package middleware

import (
	"crypto/subtle"
	"net/http"
	"strings"

	"github.com/owncast/owncast/core/data"
	"github.com/owncast/owncast/core/user"
	"github.com/owncast/owncast/utils"
	log "github.com/sirupsen/logrus"
)

// ExternalAccessTokenHandlerFunc is a function that is called after validing access.
type ExternalAccessTokenHandlerFunc func(user.ExternalAPIUser, http.ResponseWriter, *http.Request)

// UserAccessTokenHandlerFunc is a function that is called after validing user access.
type UserAccessTokenHandlerFunc func(user.User, http.ResponseWriter, *http.Request)

// RequireAdminAuth wraps a handler requiring HTTP basic auth for it using the given
// the stream key as the password and and a hardcoded "admin" for username.
func RequireAdminAuth(handler http.HandlerFunc) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		username := "admin"
		password := data.GetAdminPassword()
		realm := "Owncast Authenticated Request"

		// The following line is kind of a work around.
		// If you want HTTP Basic Auth + Cors it requires _explicit_ origins to be provided in the
		// Access-Control-Allow-Origin header.  So we just pull out the origin header and specify it.
		// If we want to lock down admin APIs to not be CORS accessible for anywhere, this is where we would do that.
		w.Header().Set("Access-Control-Allow-Origin", r.Header.Get("Origin"))
		w.Header().Set("Access-Control-Allow-Credentials", "true")
		w.Header().Set("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept, Authorization")

		// For request needing CORS, send a 204.
		if r.Method == "OPTIONS" {
			w.WriteHeader(http.StatusNoContent)
			return
		}

		user, pass, ok := r.BasicAuth()

		// Failed
		if !ok || subtle.ConstantTimeCompare([]byte(user), []byte(username)) != 1 || subtle.ConstantTimeCompare([]byte(pass), []byte(password)) != 1 {
			w.Header().Set("WWW-Authenticate", `Basic realm="`+realm+`"`)
			http.Error(w, "Unauthorized", http.StatusUnauthorized)
			log.Debugln("Failed admin authentication")
			return
		}

		handler(w, r)
	}
}

func accessDenied(w http.ResponseWriter) {
	w.WriteHeader(http.StatusUnauthorized) //nolint
	w.Write([]byte("unauthorized"))        //nolint
}

// RequireExternalAPIAccessToken will validate a 3rd party access token.
func RequireExternalAPIAccessToken(scope string, handler ExternalAccessTokenHandlerFunc) http.HandlerFunc {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		// We should accept 3rd party preflight OPTIONS requests.
		if r.Method == "OPTIONS" {
			// All OPTIONS requests should have a wildcard CORS header.
			w.Header().Set("Access-Control-Allow-Origin", "*")
			w.WriteHeader(http.StatusNoContent)
			return
		}

		authHeader := strings.Split(r.Header.Get("Authorization"), "Bearer ")
		token := strings.Join(authHeader, "")

		if len(authHeader) == 0 || token == "" {
			log.Warnln("invalid access token")
			accessDenied(w)
			return
		}

		integration, err := user.GetExternalAPIUserForAccessTokenAndScope(token, scope)
		if integration == nil || err != nil {
			accessDenied(w)
			return
		}

		// All auth'ed 3rd party requests should have a wildcard CORS header.
		w.Header().Set("Access-Control-Allow-Origin", "*")

		handler(*integration, w, r)

		if err := user.SetExternalAPIUserAccessTokenAsUsed(token); err != nil {
			log.Debugln("token not found when updating last_used timestamp")
		}
	})
}

// RequireUserAccessToken will validate a provided user's access token and make sure the associated user is enabled.
// Not to be used for validating 3rd party access.
func RequireUserAccessToken(handler UserAccessTokenHandlerFunc) http.HandlerFunc {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		accessToken := r.URL.Query().Get("accessToken")
		if accessToken == "" {
			accessDenied(w)
			return
		}

		ipAddress := utils.GetIPAddressFromRequest(r)
		// Check if this client's IP address is banned.
		if blocked, err := data.IsIPAddressBanned(ipAddress); blocked {
			log.Debugln("Client ip address has been blocked. Rejecting.")
			accessDenied(w)
			return
		} else if err != nil {
			log.Errorln("error determining if IP address is blocked: ", err)
		}

		// A user is required to use the websocket
		user := user.GetUserByToken(accessToken)
		if user == nil || !user.IsEnabled() {
			accessDenied(w)
			return
		}

		handler(*user, w, r)
	})
}

// RequireUserModerationScopeAccesstoken will validate a provided user's access token and make sure the associated user is enabled
// and has "MODERATOR" scope assigned to the user.
func RequireUserModerationScopeAccesstoken(handler http.HandlerFunc) http.HandlerFunc {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		accessToken := r.URL.Query().Get("accessToken")
		if accessToken == "" {
			accessDenied(w)
			return
		}

		// A user is required to use the websocket
		user := user.GetUserByToken(accessToken)
		if user == nil || !user.IsEnabled() || !user.IsModerator() {
			accessDenied(w)
			return
		}

		handler(w, r)
	})
}