From 2f084174df522ddb6e1124003d97c56c6302d2e7 Mon Sep 17 00:00:00 2001
From: BOHA <boha@boha.cz>
Date: Tue, 16 Jun 2026 20:07:35 +0200
Subject: [PATCH] feat(documents): selected-custom-fields encode/decode helpers

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
---
 src/__tests__/selected-custom-fields.test.ts | 38 ++++++++++++++++++++
 src/utils/custom-fields.ts                   | 33 +++++++++++++++++
 2 files changed, 71 insertions(+)
 create mode 100644 src/__tests__/selected-custom-fields.test.ts

diff --git a/src/__tests__/selected-custom-fields.test.ts b/src/__tests__/selected-custom-fields.test.ts
new file mode 100644
index 0000000..74801a9
--- /dev/null
+++ b/src/__tests__/selected-custom-fields.test.ts
@@ -0,0 +1,38 @@
+import { describe, it, expect } from "vitest";
+import {
+  encodeSelectedCustomFields,
+  parseSelectedCustomFields,
+} from "../utils/custom-fields";
+
+describe("selected custom fields encode/decode", () => {
+  it("encodes a non-empty index array to a JSON string", () => {
+    expect(encodeSelectedCustomFields([0, 2])).toBe("[0,2]");
+  });
+
+  it("encodes empty / non-array to null", () => {
+    expect(encodeSelectedCustomFields([])).toBeNull();
+    expect(encodeSelectedCustomFields(undefined)).toBeNull();
+    expect(encodeSelectedCustomFields("nope")).toBeNull();
+  });
+
+  it("dedupes, sorts, and drops invalid entries before encoding", () => {
+    expect(encodeSelectedCustomFields([2, 0, 2, -1, 1.5, 3])).toBe("[0,2,3]");
+  });
+
+  it("parses a stored string back to a number array", () => {
+    expect(parseSelectedCustomFields("[0,2]")).toEqual([0, 2]);
+  });
+
+  it("parses null / malformed to an empty array", () => {
+    expect(parseSelectedCustomFields(null)).toEqual([]);
+    expect(parseSelectedCustomFields("")).toEqual([]);
+    expect(parseSelectedCustomFields("{garbage")).toEqual([]);
+    expect(parseSelectedCustomFields('"x"')).toEqual([]);
+  });
+
+  it("parses already-array input (defensive) and filters invalid", () => {
+    expect(parseSelectedCustomFields([0, "1", 2, -3] as unknown)).toEqual([
+      0, 2,
+    ]);
+  });
+});
diff --git a/src/utils/custom-fields.ts b/src/utils/custom-fields.ts
index 3c27e5a..2883ba6 100644
--- a/src/utils/custom-fields.ts
+++ b/src/utils/custom-fields.ts
@@ -46,3 +46,36 @@ export function decodeCustomFields(raw: string | null): {
     return { custom_fields: [], field_order: [] };
   }
 }
+
+/**
+ * Per-document selection of which COMPANY custom fields print on a PDF.
+ * Stored positionally (matching the `custom_<i>` keys the PDF builder emits)
+ * as a JSON array string, e.g. "[0,2]". Null/empty means "none selected".
+ */
+export function encodeSelectedCustomFields(indices: unknown): string | null {
+  const clean = normalizeIndices(indices);
+  return clean.length > 0 ? JSON.stringify(clean) : null;
+}
+
+/** Decode the stored selection (string OR defensive array) into a clean number[]. */
+export function parseSelectedCustomFields(raw: unknown): number[] {
+  if (raw == null) return [];
+  if (Array.isArray(raw)) return normalizeIndices(raw);
+  if (typeof raw !== "string" || raw.trim() === "") return [];
+  try {
+    return normalizeIndices(JSON.parse(raw));
+  } catch {
+    // Malformed JSON in a selection column degrades to "none" (expected
+    // condition — a hand-edited/legacy row should never 500 a PDF render).
+    return [];
+  }
+}
+
+function normalizeIndices(input: unknown): number[] {
+  if (!Array.isArray(input)) return [];
+  const set = new Set<number>();
+  for (const v of input) {
+    if (typeof v === "number" && Number.isInteger(v) && v >= 0) set.add(v);
+  }
+  return [...set].sort((a, b) => a - b);
+}