package handler

import (
	"errors"
	"fmt"
	"github.com/gobuffalo/pop/v6"
	"github.com/gofrs/uuid"
	"github.com/labstack/echo/v4"
	"github.com/lestrrat-go/jwx/v2/jwt"
	auditlog "github.com/teamhanko/hanko/backend/v2/audit_log"
	"github.com/teamhanko/hanko/backend/v2/config"
	"github.com/teamhanko/hanko/backend/v2/dto"
	"github.com/teamhanko/hanko/backend/v2/persistence"
	"github.com/teamhanko/hanko/backend/v2/persistence/models"
	"github.com/teamhanko/hanko/backend/v2/webhooks/events"
	"github.com/teamhanko/hanko/backend/v2/webhooks/utils"
	"net/http"
	"strings"
)

type EmailHandler struct {
	persister   persistence.Persister
	cfg         *config.Config
	auditLogger auditlog.Logger
}

func NewEmailHandler(cfg *config.Config, persister persistence.Persister, auditLogger auditlog.Logger) *EmailHandler {
	return &EmailHandler{
		persister:   persister,
		cfg:         cfg,
		auditLogger: auditLogger,
	}
}

func (h *EmailHandler) List(c echo.Context) error {
	sessionToken, ok := c.Get("session").(jwt.Token)
	if !ok {
		return errors.New("failed to cast session object")
	}

	userId, err := uuid.FromString(sessionToken.Subject())
	if err != nil {
		return fmt.Errorf("failed to parse subject as uuid: %w", err)
	}

	emails, err := h.persister.GetEmailPersister().FindByUserId(userId)
	if err != nil {
		return fmt.Errorf("failed to fetch emails from db: %w", err)
	}

	response := make([]*dto.EmailResponse, len(emails))

	for i := range emails {
		response[i] = dto.FromEmailModel(&emails[i], h.cfg)
	}

	return c.JSON(http.StatusOK, response)
}

func (h *EmailHandler) Create(c echo.Context) error {
	sessionToken, ok := c.Get("session").(jwt.Token)
	if !ok {
		return errors.New("failed to cast session object")
	}

	userId, err := uuid.FromString(sessionToken.Subject())
	if err != nil {
		return fmt.Errorf("failed to parse subject as uuid: %w", err)
	}

	var body dto.EmailCreateRequest

	err = (&echo.DefaultBinder{}).BindBody(c, &body)
	if err != nil {
		return dto.ToHttpError(err)
	}

	emailCount, err := h.persister.GetEmailPersister().CountByUserId(userId)
	if err != nil {
		return fmt.Errorf("failed to count user emails: %w", err)
	}

	if emailCount >= h.cfg.Email.Limit {
		return echo.NewHTTPError(http.StatusConflict).SetInternal(errors.New("max number of email addresses reached"))
	}

	newEmailAddress := strings.ToLower(body.Address)

	email, err := h.persister.GetEmailPersister().FindByAddress(newEmailAddress)
	if err != nil {
		return fmt.Errorf("failed to fetch email from db: %w", err)
	}

	return h.persister.Transaction(func(tx *pop.Connection) error {
		user, err := h.persister.GetUserPersister().Get(userId)
		if err != nil {
			return fmt.Errorf("failed to fetch user from db: %w", err)
		}

		if email != nil {
			// The email address already exists.
			if email.UserID != nil {
				// The email address exists and is assigned to a user already, therefore it can't be created.
				return echo.NewHTTPError(http.StatusBadRequest).SetInternal(errors.New("email address already exists"))
			}

			if !h.cfg.Email.RequireVerification {
				// Email verification is currently not required and there is no user assigned to the existing email
				// address. This can happen, when email verification was turned on before, because then the email
				// address will be assigned to the user only after passcode verification. The email was left unassigned
				// and has not been verified, so we assign the email to the current user.
				email.UserID = &user.ID

				err = h.persister.GetEmailPersisterWithConnection(tx).Update(*email)
				if err != nil {
					return fmt.Errorf("failed to update the existing email: %w", err)
				}
			}
		} else {
			// The email address has not been registered so far.
			if h.cfg.Email.RequireVerification {
				// The email address will be assigned to the user only after passcode verification.
				email = models.NewEmail(nil, newEmailAddress)
			} else {
				// No verification required - assign the email to the given user.
				email = models.NewEmail(&user.ID, newEmailAddress)
			}

			err = h.persister.GetEmailPersisterWithConnection(tx).Create(*email)
			if err != nil {
				return fmt.Errorf("failed to store email to db: %w", err)
			}
		}

		err = h.auditLogger.CreateWithConnection(tx, c, models.AuditLogEmailCreated, user, nil)
		if err != nil {
			return fmt.Errorf("failed to create audit log: %w", err)
		}

		if !h.cfg.Email.RequireVerification {
			var evt events.Event

			if len(user.Emails) >= 1 {
				evt = events.UserEmailCreate
			} else {
				evt = events.UserCreate
			}

			utils.NotifyUserChange(c, tx, h.persister, evt, userId)

		}

		return c.JSON(http.StatusOK, email)
	})
}

func (h *EmailHandler) SetPrimaryEmail(c echo.Context) error {
	sessionToken, ok := c.Get("session").(jwt.Token)
	if !ok {
		return errors.New("failed to cast session object")
	}

	userId, err := uuid.FromString(sessionToken.Subject())
	if err != nil {
		return fmt.Errorf("failed to parse subject as uuid: %w", err)
	}

	emailId, err := uuid.FromString(c.Param("id"))
	if err != nil {
		return echo.NewHTTPError(http.StatusBadRequest).SetInternal(err)
	}

	user, err := h.persister.GetUserPersister().Get(userId)
	if err != nil {
		return fmt.Errorf("failed to fetch user from db: %w", err)
	}

	email := user.GetEmailById(emailId)
	if email == nil {
		return echo.NewHTTPError(http.StatusNotFound).SetInternal(errors.New("the email address is not assigned to the current user"))
	}

	if email.IsPrimary() {
		return c.NoContent(http.StatusNoContent)
	}

	return h.persister.Transaction(func(tx *pop.Connection) error {
		var primaryEmail *models.PrimaryEmail
		if e := user.Emails.GetPrimary(); e != nil {
			primaryEmail = e.PrimaryEmail
		}

		if primaryEmail == nil {
			primaryEmail = models.NewPrimaryEmail(email.ID, user.ID)
			err = h.persister.GetPrimaryEmailPersisterWithConnection(tx).Create(*primaryEmail)
			if err != nil {
				return fmt.Errorf("failed to store new primary email: %w", err)
			}
		} else {
			primaryEmail.EmailID = email.ID
			err = h.persister.GetPrimaryEmailPersisterWithConnection(tx).Update(*primaryEmail)
			if err != nil {
				return fmt.Errorf("failed to change primary email: %w", err)
			}
		}

		err = h.auditLogger.CreateWithConnection(tx, c, models.AuditLogPrimaryEmailChanged, user, nil)
		if err != nil {
			return fmt.Errorf("failed to create audit log: %w", err)
		}

		utils.NotifyUserChange(c, tx, h.persister, events.UserEmailPrimary, userId)

		return c.NoContent(http.StatusNoContent)
	})
}

func (h *EmailHandler) Delete(c echo.Context) error {
	sessionToken, ok := c.Get("session").(jwt.Token)
	if !ok {
		return errors.New("failed to cast session object")
	}

	userId, err := uuid.FromString(sessionToken.Subject())
	if err != nil {
		return fmt.Errorf("failed to parse subject as uuid: %w", err)
	}

	emailId, err := uuid.FromString(c.Param("id"))

	user, err := h.persister.GetUserPersister().Get(userId)
	if err != nil {
		return fmt.Errorf("failed to fetch user from db: %w", err)
	}

	emailToBeDeleted := user.GetEmailById(emailId)
	if emailToBeDeleted == nil {
		return errors.New("email with given emailId not available")
	}

	if emailToBeDeleted.IsPrimary() {
		return echo.NewHTTPError(http.StatusConflict).SetInternal(errors.New("primary email can't be deleted"))
	}

	return h.persister.Transaction(func(tx *pop.Connection) error {
		err = h.persister.GetEmailPersisterWithConnection(tx).Delete(*emailToBeDeleted)
		if err != nil {
			return fmt.Errorf("failed to delete email from db: %w", err)
		}

		err = h.auditLogger.CreateWithConnection(tx, c, models.AuditLogEmailDeleted, user, nil)
		if err != nil {
			return fmt.Errorf("failed to create audit log: %w", err)
		}

		utils.NotifyUserChange(c, tx, h.persister, events.UserEmailDelete, userId)

		return c.NoContent(http.StatusNoContent)
	})
}