package chanfitness

import (
	"testing"
	"time"

	"github.com/lightningnetwork/lnd/clock"
)

// TestAdd tests adding events to an event log. It tests the case where the
// channel is open, and should have an event added, and the case where it is
// closed and the event should not be added.
func TestAdd(t *testing.T) {
	tests := []struct {
		name     string
		eventLog *chanEventLog
		event    eventType
		expected []eventType
	}{
		{
			name: "Channel open",
			eventLog: &chanEventLog{
				clock: clock.NewTestClock(testNow),
			},
			event:    peerOnlineEvent,
			expected: []eventType{peerOnlineEvent},
		},
		{
			name: "Channel closed, event not added",
			eventLog: &chanEventLog{
				clock: clock.NewTestClock(testNow),
			},
			event:    peerOnlineEvent,
			expected: []eventType{},
		},
	}

	for _, test := range tests {
		test := test

		t.Run(test.name, func(t *testing.T) {
			test.eventLog.add(test.event)

			for i, e := range test.expected {
				eventType := test.eventLog.events[i].eventType
				if eventType != e {
					t.Fatalf("Expected event type: %v, "+
						"got: %v", e, eventType,
					)
				}
			}
		})
	}
}

// TestGetOnlinePeriod tests the getOnlinePeriod function. It tests the case
// where no events present, and the case where an additional online period
// must be added because the event log ends on an online event.
func TestGetOnlinePeriod(t *testing.T) {
	fourHoursAgo := testNow.Add(time.Hour * -4)
	threeHoursAgo := testNow.Add(time.Hour * -3)
	twoHoursAgo := testNow.Add(time.Hour * -2)
	oneHourAgo := testNow.Add(time.Hour * -1)

	tests := []struct {
		name           string
		events         []*channelEvent
		expectedOnline []*onlinePeriod
		openedAt       time.Time
		closedAt       time.Time
	}{
		{
			name: "No events",
		},
		{
			name: "Start on online period",
			events: []*channelEvent{
				{
					timestamp: threeHoursAgo,
					eventType: peerOnlineEvent,
				},
				{
					timestamp: twoHoursAgo,
					eventType: peerOfflineEvent,
				},
			},
			expectedOnline: []*onlinePeriod{
				{
					start: threeHoursAgo,
					end:   twoHoursAgo,
				},
			},
		},
		{
			name: "Start on offline period",
			events: []*channelEvent{
				{
					timestamp: fourHoursAgo,
					eventType: peerOfflineEvent,
				},
			},
		},
		{
			name: "End on an online period, channel not closed",
			events: []*channelEvent{
				{
					timestamp: fourHoursAgo,
					eventType: peerOnlineEvent,
				},
			},
			expectedOnline: []*onlinePeriod{
				{
					start: fourHoursAgo,
					end:   testNow,
				},
			},
		},
		{
			name: "End on an online period, channel closed",
			events: []*channelEvent{
				{
					timestamp: fourHoursAgo,
					eventType: peerOnlineEvent,
				},
			},
			expectedOnline: []*onlinePeriod{
				{
					start: fourHoursAgo,
					end:   oneHourAgo,
				},
			},
			closedAt: oneHourAgo,
		},
	}

	for _, test := range tests {
		test := test

		t.Run(test.name, func(t *testing.T) {
			score := &chanEventLog{
				events:   test.events,
				clock:    clock.NewTestClock(testNow),
				openedAt: test.openedAt,
				closedAt: test.closedAt,
			}

			online := score.getOnlinePeriods()

			if len(online) != len(test.expectedOnline) {
				t.Fatalf("Expectd: %v online periods, got: %v",
					len(test.expectedOnline), len(online))
			}

			for i, o := range test.expectedOnline {
				if online[i].start != o.start {
					t.Errorf("Expected start: %v, got "+
						"%v", o.start, online[i].start)
				}

				if online[i].end != o.end {
					t.Errorf("Expected end: %v, got %v",
						o.end, online[i].end)
				}
			}
		})

	}
}

// TestUptime tests channel uptime calculation based on its event log.
func TestUptime(t *testing.T) {
	fourHoursAgo := testNow.Add(time.Hour * -4)
	threeHoursAgo := testNow.Add(time.Hour * -3)
	twoHoursAgo := testNow.Add(time.Hour * -2)
	oneHourAgo := testNow.Add(time.Hour * -1)

	tests := []struct {
		name string

		// opened at is the time the channel was recorded as being open,
		// and is never expected to be zero.
		openedAt time.Time

		// closed at is the time the channel was recorded as being
		// closed, and can have a zero value if the channel is not
		// closed.
		closedAt time.Time

		// events is the set of event log that we are calculating uptime
		// for.
		events []*channelEvent

		// startTime is the beginning of the period that we are
		// calculating uptime for, it cannot have a zero value.
		startTime time.Time

		// endTime is the end of the period that we are calculating
		// uptime for, it cannot have a zero value.
		endTime time.Time

		// expectedUptime is the amount of uptime we expect to be
		// calculated over the period specified by startTime and
		// endTime.
		expectedUptime time.Duration

		// expectErr is set to true if we expect an error to be returned
		// when calling the uptime function.
		expectErr bool
	}{
		{
			name:      "End before start",
			endTime:   threeHoursAgo,
			startTime: testNow,
			expectErr: true,
		},
		{
			name:      "Zero end time",
			expectErr: true,
		},
		{
			name:     "Online event and closed",
			openedAt: fourHoursAgo,
			closedAt: oneHourAgo,
			events: []*channelEvent{
				{
					timestamp: fourHoursAgo,
					eventType: peerOnlineEvent,
				},
			},
			startTime:      fourHoursAgo,
			endTime:        testNow,
			expectedUptime: time.Hour * 3,
		},
		{
			name:     "Online event and not closed",
			openedAt: fourHoursAgo,
			events: []*channelEvent{
				{
					timestamp: fourHoursAgo,
					eventType: peerOnlineEvent,
				},
			},
			startTime:      fourHoursAgo,
			endTime:        testNow,
			expectedUptime: time.Hour * 4,
		},
		{
			name:     "Offline event and closed",
			openedAt: fourHoursAgo,
			closedAt: threeHoursAgo,
			events: []*channelEvent{
				{
					timestamp: fourHoursAgo,
					eventType: peerOfflineEvent,
				},
			},
			startTime: fourHoursAgo,
			endTime:   testNow,
		},
		{
			name:     "Online event before close",
			openedAt: fourHoursAgo,
			closedAt: oneHourAgo,
			events: []*channelEvent{
				{
					timestamp: twoHoursAgo,
					eventType: peerOnlineEvent,
				},
			},
			startTime:      fourHoursAgo,
			endTime:        testNow,
			expectedUptime: time.Hour,
		},
		{
			name:     "Online then offline event",
			openedAt: fourHoursAgo,
			closedAt: oneHourAgo,
			events: []*channelEvent{
				{
					timestamp: threeHoursAgo,
					eventType: peerOnlineEvent,
				},
				{
					timestamp: twoHoursAgo,
					eventType: peerOfflineEvent,
				},
			},
			startTime:      fourHoursAgo,
			endTime:        testNow,
			expectedUptime: time.Hour,
		},
		{
			name:     "Online event before uptime period",
			openedAt: fourHoursAgo,
			closedAt: oneHourAgo,
			events: []*channelEvent{
				{
					timestamp: threeHoursAgo,
					eventType: peerOnlineEvent,
				},
			},
			startTime:      twoHoursAgo,
			endTime:        testNow,
			expectedUptime: time.Hour,
		},
		{
			name:     "Offline event after uptime period",
			openedAt: fourHoursAgo,
			events: []*channelEvent{
				{
					timestamp: fourHoursAgo,
					eventType: peerOnlineEvent,
				},
				{
					timestamp: testNow.Add(time.Hour),
					eventType: peerOfflineEvent,
				},
			},
			startTime:      twoHoursAgo,
			endTime:        testNow,
			expectedUptime: time.Hour * 2,
		},
		{
			name:     "All events within period",
			openedAt: fourHoursAgo,
			events: []*channelEvent{
				{
					timestamp: twoHoursAgo,
					eventType: peerOnlineEvent,
				},
			},
			startTime:      threeHoursAgo,
			endTime:        oneHourAgo,
			expectedUptime: time.Hour,
		},
		{
			name:     "Multiple online and offline",
			openedAt: testNow.Add(time.Hour * -8),
			events: []*channelEvent{
				{
					timestamp: testNow.Add(time.Hour * -7),
					eventType: peerOnlineEvent,
				},
				{
					timestamp: testNow.Add(time.Hour * -6),
					eventType: peerOfflineEvent,
				},
				{
					timestamp: testNow.Add(time.Hour * -5),
					eventType: peerOnlineEvent,
				},
				{
					timestamp: testNow.Add(time.Hour * -4),
					eventType: peerOfflineEvent,
				},
				{
					timestamp: testNow.Add(time.Hour * -3),
					eventType: peerOnlineEvent,
				},
			},
			startTime:      testNow.Add(time.Hour * -8),
			endTime:        oneHourAgo,
			expectedUptime: time.Hour * 4,
		},
	}

	for _, test := range tests {
		test := test

		t.Run(test.name, func(t *testing.T) {
			score := &chanEventLog{
				events:   test.events,
				clock:    clock.NewTestClock(testNow),
				openedAt: test.openedAt,
				closedAt: test.closedAt,
			}

			uptime, err := score.uptime(
				test.startTime, test.endTime,
			)
			if test.expectErr && err == nil {
				t.Fatal("Expected an error, got nil")
			}
			if !test.expectErr && err != nil {
				t.Fatalf("Expcted no error, got: %v", err)
			}

			if uptime != test.expectedUptime {
				t.Errorf("Expected uptime: %v, got: %v",
					test.expectedUptime, uptime)
			}
		})
	}
}