package slots

import (
	"testing"
	"time"

	"github.com/prysmaticlabs/prysm/v4/config/params"
	"github.com/prysmaticlabs/prysm/v4/consensus-types/primitives"
	"github.com/stretchr/testify/require"
)

var _ Ticker = (*SlotTicker)(nil)

func TestSlotTicker(t *testing.T) {
	ticker := &SlotTicker{
		c:    make(chan primitives.Slot),
		done: make(chan struct{}),
	}
	defer ticker.Done()

	var sinceDuration time.Duration
	since := func(time.Time) time.Duration {
		return sinceDuration
	}

	var untilDuration time.Duration
	until := func(time.Time) time.Duration {
		return untilDuration
	}

	var tick chan time.Time
	after := func(time.Duration) <-chan time.Time {
		return tick
	}

	genesisTime := time.Date(2018, 1, 1, 0, 0, 0, 0, time.UTC)
	secondsPerSlot := uint64(8)

	// Test when the ticker starts immediately after genesis time.
	sinceDuration = 1 * time.Second
	untilDuration = 7 * time.Second
	// Make this a buffered channel to prevent a deadlock since
	// the other goroutine calls a function in this goroutine.
	tick = make(chan time.Time, 2)
	ticker.start(genesisTime, secondsPerSlot, since, until, after)

	// Tick once.
	tick <- time.Now()
	slot := <-ticker.C()
	if slot != 0 {
		t.Fatalf("Expected %d, got %d", 0, slot)
	}

	// Tick twice.
	tick <- time.Now()
	slot = <-ticker.C()
	if slot != 1 {
		t.Fatalf("Expected %d, got %d", 1, slot)
	}

	// Tick thrice.
	tick <- time.Now()
	slot = <-ticker.C()
	if slot != 2 {
		t.Fatalf("Expected %d, got %d", 2, slot)
	}
}

func TestSlotTickerGenesis(t *testing.T) {
	ticker := &SlotTicker{
		c:    make(chan primitives.Slot),
		done: make(chan struct{}),
	}
	defer ticker.Done()

	var sinceDuration time.Duration
	since := func(time.Time) time.Duration {
		return sinceDuration
	}

	var untilDuration time.Duration
	until := func(time.Time) time.Duration {
		return untilDuration
	}

	var tick chan time.Time
	after := func(time.Duration) <-chan time.Time {
		return tick
	}

	genesisTime := time.Date(2018, 1, 1, 0, 0, 0, 0, time.UTC)
	secondsPerSlot := uint64(8)

	// Test when the ticker starts before genesis time.
	sinceDuration = -1 * time.Second
	untilDuration = 1 * time.Second
	// Make this a buffered channel to prevent a deadlock since
	// the other goroutine calls a function in this goroutine.
	tick = make(chan time.Time, 2)
	ticker.start(genesisTime, secondsPerSlot, since, until, after)

	// Tick once.
	tick <- time.Now()
	slot := <-ticker.C()
	if slot != 0 {
		t.Fatalf("Expected %d, got %d", 0, slot)
	}

	// Tick twice.
	tick <- time.Now()
	slot = <-ticker.C()
	if slot != 1 {
		t.Fatalf("Expected %d, got %d", 1, slot)
	}
}

func TestGetSlotTickerWithOffset_OK(t *testing.T) {
	genesisTime := time.Now()
	secondsPerSlot := uint64(4)
	offset := time.Duration(secondsPerSlot/2) * time.Second

	offsetTicker := NewSlotTickerWithOffset(genesisTime, offset, secondsPerSlot)
	normalTicker := NewSlotTicker(genesisTime, secondsPerSlot)

	firstTicked := 0
	for {
		select {
		case <-offsetTicker.C():
			if firstTicked != 1 {
				t.Fatal("Expected other ticker to tick first")
			}
			return
		case <-normalTicker.C():
			if firstTicked != 0 {
				t.Fatal("Expected normal ticker to tick first")
			}
			firstTicked = 1
		}
	}
}

func TestGetSlotTickerWitIntervals(t *testing.T) {
	genesisTime := time.Now()
	offset := time.Duration(params.BeaconConfig().SecondsPerSlot) * time.Second / 3
	intervals := []time.Duration{offset, 2 * offset}

	intervalTicker := NewSlotTickerWithIntervals(genesisTime, intervals)
	normalTicker := NewSlotTicker(genesisTime, params.BeaconConfig().SecondsPerSlot)

	firstTicked := 0
	for {
		select {
		case <-intervalTicker.C():
			// interval ticks starts in second slot
			if firstTicked < 2 {
				t.Fatal("Expected other ticker to tick first")
			}
			return
		case <-normalTicker.C():
			if firstTicked > 1 {
				t.Fatal("Expected normal ticker to tick first")
			}
			firstTicked++
		}
	}
}

func TestSlotTickerWithIntervalsInputValidation(t *testing.T) {
	var genesisTime time.Time
	offset := time.Duration(params.BeaconConfig().SecondsPerSlot) * time.Second / 3
	intervals := make([]time.Duration, 0)
	panicCall := func() {
		NewSlotTickerWithIntervals(genesisTime, intervals)
	}
	require.Panics(t, panicCall, "zero genesis time")
	genesisTime = time.Now()
	require.Panics(t, panicCall, "at least one interval has to be entered")
	intervals = []time.Duration{2 * offset, offset}
	require.Panics(t, panicCall, "invalid decreasing offsets")
	intervals = []time.Duration{offset, 4 * offset}
	require.Panics(t, panicCall, "invalid ticker offset")
	intervals = []time.Duration{4 * offset, offset}
	require.Panics(t, panicCall, "invalid ticker offset")
	intervals = []time.Duration{offset, 2 * offset}
	require.NotPanics(t, panicCall)
}