package user

import (
	"context"
	"github.com/ente-io/museum/ente"
	"github.com/ente-io/museum/pkg/utils/auth"
	"github.com/ente-io/stacktrace"
	"github.com/gin-gonic/gin"
	"github.com/google/uuid"
	"github.com/kong/go-srp"
	"github.com/sirupsen/logrus"
	"net/http"
)

const Srp4096Params = 4096

func (c *UserController) SetupSRP(context *gin.Context, userID int64, req ente.SetupSRPRequest) (*ente.SetupSRPResponse, error) {
	srpB, sessionID, err := c.createAndInsertSRPSession(context, req.SrpUserID, req.SRPVerifier, req.SRPA)
	if err != nil {
		return nil, stacktrace.Propagate(err, "")
	}
	setupID, err := c.UserAuthRepo.InsertTempSRPSetup(context, req, userID, sessionID)
	if err != nil {
		return nil, stacktrace.Propagate(err, "failed to add entry in setup table")
	}

	return &ente.SetupSRPResponse{
		SetupID: *setupID,
		SRPB:    *srpB,
	}, nil
}

func (c *UserController) CompleteSRPSetup(context *gin.Context, req ente.CompleteSRPSetupRequest) (*ente.CompleteSRPSetupResponse, error) {
	userID := auth.GetUserID(context.Request.Header)
	setup, err := c.UserAuthRepo.GetTempSRPSetupEntity(context, req.SetupID)
	if err != nil {
		return nil, stacktrace.Propagate(err, "")
	}
	srpM2, err := c.verifySRPSession(context, setup.Verifier, setup.SessionID, req.SRPM1)
	if err != nil {
		return nil, err
	}
	err = c.UserAuthRepo.InsertSRPAuth(context, userID, setup.SRPUserID, setup.Verifier, setup.Salt)
	if err != nil {
		return nil, stacktrace.Propagate(err, "failed to add entry in srp auth")
	}
	return &ente.CompleteSRPSetupResponse{
		SetupID: req.SetupID,
		SRPM2:   *srpM2,
	}, nil
}

// UpdateSrpAndKeyAttributes updates the SRP and keys attributes if the SRP setup is successfully done
func (c *UserController) UpdateSrpAndKeyAttributes(context *gin.Context,
	userID int64,
	req ente.UpdateSRPAndKeysRequest,
	shouldClearTokens bool,
) (*ente.UpdateSRPSetupResponse, error) {
	setup, err := c.UserAuthRepo.GetTempSRPSetupEntity(context, req.SetupID)
	if err != nil {
		return nil, stacktrace.Propagate(err, "")
	}
	srpM2, err := c.verifySRPSession(context, setup.Verifier, setup.SessionID, req.SRPM1)
	if err != nil {
		return nil, err
	}
	err = c.UserAuthRepo.InsertOrUpdateSRPAuthAndKeyAttr(context, userID, req, setup)
	if err != nil {
		return nil, stacktrace.Propagate(err, "failed to add entry in srp auth")
	}

	if shouldClearTokens {
		token := auth.GetToken(context)
		err = c.UserAuthRepo.RemoveAllOtherTokens(userID, token)
		if err != nil {
			return nil, err
		}
	} else {
		logrus.WithField("user_id", userID).Info("not clearing tokens")
	}

	return &ente.UpdateSRPSetupResponse{
		SetupID: req.SetupID,
		SRPM2:   *srpM2,
	}, nil
}

func (c *UserController) GetSRPAttributes(context *gin.Context, email string) (*ente.GetSRPAttributesResponse, error) {
	userID, err := c.UserRepo.GetUserIDWithEmail(email)
	if err != nil {
		return nil, stacktrace.Propagate(err, "user does not exist")
	}
	srpAttributes, err := c.UserAuthRepo.GetSRPAttributes(userID)
	if err != nil {
		return nil, stacktrace.Propagate(err, "")
	}
	return srpAttributes, nil
}

func (c *UserController) CreateSrpSession(context *gin.Context, req ente.CreateSRPSessionRequest) (*ente.CreateSRPSessionResponse, error) {

	srpAuthEntity, err := c.UserAuthRepo.GetSRPAuthEntityBySRPUserID(context, req.SRPUserID)
	if err != nil {
		return nil, err
	}
	isEmailMFAEnabled, err := c.UserAuthRepo.IsEmailMFAEnabled(context, srpAuthEntity.UserID)
	if err != nil {
		return nil, stacktrace.Propagate(err, "")
	}

	if *isEmailMFAEnabled {
		return nil, stacktrace.Propagate(&ente.ApiError{
			Code:           "EMAIL_MFA_ENABLED",
			Message:        "Email MFA is enabled",
			HttpStatusCode: http.StatusConflict,
		}, "email mfa is enabled")
	}

	srpBBase64, sessionID, err := c.createAndInsertSRPSession(context, req.SRPUserID, srpAuthEntity.Verifier, req.SRPA)
	if err != nil {
		return nil, stacktrace.Propagate(err, "")
	}
	return &ente.CreateSRPSessionResponse{
		SRPB:      *srpBBase64,
		SessionID: *sessionID,
	}, nil
}

func (c *UserController) VerifySRPSession(context *gin.Context, req ente.VerifySRPSessionRequest) (*ente.EmailAuthorizationResponse, error) {
	srpAuthEntity, err := c.UserAuthRepo.GetSRPAuthEntityBySRPUserID(context, req.SRPUserID)
	if err != nil {
		return nil, stacktrace.Propagate(err, "")
	}
	srpM2, err := c.verifySRPSession(context, srpAuthEntity.Verifier, req.SessionID, req.SRPM1)
	if err != nil {
		return nil, stacktrace.Propagate(err, "")
	}
	user, err := c.UserRepo.Get(srpAuthEntity.UserID)
	if err != nil {
		return nil, err
	}
	verResponse, err := c.onVerificationSuccess(context, user.Email, nil)
	if err != nil {
		return nil, stacktrace.Propagate(err, "")
	}
	verResponse.SrpM2 = srpM2
	return &verResponse, nil
}

func (c *UserController) createAndInsertSRPSession(
	gContext *gin.Context,
	srpUserID uuid.UUID,
	srpVerifier string,
	srpA string,
) (*string, *uuid.UUID, error) {

	serverSecret := srp.GenKey()
	srpParams := srp.GetParams(Srp4096Params)
	srpServer := srp.NewServer(srpParams, convertStringToBytes(srpVerifier), serverSecret)

	if srpServer == nil {
		return nil, nil, stacktrace.NewError("server is nil")
	}

	srpServer.SetA(convertStringToBytes(srpA))

	srpB := srpServer.ComputeB()

	if srpB == nil {
		return nil, nil, stacktrace.NewError("srpB is nil")
	}

	sessionID, err := c.UserAuthRepo.AddSRPSession(srpUserID, convertBytesToString(serverSecret), srpA)

	if err != nil {
		return nil, nil, stacktrace.Propagate(err, "")
	}

	srpBBase64 := convertBytesToString(srpB)
	return &srpBBase64, &sessionID, nil
}

func (c *UserController) verifySRPSession(ctx context.Context,
	srpVerifier string,
	sessionID uuid.UUID,
	srpM1 string,
) (*string, error) {
	srpSession, err := c.UserAuthRepo.GetSrpSessionEntity(ctx, sessionID)
	if err != nil {
		return nil, stacktrace.Propagate(err, "")
	}
	if srpSession.IsVerified {
		return nil, stacktrace.Propagate(&ente.ApiError{
			Code:           "SESSION_ALREADY_VERIFIED",
			HttpStatusCode: http.StatusGone,
		}, "")
	} else if srpSession.AttemptCount >= 5 {
		return nil, stacktrace.Propagate(&ente.ApiError{
			Code:           "TOO_MANY_WRONG_ATTEMPTS",
			HttpStatusCode: http.StatusGone,
		}, "")
	}

	srpParams := srp.GetParams(Srp4096Params)
	srpServer := srp.NewServer(srpParams, convertStringToBytes(srpVerifier), convertStringToBytes(srpSession.ServerKey))

	if srpServer == nil {
		return nil, stacktrace.NewError("server is nil")
	}

	srpServer.SetA(convertStringToBytes(srpSession.SRP_A))

	srpM2Bytes, err := srpServer.CheckM1(convertStringToBytes(srpM1))

	if err != nil {
		err2 := c.UserAuthRepo.IncrementSrpSessionAttemptCount(ctx, sessionID)
		if err2 != nil {
			return nil, stacktrace.Propagate(err2, "")
		}
		return nil, stacktrace.Propagate(ente.ErrInvalidPassword, "failed to verify srp session")
	} else {
		err2 := c.UserAuthRepo.SetSrpSessionVerified(ctx, sessionID)
		if err2 != nil {
			return nil, stacktrace.Propagate(err2, "")
		}
	}
	srpM2 := convertBytesToString(srpM2Bytes)
	return &srpM2, nil
}