[MLv2] Introduce swap-clauses to reorder aggregations, etc. (#39850)

This includes some generative testing, since that felt like
a great way to try all kinds of permutations of swapping clauses.

This also patches `metabase.types/assignable?` to memoize it.
Deeply nested `assignable?` calls made 100 tests of swapping
filters take 1600ms rather than the 50-60ms of the other clauses.

I think this is safe and reasonable on memory to cache forever,
but speak up if you're concerned. There's perhaps O(60) type
keywords, so `type X type -> Boolean` is a small space impact.

Fixes #39215.

src/metabase/lib/core.cljc

@@ -33,6 +33,7 @@
    [metabase.lib.remove-replace :as lib.remove-replace]
    [metabase.lib.segment :as lib.segment]
    [metabase.lib.stage :as lib.stage]
+   [metabase.lib.swap :as lib.swap]
    [metabase.lib.table :as lib.table]
    [metabase.lib.temporal-bucket :as lib.temporal-bucket]
    [metabase.lib.util :as lib.util]
@@ -292,6 +293,8 @@
   drop-stage
   drop-empty-stages
   has-clauses?]
+ [lib.swap
+  swap-clauses]
  [lib.temporal-bucket
   describe-temporal-unit
   describe-temporal-interval

src/metabase/lib/js.cljs

@@ -345,6 +345,17 @@
    (lib.core/normalize (js->clj target-clause :keywordize-keys true))
    (lib.core/normalize (js->clj new-clause :keywordize-keys true))))
 
+(defn ^:export swap-clauses
+  "Exchanges the positions of two clauses in a list. Can be used for filters, aggregations, breakouts, and expressions.
+
+  Returns the updated query. If it can't find both clauses in a single list (therefore also in the same stage), emits a
+  warning and returns the query unchanged."
+  [a-query stage-number source-clause target-clause]
+  (lib.core/swap-clauses
+   a-query stage-number
+   (lib.core/normalize (js->clj source-clause :keywordize-keys true))
+   (lib.core/normalize (js->clj target-clause :keywordize-keys true))))
+
 (defn- prep-query-for-equals [a-query field-ids]
   (-> a-query
       mbql.js/normalize-cljs

src/metabase/lib/swap.cljc

@@ -0,0 +1,44 @@
+(ns metabase.lib.swap
+  (:require
+   [metabase.lib.options :as lib.options]
+   [metabase.lib.util :as lib.util]
+   [metabase.util.log :as log]))
+
+(defn- swap-failure-no-match [stage target-clause]
+  (log/warn "No matching clause in swap-clauses" target-clause stage))
+
+(defn- swap-failure-ambiguous [target-clause matches]
+  (log/warn "Ambiguous match for clause in swap-clauses" target-clause matches))
+
+(defn- uuid-match [stage target-clause]
+  (let [target-uuid (lib.options/uuid target-clause)
+        matches     (for [root  [:aggregation :breakout :expressions :filters :order-by]
+                          index (range (count (get stage root)))
+                          :let [path   [root index]
+                                clause (get-in stage path)]
+                          :when (= (lib.options/uuid clause) target-uuid)]
+                      path)]
+    (case (count matches)
+      1 (first matches)
+      0 (swap-failure-no-match stage target-clause)
+      (swap-failure-ambiguous target-clause matches))))
+
+(defn- do-swap [stage source-path target-path source-clause target-clause]
+  (-> stage
+      (assoc-in source-path target-clause)
+      (assoc-in target-path source-clause)))
+
+(defn swap-clauses
+  "Given a `query` and `stage-number`, and two clauses, swaps the position of these two clauses in a list of clauses on
+  this stage. Can be used to reorder clauses in the UI.
+
+  Returns the query with the two clauses exchanged.
+
+  If either clause is not found inside the same list, emits a warning and returns the query unchanged."
+  [query stage-number source-clause target-clause]
+  (let [stage       (lib.util/query-stage query stage-number)
+        source-path (uuid-match stage source-clause)
+        target-path (uuid-match stage target-clause)]
+    (if (and source-path target-path)
+      (lib.util/update-query-stage query stage-number do-swap source-path target-path source-clause target-clause)
+      query)))

src/metabase/types.cljc

@@ -356,16 +356,20 @@
 
 (declare-assignable :type/Integer :type/Decimal)
 
-(defn assignable?
+(declare assignable?)
+
+(defn- assignable?* [x y]
+  (or (isa? assignable-hierarchy x y)
+      (boolean (some #(assignable? x %) (descendants y)))
+      (boolean (some #(assignable? % y) (parents x)))))
+
+(def assignable?
   "Is a value of type `x` assignable to a variable of type `y`?
 
   When deciding assignability, We also consider the type hierarchy.
   If x is assignable to z and z is a y, then x is also assignable to y.
   Also, if z is assignable to y and x is an z, then x is assignable to y."
-  [x y]
-  (or (isa? assignable-hierarchy x y)
-      (boolean (some #(assignable? x %) (descendants y)))
-      (boolean (some #(assignable? % y) (parents x)))))
+  (memoize assignable?*))
 
 (defn- most-specific-common-ancestor*
   "Impl for [[most-specific-common-ancestor]]."

test/metabase/lib/swap_test.cljc

@@ -0,0 +1,114 @@
+(ns metabase.lib.swap-test
+  (:require
+   [clojure.test :refer [deftest is testing]]
+   [clojure.test.check.clojure-test :refer [defspec]]
+   [clojure.test.check.generators :as gen]
+   [clojure.test.check.properties :as prop]
+   [medley.core :as m]
+   [metabase.lib.core :as lib]
+   [metabase.lib.options :as lib.options]
+   [metabase.lib.test-metadata :as meta]
+   [metabase.test.util.log :as tu.log]
+   #?@(:cljs ([metabase.test-runner.assert-exprs.approximately-equal]))))
+
+#?(:cljs (comment metabase.test-runner.assert-exprs.approximately-equal/keep-me))
+
+(defn- swapped-clauses-prop [clause-fn clause-key query]
+  (prop/for-all*
+    [(gen/elements (clause-fn query))
+     (gen/elements (clause-fn query))]
+    (fn [source-clause target-clause]
+      (or (= source-clause target-clause) ; Skip any case where we happened to draw the same one twice.
+          (let [swapped (lib/swap-clauses query -1 source-clause target-clause)]
+            (and ;; Correctly rearranged the clauses.
+                 (= (for [clause (clause-fn query)]
+                      (cond
+                        (= source-clause clause) target-clause
+                        (= target-clause clause) source-clause
+                        :else                    clause))
+                    (clause-fn swapped))
+                 ;; And didn't change anything else.
+                 (= (m/dissoc-in query   [:stages 0 clause-key])
+                    (m/dissoc-in swapped [:stages 0 clause-key]))))))))
+
+(defspec swap-clauses-on-aggregations-test-permutations
+  (swapped-clauses-prop
+    lib/aggregations :aggregation
+    (-> (lib/query meta/metadata-provider (meta/table-metadata :orders))
+        (lib/aggregate (lib/count))
+        (lib/aggregate (lib/sum (meta/field-metadata :orders :subtotal)))
+        (lib/aggregate (lib/avg (meta/field-metadata :orders :discount)))
+        (lib/aggregate (lib/max (meta/field-metadata :orders :tax)))
+        (lib/aggregate (lib/min (meta/field-metadata :orders :total))))))
+
+(defspec swap-clauses-on-breakouts-test-permutations 300 ; Extra tests to hit the similar cases all the time!
+  (swapped-clauses-prop
+    lib/breakouts :breakout
+    (as-> (lib/query meta/metadata-provider (meta/table-metadata :orders)) $q
+      (lib/breakout $q (meta/field-metadata :products :category))
+      (lib/breakout $q (meta/field-metadata :people :source))
+      ;; Deliberately including the same field three times: without binning, and with two different binning settings.
+      (lib/breakout $q (meta/field-metadata :orders :subtotal))
+      (lib/breakout $q (lib/with-binning
+                         (meta/field-metadata :orders :subtotal)
+                         (second (lib/available-binning-strategies $q (meta/field-metadata :orders :subtotal)))))
+      (lib/breakout $q (lib/with-binning
+                         (meta/field-metadata :orders :subtotal)
+                         (nth (lib/available-binning-strategies $q (meta/field-metadata :orders :subtotal))
+                              2)))
+      ;; Likewise including multiple temporal buckets.
+      (lib/breakout $q (lib/with-temporal-bucket (meta/field-metadata :orders :created-at) :month))
+      (lib/breakout $q (lib/with-temporal-bucket (meta/field-metadata :orders :created-at) :year)))))
+
+(defspec swap-clauses-on-filters-test-permutations
+  (swapped-clauses-prop
+    lib/filters :filters
+    (-> (lib/query meta/metadata-provider (meta/table-metadata :orders))
+        (lib/filter (lib/= (meta/field-metadata :products :category) "Doohickey"))
+        (lib/filter (lib/< (meta/field-metadata :products :created-at) "2024-01-01T00:00:00"))
+        (lib/filter (lib/is-null (meta/field-metadata :orders :discount)))
+        (lib/filter (lib/!= (meta/field-metadata :people :source) "Facebook")))))
+
+(defspec swap-clauses-on-expressions-test-permutations
+  (swapped-clauses-prop
+    lib/expressions :expressions
+    (-> (lib/query meta/metadata-provider (meta/table-metadata :orders))
+        (lib/expression "clean-discount" (lib/coalesce (meta/field-metadata :orders :discount) 0))
+        (lib/expression "discount fraction" (lib// (meta/field-metadata :orders :discount)
+                                                   (meta/field-metadata :orders :subtotal)))
+        (lib/expression "order month" (lib/get-month (meta/field-metadata :orders :created-at)))
+        (lib/expression "signup year" (lib/get-year  (meta/field-metadata :people :created-at))))))
+
+(defspec swap-clauses-on-order-by-test-permutations
+  (swapped-clauses-prop
+    lib/order-bys :order-by
+    (-> (lib/query meta/metadata-provider (meta/table-metadata :orders))
+        (lib/order-by (meta/field-metadata :products :category))
+        (lib/order-by (meta/field-metadata :orders :subtotal) :desc)
+        (lib/order-by (meta/field-metadata :people :latitude) :asc)
+        (lib/order-by (meta/field-metadata :orders :tax) :asc)
+        (lib/order-by (meta/field-metadata :orders :discount) :desc))))
+
+(deftest ^:synchronized swap-clauses-not-found-test
+  (testing "swap-clauses emits a warning if a clause is not found"
+    (let [query       (-> (lib/query meta/metadata-provider (meta/table-metadata :orders))
+                          (lib/aggregate (lib/count))
+                          (lib/aggregate (lib/sum (meta/field-metadata :orders :subtotal)))
+                          (lib/aggregate (lib/min (meta/field-metadata :orders :total))))
+          [a1 a2 _a3] (lib/aggregations query)]
+      (is (=? [[:warn nil #"No matching clause in swap-clauses \[:count .*"]]
+              (tu.log/with-log-messages-for-level ['metabase.lib.swap :warn]
+                (lib/swap-clauses query -1 a2 (lib.options/update-options a1 assoc :lib/uuid (str (random-uuid))))))))))
+
+(deftest ^:synchronized swap-clauses-ambiguous-test
+  (testing "swap-clauses emits a warning if multiple matching clauses are found"
+    ;; This isn't really possible to do by accident, but anyway.
+    (let [query       (-> (lib/query meta/metadata-provider (meta/table-metadata :orders))
+                          (lib/aggregate (lib/count))
+                          (lib/aggregate (lib/sum (meta/field-metadata :orders :subtotal)))
+                          (lib/aggregate (lib/min (meta/field-metadata :orders :total))))
+          [a1 a2 _a3] (lib/aggregations query)
+          query       (update-in query [:stages 0 :aggregation] conj a2)]
+      (is (=? [[:warn nil #"Ambiguous match for clause in swap-clauses \[:sum .*"]]
+              (tu.log/with-log-messages-for-level ['metabase.lib.swap :warn]
+                (lib/swap-clauses query -1 a1 a2)))))))