// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements.  See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership.  The ASF licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License.  You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.

package clock

import "time"

// Clock allows for injecting fake or real clocks into code that
// needs to do arbitrary things based on time.
type Clock interface {
	Now() time.Time
	Since(time.Time) time.Duration
	After(d time.Duration) <-chan time.Time
	NewTimer(d time.Duration) Timer
	Sleep(d time.Duration)
	Tick(d time.Duration) <-chan time.Time
}

var _ = Clock(RealClock{})

// RealClock really calls time.Now()
type RealClock struct{}

// Now returns the current time.
func (RealClock) Now() time.Time {
	return time.Now()
}

// Since returns time since the specified timestamp.
func (RealClock) Since(ts time.Time) time.Duration {
	return time.Since(ts)
}

// After is the same as time.After(d).
func (RealClock) After(d time.Duration) <-chan time.Time {
	return time.After(d)
}

// NewTimer is the same as time.NewTimer(d)
func (RealClock) NewTimer(d time.Duration) Timer {
	return &realTimer{
		timer: time.NewTimer(d),
	}
}

// Tick is the same as time.Tick(d)
func (RealClock) Tick(d time.Duration) <-chan time.Time {
	return time.Tick(d)
}

// Sleep is the same as time.Sleep(d)
func (RealClock) Sleep(d time.Duration) {
	time.Sleep(d)
}

// Timer allows for injecting fake or real timers into code that
// needs to do arbitrary things based on time.
type Timer interface {
	C() <-chan time.Time
	Stop() bool
	Reset(d time.Duration) bool
}

var _ = Timer(&realTimer{})

// realTimer is backed by an actual time.Timer.
type realTimer struct {
	timer *time.Timer
}

// C returns the underlying timer's channel.
func (r *realTimer) C() <-chan time.Time {
	return r.timer.C
}

// Stop calls Stop() on the underlying timer.
func (r *realTimer) Stop() bool {
	return r.timer.Stop()
}

// Reset calls Reset() on the underlying timer.
func (r *realTimer) Reset(d time.Duration) bool {
	return r.timer.Reset(d)
}