import { DEFAULT_OPTIONS } from './constants';

import type {
    AnyFn,
    Expiration,
    IsEqual,
    IsMatchingKey,
    Key,
    Moizeable,
    Moized,
    Options,
} from '../index.d';

/**
 * @private
 *
 * @description
 * method to combine functions and return a single function that fires them all
 *
 * @param functions the functions to compose
 * @returns the composed function
 */
export function combine<Args extends any[], Result>(
    ...functions: Array<(...args: Args) => any>
): ((...args: Args) => Result) | undefined {
    return functions.reduce(function (f: any, g: any) {
        if (typeof f === 'function') {
            return typeof g === 'function'
                ? function (this: any) {
                      f.apply(this, arguments);
                      g.apply(this, arguments);
                  }
                : f;
        }

        if (typeof g === 'function') {
            return g;
        }
    });
}

/**
 * @private
 *
 * @description
 * method to compose functions and return a single function
 *
 * @param functions the functions to compose
 * @returns the composed function
 */
export function compose<Method>(...functions: Method[]): Method {
    return functions.reduce(function (f: any, g: any) {
        if (typeof f === 'function') {
            return typeof g === 'function'
                ? function (this: any) {
                      return f(g.apply(this, arguments));
                  }
                : f;
        }

        if (typeof g === 'function') {
            return g;
        }
    });
}

/**
 * @private
 *
 * @description
 * find the index of the expiration based on the key
 *
 * @param expirations the list of expirations
 * @param key the key to match
 * @returns the index of the expiration
 */
export function findExpirationIndex(expirations: Expiration[], key: Key) {
    for (let index = 0; index < expirations.length; index++) {
        if (expirations[index].key === key) {
            return index;
        }
    }

    return -1;
}

/**
 * @private
 *
 * @description
 * create function that finds the index of the key in the list of cache keys
 *
 * @param isEqual the function to test individual argument equality
 * @param isMatchingKey the function to test full key equality
 * @returns the function that finds the index of the key
 */
export function createFindKeyIndex(
    isEqual: IsEqual,
    isMatchingKey: IsMatchingKey | undefined
) {
    const areKeysEqual: IsMatchingKey =
        typeof isMatchingKey === 'function'
            ? isMatchingKey
            : function (cacheKey: Key, key: Key) {
                  for (let index = 0; index < key.length; index++) {
                      if (!isEqual(cacheKey[index], key[index])) {
                          return false;
                      }
                  }

                  return true;
              };

    return function (keys: Key[], key: Key) {
        for (let keysIndex = 0; keysIndex < keys.length; keysIndex++) {
            if (
                keys[keysIndex].length === key.length &&
                areKeysEqual(keys[keysIndex], key)
            ) {
                return keysIndex;
            }
        }

        return -1;
    };
}

type MergedOptions<
    OriginalOptions extends Options<Moizeable>,
    NewOptions extends Options<Moizeable>
> = Omit<OriginalOptions, keyof NewOptions> & NewOptions;

/**
 * @private
 *
 * @description
 * merge two options objects, combining or composing functions as necessary
 *
 * @param originalOptions the options that already exist on the method
 * @param newOptions the new options to merge
 * @returns the merged options
 */
export function mergeOptions<
    OriginalOptions extends Options<Moizeable>,
    NewOptions extends Options<Moizeable>
>(
    originalOptions: OriginalOptions,
    newOptions: NewOptions | undefined
): MergedOptions<OriginalOptions, NewOptions> {
    if (!newOptions || newOptions === DEFAULT_OPTIONS) {
        return originalOptions as unknown as MergedOptions<
            OriginalOptions,
            NewOptions
        >;
    }

    return {
        ...originalOptions,
        ...newOptions,
        onCacheAdd: combine(originalOptions.onCacheAdd, newOptions.onCacheAdd),
        onCacheChange: combine(
            originalOptions.onCacheChange,
            newOptions.onCacheChange
        ),
        onCacheHit: combine(originalOptions.onCacheHit, newOptions.onCacheHit),
        transformArgs: compose(
            originalOptions.transformArgs,
            newOptions.transformArgs
        ),
    };
}

export function isMoized(
    fn: Moizeable | Moized | Options<AnyFn>
): fn is Moized {
    return typeof fn === 'function' && (fn as Moizeable).isMoized;
}

export function setName(
    fn: Moized,
    originalFunctionName: string,
    profileName: string
) {
    try {
        const name = profileName || originalFunctionName || 'anonymous';

        Object.defineProperty(fn, 'name', {
            configurable: true,
            enumerable: false,
            value: `moized(${name})`,
            writable: true,
        });
    } catch {
        // For engines where `function.name` is not configurable, do nothing.
    }
}