import isVoid from "./isVoid.ts";
import type { Constructor } from "https://lib.deno.dev/x/ayonli_jsext@latest/index.ts";

export type TypeNames = "string"
    | "number"
    | "bigint"
    | "boolean"
    | "symbol"
    | "function"
    | "class"
    | "arguments"
    | "void";

/**
 * Returns a string representation or the constructor of the value's type.
 * NOTE: this function also returns `'void'` when testing `NaN`.
 */
export default function typeOf<T extends any>(
    target: T
): TypeNames | Constructor<T> {
    if (arguments.length === 0)
        throw new TypeError("1 argument is required, 0 given");
    else if (isVoid(target))
        return "void";

    let type = typeof target;

    if (type === "function") {
        if (isClass(<any>target)) {
            return "class";
        } else {
            return "function";
        }
    } else if (type === "object") {
        if (Object.prototype.toString.call(target) === "[object Arguments]") {
            return "arguments";
        } else {
            return (<any>target).constructor || Object;
        }
    } else {
        return <any>type;
    }
}

function isClass(obj: any) {
    if (typeof obj != "function") return false;

    // async function or arrow function
    if (obj.prototype === undefined)
        return false;

    // generator function and malformed inheritance
    if (obj.prototype.constructor !== obj)
        return false;

    // has own prototype properties
    if (Object.getOwnPropertyNames(obj.prototype).length >= 2)
        return true;

    var str = String(obj);

    // ES6 class
    if (str.slice(0, 5) == "class")
        return true;

    // anonymous function
    if (/^function\s*\(|^function anonymous\(/.test(str))
        return false;

    var hasThis = /(call|apply|_classCallCheck)\(this(, arguments)?\)|\bthis(.\S+|\[.+?\])\s*(=|\()|=\s*this[,;]/.test(str);

    // Upper-cased first char of the name and has `this` in the body, or it's
    // a native class in ES5 style.
    if (/^function\s+[A-Z]/.test(str) && (hasThis ||
        (/\[native code\]/.test(str) &&
            obj.name !== "BigInt" && // ES6 BigInt and Symbol is not class
            obj.name !== "Symbol"
        )
    )) {
        return true;
    }

    // TypeScript anonymous class to ES5 with default export
    if (hasThis && obj.name === "default_1")
        return true;

    return false;
}