package ldap

import (
	"encoding/json"
	"log"
	"net/http"
	"regexp"
	"strconv"

	"github.com/go-ldap/ldap"
	auth "imuslab.com/arozos/mod/auth"
	"imuslab.com/arozos/mod/auth/ldap/ldapreader"
	"imuslab.com/arozos/mod/auth/oauth2/syncdb"
	reg "imuslab.com/arozos/mod/auth/register"
	"imuslab.com/arozos/mod/common"
	db "imuslab.com/arozos/mod/database"
	permission "imuslab.com/arozos/mod/permission"
	"imuslab.com/arozos/mod/time/nightly"
	"imuslab.com/arozos/mod/user"
)

type ldapHandler struct {
	ag                *auth.AuthAgent
	ldapreader        *ldapreader.LdapReader
	reg               *reg.RegisterHandler
	coredb            *db.Database
	permissionHandler *permission.PermissionHandler
	userHandler       *user.UserHandler
	iconSystem        string
	syncdb            *syncdb.SyncDB
	nightlyManager    *nightly.TaskManager
}

type Config struct {
	Enabled      bool   `json:"enabled"`
	BindUsername string `json:"bind_username"`
	BindPassword string `json:"bind_password"`
	FQDN         string `json:"fqdn"`
	BaseDN       string `json:"base_dn"`
}

type UserAccount struct {
	Username   string   `json:"username"`
	Group      []string `json:"group"`
	EquivGroup []string `json:"equiv_group"`
}

//syncorizeUserReturnInterface not designed to be used outside
type syncorizeUserReturnInterface struct {
	Userinfo []UserAccount `json:"userinfo"`
	Length   int           `json:"length"`
	Error    string        `json:"error"`
}

//NewLdapHandler xxx
func NewLdapHandler(authAgent *auth.AuthAgent, register *reg.RegisterHandler, coreDb *db.Database, permissionHandler *permission.PermissionHandler, userHandler *user.UserHandler, nightlyManager *nightly.TaskManager, iconSystem string) *ldapHandler {
	//ldap handler init
	log.Println("Starting LDAP client...")
	err := coreDb.NewTable("ldap")
	if err != nil {
		log.Println("Failed to create LDAP database. Terminating.")
		panic(err)
	}

	//key value to be used for LDAP authentication
	BindUsername := readSingleConfig("BindUsername", coreDb)
	BindPassword := readSingleConfig("BindPassword", coreDb)
	FQDN := readSingleConfig("FQDN", coreDb)
	BaseDN := readSingleConfig("BaseDN", coreDb)

	LDAPHandler := ldapHandler{
		ag:                authAgent,
		ldapreader:        ldapreader.NewLDAPReader(BindUsername, BindPassword, FQDN, BaseDN),
		reg:               register,
		coredb:            coreDb,
		permissionHandler: permissionHandler,
		userHandler:       userHandler,
		iconSystem:        iconSystem,
		syncdb:            syncdb.NewSyncDB(),
		nightlyManager:    nightlyManager,
	}

	nightlyManager.RegisterNightlyTask(LDAPHandler.NightlySync)

	return &LDAPHandler
}

func (ldap *ldapHandler) ReadConfig(w http.ResponseWriter, r *http.Request) {
	//basic components
	enabled, err := strconv.ParseBool(ldap.readSingleConfig("enabled"))
	if err != nil {
		common.SendTextResponse(w, "Invalid config value [key=enabled].")
		return
	}
	//get the LDAP config from db
	BindUsername := ldap.readSingleConfig("BindUsername")
	BindPassword := ldap.readSingleConfig("BindPassword")
	FQDN := ldap.readSingleConfig("FQDN")
	BaseDN := ldap.readSingleConfig("BaseDN")

	//marshall it and return
	config, err := json.Marshal(Config{
		Enabled:      enabled,
		BindUsername: BindUsername,
		BindPassword: BindPassword,
		FQDN:         FQDN,
		BaseDN:       BaseDN,
	})
	if err != nil {
		empty, err := json.Marshal(Config{})
		if err != nil {
			common.SendErrorResponse(w, "Error while marshalling config")
		}
		common.SendJSONResponse(w, string(empty))
	}
	common.SendJSONResponse(w, string(config))
}

func (ldap *ldapHandler) WriteConfig(w http.ResponseWriter, r *http.Request) {
	//receive the parameter
	enabled, err := common.Mv(r, "enabled", true)
	if err != nil {
		common.SendErrorResponse(w, "enabled field can't be empty")
		return
	}

	//allow empty fields if enabled is false
	showError := true
	if enabled != "true" {
		showError = false
	}

	//four fields to store the LDAP authentication information
	BindUsername, err := common.Mv(r, "bind_username", true)
	if err != nil {
		if showError {
			common.SendErrorResponse(w, "bind_username field can't be empty")
			return
		}
	}
	BindPassword, err := common.Mv(r, "bind_password", true)
	if err != nil {
		if showError {
			common.SendErrorResponse(w, "bind_password field can't be empty")
			return
		}
	}
	FQDN, err := common.Mv(r, "fqdn", true)
	if err != nil {
		if showError {
			common.SendErrorResponse(w, "fqdn field can't be empty")
			return
		}
	}
	BaseDN, err := common.Mv(r, "base_dn", true)
	if err != nil {
		if showError {
			common.SendErrorResponse(w, "base_dn field can't be empty")
			return
		}
	}

	//write the data back to db
	ldap.coredb.Write("ldap", "enabled", enabled)
	ldap.coredb.Write("ldap", "BindUsername", BindUsername)
	ldap.coredb.Write("ldap", "BindPassword", BindPassword)
	ldap.coredb.Write("ldap", "FQDN", FQDN)
	ldap.coredb.Write("ldap", "BaseDN", BaseDN)

	//update the new authencation infromation
	ldap.ldapreader = ldapreader.NewLDAPReader(BindUsername, BindPassword, FQDN, BaseDN)

	//return ok
	common.SendOK(w)
}

//@para limit: -1 means unlimited
func (ldap *ldapHandler) getAllUser(limit int) ([]UserAccount, error) {
	//read the user account from ldap, if limit is -1 then it will read all USERS
	var accounts []UserAccount
	result, err := ldap.ldapreader.GetAllUser()
	if err != nil {
		return []UserAccount{}, err
	}
	//loop through the result
	for i, v := range result {
		account := ldap.convertGroup(v)
		accounts = append(accounts, account)
		if i+1 > limit && limit != -1 {
			break
		}
	}
	//check if the return struct is empty, if yes then insert empty
	if len(accounts) > 0 {
		return accounts[1:], nil
	} else {
		return []UserAccount{}, nil
	}
}

func (ldap *ldapHandler) convertGroup(ldapUser *ldap.Entry) UserAccount {
	//check the group belongs
	var Group []string
	var EquivGroup []string
	regexSyntax := regexp.MustCompile("cn=([^,]+),")
	for _, v := range ldapUser.GetAttributeValues("memberOf") {
		groups := regexSyntax.FindStringSubmatch(v)
		if len(groups) > 0 {
			//check if the LDAP group is already exists in ArOZOS system
			if ldap.permissionHandler.GroupExists(groups[1]) {
				EquivGroup = append(EquivGroup, groups[1])
			}
			//LDAP list
			Group = append(Group, groups[1])
		}
	}
	if len(EquivGroup) < 1 {
		if !ldap.permissionHandler.GroupExists(ldap.reg.GetDefaultUserGroup()) {
			//create new user group named default, prventing user don't have a group
			ldap.permissionHandler.NewPermissionGroup("default", false, 15<<30, []string{}, "Desktop")
			ldap.reg.SetDefaultUserGroup("default")
		}
		EquivGroup = append(EquivGroup, ldap.reg.GetDefaultUserGroup())
	}
	account := UserAccount{
		Username:   ldapUser.GetAttributeValue("cn"),
		Group:      Group,
		EquivGroup: EquivGroup,
	}
	return account
}

func (ldap *ldapHandler) TestConnection(w http.ResponseWriter, r *http.Request) {
	//marshall it and return the connection status
	userList, err := ldap.getAllUser(10)
	if err != nil {
		errMessage, err := json.Marshal(syncorizeUserReturnInterface{Error: err.Error()})
		if err != nil {
			common.SendErrorResponse(w, "{\"error\":\"Error while marshalling information\"}")
			return
		}
		common.SendJSONResponse(w, string(errMessage))
		return
	}
	returnJSON := syncorizeUserReturnInterface{Userinfo: userList, Length: len(userList), Error: ""}
	accountJSON, err := json.Marshal(returnJSON)
	if err != nil {
		errMessage, err := json.Marshal(syncorizeUserReturnInterface{Error: err.Error()})
		if err != nil {
			common.SendErrorResponse(w, "{\"error\":\"Error while marshalling information\"}")
			return
		}
		common.SendJSONResponse(w, string(errMessage))
		return
	}
	common.SendJSONResponse(w, string(accountJSON))
}

func (ldap *ldapHandler) checkCurrUserAdmin(w http.ResponseWriter, r *http.Request) bool {
	//check current user is admin and new update will remove it or not
	currentLoggedInUser, err := ldap.userHandler.GetUserInfoFromRequest(w, r)
	if err != nil {
		common.SendErrorResponse(w, "Error while getting user info")
		return false
	}
	ldapCurrUserInfo, err := ldap.ldapreader.GetUser(currentLoggedInUser.Username)
	if err != nil {
		common.SendErrorResponse(w, "Error while getting user info from LDAP")
		return false
	}
	isAdmin := false
	//get the croups out from LDAP group list
	regexSyntax := regexp.MustCompile("cn=([^,]+),")
	for _, v := range ldapCurrUserInfo.GetAttributeValues("memberOf") {
		//loop through all memberOf's array
		groups := regexSyntax.FindStringSubmatch(v)
		//if after regex there is still groups exists
		if len(groups) > 0 {
			//check if the LDAP group is already exists in ArOZOS system
			if ldap.permissionHandler.GroupExists(groups[1]) {
				if ldap.permissionHandler.GetPermissionGroupByName(groups[1]).IsAdmin {
					isAdmin = true
				}
			}
		}
	}
	return isAdmin
}

func (ldap *ldapHandler) SynchronizeUser(w http.ResponseWriter, r *http.Request) {
	//check if suer is admin before executing the command
	//if user is admin then check if user will lost him/her's admin access
	consistencyCheck := ldap.checkCurrUserAdmin(w, r)
	if !consistencyCheck {
		common.SendErrorResponse(w, "You will no longer become the admin after synchronizing, synchronize terminated")
		return
	}

	err := ldap.SynchronizeUserFromLDAP()
	if err != nil {
		common.SendErrorResponse(w, err.Error())
		return
	}
	common.SendOK(w)
}

func (ldap *ldapHandler) NightlySync() {
	err := ldap.SynchronizeUserFromLDAP()
	log.Println(err)
}

func (ldap *ldapHandler) SynchronizeUserFromLDAP() error {
	//check if suer is admin before executing the command
	//if user is admin then check if user will lost him/her's admin access
	ldapUsersList, err := ldap.getAllUser(-1)
	if err != nil {
		return err
	}
	for _, ldapUser := range ldapUsersList {
		//check if user exist in system
		if ldap.ag.UserExists(ldapUser.Username) {
			//if exists, then check if the user group is the same with ldap's setting
			//Get the permission groups by their ids
			userinfo, err := ldap.userHandler.GetUserInfoFromUsername(ldapUser.Username)
			if err != nil {
				return err
			}
			newPermissionGroups := ldap.permissionHandler.GetPermissionGroupByNameList(ldapUser.EquivGroup)
			//Set the user's permission to these groups
			userinfo.SetUserPermissionGroup(newPermissionGroups)
		}
	}
	return nil
}

//LOGIN related function
//functions basically same as arozos's original function
func (ldap *ldapHandler) HandleLoginPage(w http.ResponseWriter, r *http.Request) {
	checkLDAPenabled := ldap.readSingleConfig("enabled")
	if checkLDAPenabled == "false" {
		common.SendTextResponse(w, "LDAP not enabled.")
		return
	}
	//load the template from file and inject necessary variables
	red, _ := common.Mv(r, "redirect", false)

	//Append the redirection addr into the template
	imgsrc := "./web/" + ldap.iconSystem
	if !common.FileExists(imgsrc) {
		imgsrc = "./web/img/public/auth_icon.png"
	}
	imageBase64, _ := common.LoadImageAsBase64(imgsrc)
	parsedPage, err := common.Templateload("web/login.system", map[string]interface{}{
		"redirection_addr": red,
		"usercount":        strconv.Itoa(ldap.ag.GetUserCounts()),
		"service_logo":     imageBase64,
		"login_addr":       "system/auth/ldap/login",
	})
	if err != nil {
		panic("Error. Unable to parse login page. Is web directory data exists?")
	}
	w.Header().Add("Content-Type", "text/html; charset=UTF-8")
	w.Write([]byte(parsedPage))
}

func (ldap *ldapHandler) HandleNewPasswordPage(w http.ResponseWriter, r *http.Request) {
	checkLDAPenabled := ldap.readSingleConfig("enabled")
	if checkLDAPenabled == "false" {
		common.SendTextResponse(w, "LDAP not enabled.")
		return
	}
	//get the parameter from the request
	acc, err := common.Mv(r, "username", false)
	if err != nil {
		common.SendErrorResponse(w, err.Error())
		return
	}
	displayname, err := common.Mv(r, "displayname", false)
	if err != nil {
		common.SendErrorResponse(w, err.Error())
		return
	}
	key, err := common.Mv(r, "authkey", false)
	if err != nil {
		common.SendErrorResponse(w, err.Error())
		return
	}
	//init the web interface
	imgsrc := "./web/" + ldap.iconSystem
	if !common.FileExists(imgsrc) {
		imgsrc = "./web/img/public/auth_icon.png"
	}
	imageBase64, _ := common.LoadImageAsBase64(imgsrc)
	template, err := common.Templateload("system/ldap/newPasswordTemplate.html", map[string]interface{}{
		"vendor_logo":  imageBase64,
		"username":     acc,
		"display_name": displayname,
		"key":          key,
	})
	if err != nil {
		log.Fatal(err)
	}
	w.Header().Set("Content-Type", "text/html; charset=UTF-8")
	w.Write([]byte(template))
}

func (ldap *ldapHandler) HandleLogin(w http.ResponseWriter, r *http.Request) {
	checkLDAPenabled := ldap.readSingleConfig("enabled")
	if checkLDAPenabled == "false" {
		common.SendTextResponse(w, "LDAP not enabled.")
		return
	}
	//Get username from request using POST mode
	username, err := common.Mv(r, "username", true)
	if err != nil {
		//Username not defined
		log.Println("[System Auth] Someone trying to login with username: " + username)
		//Write to log
		ldap.ag.Logger.LogAuth(r, false)
		common.SendErrorResponse(w, "Username not defined or empty.")
		return
	}

	//Get password from request using POST mode
	password, err := common.Mv(r, "password", true)
	if err != nil {
		//Password not defined
		ldap.ag.Logger.LogAuth(r, false)
		common.SendErrorResponse(w, "Password not defined or empty.")
		return
	}

	//Get rememberme settings
	rememberme := false
	rmbme, _ := common.Mv(r, "rmbme", true)
	if rmbme == "true" {
		rememberme = true
	}

	//Check the database and see if this user is in the database
	passwordCorrect, err := ldap.ldapreader.Authenticate(username, password)
	if err != nil {
		ldap.ag.Logger.LogAuth(r, false)
		common.SendErrorResponse(w, "Unable to connect to LDAP server")
		log.Println("LDAP Authentication error, " + err.Error())
		return
	}
	//The database contain this user information. Check its password if it is correct
	if passwordCorrect {
		//Password correct
		//if user not exist then redirect to create pwd screen
		if !ldap.ag.UserExists(username) {
			authkey := ldap.syncdb.Store(username)
			common.SendJSONResponse(w, "{\"redirect\":\"system/auth/ldap/newPassword?username="+username+"&displayname="+username+"&authkey="+authkey+"\"}")
		} else {
			// Set user as authenticated
			ldap.ag.LoginUserByRequest(w, r, username, rememberme)
			//Print the login message to console
			log.Println(username + " logged in.")
			ldap.ag.Logger.LogAuth(r, true)
			common.SendOK(w)
		}
	} else {
		//Password incorrect
		log.Println(username + " has entered an invalid username or password")
		common.SendErrorResponse(w, "Invalid username or password")
		ldap.ag.Logger.LogAuth(r, false)
		return
	}
}

func (ldap *ldapHandler) HandleSetPassword(w http.ResponseWriter, r *http.Request) {
	checkLDAPenabled := ldap.readSingleConfig("enabled")
	if checkLDAPenabled == "false" {
		common.SendTextResponse(w, "LDAP not enabled.")
		return
	}
	//get paramters from request
	username, err := common.Mv(r, "username", true)
	if err != nil {
		common.SendErrorResponse(w, err.Error())
		return
	}
	password, err := common.Mv(r, "password", true)
	if err != nil {
		common.SendErrorResponse(w, err.Error())
		return
	}
	authkey, err := common.Mv(r, "authkey", true)
	if err != nil {
		common.SendErrorResponse(w, err.Error())
		return
	}

	//check if the input key matches the database's username
	isValid := ldap.syncdb.Read(authkey) == username
	ldap.syncdb.Delete(authkey) // remove the key, aka key is one time use only
	//if db data match the username, proceed
	if isValid {
		//if not exists
		if !ldap.ag.UserExists(username) {
			//get the user from ldap server
			ldapUser, err := ldap.ldapreader.GetUser(username)
			if err != nil {
				common.SendErrorResponse(w, err.Error())
				return
			}
			//convert the ldap usergroup to arozos usergroup
			convertedInfo := ldap.convertGroup(ldapUser)
			//create user account and login
			ldap.ag.CreateUserAccount(username, password, convertedInfo.EquivGroup)
			ldap.ag.Logger.LogAuth(r, true)
			ldap.ag.LoginUserByRequest(w, r, username, false)
			common.SendOK(w)
			return
		} else {
			//if exist then return error
			common.SendErrorResponse(w, "User exists, please contact the system administrator if you believe this is an error.")
			return
		}
	} else {
		common.SendErrorResponse(w, "Improper key detected")
		log.Println(r.RemoteAddr + " attempted to use invaild key to create new user but failed")
		return
	}
}

//CheckOAuth check if oauth is enabled
func (ldap *ldapHandler) HandleCheckLDAP(w http.ResponseWriter, r *http.Request) {
	enabledB := false
	enabled := ldap.readSingleConfig("enabled")
	if enabled == "true" {
		enabledB = true
	}

	type returnFormat struct {
		Enabled bool `json:"enabled"`
	}
	json, err := json.Marshal(returnFormat{Enabled: enabledB})
	if err != nil {
		common.SendErrorResponse(w, "Error occurred while marshalling JSON response")
	}
	common.SendJSONResponse(w, string(json))
}