package service

import (
	"fmt"
	"regexp"
	"strings"
	"sync"
	"time"
	"tinyauth/internal/config"
	"tinyauth/internal/utils"

	"github.com/gin-gonic/gin"
	"github.com/gorilla/sessions"
	"github.com/rs/zerolog/log"
	"golang.org/x/crypto/bcrypt"
)

type LoginAttempt struct {
	FailedAttempts int
	LastAttempt    time.Time
	LockedUntil    time.Time
}

type AuthServiceConfig struct {
	Users             []config.User
	OauthWhitelist    string
	SessionExpiry     int
	SecureCookie      bool
	Domain            string
	LoginTimeout      int
	LoginMaxRetries   int
	SessionCookieName string
	HMACSecret        string
	EncryptionSecret  string
}

type AuthService struct {
	Config        AuthServiceConfig
	Docker        *DockerService
	LoginAttempts map[string]*LoginAttempt
	LoginMutex    sync.RWMutex
	Store         *sessions.CookieStore
	LDAP          *LdapService
}

func NewAuthService(config AuthServiceConfig, docker *DockerService, ldap *LdapService) *AuthService {
	return &AuthService{
		Config:        config,
		Docker:        docker,
		LoginAttempts: make(map[string]*LoginAttempt),
		LDAP:          ldap,
	}
}

func (auth *AuthService) Init() error {
	store := sessions.NewCookieStore([]byte(auth.Config.HMACSecret), []byte(auth.Config.EncryptionSecret))
	store.Options = &sessions.Options{
		Path:     "/",
		MaxAge:   auth.Config.SessionExpiry,
		Secure:   auth.Config.SecureCookie,
		HttpOnly: true,
		Domain:   fmt.Sprintf(".%s", auth.Config.Domain),
	}
	auth.Store = store
	return nil
}

func (auth *AuthService) GetSession(c *gin.Context) (*sessions.Session, error) {
	session, err := auth.Store.Get(c.Request, auth.Config.SessionCookieName)

	// If there was an error getting the session, it might be invalid so let's clear it and retry
	if err != nil {
		log.Error().Err(err).Msg("Invalid session, clearing cookie and retrying")
		c.SetCookie(auth.Config.SessionCookieName, "", -1, "/", fmt.Sprintf(".%s", auth.Config.Domain), auth.Config.SecureCookie, true)
		session, err = auth.Store.Get(c.Request, auth.Config.SessionCookieName)
		if err != nil {
			log.Error().Err(err).Msg("Failed to get session")
			return nil, err
		}
	}

	return session, nil
}

func (auth *AuthService) SearchUser(username string) config.UserSearch {
	log.Debug().Str("username", username).Msg("Searching for user")

	// Check local users first
	if auth.GetLocalUser(username).Username != "" {
		log.Debug().Str("username", username).Msg("Found local user")
		return config.UserSearch{
			Username: username,
			Type:     "local",
		}
	}

	// If no user found, check LDAP
	if auth.LDAP != nil {
		log.Debug().Str("username", username).Msg("Checking LDAP for user")
		userDN, err := auth.LDAP.Search(username)
		if err != nil {
			log.Warn().Err(err).Str("username", username).Msg("Failed to find user in LDAP")
			return config.UserSearch{}
		}
		return config.UserSearch{
			Username: userDN,
			Type:     "ldap",
		}
	}

	return config.UserSearch{
		Type: "unknown",
	}
}

func (auth *AuthService) VerifyUser(search config.UserSearch, password string) bool {
	// Authenticate the user based on the type
	switch search.Type {
	case "local":
		// If local user, get the user and check the password
		user := auth.GetLocalUser(search.Username)
		return auth.CheckPassword(user, password)
	case "ldap":
		// If LDAP is configured, bind to the LDAP server with the user DN and password
		if auth.LDAP != nil {
			log.Debug().Str("username", search.Username).Msg("Binding to LDAP for user authentication")

			err := auth.LDAP.Bind(search.Username, password)
			if err != nil {
				log.Warn().Err(err).Str("username", search.Username).Msg("Failed to bind to LDAP")
				return false
			}

			// Rebind with the service account to reset the connection
			err = auth.LDAP.Bind(auth.LDAP.Config.BindDN, auth.LDAP.Config.BindPassword)
			if err != nil {
				log.Error().Err(err).Msg("Failed to rebind with service account after user authentication")
				return false
			}

			log.Debug().Str("username", search.Username).Msg("LDAP authentication successful")
			return true
		}
	default:
		log.Warn().Str("type", search.Type).Msg("Unknown user type for authentication")
		return false
	}

	// If no user found or authentication failed, return false
	log.Warn().Str("username", search.Username).Msg("User authentication failed")
	return false
}

func (auth *AuthService) GetLocalUser(username string) config.User {
	// Loop through users and return the user if the username matches
	log.Debug().Str("username", username).Msg("Searching for local user")

	for _, user := range auth.Config.Users {
		if user.Username == username {
			return user
		}
	}

	// If no user found, return an empty user
	log.Warn().Str("username", username).Msg("Local user not found")
	return config.User{}
}

func (auth *AuthService) CheckPassword(user config.User, password string) bool {
	return bcrypt.CompareHashAndPassword([]byte(user.Password), []byte(password)) == nil
}

func (auth *AuthService) IsAccountLocked(identifier string) (bool, int) {
	auth.LoginMutex.RLock()
	defer auth.LoginMutex.RUnlock()

	// Return false if rate limiting is not configured
	if auth.Config.LoginMaxRetries <= 0 || auth.Config.LoginTimeout <= 0 {
		return false, 0
	}

	// Check if the identifier exists in the map
	attempt, exists := auth.LoginAttempts[identifier]
	if !exists {
		return false, 0
	}

	// If account is locked, check if lock time has expired
	if attempt.LockedUntil.After(time.Now()) {
		// Calculate remaining lockout time in seconds
		remaining := int(time.Until(attempt.LockedUntil).Seconds())
		return true, remaining
	}

	// Lock has expired
	return false, 0
}

func (auth *AuthService) RecordLoginAttempt(identifier string, success bool) {
	// Skip if rate limiting is not configured
	if auth.Config.LoginMaxRetries <= 0 || auth.Config.LoginTimeout <= 0 {
		return
	}

	auth.LoginMutex.Lock()
	defer auth.LoginMutex.Unlock()

	// Get current attempt record or create a new one
	attempt, exists := auth.LoginAttempts[identifier]
	if !exists {
		attempt = &LoginAttempt{}
		auth.LoginAttempts[identifier] = attempt
	}

	// Update last attempt time
	attempt.LastAttempt = time.Now()

	// If successful login, reset failed attempts
	if success {
		attempt.FailedAttempts = 0
		attempt.LockedUntil = time.Time{} // Reset lock time
		return
	}

	// Increment failed attempts
	attempt.FailedAttempts++

	// If max retries reached, lock the account
	if attempt.FailedAttempts >= auth.Config.LoginMaxRetries {
		attempt.LockedUntil = time.Now().Add(time.Duration(auth.Config.LoginTimeout) * time.Second)
		log.Warn().Str("identifier", identifier).Int("timeout", auth.Config.LoginTimeout).Msg("Account locked due to too many failed login attempts")
	}
}

func (auth *AuthService) EmailWhitelisted(email string) bool {
	return utils.CheckFilter(auth.Config.OauthWhitelist, email)
}

func (auth *AuthService) CreateSessionCookie(c *gin.Context, data *config.SessionCookie) error {
	log.Debug().Msg("Creating session cookie")

	session, err := auth.GetSession(c)
	if err != nil {
		log.Error().Err(err).Msg("Failed to get session")
		return err
	}

	log.Debug().Msg("Setting session cookie")

	var sessionExpiry int

	if data.TotpPending {
		sessionExpiry = 3600
	} else {
		sessionExpiry = auth.Config.SessionExpiry
	}

	session.Values["username"] = data.Username
	session.Values["name"] = data.Name
	session.Values["email"] = data.Email
	session.Values["provider"] = data.Provider
	session.Values["expiry"] = time.Now().Add(time.Duration(sessionExpiry) * time.Second).Unix()
	session.Values["totpPending"] = data.TotpPending
	session.Values["oauthGroups"] = data.OAuthGroups

	err = session.Save(c.Request, c.Writer)
	if err != nil {
		log.Error().Err(err).Msg("Failed to save session")
		return err
	}

	return nil
}

func (auth *AuthService) DeleteSessionCookie(c *gin.Context) error {
	log.Debug().Msg("Deleting session cookie")

	session, err := auth.GetSession(c)
	if err != nil {
		log.Error().Err(err).Msg("Failed to get session")
		return err
	}

	// Delete all values in the session
	for key := range session.Values {
		delete(session.Values, key)
	}

	err = session.Save(c.Request, c.Writer)
	if err != nil {
		log.Error().Err(err).Msg("Failed to save session")
		return err
	}

	return nil
}

func (auth *AuthService) GetSessionCookie(c *gin.Context) (config.SessionCookie, error) {
	log.Debug().Msg("Getting session cookie")

	session, err := auth.GetSession(c)
	if err != nil {
		log.Error().Err(err).Msg("Failed to get session")
		return config.SessionCookie{}, err
	}

	log.Debug().Msg("Got session")

	username, usernameOk := session.Values["username"].(string)
	email, emailOk := session.Values["email"].(string)
	name, nameOk := session.Values["name"].(string)
	provider, providerOK := session.Values["provider"].(string)
	expiry, expiryOk := session.Values["expiry"].(int64)
	totpPending, totpPendingOk := session.Values["totpPending"].(bool)
	oauthGroups, oauthGroupsOk := session.Values["oauthGroups"].(string)

	// If any data is missing, delete the session cookie
	if !usernameOk || !providerOK || !expiryOk || !totpPendingOk || !emailOk || !nameOk || !oauthGroupsOk {
		log.Warn().Msg("Session cookie is invalid")
		auth.DeleteSessionCookie(c)
		return config.SessionCookie{}, nil
	}

	// If the session cookie has expired, delete it
	if time.Now().Unix() > expiry {
		log.Warn().Msg("Session cookie expired")
		auth.DeleteSessionCookie(c)
		return config.SessionCookie{}, nil
	}

	log.Debug().Str("username", username).Str("provider", provider).Int64("expiry", expiry).Bool("totpPending", totpPending).Str("name", name).Str("email", email).Str("oauthGroups", oauthGroups).Msg("Parsed cookie")
	return config.SessionCookie{
		Username:    username,
		Name:        name,
		Email:       email,
		Provider:    provider,
		TotpPending: totpPending,
		OAuthGroups: oauthGroups,
	}, nil
}

func (auth *AuthService) UserAuthConfigured() bool {
	// If there are users or LDAP is configured, return true
	return len(auth.Config.Users) > 0 || auth.LDAP != nil
}

func (auth *AuthService) ResourceAllowed(c *gin.Context, context config.UserContext, labels config.Labels) bool {
	if context.OAuth {
		log.Debug().Msg("Checking OAuth whitelist")
		return utils.CheckFilter(labels.OAuth.Whitelist, context.Email)
	}

	log.Debug().Msg("Checking users")
	return utils.CheckFilter(labels.Users, context.Username)
}

func (auth *AuthService) OAuthGroup(c *gin.Context, context config.UserContext, labels config.Labels) bool {
	if labels.OAuth.Groups == "" {
		return true
	}

	// Check if we are using the generic oauth provider
	if context.Provider != "generic" {
		log.Debug().Msg("Not using generic provider, skipping group check")
		return true
	}

	// Split the groups by comma (no need to parse since they are from the API response)
	oauthGroups := strings.Split(context.OAuthGroups, ",")

	// For every group check if it is in the required groups
	for _, group := range oauthGroups {
		if utils.CheckFilter(labels.OAuth.Groups, group) {
			log.Debug().Str("group", group).Msg("Group is in required groups")
			return true
		}
	}

	// No groups matched
	log.Debug().Msg("No groups matched")
	return false
}

func (auth *AuthService) AuthEnabled(uri string, labels config.Labels) (bool, error) {
	// If the label is empty, auth is enabled
	if labels.Allowed == "" {
		return true, nil
	}

	// Compile regex
	regex, err := regexp.Compile(labels.Allowed)

	// If there is an error, invalid regex, auth enabled
	if err != nil {
		log.Error().Err(err).Msg("Invalid regex")
		return true, err
	}

	// If the regex matches the URI, auth is not enabled
	if regex.MatchString(uri) {
		return false, nil
	}

	// Auth enabled
	return true, nil
}

func (auth *AuthService) GetBasicAuth(c *gin.Context) *config.User {
	username, password, ok := c.Request.BasicAuth()
	if !ok {
		return nil
	}
	return &config.User{
		Username: username,
		Password: password,
	}
}

func (auth *AuthService) CheckIP(labels config.Labels, ip string) bool {
	// Check if the IP is in block list
	for _, blocked := range labels.IP.Block {
		res, err := utils.FilterIP(blocked, ip)
		if err != nil {
			log.Error().Err(err).Str("item", blocked).Msg("Invalid IP/CIDR in block list")
			continue
		}
		if res {
			log.Warn().Str("ip", ip).Str("item", blocked).Msg("IP is in blocked list, denying access")
			return false
		}
	}

	// For every IP in the allow list, check if the IP matches
	for _, allowed := range labels.IP.Allow {
		res, err := utils.FilterIP(allowed, ip)
		if err != nil {
			log.Error().Err(err).Str("item", allowed).Msg("Invalid IP/CIDR in allow list")
			continue
		}
		if res {
			log.Debug().Str("ip", ip).Str("item", allowed).Msg("IP is in allowed list, allowing access")
			return true
		}
	}

	// If not in allowed range and allowed range is not empty, deny access
	if len(labels.IP.Allow) > 0 {
		log.Warn().Str("ip", ip).Msg("IP not in allow list, denying access")
		return false
	}

	log.Debug().Str("ip", ip).Msg("IP not in allow or block list, allowing by default")
	return true
}

func (auth *AuthService) BypassedIP(labels config.Labels, ip string) bool {
	// For every IP in the bypass list, check if the IP matches
	for _, bypassed := range labels.IP.Bypass {
		res, err := utils.FilterIP(bypassed, ip)
		if err != nil {
			log.Error().Err(err).Str("item", bypassed).Msg("Invalid IP/CIDR in bypass list")
			continue
		}
		if res {
			log.Debug().Str("ip", ip).Str("item", bypassed).Msg("IP is in bypass list, allowing access")
			return true
		}
	}

	log.Debug().Str("ip", ip).Msg("IP not in bypass list, continuing with authentication")
	return false
}