import { Bytes } from "./bytes";
import { Record, Tuple } from "./record";
import { AsPreserve } from "./symbols";
import { DefaultPointer, Value } from "./values";

export function fromJS<T extends object = DefaultPointer>(x: any): Value<T> {
    switch (typeof x) {
        case 'number':
            if (!Number.isInteger(x)) {
                // We require that clients be explicit about integer vs. non-integer types.
                throw new TypeError("Refusing to autoconvert non-integer number to Single or Double");
            }
            // FALL THROUGH
        case 'string':
        case 'symbol':
        case 'boolean':
            return x;

        case 'undefined':
        case 'function':
        case 'bigint':
            break;

        case 'object':
            if (x === null) {
                break;
            }
            if (typeof x[AsPreserve] === 'function') {
                return x[AsPreserve]();
            }
            if (Record.isRecord<Value<T>, Tuple<Value<T>>, T>(x)) {
                return x;
            }
            if (Array.isArray(x)) {
                return x.map<Value<T>>(fromJS);
            }
            if (ArrayBuffer.isView(x) || x instanceof ArrayBuffer) {
                return Bytes.from(x);
            }
            // Just... assume it's a T.
            return (x as T);

        default:
            break;
    }

    throw new TypeError("Cannot represent JavaScript value as Preserves: " + x);
}