Cargo selection planning now works.

src/the_great_game/merchants/merchants.clj

@@ -1,7 +1,7 @@
 (ns the-great-game.merchants.merchants
   "Trade planning for merchants, primarily."
   (:require [the-great-game.world.routes :refer [find-routes]]
-            [the-great-game.world.world :refer [actual-price]]))
+            [the-great-game.world.world :refer [actual-price default-world]]))
 
 
 (defn expected-price
@@ -36,7 +36,87 @@
         (keys cargo)))))
 
 
-(defn find-trade-plan
+(defn make-target-filter
+  "Construct a filter which, when applied to a list of maps,
+  will pass those which match these `targets`, where each target
+  is a tuple [key value]."
+  ;; TODO: this would probably be more elegant as a macro
+  [targets]
+  (eval
+    (list
+      'fn
+      (vector 'plan)
+      (cons
+        'and
+        (map
+          #(list
+             '=
+             (list (first %) 'plan)
+             (nth % 1))
+          targets)))))
+
+
+(defn generate-trade-plans
+  "Generate all possible trade plans for this `merchant` and this `commodity`
+  in this `world`.
+
+  Returned plans are maps with keys:
+
+* :merchant - the id of the `merchant` for whom the plan was created;
+* :origin - the city from which the trade starts;
+* :destination - the city to which the trade is planned;
+* :commodity - the `commodity` to be carried;
+* :buy-price - the price at which that `commodity` can be bought;
+* :expected-price - the price at which the `merchant` anticipates
+      that `commodity` can be sold;
+* :distance - the number of stages in the planned journey
+* :dist-to-home - the distance from `destination` to the `merchant`'s
+      home city."
+  [merchant world commodity]
+  (let [m (cond
+            (keyword? merchant)
+            (-> world :merchants merchant)
+            (map? merchant)
+            merchant)
+        origin (-> m :location)]
+    (map
+      #(hash-map
+         :merchant (-> m :id)
+         :origin origin
+         :destination %
+         :commodity commodity
+         :buy-price (actual-price world commodity origin)
+         :expected-price (expected-price
+                           m
+                           commodity
+                           %)
+         :distance (count
+                     (first
+                       (find-routes (:routes world) origin %)))
+         :dist-to-home (count
+                         (first
+                           (find-routes
+                             (:routes world)
+                             (:home m)
+                             %)))
+         )
+      (remove #(= % origin) (keys (-> world :cities))))))
+
+(defn nearest-with-targets
+  "Return the distance to the nearest destination among those of these
+  `plans` which match these `targets`. Plans are expected to be plans
+  as returned by `generate-trade-plans`, q.v.; `targets` are expected to be
+  as accepted by `make-target-filter`, q.v."
+  [plans targets]
+  (apply
+    min
+    (map
+      :distance
+      (filter
+        (make-target-filter targets)
+        plans))))
+
+(defn plan-trade
   "Find the best destination in this `world` for this `commodity` given this
   `merchant` and this `origin`. If two cities are anticipated to offer the
   same price, the nearer should be preferred; if two are equally distant, the
@@ -56,47 +136,51 @@
   * :distance - the number of stages in the planned journey
   * :dist-to-home - the distance from `destination` to the `merchant`'s
   home city."
+  [merchant world commodity]
+  (let [plans (generate-trade-plans merchant world commodity)
+        best-prices (filter
+                      (make-target-filter
+                        [[:expected-price
+                          (apply
+                            max
+                            (filter number? (map :expected-price plans)))]])
+                      plans)]
+    (first
+      (sort-by
+        ;; all other things being equal, a merchant would prefer to end closer
+        ;; to home.
+        #(- 0 (:dist-to-home %))
+        ;; a merchant will seek the best price, but won't go further than
+        ;; needed to get it.
+        (filter
+          (make-target-filter
+            [[:distance
+              (apply min (filter number? (map :distance best-prices)))]])
+          best-prices)))))
+
+
+(defn can-carry
+  [merchant world commodity]
+  (let [m (cond
+            (keyword? merchant)
+            (-> world :merchants merchant)
+            (map? merchant)
+            merchant)]
+    (quot
+      (- (:capacity m) (burden m world))
+      (-> world :commodities commodity :weight))))
+
+(defn can-afford
   [merchant world commodity]
   (let [m (cond
             (keyword? merchant)
             (-> world :merchants merchant)
             (map? merchant)
             merchant)
-        origin (-> m :location)
+        l (:location m)]
-        destinations (remove #(= % origin) (keys (-> world :cities)))
+    (quot
-        plans (map
+      (-> m :cash)
-                 #(hash-map
+      (-> world :cities l :prices commodity))))
-                    :merchant (-> m :id)
-                    :origin origin
-                    :destination %
-                    :commodity commodity
-                    :buy-price (actual-price world commodity origin)
-                    :expected-price (expected-price
-                                      merchant
-                                      commodity
-                                      %)
-                    :distance (count
-                                (first
-                                  (find-routes (:routes world) origin %)))
-                    :dist-to-home (count
-                                    (first
-                                      (find-routes
-                                        (:routes world)
-                                        (-> world :merchants merchant :home)
-                                        %)))
-                    )
-                 destinations)
-        best-price (apply min (filter number? (map :expected-price plans)))
-        nearest (apply min (map :distance plans))]
-    (first
-      (sort
-        #(compare (:dist-to-home %1) (:dist-to-home %2))
-        (filter
-          #(and
-             (= (:expected-price %) best-price)
-             (= (:distance %) nearest))
-          plans)))))
-
 
 (defn augment-plan
   "Augment this `plan` constructed in this `world` for this `merchant` with
@@ -105,22 +189,21 @@
 
   Returns the augmented plan."
   [merchant world plan]
-  (let [m (cond
+  (let [c (:commodity plan)
-            (keyword? merchant)
+        o (:origin plan)
-            (-> world :merchants merchant)
+        q (min
-            (map? merchant)
+            (or
-            merchant)
+              (-> world :cities o :stock c)
-        available (-> world :cities (:origin plan) :stock (:commodity plan))
+              0)
-        can-carry (quot
+            (can-carry merchant world c)
-                    (- (-> m :capacity) (burden m world))
+            (can-afford merchant world c))
-                    (-> world :commodities (:commodity plan) :weight))
-        can-afford (quot
-                     (-> merchant :cash)
-                     (-> world :commodities (:commodity plan) :weight))
-        q (min available can-carry can-afford)
         p (* q (- (:expected-price plan) (:buy-price plan)))]
     (assoc plan :quantity q :expected-profit p)))
 
+;; (-> default-world :cities :buckie :stock :iron)
+;; (burden :fiona default-world)
+;; (-> default-world :commodities :iron :weight)
+;; (quot 0 10)
 
 (defn select-cargo
   "A `merchant`, in a given location in a `world`, will choose to buy a cargo
@@ -138,19 +221,17 @@
                 #(augment-plan
                    m
                    world
-                   (find-trade-plan m world %))
+                   (plan-trade m world %))
                 (filter
                   #(let [q (-> world :cities origin :stock %)]
                      (and (number? q) (> q 0)))
-                  (keys available)))
+                  (keys available)))]
-        best-profit (apply min (filter number? (map :expected-profit plans)))
-        nearest (apply min (map :distance plans))]
     (first
-      (sort
+      (sort-by
-        #(compare (:dist-to-home %1) (:dist-to-home %2))
+        #(- 0 (:dist-to-home %))
         (filter
-          #(and
+          (make-target-filter
-             (= (:expected-profit %) best-profit)
+            [[:expected-profit
-             (= (:distance %) nearest))
+              (apply max (filter number? (map :expected-profit plans)))]])
          plans)))))
 

src/the_great_game/world/world.clj

@@ -24,7 +24,7 @@
      ;; the end of each game day.
      {:iron 1
       :cloth 10
-      :tobacco 10}
+      :whisky 10}
      :port true
      :prices
      ;; `prices`: the current price (both buying and selling, for simplicity)
@@ -34,7 +34,7 @@
       :fish 1
       :leather 1
       :iron 1
-      :tobacco 1}
+      :whisky 1}
      :stock
      ;; `stock` is the quantity of each commodity in the market at any
      ;; given time. It is adjusted for production and consumption at
@@ -43,7 +43,7 @@
       :fish 0
       :leather 0
       :iron 0
-      :tobacco 0}
+      :whisky 0}
      :cash 100}
     :buckie
     {:id :buckie
@@ -52,19 +52,19 @@
      :demands
      {:cloth 5
       :leather 3
-      :tobacco 5
+      :whisky 5
       :iron 1}
      :port true
      :prices {:cloth 1
               :fish 1
               :leather 1
               :iron 1
-              :tobacco 1}
+              :whisky 1}
      :stock {:cloth 0
              :fish 0
              :leather 0
              :iron 0
-             :tobacco 0}
+             :whisky 0}
      :cash 100}
     :callander
     {:id :callander
@@ -72,18 +72,18 @@
      :demands
      {:cloth 5
       :fish 3
-      :tobacco 5
+      :whisky 5
       :iron 1}
      :prices {:cloth 1
               :fish 1
               :leather 1
               :iron 1
-              :tobacco 1}
+              :whisky 1}
      :stock {:cloth 0
              :fish 0
              :leather 0
              :iron 0
-             :tobacco 0}
+             :whisky 0}
      :cash 100}
     :dundee {:id :dundee}
     :edinburgh {:id :dundee}
@@ -93,23 +93,23 @@
      :demands
      {:cloth 5
       :leather 3
-      :tobacco 5
+      :whisky 5
       :fish 10}
      :port true
      :prices {:cloth 1
               :fish 1
               :leather 1
               :iron 1
-              :tobacco 1}
+              :whisky 1}
      :stock {:cloth 0
              :fish 0
              :leather 0
              :iron 0
-             :tobacco 0}
+             :whisky 0}
      :cash 100}
     :glasgow
     {:id :glasgow
-     :supplies {:tobacco 10}
+     :supplies {:whisky 10}
      :demands
      {:cloth 5
       :leather 3
@@ -120,12 +120,12 @@
               :fish 1
               :leather 1
               :iron 1
-              :tobacco 1}
+              :whisky 1}
      :stock {:cloth 0
              :fish 0
              :leather 0
              :iron 0
-             :tobacco 0}
+             :whisky 0}
      :cash 100}}
    :merchants
    {:archie {:id :archie
@@ -171,7 +171,7 @@
    {:cloth {:id :cloth :cost 1 :weight 0.25}
     :fish {:id :fish :cost 1 :weight 1}
     :leather {:id :leather :cost 1 :weight 0.5}
-    :tobacco {:id :tobacco :cost 1 :weight 0.1}
+    :whisky {:id :whisky :cost 1 :weight 0.1}
     :iron {:id :iron :cost 1 :weight 10}}})
 
 (defn actual-price

test/the_great_game/merchants/merchants_test.clj

@@ -21,3 +21,89 @@
       (let [actual (expected-price (-> world :merchants :archie) :iron :buckie)
             expected 1.7] ;;
         (is (= actual expected) "if information select the most recent")))))
+
+(deftest plan-trade-test
+  (testing "Lower level trade planning"
+    (let [world (deep-merge
+                  default-world
+                  {:merchants
+                   {:fiona
+                    {:known-prices
+                     {:aberdeen
+                      {:iron
+                       [{:price 1.5 :date 1}
+                        {:price 1.3 :date 0}]}
+                      :buckie
+                      {:iron
+                       [{:price 1.7 :date 1}
+                        {:price 2 :date 0}]}}}}
+                   :cities
+                   {:falkirk
+                    {:stock {:iron 20}}}})
+          actual (plan-trade :fiona world :iron)]
+      (is (= (:origin actual) :falkirk)
+          "Fiona is in Falkirk, so her plan must originate there")
+      (is (= (:commodity actual) :iron)
+          "Iron is the only thing available in Falkirk, so plan must carry iron")
+      (is (= (:destination actual) :buckie)
+          "Fiona believes Buckie offers the best price for iron, so should go there"))))
+
+
+(deftest select-cargo-test
+  (testing "Top level single trade planning: single candidate commodity"
+    (let [world (deep-merge
+                  default-world
+                  {:merchants
+                   {:fiona
+                    {:known-prices
+                     {:aberdeen
+                      {:iron
+                       [{:price 1.5 :date 1}
+                        {:price 1.3 :date 0}]}
+                      :buckie
+                      {:iron
+                       [{:price 1.7 :date 1}
+                        {:price 2 :date 0}]}}}}
+                   :cities
+                   {:falkirk
+                    {:stock {:iron 20}}}})
+          actual (select-cargo :fiona world)]
+      (is (= (:origin actual) :falkirk)
+          "Fiona is in Falkirk, so her plan must originate there")
+      (is (= (:commodity actual) :iron)
+          "Iron is the only thing available in Falkirk, so plan must carry iron")
+      (is (= (:destination actual) :buckie)
+          "Fiona believes Buckie offers the best price for iron, so should go there")
+      (is (= (:quantity actual) 1)
+          "Fiona can carry only one unit of iron.")
+      (is (= (:expected-profit actual) 0.7))))
+  (testing "Top level single trade planning: multiple candidate commodities"
+    (let [world (deep-merge
+                  default-world
+                  {:merchants
+                   {:fiona
+                    {:known-prices
+                     {:aberdeen
+                      {:iron
+                       [{:price 1.5 :date 1}
+                        {:price 1.3 :date 0}]
+                       :whisky [{:price 4 :date 0}]}
+                      :buckie
+                      {:iron
+                       [{:price 1.7 :date 1}
+                        {:price 2 :date 0}]}}}}
+                   :cities
+                   {:falkirk
+                    {:stock
+                     {:iron 20
+                      :whisky 50}}}})
+          actual (select-cargo :fiona world)]
+      (is (= (:origin actual) :falkirk)
+          "Fiona is in Falkirk, so her plan must originate there")
+      (is (= (:commodity actual) :whisky)
+          "Whisky has the higher profit, so plan must carry whisky")
+      (is (= (:destination actual) :aberdeen)
+          "Fiona believes Aberdeen offers the best price for whisky, so should go there")
+      (is (= (:quantity actual) 50)
+          "Fiona can carry 100 units of whisky, but only 50 are available.")
+      (is (= (:expected-profit actual) 150)))))