package jmash

import (
	"fmt"
	"net/http"
	"path"
	"strings"

	"github.com/golang/glog"
	"google.golang.org/grpc"
	"google.golang.org/grpc/connectivity"
)

// openAPIServer returns OpenAPI specification files located under "/openapiv2/"
func openAPIServer(dir string) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		if !strings.HasSuffix(r.URL.Path, ".swagger.json") {
			glog.Errorf("Not Found: %s", r.URL.Path)
			http.NotFound(w, r)
			return
		}

		glog.Infof("Serving %s", r.URL.Path)
		p := strings.TrimPrefix(r.URL.Path, "/openapiv2/")
		p = path.Join(dir, p)
		http.ServeFile(w, r, p)
	}
}

// allowCORS allows Cross Origin Resoruce Sharing from any origin.
// Don't do this without consideration in production systems.
func AllowCORS(h http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if origin := r.Header.Get("Origin"); origin != "" {
			w.Header().Set("Access-Control-Allow-Origin", "*")
			if r.Method == "OPTIONS" && r.Header.Get("Access-Control-Request-Method") != "" {
				preflightHandler(w, r)
				return
			}
		}
		h.ServeHTTP(w, r)
	})
}

// preflightHandler adds the necessary headers in order to serve
// CORS from any origin using the methods "GET", "HEAD", "POST", "PUT", "DELETE"
// We insist, don't do this without consideration in production systems.
func preflightHandler(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Access-Control-Allow-Methods", "POST, GET, OPTIONS, PUT, DELETE, UPDATE, PATCH")
	w.Header().Set("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept, Authorization")
	w.Header().Set("Access-Control-Expose-Headers", "Content-Length, Access-Control-Allow-Origin, Access-Control-Allow-Headers, Cache-Control, Content-Language, Content-Type")
        w.Header().Set("Access-Control-Allow-Credentials", "true")
	glog.Infof("preflight request for %s", r.URL.Path)
}

// healthzServer returns a simple health handler which returns ok.
func HealthzServer(conn *grpc.ClientConn) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Content-Type", "text/plain")
		if s := conn.GetState(); s != connectivity.Ready {
			http.Error(w, fmt.Sprintf("grpc server is %s", s), http.StatusBadGateway)
			return
		}
		fmt.Fprintln(w, "ok")
	}
}