// MIT © 2017 azu
const hasOwn = Object.prototype.hasOwnProperty;
// Object.is ponyfill
export const is = (x: any, y: any): boolean => {
    if (x === y) {
        return x !== 0 || y !== 0 || 1 / x === 1 / y;
    } else {
        return x !== x && y !== y;
    }
};
/**
 * Return true, if `objectA` is shallow equal to `objectB`.
 * Pass Custom equality function to `customEqual`.
 * Default equality is `Object.is`
 *
 * Options:
 *
 * - `customEqual`: function should return true if the `a` value is equal to `b` value.
 * - `debug`: enable debug info to console log. This log will be disable in production build
 */
export const shallowEqual = (
    objectA: any,
    objectB: any,
    options?: {
        customEqual?: <T>(a: T, b: T) => boolean;
        // debug options available in development build
        debug?: true;
        console?: Pick<Console, "log" | "group" | "groupEnd">;
    }
): boolean => {
    if (objectA === objectB) {
        return true;
    }
    if (typeof objectA !== "object" || objectA === null) {
        if (process.env.NODE_ENV !== "production" && options && options.debug) {
            const out = options.console || console;
            out.group(`shallow-equal-object`);
            out.log("objectA is not object.");
            out.log("objectA", objectA);
            out.log("objectB", objectB);
            out.groupEnd();
        }
        return false;
    }
    if (typeof objectB !== "object" || objectB === null) {
        if (process.env.NODE_ENV !== "production" && options && options.debug) {
            const out = options.console || console;
            out.group(`shallow-equal-object`);
            out.log("objectB is not object.");
            out.log("objectA", objectA);
            out.log("objectB", objectB);
            out.groupEnd();
        }
        return false;
    }

    const keysA = Object.keys(objectA);
    const keysB = Object.keys(objectB);

    if (keysA.length !== keysB.length) {
        if (process.env.NODE_ENV !== "production" && options && options.debug) {
            const out = options.console || console;
            out.group(`shallow-equal-object`);
            out.log("object key length is not same");
            out.log("objectA", objectA);
            out.log("objectB", objectB);
            out.groupEnd();
        }
        return false;
    }

    const isEqual = options && typeof options.customEqual === "function" ? options.customEqual : is;

    for (let i = 0; i < keysA.length; i++) {
        const key = keysA[i];
        if (!hasOwn.call(objectB, key) || !isEqual(objectA[key], objectB[key])) {
            if (process.env.NODE_ENV !== "production" && options && options.debug) {
                const out = options.console || console;
                out.group(`shallow-equal-object`);
                out.log(`key:${key} is not equals between A and B.`);
                out.log(`objectA[${key}]:`, objectA[key]);
                out.log(`objectB[${key}]:`, objectB[key]);
                out.log("objectA", objectA);
                out.log("objectB", objectB);
                out.groupEnd();
            }
            return false;
        }
    }

    return true;
};