// Copyright (c) 2025 Nikolai Papin
//
// This file is part of Easywish
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
// the GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.

package services

import (
	"easywish/internal/database"
	errs "easywish/internal/errors"
	"easywish/internal/models"
	"easywish/internal/utils"
	"easywish/internal/utils/enums"

	"github.com/jackc/pgerrcode"
	"github.com/jackc/pgx/v5"
	"go.uber.org/zap"
)

type AuthService interface {
	RegistrationBegin(request models.RegistrationBeginRequest) (bool, error)
	RegistrationComplete(request models.RegistrationCompleteRequest) (*models.RegistrationCompleteResponse, error)
	Login(request models.LoginRequest) (*models.LoginResponse, error)
	Refresh(request models.RefreshRequest) (*models.RefreshResponse, error)
}

type authServiceImpl struct {
	log *zap.Logger
	dbctx database.DbContext
}

func NewAuthService(_log *zap.Logger, _dbctx database.DbContext) AuthService {
	return &authServiceImpl{log: _log, dbctx: _dbctx}
}

func (a *authServiceImpl) RegistrationBegin(request models.RegistrationBeginRequest) (bool, error) {

	var user database.User
	var generatedCode string

	helper, db, _ := database.NewDbHelperTransaction(a.dbctx)
  defer helper.Rollback()

	var err error

	if user, err = db.TXQueries.CreateUser(db.CTX, request.Username); err != nil {

		if errs.IsPgErr(err, pgerrcode.UniqueViolation) {
			a.log.Warn(
				"Attempted registration for a taken username",
				zap.String("username", request.Username),
				zap.Error(err))
			return false, errs.ErrUsernameTaken
		}

		a.log.Error("Failed to add user to database", zap.Error(err))
		return false, errs.ErrServerError
	}

	if _, err := db.TXQueries.GetUserByEmail(db.CTX, *request.Email); err == nil {
		a.log.Warn(
			"Attempted registration for a taken email",
			zap.String("email", *request.Email))
		return false, errs.ErrEmailTaken

	} else if !errs.IsPgErr(err, pgerrcode.NoData) {
		a.log.Error(
			"Failed to check if email is not taken",
			zap.String("email", *request.Email),
			zap.Error(err))
		return false, errs.ErrServerError

	} else {
		a.log.Debug("Verified that email is not taken", zap.String("email", *request.Email))
	}

	a.log.Info(
		"Registraion of a new user",
		zap.String("username", user.Username),
		zap.Int64("id", user.ID))

	if _, err = db.TXQueries.CreateLoginInformation(db.CTX, database.CreateLoginInformationParams{
		UserID: user.ID,
		Email: request.Email,
		Password: request.Password, // Hashed in database
	}); err != nil {
		a.log.Error("Failed to add login information for user to database", zap.Error(err))
		return false, errs.ErrServerError
	}

	if generatedCode, err = utils.GenerateSecure6DigitNumber(); err != nil {
		a.log.Error("Failed to generate a registration code", zap.Error(err))
		return false, errs.ErrServerError
	}

	if _, err = db.TXQueries.CreateConfirmationCode(db.CTX, database.CreateConfirmationCodeParams{
     UserID: user.ID,
		 CodeType: int32(enums.RegistrationCodeType),
		 Code: generatedCode, // Hashed in database
	}); err != nil {
		a.log.Error("Failed to add registration code to database", zap.Error(err))
		return false, errs.ErrServerError
	}

	a.log.Info("Registered a new user", zap.String("username", user.Username))

	helper.Commit()

	a.log.Debug("Declated registration code for a new user", zap.String("username", user.Username), zap.String("code", generatedCode))

	// TODO: Send verification email

	return true, nil
}

func (a *authServiceImpl) RegistrationComplete(request models.RegistrationCompleteRequest) (*models.RegistrationCompleteResponse, error) {
	
	var user database.User
	var profile database.Profile
	var session database.Session
  var confirmationCode database.ConfirmationCode
	var accessToken, refreshToken string
	var err error

	helper, db, _ := database.NewDbHelperTransaction(a.dbctx)

	user, err = db.TXQueries.GetUserByUsername(db.CTX, request.Username)

	if err != nil {
		if errs.IsPgErr(err, pgerrcode.NoData) {
			a.log.Warn(
				"Could not find user attempting to complete registration with given username", 
				zap.String("username", request.Username), 
				zap.Error(err))
			return nil, errs.ErrUserNotFound
		}

		a.log.Error(
			"Failed to get user",
			zap.String("username", request.Username),
			zap.Error(err))
		return nil, errs.ErrServerError
	}

	confirmationCode, err = db.TXQueries.GetConfirmationCodeByCode(db.CTX, database.GetConfirmationCodeByCodeParams{
    UserID: user.ID,
		CodeType: int32(enums.RegistrationCodeType),
		Code: request.VerificationCode,
	})

	if err != nil {
		if errs.IsPgErr(err, pgerrcode.NoData) {
			a.log.Warn(
				"User supplied unexistent confirmation code for completing registration",
				zap.String("username", user.Username),
				zap.String("code", request.VerificationCode),
				zap.Error(err))
			return nil, errs.ErrForbidden
		}

		a.log.Error(
			"Failed to acquire specified registration code",
			zap.String("username", user.Username),
			zap.Error(err))
		return nil, errs.ErrServerError
	}

	err = db.TXQueries.UpdateConfirmationCode(db.CTX, database.UpdateConfirmationCodeParams{
		ID: confirmationCode.ID,
		Used: utils.NewPointer(true),
	})
	
	if err != nil {
		a.log.Error(
			"Failed to update the user's registration code used state",
			zap.String("username", user.Username),
			zap.Int64("confirmation_code_id", confirmationCode.ID),
			zap.Error(err))
		return nil, errs.ErrServerError
	}

  err = db.TXQueries.UpdateUser(db.CTX, database.UpdateUserParams{
		Verified: utils.NewPointer(true),
	})

	if err != nil {
		a.log.Error("Failed to update verified status for user",
	  	zap.String("username", user.Username),
		  zap.Error(err))
		return nil, errs.ErrServerError
	}

  profile, err = db.TXQueries.CreateProfile(db.CTX, database.CreateProfileParams{
		UserID: user.ID,
		Name: request.Name,
		AvatarUrl: request.AvatarUrl,
	})

	if err != nil {
		a.log.Error("Failed to create profile for user",
			zap.String("username", user.Username),

		)
		return nil, errs.ErrServerError
	}

	_, err = db.TXQueries.CreateProfileSettings(db.CTX, profile.ID)

	if err != nil {
		a.log.Error("Failed to create profile settings for user",
	    zap.String("username", user.Username),
			zap.Error(err))
		return nil, errs.ErrServerError
	}

	// TODO: session info
	session, err = db.TXQueries.CreateSession(db.CTX, database.CreateSessionParams{
		UserID: user.ID,
		Name: utils.NewPointer("First device"),
		Platform: utils.NewPointer("Unknown"),
		LatestIp: utils.NewPointer("Unknown"),
	})

	if err != nil {
		a.log.Error(
			"Failed to create a new session during registration, rolling back registration",
			zap.String("username", user.Username),
			zap.Error(err))
		return nil, errs.ErrServerError
	}

	accessToken, refreshToken, err = utils.GenerateTokens(user.Username, session.Guid.String()) 

	if err != nil {
		a.log.Error(
			"Failed to create tokens for newly registered user, rolling back registration",
			zap.String("username", user.Username),
			zap.Error(err))
		return nil, errs.ErrServerError
	}

	helper.Commit()

	a.log.Info(
		"User verified registration",
		zap.String("username", request.Username))

	response := models.RegistrationCompleteResponse{Tokens: models.Tokens{
		AccessToken: accessToken,
		RefreshToken: refreshToken,
	}}

	return &response, errs.ErrNotImplemented
}

// TODO: totp
// TODO: banned user check
func (a *authServiceImpl) Login(request models.LoginRequest) (*models.LoginResponse, error) {
	var userRow database.GetUserByLoginCredentialsRow
	var session database.Session

	helper, db, _ := database.NewDbHelperTransaction(a.dbctx)
  defer helper.Rollback()

	var err error

	userRow, err = db.TXQueries.GetUserByLoginCredentials(db.CTX, database.GetUserByLoginCredentialsParams{
		Username: request.Username,
		Password: request.Password,
	})

	if err != nil {
		a.log.Warn(
			"Failed login attempt",
			zap.Error(err))

		var returnedError error

		switch err {
		case pgx.ErrNoRows:
			returnedError = errs.ErrForbidden
		default:
			returnedError = errs.ErrServerError
		}

		return nil, returnedError
	}

	session, err = db.TXlessQueries.CreateSession(db.CTX, database.CreateSessionParams{
		UserID: userRow.ID,
		Name: utils.NewPointer("New device"),
		Platform: utils.NewPointer("Unknown"),
		LatestIp: utils.NewPointer("Unknown"),
	})

	if err != nil {
		a.log.Error(
			"Failed to create session for a new login",
			zap.String("username", userRow.Username),
			zap.Error(err))
		return nil, errs.ErrServerError
	}

	accessToken, refreshToken, err := utils.GenerateTokens(userRow.Username, session.Guid.String())
	if err != nil {
		a.log.Error(
			"Failed to generate tokens for a new login",
			zap.String("username", userRow.Username),
			zap.Error(err))
		return nil, errs.ErrServerError
	}

	helper.Commit()

	response := models.LoginResponse{Tokens: models.Tokens{
		AccessToken: accessToken, 
		RefreshToken: refreshToken,
	}}

	return &response, nil
}

func (a *authServiceImpl) Refresh(request models.RefreshRequest) (*models.RefreshResponse, error) {
	return nil, errs.ErrNotImplemented
}