package handlers_test

import (
	"net/http"
	"regexp"
	"strings"
	"testing"
	"time"

	"github.com/google/uuid"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
	"go.uber.org/fx/fxtest"
	"gorm.io/gorm"
	"gorm.io/gorm/clause"
	"sneak.berlin/go/webhooker/internal/config"
	"sneak.berlin/go/webhooker/internal/database"
	"sneak.berlin/go/webhooker/internal/handlers"
	"sneak.berlin/go/webhooker/internal/logger"
	"sneak.berlin/go/webhooker/internal/session"
)

// statsEntrypoint adds an entrypoint to a webhook and returns its path.
func statsEntrypoint(
	t *testing.T, db *database.Database, webhookID string, active bool,
) string {
	t.Helper()

	ep := &database.Entrypoint{
		WebhookID: webhookID,
		Path:      uuid.New().String(),
	}

	require.NoError(t, db.DB().Omit(clause.Associations).Create(ep).Error)
	require.NoError(t, db.DB().Model(ep).Update("active", active).Error)

	return ep.Path
}

// statsDelivery returns an event's delivery to a target.
func statsDelivery(
	t *testing.T, webhookDB *gorm.DB, eventID, targetID string,
) database.Delivery {
	t.Helper()

	var d database.Delivery

	require.NoError(t, webhookDB.Where(
		"event_id = ? AND target_id = ?", eventID, targetID,
	).First(&d).Error)

	return d
}

// statsFinish settles a delivery as the delivery engine does: its
// final status and the time it finished, and one more on its target's
// delivered or failed total, in one transaction.
func statsFinish(
	t *testing.T,
	webhookDB *gorm.DB,
	d database.Delivery,
	status database.DeliveryStatus,
	at time.Time,
) {
	t.Helper()

	add := database.TargetTotals{TargetID: d.TargetID, Delivered: 1}
	if status == database.DeliveryStatusFailed {
		add = database.TargetTotals{TargetID: d.TargetID, Failed: 1}
	}

	require.NoError(t, webhookDB.Transaction(func(tx *gorm.DB) error {
		err := tx.Model(&database.Delivery{}).
			Where("id = ?", d.ID).
			Updates(map[string]any{"status": status, "finished_at": at}).
			Error
		if err != nil {
			return err
		}

		return database.AddTargetTotals(tx, add)
	}))
}

// statsAge moves an event's arrival back to the given time.
func statsAge(
	t *testing.T, webhookDB *gorm.DB, eventID string, at time.Time,
) {
	t.Helper()

	require.NoError(t, webhookDB.Model(&database.Event{}).
		Where("id = ?", eventID).
		Update("created_at", at).Error)
}

// statsTargetTotals reads a webhook database's target totals, keyed by
// target.
func statsTargetTotals(
	t *testing.T, webhookDB *gorm.DB,
) map[string]database.TargetTotals {
	t.Helper()

	var rows []database.TargetTotals

	require.NoError(t, webhookDB.Find(&rows).Error)

	byTarget := make(map[string]database.TargetTotals, len(rows))
	for _, row := range rows {
		byTarget[row.TargetID] = row
	}

	return byTarget
}

// statsHistory is the webhook seedStatsHistory builds: its event
// database, its newest event, and its two active targets.
type statsHistory struct {
	webhook       *database.Webhook
	webhookDB     *gorm.DB
	newest        database.Event
	first, second string
}

// seedStatsHistory builds the webhook the statistics test checks: one
// day of retention, two entrypoints (one inactive) and three targets
// (one inactive). Three events arrive through the receiver, and so
// each has a delivery to the two active targets. The oldest event is
// past retention, the middle one six hours old, the newest just in.
// Their deliveries are settled as the delivery engine would, and a
// replay adds a pending delivery to the oldest event.
func seedStatsHistory(
	t *testing.T,
	h *handlers.Handlers,
	sess *session.Session,
	db *database.Database,
	dbMgr *database.WebhookDBManager,
) statsHistory {
	t.Helper()

	wh := &database.Webhook{
		UserID: deleteTestUserID, Name: "stats", RetentionDays: 1,
	}
	require.NoError(t, db.DB().Omit(clause.Associations).Create(wh).Error)

	path := statsEntrypoint(t, db, wh.ID, true)
	statsEntrypoint(t, db, wh.ID, false)

	first := seedConfiguredTarget(
		t, db, wh.ID, database.TargetTypeHTTP,
		`{"url":"`+replayTargetURL+`"}`,
	)
	second := seedTarget(t, db, wh.ID, database.TargetTypeLog)
	inactive := seedTarget(t, db, wh.ID, database.TargetTypeLog)
	require.NoError(t, db.DB().Model(inactive).
		Update("active", false).Error)

	router := receiverRouter(h)

	for range 3 {
		require.Equal(t, http.StatusOK, postReceiver(t, router, path))
	}

	webhookDB, err := dbMgr.GetDB(wh.ID)
	require.NoError(t, err)

	events := listEvents(t, webhookDB)
	require.Len(t, events, 3)

	oldest, middle, newest := events[0], events[1], events[2]
	now := time.Now()

	statsAge(t, webhookDB, oldest.ID, now.Add(-50*time.Hour))
	statsAge(t, webhookDB, middle.ID, now.Add(-6*time.Hour))

	oldestFailure := statsDelivery(t, webhookDB, oldest.ID, first.ID)
	statsFinish(t, webhookDB, oldestFailure,
		database.DeliveryStatusFailed, now.Add(-49*time.Hour))
	statsFinish(t, webhookDB,
		statsDelivery(t, webhookDB, oldest.ID, second.ID),
		database.DeliveryStatusDelivered, now.Add(-49*time.Hour))
	statsFinish(t, webhookDB,
		statsDelivery(t, webhookDB, middle.ID, first.ID),
		database.DeliveryStatusFailed, now.Add(-5*time.Hour))
	statsFinish(t, webhookDB,
		statsDelivery(t, webhookDB, middle.ID, second.ID),
		database.DeliveryStatusFailed, now.Add(-time.Minute))
	statsFinish(t, webhookDB,
		statsDelivery(t, webhookDB, newest.ID, first.ID),
		database.DeliveryStatusDelivered, now.Add(-2*time.Minute))

	require.Equal(t, http.StatusSeeOther,
		postReplay(t, h, sess, wh.ID, oldestFailure.ID).Code)

	return statsHistory{
		webhook:   wh,
		webhookDB: webhookDB,
		newest:    newest,
		first:     first.ID,
		second:    second.ID,
	}
}

// statsPrune runs the real retention reaper until it has removed one
// event from the webhook's database, then stops it.
func statsPrune(
	t *testing.T,
	db *database.Database,
	dbMgr *database.WebhookDBManager,
	log *logger.Logger,
	webhookDB *gorm.DB,
) {
	t.Helper()

	lc := fxtest.NewLifecycle(t)
	database.NewRetentionReaper(lc, database.RetentionReaperParams{
		Config: &config.Config{
			RetentionSweepInterval: 10 * time.Millisecond,
		},
		Database:  db,
		DBManager: dbMgr,
		Logger:    log,
	})

	lc.RequireStart()

	require.Eventually(t, func() bool {
		var totals database.EventTotals

		err := webhookDB.Take(&totals).Error

		return err == nil && totals.EventsRemoved == 1
	}, 10*time.Second, 10*time.Millisecond)

	lc.RequireStop()
}

// statsPane returns the text of the statistics pane in a rendered
// webhook page, everything from its heading to the next heading on the
// page, with the markup taken out and each run of space made one
// space. A table then reads header by header and row by row, each
// row's label followed by its figures in column order.
func statsPane(t *testing.T, page string) string {
	t.Helper()

	_, pane, found := strings.Cut(page, ">Statistics</h2>")
	require.True(t, found, "the page has no statistics pane")

	pane, _, _ = strings.Cut(pane, "<h2")
	pane = regexp.MustCompile(`<[^>]*>`).ReplaceAllString(pane, " ")

	return strings.Join(strings.Fields(pane), " ")
}

// assertStatsTargets checks, for the history seedStatsHistory builds,
// each target's totals and its deliveries finished in the last 24
// hours. The first target has three deliveries and the replay, the
// second three; the inactive target has none and so no row.
func assertStatsTargets(t *testing.T, hist statsHistory) {
	t.Helper()

	first, second := hist.first, hist.second

	assert.Equal(t, map[string]database.TargetTotals{
		first: {TargetID: first, Deliveries: 4, Delivered: 1, Failed: 2},
		second: {
			TargetID: second, Deliveries: 3, Delivered: 1, Failed: 1,
		},
	}, statsTargetTotals(t, hist.webhookDB))

	lastDay, err := handlers.FinishedByTargetForTest(
		hist.webhookDB, time.Now().Add(-24*time.Hour),
	)
	require.NoError(t, err)
	assert.ElementsMatch(t, []handlers.TargetFinished{
		{TargetID: first, Delivered: 1, Failed: 1},
		{TargetID: second, Failed: 1},
	}, lastDay)
}

// assertStatsPaneAfterPrune checks the rendered statistics pane for the
// history seedStatsHistory builds, once retention has removed the
// oldest event: each figure after its label, in its column.
func assertStatsPaneAfterPrune(
	t *testing.T,
	h *handlers.Handlers,
	sess *session.Session,
	hist statsHistory,
) {
	t.Helper()

	pane := statsPane(t, renderSourceDetailPage(t, h, sess, hist.webhook.ID))
	lastEvent := hist.newest.CreatedAt.Format("2006-01-02 15:04:05 UTC")

	assert.Contains(t, pane, "Entrypoints 2 (1 active) "+
		"Targets 3 (2 active) "+
		"Deliveries in progress 1 "+
		"Last event "+lastEvent+" "+
		"Retention 1 day")
	assert.Contains(t, pane, "Lifetime Within retention "+
		"Events 3 2 "+
		"Deliveries 7 4 "+
		"Failures 3 2")
	assert.Contains(t, pane, "Last 10 minutes Last 24 hours "+
		"Events 1 2 "+
		"Failures 1 2 "+
		"Failure percentage 50.0% 66.7%")
}

// TestWebhookStats_EveryFigureAcrossRetentionPrune checks every figure
// the statistics pane shows for the history seedStatsHistory builds,
// and each target's totals and recent figures, before and after the
// real retention reaper removes the oldest event.
func TestWebhookStats_EveryFigureAcrossRetentionPrune(t *testing.T) {
	t.Parallel()

	var (
		h     *handlers.Handlers
		sess  *session.Session
		db    *database.Database
		dbMgr *database.WebhookDBManager
		log   *logger.Logger
	)

	app := newTestApp(t, &h, &sess, &db, &dbMgr, &log)
	app.RequireStart()

	t.Cleanup(app.RequireStop)

	hist := seedStatsHistory(t, h, sess, db, dbMgr)
	first, second := hist.first, hist.second

	stats := h.WebhookStatsForTest(hist.webhook.ID)
	require.NotNil(t, stats)

	assert.Equal(t, 2, stats.Entrypoints)
	assert.Equal(t, 1, stats.ActiveEntrypoints)
	assert.Equal(t, 3, stats.Targets)
	assert.Equal(t, 2, stats.ActiveTargets)
	assert.Equal(t, handlers.Counts{Events: 3, Deliveries: 7, Failures: 3},
		stats.Lifetime)
	assert.Equal(t, stats.Lifetime, stats.WithinRetention)
	assert.Equal(t, int64(2), stats.InProgress)
	require.NotNil(t, stats.LastEventAt)
	assert.True(t, hist.newest.CreatedAt.Equal(*stats.LastEventAt))
	assert.Equal(t, handlers.RecentWindow{
		Events: 1, Delivered: 1, Failed: 1,
	}, stats.Last10Minutes)
	assert.Equal(t, handlers.RecentWindow{
		Events: 2, Delivered: 1, Failed: 2,
	}, stats.Last24Hours)
	assert.Equal(t, "50.0%", stats.Last10Minutes.FailurePercent())
	assert.Equal(t, "66.7%", stats.Last24Hours.FailurePercent())

	assertStatsTargets(t, hist)

	// Retention removes the oldest event with its three deliveries:
	// the first target's failed one and the pending replay, and the
	// second target's delivered one.
	statsPrune(t, db, dbMgr, log, hist.webhookDB)

	after := h.WebhookStatsForTest(hist.webhook.ID)
	require.NotNil(t, after)

	assert.Equal(t, stats.Lifetime, after.Lifetime)
	assert.Equal(t, handlers.Counts{Events: 2, Deliveries: 4, Failures: 2},
		after.WithinRetention)
	assert.Equal(t, int64(1), after.InProgress)
	assert.Equal(t, stats.LastEventAt, after.LastEventAt)
	assert.Equal(t, stats.Last10Minutes, after.Last10Minutes)
	assert.Equal(t, stats.Last24Hours, after.Last24Hours)

	assert.Equal(t, map[string]database.TargetTotals{
		first: {
			TargetID: first, Deliveries: 4, Delivered: 1, Failed: 2,
			DeliveriesRemoved: 2, FailedRemoved: 1,
		},
		second: {
			TargetID: second, Deliveries: 3, Delivered: 1, Failed: 1,
			DeliveriesRemoved: 1,
		},
	}, statsTargetTotals(t, hist.webhookDB))

	assertStatsPaneAfterPrune(t, h, sess, hist)
}

// TestWebhookStats_LastEventSurvivesPruningEveryEvent checks that once
// retention has removed every event, the pane still shows when the last
// one arrived rather than "none".
func TestWebhookStats_LastEventSurvivesPruningEveryEvent(t *testing.T) {
	t.Parallel()

	var (
		h     *handlers.Handlers
		sess  *session.Session
		db    *database.Database
		dbMgr *database.WebhookDBManager
		log   *logger.Logger
	)

	app := newTestApp(t, &h, &sess, &db, &dbMgr, &log)
	app.RequireStart()

	t.Cleanup(app.RequireStop)

	wh := &database.Webhook{
		UserID: deleteTestUserID, Name: "pruned", RetentionDays: 1,
	}
	require.NoError(t, db.DB().Omit(clause.Associations).Create(wh).Error)

	path := statsEntrypoint(t, db, wh.ID, true)
	require.Equal(t, http.StatusOK,
		postReceiver(t, receiverRouter(h), path))

	webhookDB, err := dbMgr.GetDB(wh.ID)
	require.NoError(t, err)

	events := listEvents(t, webhookDB)
	require.Len(t, events, 1)

	arrived := events[0].CreatedAt

	statsAge(t, webhookDB, events[0].ID, time.Now().Add(-50*time.Hour))
	statsPrune(t, db, dbMgr, log, webhookDB)
	require.Empty(t, listEvents(t, webhookDB))

	stats := h.WebhookStatsForTest(wh.ID)
	require.NotNil(t, stats)
	require.NotNil(t, stats.LastEventAt)
	assert.True(t, arrived.Equal(*stats.LastEventAt))

	pane := statsPane(t, renderSourceDetailPage(t, h, sess, wh.ID))
	assert.Contains(t, pane,
		"Last event "+arrived.Format("2006-01-02 15:04:05 UTC"))
}

// TestWebhookStats_PaneShowsRetentionPeriod checks that the statistics
// pane itself, not only the line at the foot of the page, shows the
// webhook's retention period, for a finite one and for forever.
func TestWebhookStats_PaneShowsRetentionPeriod(t *testing.T) {
	t.Parallel()

	var (
		h    *handlers.Handlers
		sess *session.Session
		db   *database.Database
	)

	app := newTestApp(t, &h, &sess, &db)
	app.RequireStart()

	t.Cleanup(app.RequireStop)

	tests := []struct {
		retentionDays int
		want          string
	}{
		{30, "30 days"},
		{database.RetentionForeverDays, "forever"},
	}

	for _, tt := range tests {
		wh := &database.Webhook{
			UserID:        deleteTestUserID,
			Name:          "retention",
			RetentionDays: tt.retentionDays,
		}
		require.NoError(t,
			db.DB().Omit(clause.Associations).Create(wh).Error)

		pane := statsPane(t, renderSourceDetailPage(t, h, sess, wh.ID))
		assert.Contains(t, pane, "Retention "+tt.want)
	}
}

// TestWebhookStats_WebhookWithNoEvents covers a webhook whose event
// database has never been opened: every count is zero, the
// percentages are a dash, and showing the page does not create the
// database.
func TestWebhookStats_WebhookWithNoEvents(t *testing.T) {
	t.Parallel()

	var (
		h     *handlers.Handlers
		sess  *session.Session
		db    *database.Database
		dbMgr *database.WebhookDBManager
	)

	app := newTestApp(t, &h, &sess, &db, &dbMgr)
	app.RequireStart()

	t.Cleanup(app.RequireStop)

	wh := seedWebhook(t, db)

	assert.Equal(t, &handlers.WebhookStats{}, h.WebhookStatsForTest(wh.ID))
	assert.Equal(t, "—", handlers.RecentWindow{}.FailurePercent())

	pane := statsPane(t, renderSourceDetailPage(t, h, sess, wh.ID))
	assert.Contains(t, pane, "Last event none")
	assert.Contains(t, pane, "Failure percentage — —")
	assert.False(t, dbMgr.DBExists(wh.ID))
}

// TestRecentWindow_FailurePercent pins the percentage: failed
// deliveries out of all that finished in the window.
func TestRecentWindow_FailurePercent(t *testing.T) {
	t.Parallel()

	tests := []struct {
		window handlers.RecentWindow
		want   string
	}{
		{handlers.RecentWindow{}, "—"},
		{handlers.RecentWindow{Events: 4}, "—"},
		{handlers.RecentWindow{Delivered: 3, Failed: 1}, "25.0%"},
		{handlers.RecentWindow{Failed: 2}, "100.0%"},
		{handlers.RecentWindow{Delivered: 2}, "0.0%"},
	}

	for _, tt := range tests {
		assert.Equal(t, tt.want, tt.window.FailurePercent(), tt.window)
	}
}