package middleware

import (
	"net/http"

	"github.com/google/uuid"
)

const requestIDHeaderKey = "X-Request-ID"

type requestIDMiddleware struct {
	handler http.Handler
}

func (rm *requestIDMiddleware) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	requestID := r.Header.Get(requestIDHeaderKey)
	if _, err := uuid.Parse(requestID); err != nil {
		// no request ID or invalid. let's generate a new one
		requestID = uuid.New().String()
	}

	// XXX: Add request_id to the context, push the context to r & edit logger middleware to add the request_id as fields

	// add the request ID to the response query
	w.Header().Set(requestIDHeaderKey, requestID)

	// and exec the next handler
	rm.handler.ServeHTTP(w, r)
}

// NewRequestIDMiddleware will declare a new middleware on the provided handler. It will analyse the incoming
// query to find a x-request-id header. It will had it to the response and also to the context.
// If request-id header doesn't exist. A new one will be generated.
func NewRequestIDMiddleware(h http.Handler) http.Handler {
	return &requestIDMiddleware{
		handler: h,
	}
}