1+ import { Principal } from "@dfinity/principal" ;
2+ import { nonNullish } from "@dfinity/utils" ;
3+
4+ const JSON_KEY_BIGINT = "__bigint__" ;
5+ const JSON_KEY_PRINCIPAL = "__principal__" ;
6+ const JSON_KEY_UINT8ARRAY = "__uint8array__" ;
7+ const JSON_KEY_ARRAYBUFFER = "__arraybuffer__" ;
8+
9+ // Helper function to convert ArrayBuffer to Base64
10+ const arrayBufferToBase64 = ( buffer : ArrayBuffer ) : string => {
11+ let binary = "" ;
12+ const bytes = new Uint8Array ( buffer ) ;
13+ const len = bytes . byteLength ;
14+ for ( let i = 0 ; i < len ; i ++ ) {
15+ binary += String . fromCharCode ( bytes [ i ] ) ;
16+ }
17+ return btoa ( binary ) ;
18+ } ;
19+
20+ // Helper function to convert Base64 to ArrayBuffer
21+ const base64ToArrayBuffer = ( base64 : string ) : ArrayBuffer => {
22+ const binary_string = atob ( base64 ) ;
23+ const len = binary_string . length ;
24+ const bytes = new Uint8Array ( len ) ;
25+ for ( let i = 0 ; i < len ; i ++ ) {
26+ bytes [ i ] = binary_string . charCodeAt ( i ) ;
27+ }
28+ return bytes . buffer ;
29+ } ;
30+
31+ /**
32+ * A custom replacer for `JSON.stringify` that converts specific types not natively supported
33+ * by the API into JSON-compatible formats.
34+ *
35+ * Supported conversions:
36+ * - `BigInt` → `{ "__bigint__": string }`
37+ * - `Principal` → `{ "__principal__": string }`
38+ * - `Uint8Array` → `{ "__uint8array__": number[] }`
39+ * - `ArrayBuffer` → `{ "__arraybuffer__": string }` (base64 encoded)
40+ *
41+ * @param {string } _key - Ignored. Only provided for API compatibility.
42+ * @param {unknown } value - The value to transform before stringification.
43+ * @returns {unknown } The transformed value if it matches a known type, otherwise the original value.
44+ */
45+ export const jsonReplacer = ( _key : string , value : unknown ) : unknown => {
46+ if ( typeof value === "bigint" ) {
47+ return { [ JSON_KEY_BIGINT ] : `${ value } } ;
48+ }
49+
50+ if ( nonNullish ( value ) && value instanceof Principal ) {
51+ return { [ JSON_KEY_PRINCIPAL ] : value . toText ( ) } ;
52+ }
53+
54+ if ( nonNullish ( value ) && value instanceof Uint8Array ) {
55+ return { [ JSON_KEY_UINT8ARRAY ] : Array . from ( value ) } ;
56+ }
57+
58+ if ( nonNullish ( value ) && value instanceof ArrayBuffer ) {
59+ return { [ JSON_KEY_ARRAYBUFFER ] : arrayBufferToBase64 ( value ) } ;
60+ }
61+
62+ return value ;
63+ } ;
64+
65+ /**
66+ * A custom reviver for `JSON.parse` that reconstructs specific types from their JSON-encoded representations.
67+ *
68+ * This reverses the transformations applied by `jsonReplacer`, restoring the original types.
69+ *
70+ * Supported conversions:
71+ * - `{ "__bigint__": string }` → `BigInt`
72+ * - `{ "__principal__": string }` → `Principal`
73+ * - `{ "__uint8array__": number[] }` → `Uint8Array`
74+ * - `{ "__arraybuffer__": string }` → `ArrayBuffer` (from base64)
75+ *
76+ * @param {string } _key - Ignored but provided for API compatibility.
77+ * @param {unknown } value - The parsed value to transform.
78+ * @returns {unknown } The reconstructed value if it matches a known type, otherwise the original value.
79+ */
80+ export const jsonReviver = ( _key : string , value : unknown ) : unknown => {
81+ const mapValue = < T > ( key : string ) : T => ( value as Record < string , T > ) [ key ] ;
82+
83+ if (
84+ nonNullish ( value ) &&
85+ typeof value === "object" &&
86+ JSON_KEY_BIGINT in value
87+ ) {
88+ return BigInt ( mapValue ( JSON_KEY_BIGINT ) ) ;
89+ }
90+
91+ if (
92+ nonNullish ( value ) &&
93+ typeof value === "object" &&
94+ JSON_KEY_PRINCIPAL in value
95+ ) {
96+ return Principal . fromText ( mapValue ( JSON_KEY_PRINCIPAL ) ) ;
97+ }
98+
99+ if (
100+ nonNullish ( value ) &&
101+ typeof value === "object" &&
102+ JSON_KEY_UINT8ARRAY in value
103+ ) {
104+ return Uint8Array . from ( mapValue ( JSON_KEY_UINT8ARRAY ) ) ;
105+ }
106+
107+ if (
108+ nonNullish ( value ) &&
109+ typeof value === "object" &&
110+ JSON_KEY_ARRAYBUFFER in value
111+ ) {
112+ return base64ToArrayBuffer ( mapValue ( JSON_KEY_ARRAYBUFFER ) ) ;
113+ }
114+
115+ return value ;
116+ } ;
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