package middleware

import (
	"fmt"
	"net/http"
	"runtime/debug"
	"strings"

	"git.dev.m-and-m.ovh/mderasse/gocommon/commonctx"
	"github.com/sirupsen/logrus"
)

type recoveryFuncSignature func(w http.ResponseWriter, r *http.Request)

type recoveryMiddleware struct {
	handler  http.Handler
	respFunc recoveryFuncSignature
}

func (rm *recoveryMiddleware) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	defer func() {
		if err := recover(); err != nil {
			// log the error
			log := commonctx.GetLoggerWithFields(r.Context(), logrus.Fields{
				"error":      err,
				"stacktrace": fmt.Sprintf("%v\n%s", err, getStackrace()),
			})
			if log == nil {
				fmt.Print("Impossible to log the panic as the logger is not part of the context\n")
			} else {
				log.Error("A Panic happened and has been caught")
			}
			// execute the recovery function
			rm.respFunc(w, r)
		}
	}()
	rm.handler.ServeHTTP(w, r)
}

func getStackrace() string {
	stackLines := strings.Split(string(debug.Stack()), "\n")
	// removing a few first line as they are either that function or the middleware
	return strings.Join(stackLines[9:], "\n")
}

// NewRecoveryMiddleware will declare a new middleware on the provided handler. It will recover any panic and log it.
// By default, the middleware will return a default error object in json with a 500 Http code. That can be overide by providing a recoveryFunc.
func NewRecoveryMiddleware(h http.Handler, recoveryFunc recoveryFuncSignature) http.Handler {
	recovery := &recoveryMiddleware{
		handler:  h,
		respFunc: recoveryFunc,
	}
	if recovery.respFunc == nil {
		recovery.respFunc = func(w http.ResponseWriter, r *http.Request) {
			w.Header().Set("X-Content-Type-Options", "nosniff")
			w.Header().Set("Content-Type", "application/json; charset=utf-8")
			w.WriteHeader(http.StatusInternalServerError)
			w.Write([]byte(
				fmt.Sprintf("{\"code\":%d,\"message\":\"An error happened during the execution of your request.\"}", http.StatusInternalServerError),
			))
		}
	}
	return recovery
}