package database_test

import (
	"context"
	"reflect"
	"strconv"
	"testing"
	"time"

	"github.com/google/uuid"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
	"gorm.io/gorm"
	"gorm.io/gorm/clause"
	"sneak.berlin/go/webhooker/internal/database"
)

// startedTestDB returns a started main database for model-level tests.
func startedTestDB(t *testing.T) *gorm.DB {
	t.Helper()

	db, lc := setupTestDB(t)

	ctx := context.Background()
	require.NoError(t, lc.Start(ctx))
	t.Cleanup(func() { require.NoError(t, lc.Stop(ctx)) })

	return db.DB()
}

// storedRetention reads the retention_days column straight out of the
// row, so the assertion is about what was persisted rather than about
// whatever the in-memory struct happens to hold.
func storedRetention(t *testing.T, db *gorm.DB, id string) int {
	t.Helper()

	var got int

	require.NoError(
		t,
		db.Model(&database.Webhook{}).
			Where("id = ?", id).
			Pluck("retention_days", &got).Error,
	)

	return got
}

// newWebhookWithRetention creates a webhook through the ordinary Create
// path, so the BeforeSave hook and the GORM column default both apply
// exactly as they do in production.
func newWebhookWithRetention(
	t *testing.T,
	db *gorm.DB,
	wh *database.Webhook,
) string {
	t.Helper()

	wh.UserID = uuid.New().String()
	wh.Name = testWebhookName

	require.NoError(
		t,
		db.Omit(clause.Associations).Create(wh).Error,
	)

	return wh.ID
}

func TestWebhookBeforeSave_ZeroBecomesForeverSentinel(t *testing.T) {
	t.Parallel()

	db := startedTestDB(t)

	wh := &database.Webhook{RetentionDays: 0}
	id := newWebhookWithRetention(t, db, wh)

	assert.Equal(
		t,
		database.RetentionForeverDays,
		storedRetention(t, db, id),
		"a zero retention must be stored as the sentinel, "+
			"not replaced by the column default",
	)
}

func TestWebhookBeforeSave_NegativeBecomesForeverSentinel(t *testing.T) {
	t.Parallel()

	db := startedTestDB(t)

	wh := &database.Webhook{RetentionDays: -5}
	id := newWebhookWithRetention(t, db, wh)

	assert.Equal(
		t,
		database.RetentionForeverDays,
		storedRetention(t, db, id),
	)
}

func TestWebhookBeforeSave_PositiveIsPreserved(t *testing.T) {
	t.Parallel()

	db := startedTestDB(t)

	wh := &database.Webhook{RetentionDays: 7}
	id := newWebhookWithRetention(t, db, wh)

	assert.Equal(t, 7, storedRetention(t, db, id))
}

// TestWebhookBeforeSave_UpdateToZeroBecomesSentinel proves the hook
// fires on update as well as insert, via the same Save call the edit
// handler makes.
func TestWebhookBeforeSave_UpdateToZeroBecomesSentinel(t *testing.T) {
	t.Parallel()

	db := startedTestDB(t)

	wh := &database.Webhook{RetentionDays: 30}
	id := newWebhookWithRetention(t, db, wh)
	require.Equal(t, 30, storedRetention(t, db, id))

	wh.RetentionDays = 0
	require.NoError(t, db.Omit(clause.Associations).Save(wh).Error)

	assert.Equal(
		t,
		database.RetentionForeverDays,
		storedRetention(t, db, id),
	)
}

// TestWebhookRetentionColumnDefaultMatchesConstant guards the one place
// the default lives twice: a struct tag cannot reference a constant, so
// this asserts the tag and DefaultRetentionDays agree.
func TestWebhookRetentionColumnDefaultMatchesConstant(t *testing.T) {
	t.Parallel()

	field, ok := reflect.TypeFor[database.Webhook]().
		FieldByName("RetentionDays")
	require.True(t, ok, "Webhook.RetentionDays must exist")

	assert.Equal(
		t,
		"default:"+strconv.Itoa(database.DefaultRetentionDays),
		field.Tag.Get("gorm"),
	)
}

// TestMaxFiniteRetentionDaysIsTheOverflowCeiling asserts that the
// constant is exactly where the cutoff arithmetic stops working, which
// is what makes it a derived bound rather than a round number someone
// liked. One day more wraps the int64 nanosecond count negative, and a
// negative span is precisely what turned a cutoff into a future
// timestamp that matched — and deleted — every row.
//
// The multiplications are done through variables on purpose: as
// constant expressions the overflowing one would not compile.
func TestMaxFiniteRetentionDaysIsTheOverflowCeiling(t *testing.T) {
	t.Parallel()

	const hoursPerDay = 24

	atCeiling := database.MaxFiniteRetentionDays
	overCeiling := database.MaxFiniteRetentionDays + 1

	assert.Positive(
		t,
		time.Duration(atCeiling*hoursPerDay)*time.Hour,
		"the ceiling itself must still be representable",
	)
	assert.Negative(
		t,
		time.Duration(overCeiling*hoursPerDay)*time.Hour,
		"one day past the ceiling must overflow",
	)

	assert.Less(
		t,
		database.MaxFiniteRetentionDays,
		database.RetentionForeverDays,
		"the sentinel sits above the ceiling and is only safe "+
			"because retain-forever webhooks skip the arithmetic",
	)
}

func TestWebhookRetainsForeverAndLabel(t *testing.T) {
	t.Parallel()

	cases := []struct {
		name    string
		days    int
		forever bool
		label   string
	}{
		{
			"sentinel",
			database.RetentionForeverDays, true, testForeverLabel,
		},
		{
			"above sentinel",
			database.RetentionForeverDays + 1, true, testForeverLabel,
		},
		{"legacy zero", 0, true, testForeverLabel},
		{"legacy negative", -1, true, testForeverLabel},
		{"default", database.DefaultRetentionDays, false, "30 days"},
		{"one day", 1, false, "1 day"},
	}

	for _, tc := range cases {
		t.Run(tc.name, func(t *testing.T) {
			t.Parallel()

			wh := database.Webhook{RetentionDays: tc.days}

			assert.Equal(t, tc.forever, wh.RetainsForever())
			assert.Equal(t, tc.label, wh.RetentionLabel())
		})
	}
}