package moffas

import (
	"encoding/json"
	"errors"
	"moffas_go/db"
	"moffas_go/helper"
	"moffas_go/logger"
	"strconv"
	"strings"
	"time"
)

type GeneratedChallenge struct {
	Full_nonce string
	User_id    int64
	Salt       string
	Iterations int
}

type VerificationResult struct {
	Server_hash       string
	Final_nonce       string
	Session_id        string
	Privileges        map[string]interface{}
	Tier              string
	Full_name         string
	Organization_data map[string]interface{}
}

func Generate_challenge(reference_id, username string, half_nonce string) (GeneratedChallenge, error) {
	logger.Debug(reference_id, " -- start generate_challenge")
	startTime := time.Now()
	defer func() {
		dur := time.Since(startTime)
		logger.Debug(reference_id, " -- generate_challenge done in ", dur)
	}()

	conn, err := db.GetConnection()
	if err != nil {
		return GeneratedChallenge{}, err
	}
	defer db.ReleaseConnection()

	current_time := time.Now().Unix()
	nonce, err := helper.GenerateRandomString(8)
	if err != nil {
		return GeneratedChallenge{}, err
	}

	full_nonce := half_nonce + nonce

	logger.Info(reference_id, "HALF NONCE : ", half_nonce)
	logger.Info(reference_id, "USERNAME : ", username)
	logger.Info(reference_id, "FULL NONCE : ", full_nonce)

	type DBResult struct {
		User_id       int64  `db:"id"`
		Salt          string `db:"salt"`
		Iterations    int    `db:"iterations"`
		Timestamp     int64  `db:"tstamp"`
		SaltedPasword string `db:"saltedpassword"`
	}

	query := `
	SELECT 
	    a.id,a.salt,a.saltedpassword,a.iterations,
	    COALESCE(b.tstamp,0) as tstamp
	FROM servouser.user a
	LEFT JOIN servouser.challenge_response b ON b.user_id = a.id
	WHERE a.username = $1 AND a.st=1 LIMIT 1`

	sql := strings.ReplaceAll(strings.ReplaceAll(strings.ReplaceAll(query, "\t", " "), "\n", " "), "  ", " ")
	logger.Debug(reference_id, "SQL : ", sql)

	dbresult := DBResult{}
	err = conn.Get(&dbresult, sql, username)
	if err != nil {
		return GeneratedChallenge{}, err
	}

	logger.Info(reference_id, "USER ID : ", dbresult.User_id)
	waittime, err := strconv.Atoi(helper.GetEnv("AUTH_WAIT_TIME", "10"))
	if err != nil {
		waittime = 10
	}
	wait_until := dbresult.Timestamp + int64(waittime)
	logger.Debug(reference_id, "LAST AUTH REQUEST : ", dbresult.Timestamp)
	logger.Debug(reference_id, "WAIT TIME  : ", waittime)
	logger.Debug(reference_id, "WAIT UNTIL : ", wait_until)
	logger.Debug(reference_id, "CURRENT TIME : ", current_time)

	if wait_until > current_time {
		logger.Info(reference_id, "!!! WAIT TIME FOR THE USER ID HAS NOT ELAPSED")
		err = errors.New("wait time has not elapsed")
		return GeneratedChallenge{}, err
	}

	//----- CONTEKAN DOANG -----
	sharedSecret := helper.GetEnv("SHARED_SECRET", "Winter is coming")
	logger.Info(reference_id, "SHARED SECRET : ", sharedSecret)
	logger.Info(reference_id, "SALTED PASSWORD : ", dbresult.SaltedPasword)

	hash1, err := helper.HMAC_SHA256(sharedSecret, dbresult.SaltedPasword)
	if err != nil {
		return GeneratedChallenge{}, err
	}
	logger.Info(reference_id, "HASH1 : ", hash1)

	calculated_client_hash, err := helper.HMAC_SHA256(full_nonce, hash1)
	if err != nil {
		return GeneratedChallenge{}, err
	}
	logger.Info(reference_id, "CALCULATED CLIENT HASH : ", calculated_client_hash)
	//----- CONTEKAN DOANG -----

	err = upsert_challenge(reference_id, full_nonce, dbresult.User_id)
	if err != nil {
		return GeneratedChallenge{}, err
	}
	return GeneratedChallenge{
		User_id:    dbresult.User_id,
		Salt:       dbresult.Salt,
		Iterations: dbresult.Iterations,
		Full_nonce: full_nonce,
	}, nil
}

func Verify_challenge(reference_id string, full_nonce string, client_hash string, next_nonce string) (VerificationResult, error) {
	logger.Debug(reference_id, " start verify_challenge")
	startTime := time.Now()
	defer func() {
		dur := time.Since(startTime)
		logger.Debug(reference_id, " -- verify_challenge done in ", dur)
	}()

	conn, err := db.GetConnection()
	if err != nil {
		return VerificationResult{}, err
	}
	defer db.ReleaseConnection()

	current_time := time.Now().Unix()
	nonce, err := helper.GenerateRandomString(8)
	if err != nil {
		return VerificationResult{}, err
	}

	logger.Info(reference_id, "FULL NONCE : ", full_nonce)

	type DBResult struct {
		User_id           int64  `db:"user_id"`
		Timestamp         int64  `db:"tstamp"`
		Fullname          string `db:"full_name"`
		Privileges        string `db:"privileges"`
		Tier              string `db:"tier"`
		SaltedPasword     string `db:"saltedpassword"`
		Organization_data string `db:"organization_data"`
	}
	dbresult := DBResult{}

	query := `
	SELECT 
		a.user_id, a.tstamp,
		b.full_name, b.saltedpassword,
		c.privileges,
		d.tier, d.data organization_data
	FROM servouser.challenge_response a
	LEFT JOIN servouser.user b ON b.id = a.user_id
	LEFT JOIN servouser.role c ON c.name = b.role
	LEFT JOIN servouser.organization d ON d.id = b.organization_id
	WHERE a.full_nonce = $1 AND b.id IS NOT NULL AND c.privileges IS NOT NULL AND b.st = 1
	LIMIT 1`

	sql := strings.ReplaceAll(strings.ReplaceAll(query, "\t", " "), "\n", " ")
	logger.Debug(reference_id, "SQL : ", sql)
	err = conn.Get(&dbresult, sql, full_nonce)
	if err != nil {
		return VerificationResult{}, err
	}
	rep_nonce := full_nonce[0:15]
	logger.Debug(reference_id, "replacement nonce : ", rep_nonce)

	query = "UPDATE servouser.challenge_response SET full_nonce = $1 WHERE full_nonce = $2"
	logger.Debug(reference_id, "SQL : ", query)
	_, err = conn.Exec(query, rep_nonce, full_nonce)
	if err != nil {
		return VerificationResult{}, err
	}

	timeout, err := strconv.Atoi(helper.GetEnv("AUTH_TIMEOUT", "300"))
	if err != nil {
		timeout = 300
	}
	logger.Info(reference_id, "AUTH TIMEOUT : ", timeout)

	expire_limit := dbresult.Timestamp + int64(timeout)
	logger.Info(reference_id, "AUTH EXPIRATION TIME : ", expire_limit)
	logger.Info(reference_id, "CURRENT TIME : ", current_time)
	if current_time > expire_limit {
		logger.Error(reference_id, "!!! CHALLENGE EXPIRED")
		err = errors.New("client expired")
		return VerificationResult{}, err
	}

	sharedSecret := helper.GetEnv("SHARED_SECRET", "Winter is coming")
	logger.Info(reference_id, "SHARED SECRET : ", sharedSecret)
	logger.Info(reference_id, "SALTED PASSWORD : ", dbresult.SaltedPasword)

	hash1, err := helper.HMAC_SHA256(sharedSecret, dbresult.SaltedPasword)
	if err != nil {
		return VerificationResult{}, err
	}
	logger.Info(reference_id, "HASH1 : ", hash1)

	calculated_client_hash, err := helper.HMAC_SHA256(full_nonce, hash1)
	if err != nil {
		return VerificationResult{}, err
	}
	logger.Info(reference_id, "CALCULATED CLIENT HASH : ", calculated_client_hash)
	logger.Info(reference_id, "CLIENT HASH : ", client_hash)
	if calculated_client_hash != client_hash {
		logger.Warning(reference_id, "!!! CLIENT HASH DOES NOT MATCH STORED CHALLENGE RESPONSE")
		err = errors.New("client hash does not match stored challenge response")
		return VerificationResult{}, err
	}

	logger.Info(reference_id, "NEXT NONCE : ", next_nonce)
	final_nonce := next_nonce + nonce
	logger.Info(reference_id, "FINAL NONCE : ", final_nonce)

	server_hash, err := helper.HMAC_SHA256(final_nonce, hash1)
	if err != nil {
		return VerificationResult{}, err
	}
	logger.Info(reference_id, "SERVER HASH : ", server_hash)

	session_secret, err := helper.HMAC_SHA256(full_nonce+final_nonce, hash1)
	if err != nil {
		return VerificationResult{}, err
	}
	logger.Info(reference_id, "SESSION SECRET : ", session_secret)
	session_id, _ := helper.GenerateRandomString(16)
	logger.Info(reference_id, "SESSION ID : ", session_id)

	err = upsert_session(reference_id, session_id, dbresult.User_id, session_secret)
	if err != nil {
		return VerificationResult{}, err
	}

	privileges := make(map[string]interface{})
	organization_data := make(map[string]interface{})

	err = json.Unmarshal([]byte(dbresult.Privileges), &privileges)
	if err != nil {
		return VerificationResult{}, err
	}

	err = json.Unmarshal([]byte(dbresult.Organization_data), &organization_data)
	if err != nil {
		return VerificationResult{}, err
	}

	return VerificationResult{
		Final_nonce:       final_nonce,
		Server_hash:       server_hash,
		Session_id:        session_id,
		Privileges:        privileges,
		Tier:              dbresult.Tier,
		Full_name:         dbresult.Fullname,
		Organization_data: organization_data,
	}, nil
}

func upsert_challenge(reference_id, full_nonce string, user_id int64) error {
	logger.Debug(reference_id, " start upsert_challenge")
	startTime := time.Now()
	defer func() {
		dur := time.Since(startTime)
		logger.Debug(reference_id, " -- upsert_challenge done in ", dur)
	}()

	conn, err := db.GetConnection()
	if err != nil {
		return err
	}
	defer db.ReleaseConnection()

	query := "DELETE FROM servouser.challenge_response WHERE full_nonce = $1 OR user_id = $2"
	sql := strings.ReplaceAll(strings.ReplaceAll(query, "\t", " "), "\n", " ")
	logger.Debug(reference_id, "SQL : ", sql)
	_, err = conn.Exec(query, full_nonce, user_id)
	if err != nil {
		return err
	}

	query = `
	INSERT INTO 
		servouser.challenge_response (full_nonce,user_id,challenge_response,tstamp)
	VALUES 
		($1,$2,'0123456789abcdefghijklmnopqrstuv',$3)`
	sql = strings.ReplaceAll(strings.ReplaceAll(query, "\t", " "), "\n", " ")
	logger.Debug(reference_id, "SQL : ", sql)
	_, err = conn.Exec(sql, full_nonce, user_id, time.Now().Unix())

	return err
}

func upsert_session(reference_id, session_id string, user_id int64, session_secret string) error {
	logger.Debug(reference_id, " start upsert_challenge")

	startTime := time.Now()
	defer func() {
		dur := time.Since(startTime)
		logger.Debug(reference_id, " -- upsert_session done in ", dur)
	}()

	conn, err := db.GetConnection()
	if err != nil {
		return err
	}
	defer db.ReleaseConnection()

	query := "DELETE FROM servouser.session WHERE session_id = $1 OR user_id = $2"
	sql := strings.ReplaceAll(strings.ReplaceAll(query, "\t", " "), "\n", " ")
	logger.Debug(reference_id, "SQL : ", sql)
	_, err = conn.Exec(query, session_id, user_id)
	if err != nil {
		return err
	}
	query = `
	INSERT INTO
		servouser.session (session_id,user_id,session_secret,tstamp,st,last_ms_tstamp,last_sequence)
	VALUES 
		($1,$2,$3,$4,1,0,0)`

	sql = strings.ReplaceAll(strings.ReplaceAll(query, "\t", " "), "\n", " ")
	logger.Debug(reference_id, "SQL : ", sql)
	_, err = conn.Exec(query, session_id, user_id, session_secret, time.Now().Unix())
	return err
}