const DTYPE_QUALIFIED = "plist";
const DTYPE_PUBLIC = "-//Apple Inc//DTD PLIST 1.0//EN";
const DTYPE_SYSTEM = "http://www.apple.com/DTDs/PropertyList-1.0.dtd";

const PLIST_VERSION = "1.0";
const XML_HEADER = '<?xml version="1.0" encoding="UTF-8"?>\n';

export class Plist {
  static stringify(value: unknown) {
    const root = document.implementation.createDocument(
      null,
      "plist",
      document.implementation.createDocumentType(
        DTYPE_QUALIFIED,
        DTYPE_PUBLIC,
        DTYPE_SYSTEM,
      ),
    );
    root.lastElementChild!.setAttribute("version", PLIST_VERSION);

    new Serializer(root)
      .insert(root.lastElementChild!, value);

    return XML_HEADER + new XMLSerializer().serializeToString(root);
  }
}

class Serializer {
  #doc: XMLDocument;

  constructor(doc: XMLDocument) {
    this.#doc = doc;
  }

  insert(cur: Element, value: unknown) {
    switch (typeof value) {
      case "bigint": {
        const int = this.#doc.createElement("integer");
        int.textContent = value.toString();
        cur.append(int);
        break;
      }
      case "number": {
        const real = this.#doc.createElement("real");
        real.textContent = value.toString();
        cur.append(real);
        break;
      }
      case "object":
        if (Array.isArray(value)) {
          const arr = this.#doc.createElement("array");
          cur.append(arr);

          for (const val of value) {
            this.insert(arr, val);
          }
        } else if (value instanceof Uint8Array) {
          const data = this.#doc.createElement("data");
          data.textContent = btoa(String.fromCharCode(...value));
          cur.append(data);
        } else if (value !== null) {
          const dict = this.#doc.createElement("dict");
          cur.append(dict);

          for (const [key, val] of Object.entries(value)) {
            const pKey = this.#doc.createElement("key");
            pKey.textContent = key;
            dict.append(pKey);
            this.insert(dict, val);
          }
        } else {
          throw new TypeError(`Unsupported plist type 'null'`);
        }
        break;
      case "string": {
        const str = this.#doc.createElement("string");
        str.textContent = value;
        cur.append(str);
        break;
      }
      default:
        throw new TypeError(`Unsupported plist type '${typeof value}'`);
    }
  }
}