From 3363a188564f6c2e7915ba28b56dc3b90ef4afd3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Greg=20Berg=C3=A9?= <berge.greg@gmail.com>
Date: Wed, 16 Apr 2025 11:14:12 +0200
Subject: [PATCH] Merge simple alternatives (#3165)

---
 .changeset/kind-lobsters-grab.md              |  5 ++
 .../react-openapi/src/OpenAPISchema.test.ts   | 80 +++++++++++++++++
 packages/react-openapi/src/OpenAPISchema.tsx  | 86 ++++++++++++++++++-
 3 files changed, 170 insertions(+), 1 deletion(-)
 create mode 100644 .changeset/kind-lobsters-grab.md

diff --git a/.changeset/kind-lobsters-grab.md b/.changeset/kind-lobsters-grab.md
new file mode 100644
index 000000000..c4247d6d4
--- /dev/null
+++ b/.changeset/kind-lobsters-grab.md
@@ -0,0 +1,5 @@
+---
+"@gitbook/react-openapi": patch
+---
+
+Merge simple alternatives
diff --git a/packages/react-openapi/src/OpenAPISchema.test.ts b/packages/react-openapi/src/OpenAPISchema.test.ts
index e3fdc754c..4d2adcfc0 100644
--- a/packages/react-openapi/src/OpenAPISchema.test.ts
+++ b/packages/react-openapi/src/OpenAPISchema.test.ts
@@ -35,6 +35,86 @@ describe('getSchemaAlternatives', () => {
         ]);
     });
 
+    it('merges string enum', () => {
+        expect(
+            getSchemaAlternatives({
+                oneOf: [
+                    {
+                        oneOf: [
+                            {
+                                type: 'string',
+                                enum: ['a', 'b'],
+                            },
+                            {
+                                type: 'string',
+                                enum: ['c', 'd'],
+                                nullable: true,
+                            },
+                        ],
+                    },
+                ],
+            })
+        ).toEqual([
+            {
+                type: 'string',
+                enum: ['a', 'b', 'c', 'd'],
+                nullable: true,
+            },
+        ]);
+    });
+
+    it('merges objects with allOf', () => {
+        expect(
+            getSchemaAlternatives({
+                allOf: [
+                    {
+                        type: 'object',
+                        properties: {
+                            name: {
+                                type: 'string',
+                            },
+                            map: {
+                                type: 'string',
+                            },
+                            description: {
+                                type: 'string',
+                            },
+                        },
+                        required: ['name'],
+                    },
+                    {
+                        type: 'object',
+                        properties: {
+                            externalId: {
+                                type: 'string',
+                            },
+                        },
+                        required: ['map', 'externalId'],
+                    },
+                ],
+            })
+        ).toEqual([
+            {
+                type: 'object',
+                properties: {
+                    name: {
+                        type: 'string',
+                    },
+                    map: {
+                        type: 'string',
+                    },
+                    description: {
+                        type: 'string',
+                    },
+                    externalId: {
+                        type: 'string',
+                    },
+                },
+                required: ['name', 'map', 'externalId'],
+            },
+        ]);
+    });
+
     it('should not flatten oneOf and allOf', () => {
         expect(
             getSchemaAlternatives({
diff --git a/packages/react-openapi/src/OpenAPISchema.tsx b/packages/react-openapi/src/OpenAPISchema.tsx
index 0b76efc14..0c2593432 100644
--- a/packages/react-openapi/src/OpenAPISchema.tsx
+++ b/packages/react-openapi/src/OpenAPISchema.tsx
@@ -450,7 +450,91 @@ export function getSchemaAlternatives(
     }
 
     const [type, schemas] = alternatives;
-    return flattenAlternatives(type, schemas, new Set(ancestors).add(schema));
+    return mergeAlternatives(
+        type,
+        flattenAlternatives(type, schemas, new Set(ancestors).add(schema))
+    );
+}
+
+/**
+ * Merge alternatives of the same type into a single schema.
+ * - Merge string enums
+ */
+function mergeAlternatives(
+    alternativeType: AlternativeType,
+    schemasOrRefs: OpenAPIV3.SchemaObject[]
+): OpenAPIV3.SchemaObject[] | null {
+    switch (alternativeType) {
+        case 'oneOf': {
+            return schemasOrRefs.reduce<OpenAPIV3.SchemaObject[]>((acc, schemaOrRef) => {
+                const latest = acc.at(-1);
+
+                if (
+                    latest &&
+                    latest.type === 'string' &&
+                    latest.enum &&
+                    schemaOrRef.type === 'string' &&
+                    schemaOrRef.enum
+                ) {
+                    latest.enum = Array.from(new Set([...latest.enum, ...schemaOrRef.enum]));
+                    latest.nullable = latest.nullable || schemaOrRef.nullable;
+                    return acc;
+                }
+
+                acc.push(schemaOrRef);
+                return acc;
+            }, []);
+        }
+        case 'allOf': {
+            return schemasOrRefs.reduce<OpenAPIV3.SchemaObject[]>((acc, schemaOrRef) => {
+                const latest = acc.at(-1);
+
+                if (
+                    latest &&
+                    latest.type === 'string' &&
+                    latest.enum &&
+                    schemaOrRef.type === 'string' &&
+                    schemaOrRef.enum
+                ) {
+                    const keys = Object.keys(schemaOrRef);
+                    if (keys.every((key) => ['type', 'enum', 'nullable'].includes(key))) {
+                        latest.enum = Array.from(new Set([...latest.enum, ...schemaOrRef.enum]));
+                        latest.nullable = latest.nullable || schemaOrRef.nullable;
+                        return acc;
+                    }
+                }
+
+                if (latest && latest.type === 'object' && schemaOrRef.type === 'object') {
+                    const keys = Object.keys(schemaOrRef);
+                    if (
+                        keys.every((key) =>
+                            ['type', 'properties', 'required', 'nullable'].includes(key)
+                        )
+                    ) {
+                        latest.properties = {
+                            ...latest.properties,
+                            ...schemaOrRef.properties,
+                        };
+                        latest.required = Array.from(
+                            new Set([
+                                ...(Array.isArray(latest.required) ? latest.required : []),
+                                ...(Array.isArray(schemaOrRef.required)
+                                    ? schemaOrRef.required
+                                    : []),
+                            ])
+                        );
+                        latest.nullable = latest.nullable || schemaOrRef.nullable;
+                        return acc;
+                    }
+                }
+
+                acc.push(schemaOrRef);
+                return acc;
+            }, []);
+        }
+        default:
+            return schemasOrRefs;
+    }
 }
 
 function flattenAlternatives(