// Copyright (c) 2021 Uber Technologies, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

package fxclock

import (
	"context"
	"time"
)

// Clock defines how Fx accesses time.
// The interface is pretty minimal but it matches github.com/benbjohnson/clock.
// We intentionally don't use that interface directly;
// this keeps it a test dependency for us.
type Clock interface {
	Now() time.Time
	Since(time.Time) time.Duration
	Sleep(time.Duration)
	WithTimeout(context.Context, time.Duration) (context.Context, context.CancelFunc)
}

// System is the default implementation of Clock based on real time.
var System Clock = systemClock{}

type systemClock struct{}

func (systemClock) Now() time.Time {
	return time.Now()
}

func (systemClock) Since(t time.Time) time.Duration {
	return time.Since(t)
}

func (systemClock) Sleep(d time.Duration) {
	time.Sleep(d)
}

func (systemClock) WithTimeout(ctx context.Context, d time.Duration) (context.Context, context.CancelFunc) {
	return context.WithTimeout(ctx, d)
}