// Copyright or © or Copr. happyDNS (2020)
//
// contact@happydomain.org
//
// This software is a computer program whose purpose is to provide a modern
// interface to interact with DNS systems.
//
// This software is governed by the CeCILL license under French law and abiding
// by the rules of distribution of free software.  You can use, modify and/or
// redistribute the software under the terms of the CeCILL license as
// circulated by CEA, CNRS and INRIA at the following URL
// "http://www.cecill.info".
//
// As a counterpart to the access to the source code and rights to copy, modify
// and redistribute granted by the license, users are provided only with a
// limited warranty and the software's author, the holder of the economic
// rights, and the successive licensors have only limited liability.
//
// In this respect, the user's attention is drawn to the risks associated with
// loading, using, modifying and/or developing or reproducing the software by
// the user in light of its specific status of free software, that may mean
// that it is complicated to manipulate, and that also therefore means that it
// is reserved for developers and experienced professionals having in-depth
// computer knowledge. Users are therefore encouraged to load and test the
// software's suitability as regards their requirements in conditions enabling
// the security of their systems and/or data to be ensured and, more generally,
// to use and operate it in the same conditions as regards security.
//
// The fact that you are presently reading this means that you have had
// knowledge of the CeCILL license and that you accept its terms.

package api

import (
	"bytes"
	"encoding/base64"
	"fmt"
	"log"
	"net/http"
	"strings"

	"github.com/gin-gonic/gin"

	"git.happydns.org/happydomain/actions"
	"git.happydns.org/happydomain/config"
	"git.happydns.org/happydomain/model"
	"git.happydns.org/happydomain/storage"
)

func declareUsersRoutes(opts *config.Options, router *gin.RouterGroup) {
	router.POST("/users", func(c *gin.Context) {
		registerUser(opts, c)
	})
	router.PATCH("/users", func(c *gin.Context) {
		specialUserOperations(opts, c)
	})

	apiUserRoutes := router.Group("/users/:uid")
	apiUserRoutes.Use(userAuthHandler)

	apiUserRoutes.POST("/email", validateUserAddress)
	apiUserRoutes.POST("/recovery", recoverUserAccount)
}

func declareUsersAuthRoutes(opts *config.Options, router *gin.RouterGroup) {
	router.GET("/session", getSession)
	router.DELETE("/session", clearSession)

	apiUserRoutes := router.Group("/users/:uid")
	apiUserRoutes.Use(userHandler)
	apiUserRoutes.Use(SameUserHandler)

	apiUserRoutes.GET("", getUser)
	apiUserRoutes.GET("/settings", getUserSettings)
	apiUserRoutes.POST("/settings", changeUserSettings)

	apiUserAuthRoutes := router.Group("/users/:uid")
	apiUserAuthRoutes.Use(userAuthHandler)
	apiUserAuthRoutes.POST("/delete", func(c *gin.Context) {
		deleteUser(opts, c)
	})
	apiUserAuthRoutes.POST("/new_password", func(c *gin.Context) {
		changePassword(opts, c)
	})
}

func myUser(c *gin.Context) (user *happydns.User) {
	if u, exists := c.Get("LoggedUser"); exists {
		user = u.(*happydns.User)
	} else if u, exists := c.Get("user"); exists {
		user = u.(*happydns.User)
	}
	return
}

type UploadedUser struct {
	Kind       string
	Email      string
	Password   string
	Language   string `json:"lang,omitempty"`
	Newsletter bool   `json:"wantReceiveUpdate,omitempty"`
}

func registerUser(opts *config.Options, c *gin.Context) {
	var uu UploadedUser
	err := c.ShouldBindJSON(&uu)
	if err != nil {
		log.Printf("%s sends invalid User JSON: %s", c.ClientIP(), err.Error())
		c.AbortWithStatusJSON(http.StatusBadRequest, gin.H{"errmsg": fmt.Sprintf("Something is wrong in received data: %s", err.Error())})
		return
	}

	if len(uu.Email) <= 3 || strings.Index(uu.Email, "@") == -1 {
		c.AbortWithStatusJSON(http.StatusBadRequest, gin.H{"errmsg": "The given email is invalid."})
		return
	}

	if len(uu.Password) <= 7 {
		c.AbortWithStatusJSON(http.StatusBadRequest, gin.H{"errmsg": "The given password is invalid."})
		return
	}

	if storage.MainStore.AuthUserExists(uu.Email) {
		c.AbortWithStatusJSON(http.StatusBadRequest, gin.H{"errmsg": "An account already exists with the given address. Try login now."})
		return
	}

	user, err := happydns.NewUserAuth(uu.Email, uu.Password)
	if err != nil {
		c.AbortWithStatusJSON(http.StatusBadRequest, gin.H{"errmsg": err.Error()})
		return
	}

	user.AllowCommercials = uu.Newsletter

	if err := storage.MainStore.CreateAuthUser(user); err != nil {
		log.Printf("%s: unable to CreateUser in registerUser: %s", c.ClientIP(), err.Error())
		c.AbortWithStatusJSON(http.StatusInternalServerError, gin.H{"errmsg": "Sorry, we are currently unable to create your account. Please try again later."})
		return
	}

	if actions.SendValidationLink(opts, user); err != nil {
		log.Printf("%s: unable to SendValidationLink in registerUser: %s", c.ClientIP(), err.Error())
		c.AbortWithStatusJSON(http.StatusInternalServerError, gin.H{"errmsg": "Sorry, we are currently unable to sent email validation link. Please try again later."})
		return
	}

	log.Printf("%s: registers new user: %s", c.ClientIP(), user.Email)

	c.JSON(http.StatusOK, user)
}

func specialUserOperations(opts *config.Options, c *gin.Context) {
	var uu UploadedUser
	err := c.ShouldBindJSON(&uu)
	if err != nil {
		log.Printf("%s sends invalid User JSON: %s", c.ClientIP(), err.Error())
		c.AbortWithStatusJSON(http.StatusBadRequest, gin.H{"errmsg": fmt.Sprintf("Something is wrong in received data: %s", err.Error())})
		return
	}

	res := gin.H{"errmsg": "If this address exists in our database, you'll receive a new e-mail."}

	if user, err := storage.MainStore.GetAuthUserByEmail(uu.Email); err != nil {
		log.Printf("%s: unable to retrieve user %q: %s", c.ClientIP(), uu.Email, err.Error())
		c.JSON(http.StatusOK, res)
		return
	} else {
		if uu.Kind == "recovery" {
			if user.EmailVerification == nil {
				if err = actions.SendValidationLink(opts, user); err != nil {
					log.Printf("%s: unable to SendValidationLink in specialUserOperations: %s", c.ClientIP(), err.Error())
					c.AbortWithStatusJSON(http.StatusInternalServerError, gin.H{"errmsg": "Sorry, we are currently unable to sent email validation link. Please try again later."})
					return
				}

				log.Printf("%s: Sent validation link to: %s", c.ClientIP(), user.Email)
			} else {
				if err = actions.SendRecoveryLink(opts, user); err != nil {
					log.Printf("%s: unable to SendRecoveryLink in specialUserOperations: %s", c.ClientIP(), err.Error())
					c.AbortWithStatusJSON(http.StatusInternalServerError, gin.H{"errmsg": "Sorry, we are currently unable to sent accont recovery link. Please try again later."})
					return
				}

				if err := storage.MainStore.UpdateAuthUser(user); err != nil {
					log.Printf("%s: unable to UpdateUser in specialUserOperations: %s", c.ClientIP(), err.Error())
					c.AbortWithStatusJSON(http.StatusInternalServerError, gin.H{"errmsg": "Sorry, we are currently unable to update your profile. Please try again later."})
					return
				}

				log.Printf("%s: Sent recovery link to: %s", c.ClientIP(), user.Email)
			}
		} else if uu.Kind == "validation" {
			// Email have already been validated, do nothing
			if user.EmailVerification != nil {
				c.JSON(http.StatusOK, res)
				return
			}

			if err = actions.SendValidationLink(opts, user); err != nil {
				log.Printf("%s: unable to SendValidationLink 2 in specialUserOperations: %s", c.ClientIP(), err.Error())
				c.AbortWithStatusJSON(http.StatusInternalServerError, gin.H{"errmsg": "Sorry, we are currently unable to sent email validation link. Please try again later."})
				return
			}

			log.Printf("%s: Sent validation link to: %s", c.ClientIP(), user.Email)
		}
	}

	c.JSON(http.StatusOK, res)
}

func SameUserHandler(c *gin.Context) {
	myuser := c.MustGet("LoggedUser").(*happydns.User)
	user := c.MustGet("user").(*happydns.User)

	if !bytes.Equal(user.Id, myuser.Id) {
		log.Printf("%s: tries to do action as %s (logged %s)", c.ClientIP(), myuser, user)
		c.AbortWithStatusJSON(http.StatusForbidden, gin.H{"errmsg": "Not authorized"})
		return
	}

	c.Next()
}

func getUser(c *gin.Context) {
	user := c.MustGet("user").(*happydns.User)

	c.JSON(http.StatusOK, user)
}

func getUserSettings(c *gin.Context) {
	user := c.MustGet("user").(*happydns.User)

	c.JSON(http.StatusOK, user.Settings)
}

func changeUserSettings(c *gin.Context) {
	user := c.MustGet("user").(*happydns.User)

	var us happydns.UserSettings
	if err := c.ShouldBindJSON(&us); err != nil {
		log.Printf("%s sends invalid UserSettings JSON: %s", c.ClientIP(), err.Error())
		c.AbortWithStatusJSON(http.StatusBadRequest, gin.H{"errmsg": fmt.Sprintf("Something is wrong in received data: %s", err.Error())})
		return
	}

	user.Settings = us

	if err := storage.MainStore.UpdateUser(user); err != nil {
		log.Printf("%s: unable to UpdateUser in changeUserSettings: %s", c.ClientIP(), err.Error())
		c.AbortWithStatusJSON(http.StatusInternalServerError, gin.H{"errmsg": "Sorry, we are currently unable to update your profile. Please try again later."})
		return
	}

	c.JSON(http.StatusOK, user.Settings)
}

type passwordForm struct {
	Current         string
	Password        string
	PasswordConfirm string
}

func changePassword(opts *config.Options, c *gin.Context) {
	user := c.MustGet("authuser").(*happydns.UserAuth)

	var lf passwordForm
	if err := c.ShouldBindJSON(&lf); err != nil {
		log.Printf("%s sends invalid passwordForm JSON: %s", c.ClientIP(), err.Error())
		c.AbortWithStatusJSON(http.StatusBadRequest, gin.H{"errmsg": fmt.Sprintf("Something is wrong in received data: %s", err.Error())})
		return
	}

	if !user.CheckAuth(lf.Current) {
		c.AbortWithStatusJSON(http.StatusForbidden, gin.H{"errmsg": "The given current password is invalid."})
		return
	}

	if lf.Password != lf.PasswordConfirm {
		c.AbortWithStatusJSON(http.StatusBadRequest, gin.H{"errmsg": "The new password and its confirmation are different."})
		return
	}

	if err := user.DefinePassword(lf.Password); err != nil {
		log.Printf("%s: unable to DefinePassword in changePassword: %s", c.ClientIP(), err.Error())
		c.AbortWithStatusJSON(http.StatusInternalServerError, gin.H{"errmsg": "Sorry, we are currently unable to update your profile. Please try again later."})
		return
	}

	// Retrieve all user's sessions to disconnect them
	sessions, err := storage.MainStore.GetAuthUserSessions(user)
	if err != nil {
		log.Printf("%s: unable to GetUserSessions in changePassword: %s", c.ClientIP(), err.Error())
		c.AbortWithStatusJSON(http.StatusInternalServerError, gin.H{"errmsg": "Sorry, we are currently unable to update your profile. Please try again later."})
		return
	}

	if err = storage.MainStore.UpdateAuthUser(user); err != nil {
		log.Printf("%s: unable to DefinePassword in changePassword: %s", c.ClientIP(), err.Error())
		c.AbortWithStatusJSON(http.StatusInternalServerError, gin.H{"errmsg": "Sorry, we are currently unable to update your profile. Please try again later."})
		return
	}

	log.Printf("%s changes password for user %s", c.ClientIP(), user.Email)

	for _, session := range sessions {
		err = storage.MainStore.DeleteSession(session)
		if err != nil {
			log.Println("%s: unable to delete session (password changed): %s", c.ClientIP(), err.Error())
		}
	}

	logout(opts, c)
}

func deleteUser(opts *config.Options, c *gin.Context) {
	user := c.MustGet("authuser").(*happydns.UserAuth)

	var lf passwordForm
	if err := c.ShouldBindJSON(&lf); err != nil {
		log.Printf("%s sends invalid passwordForm JSON: %s", c.ClientIP(), err.Error())
		c.AbortWithStatusJSON(http.StatusBadRequest, gin.H{"errmsg": fmt.Sprintf("Something is wrong in received data: %s", err.Error())})
		return
	}

	if !user.CheckAuth(lf.Current) {
		c.AbortWithStatusJSON(http.StatusForbidden, gin.H{"errmsg": "The given current password is invalid."})
		return
	}

	// Retrieve all user's sessions to disconnect them
	sessions, err := storage.MainStore.GetAuthUserSessions(user)
	if err != nil {
		log.Printf("%s: unable to GetUserSessions in deleteUser: %s", c.ClientIP(), err.Error())
		c.AbortWithStatusJSON(http.StatusInternalServerError, gin.H{"errmsg": "Sorry, we are currently unable to update your profile. Please try again later."})
		return
	}

	if err = storage.MainStore.DeleteAuthUser(user); err != nil {
		log.Printf("%s: unable to DefinePassword in deleteuser: %s", c.ClientIP(), err.Error())
		c.AbortWithStatusJSON(http.StatusInternalServerError, gin.H{"errmsg": "Sorry, we are currently unable to update your profile. Please try again later."})
		return
	}

	log.Printf("%s: deletes user: %s", c.ClientIP(), user.Email)

	for _, session := range sessions {
		err = storage.MainStore.DeleteSession(session)
		if err != nil {
			log.Println("%s: unable to delete session (drop account): %s", c.ClientIP(), err.Error())
		}
	}

	logout(opts, c)
}

func UserHandlerBase(c *gin.Context) (*happydns.User, error) {
	uid, err := base64.RawURLEncoding.DecodeString(c.Param("uid"))
	if err != nil {
		return nil, fmt.Errorf("Invalid user identifier given: %w", err)
	}

	user, err := storage.MainStore.GetUser(uid)
	if err != nil {
		return nil, fmt.Errorf("User not found")
	}

	return user, nil
}

func userHandler(c *gin.Context) {
	user, err := UserHandlerBase(c)
	if err != nil {
		c.AbortWithStatusJSON(http.StatusNotFound, gin.H{"errmsg": err.Error()})
		return
	}

	c.Set("user", user)

	c.Next()
}

func UserAuthHandlerBase(c *gin.Context) (*happydns.UserAuth, error) {
	uid, err := base64.RawURLEncoding.DecodeString(c.Param("uid"))
	if err != nil {
		return nil, fmt.Errorf("Invalid user identifier given: %w", err)
	}

	user, err := storage.MainStore.GetAuthUser(uid)
	if err != nil {
		return nil, fmt.Errorf("User not found")
	}

	return user, nil
}

func userAuthHandler(c *gin.Context) {
	user, err := UserAuthHandlerBase(c)
	if err != nil {
		c.AbortWithStatusJSON(http.StatusNotFound, gin.H{"errmsg": err.Error()})
		return
	}

	c.Set("authuser", user)

	c.Next()
}

type UploadedAddressValidation struct {
	Key string
}

func validateUserAddress(c *gin.Context) {
	user := c.MustGet("authuser").(*happydns.UserAuth)

	var uav UploadedAddressValidation
	err := c.ShouldBindJSON(&uav)
	if err != nil {
		log.Printf("%s sends invalid AddressValidation JSON: %s", c.ClientIP(), err.Error())
		c.AbortWithStatusJSON(http.StatusBadRequest, gin.H{"errmsg": fmt.Sprintf("Something is wrong in received data: %s", err.Error())})
		return
	}

	if err := user.ValidateEmail(uav.Key); err != nil {
		log.Printf("%s bad email validation key: %s", c.ClientIP(), err.Error())
		c.AbortWithStatusJSON(http.StatusBadRequest, gin.H{"errmsg": fmt.Sprintf("Bad validation key: %s", err.Error())})
		return
	}

	if err := storage.MainStore.UpdateAuthUser(user); err != nil {
		log.Printf("%s: unable to UpdateUser in ValidateUserAddress: %s", c.ClientIP(), err.Error())
		c.AbortWithStatusJSON(http.StatusInternalServerError, gin.H{"errmsg": "Sorry, we are currently unable to update your profile. Please try again later."})
		return
	}

	c.JSON(http.StatusOK, true)
}

type UploadedAccountRecovery struct {
	Key      string
	Password string
}

func recoverUserAccount(c *gin.Context) {
	user := c.MustGet("authuser").(*happydns.UserAuth)

	var uar UploadedAccountRecovery
	err := c.ShouldBindJSON(&uar)
	if err != nil {
		log.Printf("%s sends invalid AccountRecovey JSON: %s", c.ClientIP(), err.Error())
		c.AbortWithStatusJSON(http.StatusBadRequest, gin.H{"errmsg": fmt.Sprintf("Something is wrong in received data: %s", err.Error())})
		return
	}

	if err := user.CanRecoverAccount(uar.Key); err != nil {
		c.AbortWithStatusJSON(http.StatusForbidden, gin.H{"errmsg": err.Error()})
		return
	}

	if len(uar.Password) == 0 {
		c.AbortWithStatusJSON(http.StatusBadRequest, gin.H{"errmsg": "Password can't be empty!"})
		return
	}

	if err := user.DefinePassword(uar.Password); err != nil {
		c.AbortWithStatusJSON(http.StatusBadRequest, gin.H{"errmsg": err.Error()})
		return
	}

	if err := storage.MainStore.UpdateAuthUser(user); err != nil {
		log.Printf("%s: unable to UpdateUser in recoverUserAccount: %s", c.ClientIP(), err.Error())
		c.AbortWithStatusJSON(http.StatusInternalServerError, gin.H{"errmsg": "Sorry, we are currently unable to update your profile. Please try again later."})
		return
	}

	log.Printf("%s: User recovered: %s", c.ClientIP(), user.Email)
	c.JSON(http.StatusOK, true)
}

func getSession(c *gin.Context) {
	session := c.MustGet("MySession").(*happydns.Session)

	c.JSON(http.StatusOK, session)
}

func clearSession(c *gin.Context) {
	session := c.MustGet("MySession").(*happydns.Session)

	session.ClearSession()

	c.JSON(http.StatusOK, true)
}