-    # for if you just want the number available, 1 query to get
-    # relevant reservations
-    relevant_reservations = Reservation.for_eq_model(id).active
-                            .overlaps_with_date_range(start_date, due_date)
-                            .all
-    num_available_from_source(start_date, due_date, relevant_reservations)
-  end
-
-  # Returns true if the reserver is ineligible to checkout the model.
-  def model_restricted?(reserver_id)
-    return false if reserver_id.nil?
-    reserver = User.find(reserver_id)
-    !(requirements - reserver.requirements).empty?
-  end
-
-  # Returns the number of overdue objects for a given model,
-  # as long as they have been checked out.
-  def number_overdue
-    Reservation.overdue.for_eq_model(id).size
+    # 1 queries if source given; 2 otherwise
+    #
+    # source is an array of reservations that can replace a database call
+    #   for database query optimization purposes
+    unless source
+      source = reservations.active.overlaps_with_date_range(start_date,
+                                                            due_date)
+    end
+    equipment_items.active.count - num_busy(start_date, due_date, source)
   end
 
-  def available_count(date)
+  def num_available_on(date)
     # get the total number of items of this kind then subtract the total
     # quantity currently reserved, checked-out, and overdue
-    total = equipment_items.active.count
-    reserved = Reservation.reserved_on_date(date).for_eq_model(id).count
-    total - reserved - number_overdue
+    busy = reservations.active.overlaps_with_date_range(date, date).count
+    equipment_items.active.count - busy - overdue_count
   end
 
   # figure out the qualitative status of this model's items
   def availability(date)
-    num = available_count(date)
+    num = num_available_on(date)
     total = equipment_items.active.count
-    if num == 0 then 'none'
+    if num <= 0 then 'none'
     elsif num == total then 'all'
     else 'some'
     end
   end
 
+  # Returns true if the reserver is ineligible to checkout the model.
+  def model_restricted?(reserver_id)
+    return false if reserver_id.nil?
+    reserver = User.find(reserver_id)
+    !(requirements - reserver.requirements).empty?
+  end
+
   def available_item_select_options
     equipment_items.includes(:reservations).active.select(&:available?)\
       .sort_by(&:name)\