/*---------------------------------------------------------------------------------------------
 *  Copyright (c) Microsoft Corporation. All rights reserved.
 *  Licensed under the MIT License. See License.txt in the project root for license information.
 *--------------------------------------------------------------------------------------------*/
import { CancellationTokenSource } from './cancellation';
import * as errors from './errors';
import { toDisposable } from './lifecycle';
export function isThenable(obj) {
    return obj && typeof obj.then === 'function';
}
export function createCancelablePromise(callback) {
    const source = new CancellationTokenSource();
    const thenable = callback(source.token);
    const promise = new Promise((resolve, reject) => {
        source.token.onCancellationRequested(() => {
            reject(errors.canceled());
        });
        Promise.resolve(thenable).then(value => {
            source.dispose();
            resolve(value);
        }, err => {
            source.dispose();
            reject(err);
        });
    });
    return new class {
        cancel() {
            source.cancel();
        }
        then(resolve, reject) {
            return promise.then(resolve, reject);
        }
        catch(reject) {
            return this.then(undefined, reject);
        }
        finally(onfinally) {
            return promise.finally(onfinally);
        }
    };
}
export function raceCancellation(promise, token, defaultValue) {
    return Promise.race([promise, new Promise(resolve => token.onCancellationRequested(() => resolve(defaultValue)))]);
}
/**
 * A helper to delay (debounce) execution of a task that is being requested often.
 *
 * Following the throttler, now imagine the mail man wants to optimize the number of
 * trips proactively. The trip itself can be long, so he decides not to make the trip
 * as soon as a letter is submitted. Instead he waits a while, in case more
 * letters are submitted. After said waiting period, if no letters were submitted, he
 * decides to make the trip. Imagine that N more letters were submitted after the first
 * one, all within a short period of time between each other. Even though N+1
 * submissions occurred, only 1 delivery was made.
 *
 * The delayer offers this behavior via the trigger() method, into which both the task
 * to be executed and the waiting period (delay) must be passed in as arguments. Following
 * the example:
 *
 * 		const delayer = new Delayer(WAITING_PERIOD);
 * 		const letters = [];
 *
 * 		function letterReceived(l) {
 * 			letters.push(l);
 * 			delayer.trigger(() => { return makeTheTrip(); });
 * 		}
 */
export class Delayer {
    constructor(defaultDelay) {
        this.defaultDelay = defaultDelay;
        this.timeout = null;
        this.completionPromise = null;
        this.doResolve = null;
        this.doReject = null;
        this.task = null;
    }
    trigger(task, delay = this.defaultDelay) {
        this.task = task;
        this.cancelTimeout();
        if (!this.completionPromise) {
            this.completionPromise = new Promise((resolve, reject) => {
                this.doResolve = resolve;
                this.doReject = reject;
            }).then(() => {
                this.completionPromise = null;
                this.doResolve = null;
                if (this.task) {
                    const task = this.task;
                    this.task = null;
                    return task();
                }
                return undefined;
            });
        }
        this.timeout = setTimeout(() => {
            this.timeout = null;
            if (this.doResolve) {
                this.doResolve(null);
            }
        }, delay);
        return this.completionPromise;
    }
    isTriggered() {
        return this.timeout !== null;
    }
    cancel() {
        this.cancelTimeout();
        if (this.completionPromise) {
            if (this.doReject) {
                this.doReject(errors.canceled());
            }
            this.completionPromise = null;
        }
    }
    cancelTimeout() {
        if (this.timeout !== null) {
            clearTimeout(this.timeout);
            this.timeout = null;
        }
    }
    dispose() {
        this.cancelTimeout();
    }
}
export function timeout(millis, token) {
    if (!token) {
        return createCancelablePromise(token => timeout(millis, token));
    }
    return new Promise((resolve, reject) => {
        const handle = setTimeout(resolve, millis);
        token.onCancellationRequested(() => {
            clearTimeout(handle);
            reject(errors.canceled());
        });
    });
}
export function disposableTimeout(handler, timeout = 0) {
    const timer = setTimeout(handler, timeout);
    return toDisposable(() => clearTimeout(timer));
}
export function first(promiseFactories, shouldStop = t => !!t, defaultValue = null) {
    let index = 0;
    const len = promiseFactories.length;
    const loop = () => {
        if (index >= len) {
            return Promise.resolve(defaultValue);
        }
        const factory = promiseFactories[index++];
        const promise = Promise.resolve(factory());
        return promise.then(result => {
            if (shouldStop(result)) {
                return Promise.resolve(result);
            }
            return loop();
        });
    };
    return loop();
}
export class TimeoutTimer {
    constructor(runner, timeout) {
        this._token = -1;
        if (typeof runner === 'function' && typeof timeout === 'number') {
            this.setIfNotSet(runner, timeout);
        }
    }
    dispose() {
        this.cancel();
    }
    cancel() {
        if (this._token !== -1) {
            clearTimeout(this._token);
            this._token = -1;
        }
    }
    cancelAndSet(runner, timeout) {
        this.cancel();
        this._token = setTimeout(() => {
            this._token = -1;
            runner();
        }, timeout);
    }
    setIfNotSet(runner, timeout) {
        if (this._token !== -1) {
            // timer is already set
            return;
        }
        this._token = setTimeout(() => {
            this._token = -1;
            runner();
        }, timeout);
    }
}
export class IntervalTimer {
    constructor() {
        this._token = -1;
    }
    dispose() {
        this.cancel();
    }
    cancel() {
        if (this._token !== -1) {
            clearInterval(this._token);
            this._token = -1;
        }
    }
    cancelAndSet(runner, interval) {
        this.cancel();
        this._token = setInterval(() => {
            runner();
        }, interval);
    }
}
export class RunOnceScheduler {
    constructor(runner, delay) {
        this.timeoutToken = -1;
        this.runner = runner;
        this.timeout = delay;
        this.timeoutHandler = this.onTimeout.bind(this);
    }
    /**
     * Dispose RunOnceScheduler
     */
    dispose() {
        this.cancel();
        this.runner = null;
    }
    /**
     * Cancel current scheduled runner (if any).
     */
    cancel() {
        if (this.isScheduled()) {
            clearTimeout(this.timeoutToken);
            this.timeoutToken = -1;
        }
    }
    /**
     * Cancel previous runner (if any) & schedule a new runner.
     */
    schedule(delay = this.timeout) {
        this.cancel();
        this.timeoutToken = setTimeout(this.timeoutHandler, delay);
    }
    get delay() {
        return this.timeout;
    }
    set delay(value) {
        this.timeout = value;
    }
    /**
     * Returns true if scheduled.
     */
    isScheduled() {
        return this.timeoutToken !== -1;
    }
    onTimeout() {
        this.timeoutToken = -1;
        if (this.runner) {
            this.doRun();
        }
    }
    doRun() {
        if (this.runner) {
            this.runner();
        }
    }
}
/**
 * Execute the callback the next time the browser is idle
 */
export let runWhenIdle;
(function () {
    if (typeof requestIdleCallback !== 'function' || typeof cancelIdleCallback !== 'function') {
        const dummyIdle = Object.freeze({
            didTimeout: true,
            timeRemaining() { return 15; }
        });
        runWhenIdle = (runner) => {
            const handle = setTimeout(() => runner(dummyIdle));
            let disposed = false;
            return {
                dispose() {
                    if (disposed) {
                        return;
                    }
                    disposed = true;
                    clearTimeout(handle);
                }
            };
        };
    }
    else {
        runWhenIdle = (runner, timeout) => {
            const handle = requestIdleCallback(runner, typeof timeout === 'number' ? { timeout } : undefined);
            let disposed = false;
            return {
                dispose() {
                    if (disposed) {
                        return;
                    }
                    disposed = true;
                    cancelIdleCallback(handle);
                }
            };
        };
    }
})();
/**
 * An implementation of the "idle-until-urgent"-strategy as introduced
 * here: https://philipwalton.com/articles/idle-until-urgent/
 */
export class IdleValue {
    constructor(executor) {
        this._didRun = false;
        this._executor = () => {
            try {
                this._value = executor();
            }
            catch (err) {
                this._error = err;
            }
            finally {
                this._didRun = true;
            }
        };
        this._handle = runWhenIdle(() => this._executor());
    }
    dispose() {
        this._handle.dispose();
    }
    get value() {
        if (!this._didRun) {
            this._handle.dispose();
            this._executor();
        }
        if (this._error) {
            throw this._error;
        }
        return this._value;
    }
}
