package api

import (
	"bytes"
	"encoding/json"
	"math/rand"
	"net/http"
	"time"

	"github.com/stefanprodan/podinfo/pkg/version"
	"go.uber.org/zap"
)

func randomDelayMiddleware(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		min := 0
		max := 5
		rand.Seed(time.Now().Unix())
		delay := rand.Intn(max-min) + min
		time.Sleep(time.Duration(delay) * time.Second)
		next.ServeHTTP(w, r)
	})
}

func randomErrorMiddleware(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		rand.Seed(time.Now().Unix())
		if rand.Int31n(3) == 0 {

			errors := []int{http.StatusInternalServerError, http.StatusBadRequest, http.StatusConflict}
			w.WriteHeader(errors[rand.Intn(len(errors))])
			return
		}
		next.ServeHTTP(w, r)
	})
}

func versionMiddleware(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		r.Header.Set("X-API-Version", version.VERSION)
		r.Header.Set("X-API-Revision", version.REVISION)

		next.ServeHTTP(w, r)
	})
}

// TODO: use Istio tracing package
// https://github.com/istio/istio/blob/master/pkg/tracing/config.go
func copyTracingHeaders(from *http.Request, to *http.Request) {
	headers := []string{
		"x-request-id",
		"x-b3-traceid",
		"x-b3-spanid",
		"x-b3-parentspanid",
		"x-b3-sampled",
		"x-b3-flags",
		"x-ot-span-context",
	}

	for i := range headers {
		headerValue := from.Header.Get(headers[i])
		if len(headerValue) > 0 {
			to.Header.Set(headers[i], headerValue)
		}
	}
}

func (s *Server) JSONResponse(w http.ResponseWriter, r *http.Request, result interface{}) {
	body, err := json.Marshal(result)
	if err != nil {
		w.WriteHeader(http.StatusInternalServerError)
		s.logger.Error("JSON marshal failed", zap.Error(err))
		return
	}

	w.Header().Set("Content-Type", "application/json; charset=utf-8")
	w.Header().Set("X-Content-Type-Options", "nosniff")
	w.WriteHeader(http.StatusOK)
	w.Write(prettyJSON(body))
}

func (s *Server) JSONResponseCode(w http.ResponseWriter, r *http.Request, result interface{}, responseCode int) {
	body, err := json.Marshal(result)
	if err != nil {
		w.WriteHeader(http.StatusInternalServerError)
		s.logger.Error("JSON marshal failed", zap.Error(err))
		return
	}

	w.Header().Set("Content-Type", "application/json; charset=utf-8")
	w.Header().Set("X-Content-Type-Options", "nosniff")
	w.WriteHeader(responseCode)
	w.Write(prettyJSON(body))
}

func (s *Server) ErrorResponse(w http.ResponseWriter, r *http.Request, error string, code int) {
	data := struct {
		Code    int    `json:"code"`
		Message string `json:"message"`
	}{
		Code:    code,
		Message: error,
	}

	body, err := json.Marshal(data)
	if err != nil {
		w.WriteHeader(http.StatusInternalServerError)
		s.logger.Error("JSON marshal failed", zap.Error(err))
		return
	}

	w.Header().Set("Content-Type", "application/json; charset=utf-8")
	w.Header().Set("X-Content-Type-Options", "nosniff")
	w.WriteHeader(http.StatusOK)
	w.Write(prettyJSON(body))
}

func prettyJSON(b []byte) []byte {
	var out bytes.Buffer
	json.Indent(&out, b, "", "  ")
	return out.Bytes()
}