package delivery_test

import (
	"os"
	"path/filepath"
	"strings"
	"testing"
	"time"

	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
	"sneak.berlin/go/webhooker/internal/database"
	"sneak.berlin/go/webhooker/internal/delivery"
)

// The archive rotations, and the configs of a daily target and of one
// whose rotation is not one of the four.
const (
	rotationNone    = "none"
	rotationMonthly = "monthly"
	rotationDaily   = "daily"
	rotationHourly  = "hourly"

	dailyConfig  = `{"rotation":"daily"}`
	weeklyConfig = `{"rotation":"weekly"}`
)

// The periods the tests archive into most: two days, and an hour of
// the first.
const (
	dayPeriod     = "2026-03-04"
	nextDayPeriod = "2026-03-05"
	hourPeriod    = "2026-03-04-05"
)

// periodPath returns the archive file for a period of the target whose
// file without a period is path.
func periodPath(path, period string) string {
	return strings.TrimSuffix(path, ".db") + "-" + period + ".db"
}

// deliverReceivedAt delivers to a database target an event whose
// receive time is receivedAt, and returns the event's id. The receive
// time is what decides a rotated archive's file, so setting it is how
// these tests move the clock across a period boundary.
func (env *archiveEnv) deliverReceivedAt(
	t *testing.T, tgt *database.Target, receivedAt time.Time,
) string {
	t.Helper()

	webhookDB := testWebhookDB(t)
	event := seedEvent(t, webhookDB, `{"n":1}`)
	event.CreatedAt = receivedAt

	env.eng.ExportDeliverDatabase(
		webhookDB, seedDatabaseTargetDelivery(t, webhookDB, event, tgt),
	)

	return event.ID
}

// TestDeliverDatabase_RotatesAtEachPeriodBoundary delivers, for each
// rotation, an event received in the last second of a period and one
// received in the first second of the next, and checks each lands in
// the file named for its own period, in UTC. Rotation none keeps both
// in the one file.
func TestDeliverDatabase_RotatesAtEachPeriodBoundary(t *testing.T) {
	t.Parallel()

	berlin := time.FixedZone("CEST", 2*60*60)

	cases := []struct {
		name          string
		rotation      string
		before, after time.Time
		// periods are the periods of before and after.
		periods [2]string
	}{
		{
			rotationMonthly, rotationMonthly,
			time.Date(2026, 1, 31, 23, 59, 59, 0, time.UTC),
			time.Date(2026, 2, 1, 0, 0, 0, 0, time.UTC),
			[2]string{"2026-01", "2026-02"},
		},
		{
			rotationDaily, rotationDaily,
			time.Date(2026, 3, 4, 23, 59, 59, 0, time.UTC),
			time.Date(2026, 3, 5, 0, 0, 0, 0, time.UTC),
			[2]string{dayPeriod, nextDayPeriod},
		},
		{
			// The same instants, received in a zone two hours ahead
			// of UTC, where they fall on 5 March: the period is UTC's.
			"daily in another zone", rotationDaily,
			time.Date(2026, 3, 5, 1, 59, 59, 0, berlin),
			time.Date(2026, 3, 5, 2, 0, 0, 0, berlin),
			[2]string{dayPeriod, nextDayPeriod},
		},
		{
			rotationHourly, rotationHourly,
			time.Date(2026, 3, 4, 5, 59, 59, 0, time.UTC),
			time.Date(2026, 3, 4, 6, 0, 0, 0, time.UTC),
			[2]string{hourPeriod, "2026-03-04-06"},
		},
	}

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

			env := setupArchiveTest(t)
			tgt := env.seedDatabaseTarget(t, `{"rotation":"`+tc.rotation+`"}`)
			path := env.archivePath(tgt)

			first := env.deliverReceivedAt(t, tgt, tc.before)
			second := env.deliverReceivedAt(t, tgt, tc.after)

			assert.Equal(t, []string{first},
				archivedEventIDs(t, periodPath(path, tc.periods[0])))
			assert.Equal(t, []string{second},
				archivedEventIDs(t, periodPath(path, tc.periods[1])))
			assert.NoFileExists(t, path,
				"a rotated target never writes the file without a period")
		})
	}

	t.Run(rotationNone, func(t *testing.T) {
		t.Parallel()

		env := setupArchiveTest(t)
		tgt := env.seedDatabaseTarget(t, `{"rotation":"`+rotationNone+`"}`)

		first := env.deliverReceivedAt(t, tgt, cases[0].before)
		second := env.deliverReceivedAt(t, tgt, cases[0].after)

		assert.ElementsMatch(t, []string{first, second},
			archivedEventIDs(t, env.archivePath(tgt)))
	})
}

// TestDeliverDatabase_EventWithoutReceiveTime proves an event whose
// receive time is not known goes to the file for the time it is
// archived, rather than to one for the year 1.
func TestDeliverDatabase_EventWithoutReceiveTime(t *testing.T) {
	t.Parallel()

	env := setupArchiveTest(t)
	tgt := env.seedDatabaseTarget(t, `{"rotation":"`+rotationMonthly+`"}`)
	path := env.archivePath(tgt)

	before := time.Now().UTC().Format("2006-01")
	id := env.deliverReceivedAt(t, tgt, time.Time{})

	file := periodPath(path, time.Now().UTC().Format("2006-01"))

	_, err := os.Stat(file)
	if err != nil {
		// The month turned during the delivery.
		file = periodPath(path, before)
	}

	assert.Equal(t, []string{id}, archivedEventIDs(t, file))
	assert.NoFileExists(t, periodPath(path, "0001-01"))
}

// TestDeliverDatabase_RotationChangeKeepsOldFiles changes a target's
// rotation from none to daily between two events, and checks the
// second goes to the daily file while the first stays where it was.
func TestDeliverDatabase_RotationChangeKeepsOldFiles(t *testing.T) {
	t.Parallel()

	env := setupArchiveTest(t)
	tgt := env.seedDatabaseTarget(t, "")
	path := env.archivePath(tgt)
	at := time.Date(2026, 3, 4, 12, 0, 0, 0, time.UTC)

	first := env.deliverReceivedAt(t, tgt, at)

	tgt.Config = dailyConfig
	second := env.deliverReceivedAt(t, tgt, at)

	assert.Equal(t, []string{first}, archivedEventIDs(t, path))
	assert.Equal(t, []string{second},
		archivedEventIDs(t, periodPath(path, dayPeriod)))
}

// TestArchiveSweep_PrunesEveryFile gives a daily target three files:
// the file without a period, left from before it rotated, and two
// daily files. Each holds a row older than the expiry, and one daily
// file also a newer row. The sweep prunes the old row from every file,
// deletes the daily file it leaves empty, and keeps the file without a
// period although it is empty too.
func TestArchiveSweep_PrunesEveryFile(t *testing.T) {
	t.Parallel()

	env := setupArchiveTest(t)
	tgt := env.seedDatabaseTarget(
		t, `{"expiry":"1h","rotation":"`+rotationDaily+`"}`,
	)
	path := env.archivePath(tgt)
	emptied := periodPath(path, dayPeriod)
	kept := periodPath(path, nextDayPeriod)

	now := time.Now()
	old := now.Add(-48 * time.Hour)

	seedArchiveFile(t, path, tgt.WebhookID, old)
	seedArchiveFile(t, emptied, tgt.WebhookID, old)
	seedArchiveFile(t, kept, tgt.WebhookID, old, now.Add(-time.Minute))

	env.sweeper.ExportSweep(t.Context())

	assert.Empty(t, archivedEventIDs(t, path))
	assert.Equal(t, []string{sweepRowNew}, archivedEventIDs(t, kept))

	for _, suffix := range archiveFileSuffixes() {
		assert.NoFileExists(t, emptied+suffix)
	}
}

// TestRename_MovesEveryFile renames a daily target that also has a
// file without a period, and checks every file moves to the new name
// with its period, rows and all, and that a later write uses the new
// name.
func TestRename_MovesEveryFile(t *testing.T) {
	t.Parallel()

	env := setupArchiveTest(t)
	tgt := env.seedDatabaseTarget(t, "")
	oldPath := env.archivePath(tgt)
	day := time.Date(2026, 3, 4, 12, 0, 0, 0, time.UTC)

	unrotated := env.deliverReceivedAt(t, tgt, day)

	tgt.Config = dailyConfig
	first := env.deliverReceivedAt(t, tgt, day)
	second := env.deliverReceivedAt(t, tgt, day.Add(24*time.Hour))

	require.NoError(t, env.eng.Rename(tgt.ID, "Orders", "Long Term"))

	newPath := filepath.Join(
		env.dataDir, "archive-orders-long-term-"+tgt.ID+".db",
	)

	for _, old := range []string{
		oldPath,
		periodPath(oldPath, dayPeriod),
		periodPath(oldPath, nextDayPeriod),
	} {
		assert.NoFileExists(t, old)
	}

	assert.Equal(t, []string{unrotated}, archivedEventIDs(t, newPath))
	assert.Equal(t, []string{first},
		archivedEventIDs(t, periodPath(newPath, dayPeriod)))
	assert.Equal(t, []string{second},
		archivedEventIDs(t, periodPath(newPath, nextDayPeriod)))

	third := env.deliverReceivedAt(t, tgt, day.Add(48*time.Hour))
	assert.Equal(t, []string{third},
		archivedEventIDs(t, periodPath(newPath, "2026-03-06")))
}

// TestRename_NeverReplacesARotatedFile plants a file at the new name
// of a target's daily file, and proves the rename is refused and moves
// none of the target's files.
func TestRename_NeverReplacesARotatedFile(t *testing.T) {
	t.Parallel()

	env := setupArchiveTest(t)
	tgt := env.seedDatabaseTarget(t, dailyConfig)
	oldPath := env.archivePath(tgt)
	day := time.Date(2026, 3, 4, 12, 0, 0, 0, time.UTC)

	env.deliverReceivedAt(t, tgt, day)
	env.deliverReceivedAt(t, tgt, day.Add(24*time.Hour))

	newPath := filepath.Join(
		env.dataDir, "archive-orders-long-term-"+tgt.ID+".db",
	)
	planted := periodPath(newPath, nextDayPeriod)
	require.NoError(t, os.WriteFile(planted, []byte("planted"), 0o600))

	require.ErrorIs(
		t, env.eng.Rename(tgt.ID, "Orders", "Long Term"),
		delivery.ErrArchiveNameTaken,
	)

	assert.FileExists(t, periodPath(oldPath, dayPeriod))
	assert.FileExists(t, periodPath(oldPath, nextDayPeriod))
	assert.NoFileExists(t, periodPath(newPath, dayPeriod))
}

// TestStatArchive_EveryFile proves StatArchive counts and adds up every
// one of a target's files, takes the latest write of any of them, and
// leaves out files whose names only look like the target's.
func TestStatArchive_EveryFile(t *testing.T) {
	t.Parallel()

	dir := t.TempDir()
	path := filepath.Join(dir, "archive-wh.db")
	files := []string{
		path, periodPath(path, "2026-03"), periodPath(path, hourPeriod),
	}
	written := time.Date(2026, 3, 4, 5, 6, 7, 0, time.UTC)

	var size int64

	for i, file := range files {
		require.NoError(t, os.WriteFile(file, make([]byte, 100*(i+1)), 0o600))

		size += int64(100 * (i + 1))
		at := written.Add(-time.Duration(i) * time.Hour)
		require.NoError(t, os.Chtimes(file, at, at))
	}

	for _, other := range []string{
		"archive-wh-2026-13.db", "archive-wh-2026-3.db",
		"archive-wh-other.db", "archive-wh-2026-03.json",
		"archive-whx.db",
	} {
		require.NoError(t,
			os.WriteFile(filepath.Join(dir, other), []byte("x"), 0o600))
	}

	got, err := delivery.StatArchive(path)
	require.NoError(t, err)
	assert.Equal(t, len(files), got.Files)
	assert.Equal(t, size, got.Size)
	assert.True(t, written.Equal(got.Written), got.Written)
}

// TestArchivePathAt names the file each rotation writes an event to.
func TestArchivePathAt(t *testing.T) {
	t.Parallel()

	dataDir := t.TempDir()
	dbMgr := database.NewTestWebhookDBManager(dataDir)
	webhook := &database.Webhook{
		BaseModel: database.BaseModel{ID: "wh-id"}, Name: "Orders",
	}
	at := time.Date(2026, 10, 1, 19, 30, 0, 0, time.UTC)

	cases := map[string]string{
		"":                                       "",
		`{"rotation":"` + rotationNone + `"}`:    "",
		`{"rotation":"` + rotationMonthly + `"}`: "-2026-10",
		dailyConfig:                              "-2026-10-01",
		`{"rotation":"` + rotationHourly + `"}`:  "-2026-10-01-19",
	}

	for config, period := range cases {
		target := &database.Target{
			BaseModel: database.BaseModel{ID: "tgt-id"},
			Name:      "Archive",
			Config:    config,
		}

		got, err := delivery.ArchivePathAt(dbMgr, webhook, target, at)
		require.NoError(t, err, config)
		assert.Equal(t,
			filepath.Join(
				dataDir, "archive-orders-archive-tgt-id"+period+".db",
			),
			got, config,
		)
	}

	_, err := delivery.ArchivePathAt(dbMgr, webhook, &database.Target{
		Config: weeklyConfig,
	}, at)
	require.Error(t, err)
}

// TestValidateArchiveRotation accepts the four rotations, and empty,
// and refuses anything else.
func TestValidateArchiveRotation(t *testing.T) {
	t.Parallel()

	for _, ok := range []string{
		"", rotationNone, rotationMonthly, rotationDaily, rotationHourly,
	} {
		require.NoError(t, delivery.ValidateArchiveRotation(ok), ok)
	}

	for _, bad := range []string{"weekly", "Daily", "hourly "} {
		require.Error(t, delivery.ValidateArchiveRotation(bad), bad)
	}
}