import { useRef } from "react";
import { shallowArraysEqual } from "./utils";

/**
 * Calls a function only once during component lifecycle;
 * When dependency array is provided, will call the function again if at least one of the dependencies changed
 * @param callback The function to execute only once
 * @param dependencies A list of dependencies whose value, if changed since last call,
 * will trigger the execution of the callback
 */
// eslint-disable-next-line @typescript-eslint/explicit-function-return-type
export const useSingleton = (callback: () => any, dependencies: any[] = []) => {
    const hasRan = useRef<boolean>(false);
    const lastDependencies = useRef<any[]>([]);

    // Parameters type check
    if (typeof callback !== "function") {
        throw new Error(
            `Incorrect callback parameter for useSingleton hook; expected a function, but got: '${typeof callback}'.`
        );
    }
    if (!Array.isArray(dependencies)) {
        throw new Error(
            `Incorrect dependencies parameter for useSingleton; expected an array, but got: '${typeof dependencies}'.`
        );
    }

    const hasDependencies = Array.isArray(dependencies) && dependencies.length > 0;
    if (hasDependencies) {
        // Has dependencies
        const hasAnyDependencyChanged = !shallowArraysEqual(lastDependencies.current, dependencies);
        if (hasAnyDependencyChanged) {
            // Any dep has changed => overwrite last dependencies and execute callback
            lastDependencies.current = dependencies;
        } else if (hasRan.current) {
            // No dep has changed => same behaviour as if no dependencies
            return;
        }
    } else if (hasRan.current) {
        // No dependencies
        return;
    }

    callback();
    hasRan.current = true;
};