"use strict"

import {timeout} from "./timeout";

export interface RetryConfig<T = any> {
    /**
     * number of maximal retry attempts
     * @defaultValue 10
     */
    retries: number | "INFINITELY";

    /**
     * wait time between retries in ms
     * @defaultValue 100
     */
    delay: number;

    /**
     * check the result, will retry until true
     * @defaultValue () => true
     */
    until: (t: T) => boolean;

    /**
     * log events
     * @defaultValue () => undefined
     */
    logger: (msg: string) => void;

    /**
     * overall timeout in ms
     * @defaultValue 60 * 1000
     */
    timeout: number | "INFINITELY";

    /**
     * increase delay with every retry
     * @defaultValue "FIXED"
     */
    backoff: "FIXED" | "EXPONENTIAL" | "LINEAR" | ((attempt: number, delay: number) => number);

    /**
     * maximal backoff in ms
     * @defaultValue 5 * 60 * 1000
     */
    maxBackOff: number;

    /**
     * allows to abort retrying for certain errors
     */
    retryIf: (error: any) => boolean
}

const fixedBackoff = (attempt: number, delay: number) => delay;
const linearBackoff = (attempt: number, delay: number) => attempt * delay;
const exponentialBackoff = (attempt: number, delay: number) => Math.pow(delay, attempt);

export const defaultRetryConfig: RetryConfig<any> = {
    backoff: "FIXED",
    delay: 100,
    logger: () => undefined,
    maxBackOff: 5 * 60 * 1000,
    retries: 10,
    timeout: 60 * 1000,
    until: () => true,
    retryIf: () => true
};

export async function wait(ms: number): Promise<void> {
    return new Promise<void>((resolve) => setTimeout(resolve, ms));
}

export async function retry<T>(f: () => Promise<T>, config?: Partial<RetryConfig<T>>): Promise<T> {
    const effectiveConfig: RetryConfig<T> = Object.assign({}, defaultRetryConfig, config) as RetryConfig<T>;
    return timeout(effectiveConfig.timeout, (done) => _retry(f, effectiveConfig, done));
}

export function retryDecorator<T, F extends (...args: any[]) => Promise<T>>(func: F, config?: Partial<RetryConfig<T>>): (...funcArgs: Parameters<F>) => ReturnType<F> {
    return (...args: Parameters<F>) => retry(() => func(...args), config) as ReturnType<F>;
}

export function customizeDecorator<T>(customConfig: Partial<RetryConfig<T>>): typeof retryDecorator {
    return (args, config) => retryDecorator(args, Object.assign({}, customConfig, config));
}

// tslint:disable-next-line
export function customizeRetry<T>(customConfig: Partial<RetryConfig<T>>): (f: () => Promise<T>, config?: Partial<RetryConfig<T>>) => Promise<T> {
    return (f, c) => {
        const customized = Object.assign({}, customConfig, c);
        return retry(f, customized);
    };
}

async function _retry<T>(f: () => Promise<T>, config: RetryConfig<T>, done: () => boolean): Promise<T> {
    let lastError: Error;

    let delay: (attempt: number, delay: number) => number;

    switch (config.backoff) {
        case "EXPONENTIAL":
            delay = exponentialBackoff;
            break;
        case "FIXED":
            delay = fixedBackoff;
            break;
        case "LINEAR":
            delay = linearBackoff;
            break;
        default:
            delay = config.backoff;
    }

    let retries: number;
    if (config.retries === "INFINITELY") {
        retries = Number.MAX_SAFE_INTEGER;
    } else {
        retries = config.retries;
    }

    for (let i = 0; i <= retries; i++) {
        try {
            const result = await f();
            if (config.until(result)) {
                return result;
            }
            config.logger("Until condition not met by " + result);
        } catch (error) {
            if (!config.retryIf(error)) {
                throw error;
            }

            if (error.name === NotRetryableError.name) {
                throw new RetryError(
                  `Met not retryable error. Last error: ${error}`,
                  error
                )
            }
            lastError = error;
            config.logger("Retry failed: " + error.message);
        }
        const millisToWait = delay(i + 1, config.delay);
        await wait(millisToWait > config.maxBackOff ? config.maxBackOff : millisToWait);

        if (done()) {
            break;
        }
    }
    throw new RetryError(`All retries failed. Last error: ${lastError!}`, lastError!);
}

export const notEmpty = (result: any) => {
    if (Array.isArray(result)) {
        return result.length > 0;
    }
    return result !== null && result !== undefined;
};

export class RetryError extends Error {
    /*  istanbul ignore next  */
    constructor(message: string, public readonly lastError: Error) {
        super(message);
    }
}

// tslint:disable-next-line:max-classes-per-file
class BaseError {
    constructor (public message?: string, ...args: unknown[]) {
        Error.apply(this, args as any);
    }
}

BaseError.prototype = new Error();

// tslint:disable-next-line:max-classes-per-file
export class NotRetryableError extends BaseError {
    constructor(message?: string) {
        super(message);
        Object.defineProperty(this, 'name', { value: this.constructor.name })
    }
}