package profileinstance

import (
	"flag"
	"log"
	"net/http"
	"os"
	"path"
	"sync"

	"github.com/go-chi/chi/v5"
	"github.com/google/pprof/driver"
	"github.com/rs/xid"
	"tuxpa.in/a/pprofweb/pkg/flagset"
)

type Instance struct {
	id  xid.ID
	dat []byte

	handler http.Handler

	mu sync.RWMutex
}

func (i *Instance) Id() xid.ID {
	return i.id
}

func (i *Instance) startServer() error {
	file, err := os.CreateTemp("", i.id.String())
	if err != nil {
		return err
	}
	file.Write(i.dat)
	flags := &flagset.Set{
		Argz: []string{"-http=localhost.invalid:0", "-no_browser", file.Name()},
	}
	options := &driver.Options{
		Flagset:    flags,
		HTTPServer: i.startHTTP,
	}
	if err := driver.PProf(options); err != nil {
		return err
	}
	return nil
}
func (i *Instance) startHTTP(args *driver.HTTPServerArgs) error {
	r := chi.NewRouter()
	for pattern, handler := range args.Handlers {
		jpat := path.Join(pattern)
		r.Handle(jpat, handler)
		r.Handle(jpat+"/", handler)
	}
	i.handler = r
	return nil
}

func (i *Instance) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	log.Printf("serveInstanceHTTP %s %s", i.id, r.URL.String())
	i.handler.ServeHTTP(w, r)
}

// Mostly copied from https://github.com/google/pprof/blob/master/internal/driver/flags.go
type pprofFlags struct {
	args  []string
	s     flag.FlagSet
	usage []string
}