package usersignup

import (
	"context"
	"errors"
	"testing"
	"time"

	"github.com/stretchr/testify/require"
	"gorm.io/gorm"

	"github.com/pocket-id/pocket-id/backend/internal/appconfig"
	"github.com/pocket-id/pocket-id/backend/internal/apperror"
	"github.com/pocket-id/pocket-id/backend/internal/auditlogs"
	"github.com/pocket-id/pocket-id/backend/internal/dto"
	"github.com/pocket-id/pocket-id/backend/internal/model"
	"github.com/pocket-id/pocket-id/backend/internal/utils"
	testutils "github.com/pocket-id/pocket-id/backend/internal/utils/testing"
)

type fakeUserCreator struct {
	err  error
	user model.User
}

func (f fakeUserCreator) CreateUserInternal(_ context.Context, _ *appconfig.AppConfigModel, _ dto.UserCreateDto, _ bool, _ *gorm.DB) (model.User, error) {
	if f.err != nil {
		return model.User{}, f.err
	}
	return f.user, nil
}

// dbUserCreator stores the user in the signup transaction, so changes made later in that transaction can be asserted
type dbUserCreator struct{}

func (dbUserCreator) CreateUserInternal(_ context.Context, _ *appconfig.AppConfigModel, input dto.UserCreateDto, _ bool, tx *gorm.DB) (model.User, error) {
	user := model.User{Username: input.Username, Email: input.Email, EmailVerified: input.EmailVerified}
	err := tx.Create(&user).Error
	return user, err
}

type fakeEmailVerificationSender struct {
	err     error
	userIDs []string
}

func (f *fakeEmailVerificationSender) Send(_ context.Context, _ *appconfig.AppConfigModel, userID string) error {
	f.userIDs = append(f.userIDs, userID)
	return f.err
}

type fakeSigner struct{}

func (fakeSigner) GenerateAccessToken(_ model.User, _ string, _ time.Duration) (string, error) {
	return "access-token", nil
}

type fakeAuditLogger struct{}

func (fakeAuditLogger) Create(_ context.Context, _ auditlogs.Event, _, _, _ string, _ auditlogs.Data, _ *gorm.DB) (auditlogs.AuditLog, bool) {
	return auditlogs.AuditLog{}, true
}

func newSignupServiceForTest(t *testing.T, db *gorm.DB, userCreator UserCreator) *Service {
	t.Helper()
	actorService := newSignupTokenActorService(t)
	return newService(Dependencies{
		DB:          db,
		UserCreator: userCreator,
		Signer:      fakeSigner{},
		AuditLog:    fakeAuditLogger{},
	}, actorService)
}

func signupTokenUsageCount(t *testing.T, svc *Service, tokenID string) int {
	t.Helper()
	tokens, _, err := svc.ListSignupTokens(t.Context(), listAllOptions())
	require.NoError(t, err)
	for _, tok := range tokens {
		if tok.ID == tokenID {
			return tok.UsageCount
		}
	}
	t.Fatalf("signup token %q not found", tokenID)
	return 0
}

func TestSignUpConsumesTokenOnSuccess(t *testing.T) {
	db := testutils.NewDatabaseForTest(t)
	svc := newSignupServiceForTest(t, db, fakeUserCreator{user: model.User{Base: model.Base{ID: "new-user"}}})

	token, err := svc.CreateSignupToken(t.Context(), time.Hour, 2, nil)
	require.NoError(t, err)

	config := appconfig.NewTestConfig(nil)
	user, accessToken, err := svc.SignUp(t.Context(), config, signUpDto{
		Username: "newuser",
		Token:    token.Token,
	}, "1.2.3.4", "test-agent")
	require.NoError(t, err)
	require.Equal(t, "new-user", user.ID)
	require.Equal(t, "access-token", accessToken)

	// The token's usage count must have been incremented and not rolled back
	require.Equal(t, 1, signupTokenUsageCount(t, svc, token.ID))
}

func TestSignUpCompensatesTokenOnFailure(t *testing.T) {
	db := testutils.NewDatabaseForTest(t)
	boom := errors.New("could not create user")
	svc := newSignupServiceForTest(t, db, fakeUserCreator{err: boom})

	token, err := svc.CreateSignupToken(t.Context(), time.Hour, 2, nil)
	require.NoError(t, err)

	config := appconfig.NewTestConfig(nil)
	_, _, err = svc.SignUp(t.Context(), config, signUpDto{
		Username: "newuser",
		Token:    token.Token,
	}, "1.2.3.4", "test-agent")
	require.ErrorIs(t, err, boom)

	// The usage count increment must have been compensated (reverted back to 0)
	require.Equal(t, 0, signupTokenUsageCount(t, svc, token.ID))
}

func TestSignUpRejectsInvalidToken(t *testing.T) {
	db := testutils.NewDatabaseForTest(t)
	svc := newSignupServiceForTest(t, db, fakeUserCreator{user: model.User{Base: model.Base{ID: "new-user"}}})

	config := appconfig.NewTestConfig(nil)
	_, _, err := svc.SignUp(t.Context(), config, signUpDto{
		Username: "newuser",
		Token:    "not-a-real-token",
	}, "1.2.3.4", "test-agent")

	require.True(t, apperror.IsCode(err, apperror.CodeTokenInvalidOrExpired))
}

func TestSignUpInitialAdminCreatesAdmin(t *testing.T) {
	db := testutils.NewDatabaseForTest(t)
	svc := newSignupServiceForTest(t, db, fakeUserCreator{user: model.User{Base: model.Base{ID: "new-admin"}}})
	config := appconfig.NewTestConfig(nil)

	// Complete setup and return the generated administrator session
	user, accessToken, err := svc.SignUpInitialAdmin(t.Context(), config, signUpDto{Username: "new-admin"})
	require.NoError(t, err)
	require.Equal(t, "new-admin", user.ID)
	require.Equal(t, "access-token", accessToken)
}

func TestSignUpInitialAdminAllowsRetryAfterFailure(t *testing.T) {
	db := testutils.NewDatabaseForTest(t)
	boom := errors.New("could not create initial admin")
	svc := newSignupServiceForTest(t, db, fakeUserCreator{err: boom})
	config := appconfig.NewTestConfig(nil)

	// Fail the first setup transaction before it can commit
	_, _, err := svc.SignUpInitialAdmin(t.Context(), config, signUpDto{Username: "failed-admin"})
	require.ErrorIs(t, err, boom)

	// Confirm a later setup can complete after the failed transaction rolls back
	svc.userCreator = fakeUserCreator{user: model.User{Base: model.Base{ID: "new-admin"}}}
	user, _, err := svc.SignUpInitialAdmin(t.Context(), config, signUpDto{Username: "new-admin"})
	require.NoError(t, err)
	require.Equal(t, "new-admin", user.ID)
}

func TestSignUpInitialAdminRejectsExistingInstallation(t *testing.T) {
	db := testutils.NewDatabaseForTest(t)
	require.NoError(t, db.Create(&model.User{Username: "existing-admin", IsAdmin: true}).Error)
	svc := newSignupServiceForTest(t, db, fakeUserCreator{user: model.User{Base: model.Base{ID: "new-admin"}}})

	// Reject setup when the installation already contains a user
	_, _, err := svc.SignUpInitialAdmin(t.Context(), appconfig.NewTestConfig(nil), signUpDto{Username: "new-admin"})
	require.True(t, apperror.IsCode(err, apperror.CodeSetupAlreadyCompleted))
}

// listAllOptions returns list options that return every token on a single page.
func listAllOptions() utils.ListRequestOptions {
	var opts utils.ListRequestOptions
	opts.Pagination.Page = 1
	opts.Pagination.Limit = 100
	return opts
}

func TestSignUpRequiresEmailVerification(t *testing.T) {
	signUp := func(t *testing.T, mode string, sender *fakeEmailVerificationSender) (*gorm.DB, model.User) {
		t.Helper()

		db := testutils.NewDatabaseForTest(t)
		svc := newSignupServiceForTest(t, db, dbUserCreator{})
		svc.emailVerification = sender

		config := appconfig.NewTestConfig(nil)
		config.AllowUserSignups = "open"
		config.EmailVerification = appconfig.AppConfigValue(mode)
		user, _, err := svc.SignUp(t.Context(), config, signUpDto{
			Username: "newuser",
			Email:    new("newuser@example.com"),
		}, "1.2.3.4", "test-agent")
		require.NoError(t, err)

		return db, user
	}

	t.Run("sets a deadline and sends the verification email when verification is required", func(t *testing.T) {
		sender := &fakeEmailVerificationSender{}
		before := time.Now()
		db, user := signUp(t, appconfig.EmailVerificationRequired, sender)

		require.NotNil(t, user.EmailVerificationDeadline)
		require.WithinDuration(t, before.Add(24*time.Hour), user.EmailVerificationDeadline.ToTime(), time.Minute)

		var stored model.User
		require.NoError(t, db.First(&stored, "id = ?", user.ID).Error)
		require.NotNil(t, stored.EmailVerificationDeadline)
		require.Equal(t, []string{user.ID}, sender.userIDs)
	})

	t.Run("keeps the account without a deadline when verification is optional", func(t *testing.T) {
		sender := &fakeEmailVerificationSender{}
		db, user := signUp(t, appconfig.EmailVerificationOptional, sender)

		var stored model.User
		require.NoError(t, db.First(&stored, "id = ?", user.ID).Error)
		require.Nil(t, stored.EmailVerificationDeadline)
		require.Empty(t, sender.userIDs)
	})

	t.Run("a failed delivery does not fail the signup", func(t *testing.T) {
		sender := &fakeEmailVerificationSender{err: errors.New("smtp unavailable")}
		_, user := signUp(t, appconfig.EmailVerificationRequired, sender)

		require.NotNil(t, user.EmailVerificationDeadline)
		require.Equal(t, []string{user.ID}, sender.userIDs)
	})
}