package goroutineinstance

import (
	"encoding/json"
	"flag"
	"log"
	"net/http"
	"path"
	"sync"

	"github.com/DataDog/gostackparse"
	"github.com/go-chi/chi/v5"
	"github.com/go-chi/chi/v5/middleware"
	"github.com/rs/xid"
)

type Instance struct {
	id  xid.ID
	dat []*gostackparse.Goroutine

	mu sync.RWMutex

	once    sync.Once
	handler http.Handler
}

func (i *Instance) Id() xid.ID {
	return i.id
}
func (i *Instance) ServeHTTP(tw http.ResponseWriter, tr *http.Request) {
	i.once.Do(func() {
		r := chi.NewRouter()
		r.Use(middleware.StripSlashes)
		r.Get("/", func(w http.ResponseWriter, r *http.Request) {
			http.Redirect(w, r, path.Join(r.URL.Path, "app"), http.StatusSeeOther)
		})
		r.Get("/app", func(w http.ResponseWriter, r *http.Request) {
			w.Write(IndexHtmlEmbed)
		})

		r.Get("/raw", func(w http.ResponseWriter, r *http.Request) {
			json.NewEncoder(w).Encode(i.dat)
		})
		i.handler = r
	})
	log.Printf("serve goroutine instance %s %s", i.id, tr.URL.String())
	i.handler.ServeHTTP(tw, tr)
}

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