package snap

import (
	"bytes"
	"encoding/json"
	"expvar"
	"fmt"
	"log"
	"net/http"
	"net/http/pprof"
	"runtime"

	"github.com/gorilla/mux"
)

func stackHandler(w http.ResponseWriter, r *http.Request) {
	http.Redirect(w, r, "/sovereign/debug/pprof/goroutine?debug=2", http.StatusSeeOther)
}

// copy pasted from http://golang.org/src/expvar/expvar.go#L308
func varsHandler(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "application/json; charset=utf-8")

	buf := make([]byte, 0, 16384)
	body := bytes.NewBuffer(buf)

	fmt.Fprintf(body, "{")
	expvar.Do(func(kv expvar.KeyValue) {
		fmt.Fprintf(body, "%q: %s,", kv.Key, kv.Value)
	})

	fmt.Fprintf(body, "%q: %d", "NumGoRoutines", runtime.NumGoroutine())
	fmt.Fprintf(body, "}")

	var prettyJSON bytes.Buffer
	err := json.Indent(&prettyJSON, body.Bytes(), "", "    ")
	if err != nil {
		log.Println(err, string(body.Bytes()))
	}

	w.Write(prettyJSON.Bytes())
}

func setupDebugHandler(r *mux.Router) {
	r.HandleFunc("/stack", stackHandler)
	r.HandleFunc("/vars", varsHandler)
	r.HandleFunc("/pprof/", http.HandlerFunc(pprof.Index))
	r.HandleFunc("/pprof/cmdline", http.HandlerFunc(pprof.Cmdline))
	r.HandleFunc("/pprof/profile", http.HandlerFunc(pprof.Profile))
	r.HandleFunc("/pprof/symbol", http.HandlerFunc(pprof.Symbol))
	r.HandleFunc("/pprof/trace", http.HandlerFunc(pprof.Trace))
	r.HandleFunc("/pprof/goroutine", pprof.Handler("goroutine").ServeHTTP)
	r.HandleFunc("/pprof/allocs", pprof.Handler("allocs").ServeHTTP)
	r.HandleFunc("/pprof/block", pprof.Handler("block").ServeHTTP)
	r.HandleFunc("/pprof/heap", pprof.Handler("heap").ServeHTTP)
	r.HandleFunc("/pprof/mutex", pprof.Handler("mutex").ServeHTTP)
}