package auth

import (
	"context"
	"encoding/json"
	"fmt"
	"net/http"
	"strings"
	"time"

	"acooldomain.co/backend/models"
	"github.com/gin-gonic/gin"
	"github.com/golang-jwt/jwt"
	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
	"golang.org/x/crypto/bcrypt"
)

var secret []byte
var method string
var DOMAIN string

type Connection struct {
	DatabaseConnection *mongo.Client
}

type TokenInfo struct {
	Username    string            `json:"username"`
	Permissions models.Permission `json:"permissions"`
}

type AuthClaims struct {
	*jwt.StandardClaims
	TokenInfo
}

type InviteToken struct {
	Email       string            `bson:"Email"`
	Permissions models.Permission `bson:"Permissions"`
	Token       string            `bson:"Token"`
}

func signToken(token TokenInfo) (string, error) {

	t := jwt.New(jwt.GetSigningMethod(method))

	t.Claims = &AuthClaims{
		&jwt.StandardClaims{
			ExpiresAt: time.Now().Add(time.Hour * 24 * 30).Unix(),
		},
		token,
	}

	return t.SignedString(secret)
}

func hashPassword(password string) (string, error) {
	bytes, err := bcrypt.GenerateFromPassword([]byte(password), bcrypt.DefaultCost)
	return string(bytes), err
}

func AuthorizedTo(requiredPermissions models.Permission, overwriters ...func(*gin.Context) bool) gin.HandlerFunc {
	return func(ctx *gin.Context) {
		authCookie, err := ctx.Request.Cookie("auth")
		if err != nil {
			ctx.AbortWithError(403, err)
			return
		}

		token, err := jwt.ParseWithClaims(authCookie.Value, &AuthClaims{}, func(token *jwt.Token) (interface{}, error) {
			// Don't forget to validate the alg is what you expect:
			if _, ok := token.Method.(*jwt.SigningMethodHMAC); !ok {
				return nil, fmt.Errorf("unexpected signing method: %v", token.Header["alg"])
			}

			// hmacSampleSecret is a []byte containing your secret, e.g. []byte("my_secret_key")
			return secret, nil
		})
		if err != nil {
			ctx.AbortWithError(403, err)
			return
		}
		if claims, ok := token.Claims.(*AuthClaims); ok && token.Valid {
			ctx.Set("claims", claims)
			if (requiredPermissions&claims.Permissions != requiredPermissions) && (models.Admin&claims.Permissions != models.Admin) {
				for _, overwrite := range overwriters {
					if overwrite(ctx) {
						return
					}
				}
				ctx.AbortWithStatus(403)
				return
			}
		} else {
			ctx.AbortWithStatus(500)
		}
	}
}

type SignUpRequest struct {
	Token    string
	Username string
	Password string
}

func (con Connection) signUp(c *gin.Context) {
	var request SignUpRequest

	err := json.NewDecoder(c.Request.Body).Decode(&request)
	if err != nil {
		c.AbortWithError(500, err)
	}

	var token InviteToken

	err = con.DatabaseConnection.Database("Backend").Collection("Tokens").FindOne(
		context.TODO(),
		bson.D{{}},
		options.FindOne(),
	).Decode(&token)

	if err != nil {
		c.AbortWithError(500, err)
		return
	}
	if token.Token == "" {
		c.AbortWithStatusJSON(403, "PermissionDenied")
		return
	}

	hashedPass, err := hashPassword(request.Password)
	if err != nil {
		c.AbortWithError(500, err)
		return
	}

	_, err = con.DatabaseConnection.Database("Backend").Collection("Users").InsertOne(context.TODO(), &models.User{
		Username:        request.Username,
		HashedPass:      hashedPass,
		Permissions:     token.Permissions,
		MaxOwnedServers: 5,
		Email:           token.Email,
	}, &options.InsertOneOptions{})

	if err != nil {
		c.AbortWithError(500, err)
		return
	}

	con.signIn(c)
}

type SignInRequest struct {
	Username string
	Password string
}

func (con Connection) signIn(c *gin.Context) {

	var request SignInRequest
	err := json.NewDecoder(c.Request.Body).Decode(&request)

	if err != nil {
		c.AbortWithError(500, err)
		return
	}
	var userItem models.User
	err = con.DatabaseConnection.Database("Backend").Collection("Users").FindOne(context.TODO(), bson.D{{Key: "Username", Value: request.Username}}).Decode(&userItem)
	if err != nil {
		c.AbortWithError(403, err)
		return
	}

	if bcrypt.CompareHashAndPassword([]byte(userItem.HashedPass), []byte(request.Password)) != nil {
		c.AbortWithStatus(403)
		return
	}

	token := TokenInfo{
		Username:    userItem.Username,
		Permissions: userItem.Permissions,
	}

	signedToken, err := signToken(token)
	if err != nil {
		c.AbortWithError(500, err)
		return
	}

	c.SetCookie("auth", signedToken, -1, "", ".games.acooldomain.co", true, true)
	c.IndentedJSON(http.StatusOK, signedToken)
}

func (con Connection) verify(c *gin.Context) {
	claims, exists := c.Get("claims")
	if !exists {
		fmt.Println("No Claims")
		c.AbortWithStatus(403)
		return
	}

	forwarded_host := c.Request.Header.Get("x-forwarded-host")
	domainSegments := strings.Split(forwarded_host, ".")

	serverId, service := domainSegments[0], domainSegments[1]
	c.AddParam("server_id", serverId)

	if service == "browsers" {
		if claims.(*AuthClaims).Permissions&models.Browse == models.Browse || claims.(*AuthClaims).Permissions&models.Admin == models.Admin || con.ServerAuthorized(models.Browse)(c) {
			c.Header("X-Username", claims.(*AuthClaims).Username)
			c.Status(200)
			return
		}

	}

	if service == "cloud" {
		if claims.(*AuthClaims).Permissions&models.Cloud == models.Cloud || claims.(*AuthClaims).Permissions&models.Admin == models.Admin {
			c.Header("X-Username", claims.(*AuthClaims).Username)
			c.Status(200)
			return
		}
	}

	c.Redirect(303, fmt.Sprintf("http://%s/login", DOMAIN))
}

func (con Connection) ServerAuthorized(permissions models.Permission) func(*gin.Context) bool {
	return func(ctx *gin.Context) bool {
		claims, exists := ctx.Get("claims")
		if !exists {
			return false
		}

		server_id := ctx.Param("server_id")
		if server_id == "" {
			return false
		}

		var serverData models.ServerData

		con.DatabaseConnection.Database("Backend").Collection("Servers").FindOne(context.TODO(), bson.D{{Key: "Id", Value: server_id}}).Decode(&serverData)

		if serverData.OwnerId == claims.(*AuthClaims).Username {
			return true
		}

		userPermissions := serverData.UserPermissions[claims.(*AuthClaims).Username]

		if userPermissions&permissions == permissions || userPermissions&models.Admin == models.Admin {
			return true
		}

		return false
	}
}

func LoadGroup(group *gin.RouterGroup, client *mongo.Client, config models.GlobalConfig) {
	connection := Connection{DatabaseConnection: client}

	secret = []byte(config.Key)
	method = config.Algorithm
	DOMAIN = config.Domain

	group.POST("/signin", connection.signIn)
	group.POST("/signup", AuthorizedTo(models.Admin), connection.signUp)
	group.GET("/verify", AuthorizedTo(0), connection.verify)
}