From 2bcf5a667ee00453de35fe2ca191fcf605dba79b Mon Sep 17 00:00:00 2001
From: Damian Hryniewicz <damian.hryniewicz@gmail.com>
Date: Tue, 9 Jan 2024 11:51:43 +0100
Subject: [PATCH] Support transform of multi-spec to JSON Schema

---
 CHANGELOG.md                               |  4 ++++
 src/spec_tools/json_schema.cljc            |  3 +++
 src/spec_tools/visitor.cljc                |  6 ++++++
 test/cljc/spec_tools/json_schema_test.cljc | 22 ++++++++++++++++++++++
 4 files changed, 35 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index f53f7e06..cb6d53d1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+# Unreleased
+
+* Support tranforming schema to JSON Schema. PR [#281](https://github.com/metosin/spec-tools/pull/281)
+
 # 0.10.6 (2023-08-28)
 
 * Deprecate `spec-tools.openapi/openapi-spec`
diff --git a/src/spec_tools/json_schema.cljc b/src/spec_tools/json_schema.cljc
index 00804d69..02f00683 100644
--- a/src/spec_tools/json_schema.cljc
+++ b/src/spec_tools/json_schema.cljc
@@ -228,6 +228,9 @@
 (defmethod accept-spec 'spec-tools.core/merge [_ spec children options]
   (accept-merge children spec options))
 
+(defmethod accept-spec 'clojure.spec.alpha/multi-spec [_ _ children _]
+  {:anyOf children})
+
 (defmethod accept-spec 'clojure.spec.alpha/every [_ spec children options]
   (let [form (impl/extract-form spec)
         {:keys [type]} (parse/parse-spec form)]
diff --git a/src/spec_tools/visitor.cljc b/src/spec_tools/visitor.cljc
index cef5755c..a4dfc2b3 100644
--- a/src/spec_tools/visitor.cljc
+++ b/src/spec_tools/visitor.cljc
@@ -77,6 +77,12 @@
 (defmethod visit-spec 'spec-tools.core/merge [spec accept options]
   (visit-merge spec accept options))
 
+(defmethod visit-spec 'clojure.spec.alpha/multi-spec [spec accept options]
+  (let [methods-specs (->> (impl/extract-form spec)
+                               (parse/get-multi-spec-sub-specs)
+                               (into {}))]
+    (accept 'clojure.spec.alpha/multi-spec spec (mapv #(visit (val %) accept options) methods-specs) options)))
+
 (defmethod visit-spec 'clojure.spec.alpha/every [spec accept options]
   (let [[_ inner-spec] (impl/extract-form spec)]
     (accept 'clojure.spec.alpha/every spec [(visit inner-spec accept options)] options)))
diff --git a/test/cljc/spec_tools/json_schema_test.cljc b/test/cljc/spec_tools/json_schema_test.cljc
index 1be106d4..3b0d1bec 100644
--- a/test/cljc/spec_tools/json_schema_test.cljc
+++ b/test/cljc/spec_tools/json_schema_test.cljc
@@ -27,6 +27,23 @@
 (s/def ::keys-no-req (s/keys :opt [::e]
                              :opt-un [::e]))
 
+(defmulti event-payload :action)
+
+(s/def :event.payload.add/action #{:add})
+(s/def :event.payload.add/payload int?)
+
+(defmethod event-payload :add
+  [_]
+  (s/keys :req-un [:event.payload.add/action :event.payload.add/payload]))
+
+(s/def :event.payload.result/action #{:result})
+(s/def :event.payload.result/payload nil?)
+
+(defmethod event-payload :result
+  [_]
+  (s/keys :req-un [:event.payload.result/action]
+          :opt-un [:event.payload.result/payload]))
+
 (deftest simple-spec-test
   (testing "primitive predicates"
     ;; You're intented to call jsc/to-json with a registered spec, but to avoid
@@ -99,6 +116,11 @@
             :properties {"spec-tools.json-schema-test/integer" {:type "integer"}
                          "spec-tools.json-schema-test/string" {:type "string"}}
             :required ["spec-tools.json-schema-test/integer" "spec-tools.json-schema-test/string"]}))
+    (is (= (jsc/transform (s/multi-spec event-payload :action))
+           {:anyOf [{:type "object" :properties {"action" {:enum [:result]} "payload" {:type "null"}} :required ["action"]}
+                    {:type "object"
+                     :properties {"action" {:enum [:add]} "payload" {:type "integer" :format "int64"}}
+                     :required ["action" "payload"]}]}))
     (is (= (jsc/transform (s/every integer?)) {:type "array" :items {:type "integer"}}))
     (is (= (jsc/transform (s/every-kv string? integer?))
            {:type "object" :additionalProperties {:type "integer"}}))