package challengestore

import (
	"context"
	"crypto/ed25519"
	"encoding/json"
	"testing"
	"time"

	"galaxy/authsession/internal/adapters/contracttest"
	"galaxy/authsession/internal/domain/challenge"
	"galaxy/authsession/internal/domain/common"
	"galaxy/authsession/internal/ports"

	"github.com/alicebob/miniredis/v2"
	"github.com/redis/go-redis/v9"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
)

func newRedisClient(t *testing.T, server *miniredis.Miniredis) *redis.Client {
	t.Helper()

	client := redis.NewClient(&redis.Options{
		Addr:            server.Addr(),
		Protocol:        2,
		DisableIdentity: true,
	})
	t.Cleanup(func() {
		assert.NoError(t, client.Close())
	})

	return client
}

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

	contracttest.RunChallengeStoreContractTests(t, func(t *testing.T) ports.ChallengeStore {
		t.Helper()

		server := miniredis.RunT(t)
		return newTestStore(t, server, Config{})
	})
}

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

	server := miniredis.RunT(t)
	client := newRedisClient(t, server)

	tests := []struct {
		name    string
		client  *redis.Client
		cfg     Config
		wantErr string
	}{
		{
			name:   "valid config",
			client: client,
			cfg:    Config{KeyPrefix: "authsession:challenge:", OperationTimeout: 250 * time.Millisecond},
		},
		{
			name:    "nil client",
			client:  nil,
			cfg:     Config{KeyPrefix: "authsession:challenge:", OperationTimeout: 250 * time.Millisecond},
			wantErr: "nil redis client",
		},
		{
			name:    "empty key prefix",
			client:  client,
			cfg:     Config{OperationTimeout: 250 * time.Millisecond},
			wantErr: "redis key prefix must not be empty",
		},
		{
			name:    "non-positive operation timeout",
			client:  client,
			cfg:     Config{KeyPrefix: "authsession:challenge:"},
			wantErr: "operation timeout must be positive",
		},
	}

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

			store, err := New(tt.client, tt.cfg)
			if tt.wantErr != "" {
				require.Error(t, err)
				assert.ErrorContains(t, err, tt.wantErr)
				return
			}

			require.NoError(t, err)
			require.NotNil(t, store)
		})
	}
}

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

	server := miniredis.RunT(t)
	store := newTestStore(t, server, Config{})
	now := time.Unix(1_775_130_000, 0).UTC()

	record := testChallenge(now)

	require.NoError(t, store.Create(context.Background(), record))

	got, err := store.Get(context.Background(), record.ID)
	require.NoError(t, err)
	assert.Equal(t, record, got)

	got.CodeHash[0] = 0xFF
	keyBytes := got.Confirmation.ClientPublicKey.PublicKey()
	keyBytes[0] = 0xFE

	again, err := store.Get(context.Background(), record.ID)
	require.NoError(t, err)
	assert.Equal(t, record.CodeHash, again.CodeHash)
	require.NotNil(t, again.Confirmation)
	assert.Equal(t, record.Confirmation.ClientPublicKey.String(), again.Confirmation.ClientPublicKey.String())
}

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

	server := miniredis.RunT(t)
	store := newTestStore(t, server, Config{})
	now := time.Unix(1_775_130_100, 0).UTC()

	record := testPendingChallenge(now)

	require.NoError(t, store.Create(context.Background(), record))

	got, err := store.Get(context.Background(), record.ID)
	require.NoError(t, err)
	assert.Equal(t, record, got)
}

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

	server := miniredis.RunT(t)
	store := newTestStore(t, server, Config{})
	now := time.Unix(1_775_130_150, 0).UTC()

	record := testPendingChallenge(now)
	record.Status = challenge.StatusDeliveryThrottled
	record.DeliveryState = challenge.DeliveryThrottled
	record.Attempts.Send = 1
	record.Abuse.LastAttemptAt = timePointer(now)
	require.NoError(t, record.Validate())

	require.NoError(t, store.Create(context.Background(), record))

	got, err := store.Get(context.Background(), record.ID)
	require.NoError(t, err)
	assert.Equal(t, record, got)
}

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

	now := time.Unix(1_775_130_200, 0).UTC()
	baseRecord := testChallenge(now)
	baseStored, err := redisRecordFromChallenge(baseRecord)
	require.NoError(t, err)

	tests := []struct {
		name        string
		mutate      func(redisRecord) string
		wantErrText string
	}{
		{
			name: "malformed json",
			mutate: func(_ redisRecord) string {
				return "{"
			},
			wantErrText: "decode redis challenge record",
		},
		{
			name: "trailing json input",
			mutate: func(record redisRecord) string {
				return mustMarshalJSON(t, record) + "{}"
			},
			wantErrText: "unexpected trailing JSON input",
		},
		{
			name: "unknown field",
			mutate: func(record redisRecord) string {
				payload := map[string]any{
					"challenge_id":                record.ChallengeID,
					"email":                       record.Email,
					"code_hash_base64":            record.CodeHashBase64,
					"status":                      record.Status,
					"delivery_state":              record.DeliveryState,
					"created_at":                  record.CreatedAt,
					"expires_at":                  record.ExpiresAt,
					"send_attempt_count":          record.SendAttemptCount,
					"confirm_attempt_count":       record.ConfirmAttemptCount,
					"last_attempt_at":             record.LastAttemptAt,
					"confirmed_session_id":        record.ConfirmedSessionID,
					"confirmed_client_public_key": record.ConfirmedClientPublicKey,
					"confirmed_at":                record.ConfirmedAt,
					"unexpected":                  true,
				}
				return mustMarshalJSON(t, payload)
			},
			wantErrText: "unknown field",
		},
		{
			name: "unsupported status",
			mutate: func(record redisRecord) string {
				record.Status = challenge.Status("paused")
				return mustMarshalJSON(t, record)
			},
			wantErrText: `status "paused" is unsupported`,
		},
		{
			name: "unsupported delivery state",
			mutate: func(record redisRecord) string {
				record.DeliveryState = challenge.DeliveryState("queued")
				return mustMarshalJSON(t, record)
			},
			wantErrText: `delivery state "queued" is unsupported`,
		},
		{
			name: "missing required email",
			mutate: func(record redisRecord) string {
				record.Email = ""
				return mustMarshalJSON(t, record)
			},
			wantErrText: "challenge email",
		},
		{
			name: "challenge id mismatch",
			mutate: func(record redisRecord) string {
				record.ChallengeID = "other-challenge"
				return mustMarshalJSON(t, record)
			},
			wantErrText: `does not match requested`,
		},
		{
			name: "non canonical utc timestamp",
			mutate: func(record redisRecord) string {
				record.CreatedAt = "2026-04-04T12:00:00+03:00"
				return mustMarshalJSON(t, record)
			},
			wantErrText: "canonical UTC RFC3339Nano timestamp",
		},
		{
			name: "partial confirmation metadata",
			mutate: func(record redisRecord) string {
				record.ConfirmedAt = nil
				return mustMarshalJSON(t, record)
			},
			wantErrText: "confirmation metadata must be either fully present or fully absent",
		},
	}

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

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

			server := miniredis.RunT(t)
			store := newTestStore(t, server, Config{})
			server.Set(store.lookupKey(baseRecord.ID), tt.mutate(baseStored))

			_, err := store.Get(context.Background(), baseRecord.ID)
			require.Error(t, err)
			assert.ErrorContains(t, err, tt.wantErrText)
		})
	}
}

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

	server := miniredis.RunT(t)
	store := newTestStore(t, server, Config{KeyPrefix: "authsession:challenge:"})
	now := time.Now().UTC()

	prefixed := testPendingChallenge(now)
	prefixed.ID = common.ChallengeID("challenge:opaque/id?value")
	require.NoError(t, store.Create(context.Background(), prefixed))

	key := store.lookupKey(prefixed.ID)
	assert.Equal(t, "authsession:challenge:"+encodeKeyComponent(prefixed.ID.String()), key)
	assert.True(t, server.Exists(key))

	freshTTL := server.TTL(key)
	assert.LessOrEqual(t, freshTTL, challenge.InitialTTL+expirationGracePeriod)
	assert.GreaterOrEqual(t, freshTTL, challenge.InitialTTL+expirationGracePeriod-2*time.Second)

	expired := testPendingChallenge(now.Add(-10 * time.Minute))
	expired.ID = common.ChallengeID("expired-challenge")
	expired.CreatedAt = now.Add(-20 * time.Minute)
	expired.ExpiresAt = now.Add(-1 * time.Minute)
	require.NoError(t, store.Create(context.Background(), expired))

	expiredTTL := server.TTL(store.lookupKey(expired.ID))
	assert.LessOrEqual(t, expiredTTL, expirationGracePeriod)
	assert.GreaterOrEqual(t, expiredTTL, expirationGracePeriod-2*time.Second)
}

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

	server := miniredis.RunT(t)
	store := newTestStore(t, server, Config{})
	record := testPendingChallenge(time.Unix(1_775_130_300, 0).UTC())

	require.NoError(t, store.Create(context.Background(), record))

	err := store.Create(context.Background(), record)
	require.Error(t, err)
	assert.ErrorIs(t, err, ports.ErrConflict)
}

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

	server := miniredis.RunT(t)
	store := newTestStore(t, server, Config{})

	_, err := store.Get(context.Background(), common.ChallengeID("missing-challenge"))
	require.Error(t, err)
	assert.ErrorIs(t, err, ports.ErrNotFound)
}

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

	now := time.Unix(1_775_130_400, 0).UTC()

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

		server := miniredis.RunT(t)
		store := newTestStore(t, server, Config{})
		previous := testPendingChallenge(now)
		next := previous
		next.Status = challenge.StatusSent
		next.DeliveryState = challenge.DeliverySent
		next.Attempts.Send = 1
		next.Abuse.LastAttemptAt = timePointer(now.Add(1 * time.Minute))

		require.NoError(t, store.Create(context.Background(), previous))
		require.NoError(t, store.CompareAndSwap(context.Background(), previous, next))

		got, err := store.Get(context.Background(), previous.ID)
		require.NoError(t, err)
		assert.Equal(t, next, got)
	})

	t.Run("conflict when stored record differs", func(t *testing.T) {
		t.Parallel()

		server := miniredis.RunT(t)
		store := newTestStore(t, server, Config{})
		stored := testPendingChallenge(now)
		previous := stored
		previous.Attempts.Send = 99
		next := stored
		next.Status = challenge.StatusSent
		next.DeliveryState = challenge.DeliverySent

		require.NoError(t, store.Create(context.Background(), stored))

		err := store.CompareAndSwap(context.Background(), previous, next)
		require.Error(t, err)
		assert.ErrorIs(t, err, ports.ErrConflict)
	})

	t.Run("not found", func(t *testing.T) {
		t.Parallel()

		server := miniredis.RunT(t)
		store := newTestStore(t, server, Config{})
		previous := testPendingChallenge(now)
		next := previous
		next.Status = challenge.StatusSent
		next.DeliveryState = challenge.DeliverySent

		err := store.CompareAndSwap(context.Background(), previous, next)
		require.Error(t, err)
		assert.ErrorIs(t, err, ports.ErrNotFound)
	})

	t.Run("corrupt stored record returns adapter error", func(t *testing.T) {
		t.Parallel()

		server := miniredis.RunT(t)
		store := newTestStore(t, server, Config{})
		previous := testPendingChallenge(now)
		next := previous
		next.Status = challenge.StatusSent
		next.DeliveryState = challenge.DeliverySent

		server.Set(store.lookupKey(previous.ID), "{")

		err := store.CompareAndSwap(context.Background(), previous, next)
		require.Error(t, err)
		assert.NotErrorIs(t, err, ports.ErrConflict)
		assert.ErrorContains(t, err, "decode redis challenge record")
	})
}

func newTestStore(t *testing.T, server *miniredis.Miniredis, cfg Config) *Store {
	t.Helper()

	if cfg.KeyPrefix == "" {
		cfg.KeyPrefix = "authsession:challenge:"
	}
	if cfg.OperationTimeout == 0 {
		cfg.OperationTimeout = 250 * time.Millisecond
	}

	store, err := New(newRedisClient(t, server), cfg)
	require.NoError(t, err)

	return store
}

func testPendingChallenge(now time.Time) challenge.Challenge {
	return challenge.Challenge{
		ID:                common.ChallengeID("challenge-pending"),
		Email:             common.Email("pilot@example.com"),
		CodeHash:          []byte("hashed-pending-code"),
		PreferredLanguage: "en",
		Status:            challenge.StatusPendingSend,
		DeliveryState:     challenge.DeliveryPending,
		CreatedAt:         now,
		ExpiresAt:         now.Add(challenge.InitialTTL),
	}
}

func testChallenge(now time.Time) challenge.Challenge {
	clientPublicKey, err := common.NewClientPublicKey(ed25519.PublicKey{
		0, 1, 2, 3, 4, 5, 6, 7,
		8, 9, 10, 11, 12, 13, 14, 15,
		16, 17, 18, 19, 20, 21, 22, 23,
		24, 25, 26, 27, 28, 29, 30, 31,
	})
	if err != nil {
		panic(err)
	}

	return challenge.Challenge{
		ID:                common.ChallengeID("challenge-confirmed"),
		Email:             common.Email("pilot@example.com"),
		CodeHash:          []byte("hashed-code"),
		PreferredLanguage: "en",
		Status:            challenge.StatusConfirmedPendingExpire,
		DeliveryState:     challenge.DeliverySent,
		CreatedAt:         now,
		ExpiresAt:         now.Add(challenge.ConfirmedRetention),
		Attempts: challenge.AttemptCounters{
			Send:    1,
			Confirm: 2,
		},
		Abuse: challenge.AbuseMetadata{
			LastAttemptAt: timePointer(now.Add(30 * time.Second)),
		},
		Confirmation: &challenge.Confirmation{
			SessionID:       common.DeviceSessionID("device-session-1"),
			ClientPublicKey: clientPublicKey,
			ConfirmedAt:     now.Add(1 * time.Minute),
		},
	}
}

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

	server := miniredis.RunT(t)
	store := newTestStore(t, server, Config{})
	now := time.Unix(1_775_130_250, 0).UTC()

	record := testPendingChallenge(now)
	stored, err := redisRecordFromChallenge(record)
	require.NoError(t, err)
	stored.PreferredLanguage = ""

	payload := mustMarshalJSON(t, map[string]any{
		"challenge_id":          stored.ChallengeID,
		"email":                 stored.Email,
		"code_hash_base64":      stored.CodeHashBase64,
		"status":                stored.Status,
		"delivery_state":        stored.DeliveryState,
		"created_at":            stored.CreatedAt,
		"expires_at":            stored.ExpiresAt,
		"send_attempt_count":    stored.SendAttemptCount,
		"confirm_attempt_count": stored.ConfirmAttemptCount,
	})
	server.Set(store.lookupKey(record.ID), payload)

	got, err := store.Get(context.Background(), record.ID)
	require.NoError(t, err)
	assert.Equal(t, "en", got.PreferredLanguage)
}

func timePointer(value time.Time) *time.Time {
	return &value
}

func mustMarshalJSON(t *testing.T, value any) string {
	t.Helper()

	payload, err := json.Marshal(value)
	require.NoError(t, err)

	return string(payload)
}

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

	server := miniredis.RunT(t)
	store := newTestStore(t, server, Config{})

	_, err := store.Get(nil, common.ChallengeID("challenge"))
	require.Error(t, err)
	assert.ErrorContains(t, err, "nil context")
}