From b2a9c3323f2954eb74226e3f3a3a3a18e8d913d8 Mon Sep 17 00:00:00 2001
From: Evgeny Gamov <smartass@smartass.pw>
Date: Tue, 16 Jun 2026 20:48:10 +0500
Subject: [PATCH] feat(esmole): mapping flatten

---
 packages/esmole-mcp/src/es/mapping.ts         | 37 +++++++++++++++++
 .../esmole-mcp/test/unit/es/mapping.test.ts   | 40 +++++++++++++++++++
 2 files changed, 77 insertions(+)
 create mode 100644 packages/esmole-mcp/src/es/mapping.ts
 create mode 100644 packages/esmole-mcp/test/unit/es/mapping.test.ts

diff --git a/packages/esmole-mcp/src/es/mapping.ts b/packages/esmole-mcp/src/es/mapping.ts
new file mode 100644
index 0000000..09dbc6b
--- /dev/null
+++ b/packages/esmole-mcp/src/es/mapping.ts
@@ -0,0 +1,37 @@
+export type MappingRow = { index?: string; field: string; type: string }
+
+type Props = Record<string, { type?: string; properties?: Props; fields?: Props }>
+
+const walk = (props: Props, prefix: string, rows: MappingRow[], index?: string): void => {
+    for (const [name, def] of Object.entries(props)) {
+        const field = prefix ? prefix + '.' + name : name
+        if (def.type) {
+            rows.push(index ? { index, field, type: def.type } : { field, type: def.type })
+        }
+        if (def.fields) {
+            walk(def.fields, field, rows, index)
+        }
+        if (def.properties) {
+            walk(def.properties, field, rows, index)
+        }
+    }
+}
+
+// Flattens an ES `GET /{index}/_mapping` response into dotted field:type rows.
+// With a single index the `index` key is omitted; with multiple indices each
+// row carries its index name.
+export const flattenMapping = (raw: unknown): MappingRow[] => {
+    const rows: MappingRow[] = []
+    if (typeof raw !== 'object' || raw === null) {
+        return rows
+    }
+    const indices = Object.entries(raw as Record<string, { mappings?: { properties?: Props } }>)
+    const multi = indices.length > 1
+    for (const [indexName, body] of indices) {
+        const props = body?.mappings?.properties
+        if (props) {
+            walk(props, '', rows, multi ? indexName : undefined)
+        }
+    }
+    return rows
+}
diff --git a/packages/esmole-mcp/test/unit/es/mapping.test.ts b/packages/esmole-mcp/test/unit/es/mapping.test.ts
new file mode 100644
index 0000000..0702983
--- /dev/null
+++ b/packages/esmole-mcp/test/unit/es/mapping.test.ts
@@ -0,0 +1,40 @@
+import { describe, expect, it } from 'vitest'
+import { flattenMapping } from '../../../src/es/mapping.js'
+
+const raw = {
+    myindex: {
+        mappings: {
+            properties: {
+                id: { type: 'keyword' },
+                title: { type: 'text', fields: { raw: { type: 'keyword' } } },
+                author: { properties: { name: { type: 'text' }, age: { type: 'integer' } } }
+            }
+        }
+    }
+}
+
+describe('flattenMapping', () => {
+    it('flattens nested properties to dotted field:type rows', () => {
+        const rows = flattenMapping(raw)
+        expect(rows).toContainEqual({ field: 'id', type: 'keyword' })
+        expect(rows).toContainEqual({ field: 'title', type: 'text' })
+        expect(rows).toContainEqual({ field: 'title.raw', type: 'keyword' })
+        expect(rows).toContainEqual({ field: 'author.name', type: 'text' })
+        expect(rows).toContainEqual({ field: 'author.age', type: 'integer' })
+    })
+    it('handles multiple indices by prefixing the index name', () => {
+        const rows = flattenMapping({
+            a: { mappings: { properties: { x: { type: 'long' } } } },
+            b: { mappings: { properties: { y: { type: 'date' } } } }
+        })
+        expect(rows).toContainEqual({ index: 'a', field: 'x', type: 'long' })
+        expect(rows).toContainEqual({ index: 'b', field: 'y', type: 'date' })
+    })
+    it('returns empty array for an empty mapping', () => {
+        expect(flattenMapping({ idx: { mappings: {} } })).toEqual([])
+    })
+    it('returns empty array for a non-object input', () => {
+        expect(flattenMapping(null)).toEqual([])
+        expect(flattenMapping('nope')).toEqual([])
+    })
+})