package api

import (
	"context"
	"encoding/json"
	"fmt"
	"log"
	"net/http"
	"time"

	"git.freecumextremist.com/grumbulon/pomme/internal"
	"git.freecumextremist.com/grumbulon/pomme/internal/db"
	"github.com/go-chi/chi/v5"
	"github.com/go-chi/httplog"
	"github.com/go-chi/httprate"
	"github.com/go-chi/jwtauth/v5"
	"github.com/go-chi/render"
	"gorm.io/gorm"
)

type key int

const (
	keyPrincipalContextID key = iota
)

// setDBMiddleware is the http Handler func for the GORM middleware with context.
func setDBMiddleware(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		var pommeDB *gorm.DB
		c, err := internal.ReadConfig()
		if err != nil {
			log.Printf("No config file defined: %v", err)
		}

		switch r.Header.Get("User-Agent") {
		case "pomme-api-test-slave":
			pommeDB = db.InitDb(c.TestDB)
		default:
			pommeDB = db.InitDb(c.DB)
		}

		timeoutContext, cancelContext := context.WithTimeout(context.Background(), time.Second)
		ctx := context.WithValue(r.Context(), keyPrincipalContextID, pommeDB.WithContext(timeoutContext))
		defer cancelContext()
		next.ServeHTTP(w, r.WithContext(ctx))
	})
}

// handlers for very common errors.
func authFailed(w http.ResponseWriter, r *http.Request, realm string) {
	w.Header().Set("X-Content-Type-Options", "nosniff")
	w.Header().Add("WWW-Authenticate", fmt.Sprintf(`Realm="%s"`, realm))
	w.WriteHeader(http.StatusUnauthorized)

	resp := internal.Response{
		Message:      fmt.Sprintf(`Login failed -- Realm="%s"`, realm),
		HTTPResponse: http.StatusUnauthorized,
	}

	render.JSON(w, r, resp)
}

func internalServerError(w http.ResponseWriter, r *http.Request, errMsg string) {
	logger := httplog.NewLogger("Pomme", httplog.Options{
		JSON: true,
	})

	w.Header().Set("X-Content-Type-Options", "nosniff")
	w.Header().Add("Internal Server Error", errMsg)
	w.WriteHeader(http.StatusInternalServerError)

	resp := internal.Response{
		Message:      errMsg,
		HTTPResponse: http.StatusInternalServerError,
	}

	render.JSON(w, r, resp)

	logger.Error().Msg(errMsg)
}

// API subroute handler.
func API() http.Handler {
	api := chi.NewRouter()

	// Protected routes
	api.Group(func(api chi.Router) {
		api.Use(httprate.Limit(
			10,             // requests
			10*time.Second, // per duration
			httprate.WithKeyFuncs(httprate.KeyByIP, httprate.KeyByEndpoint),
			httprate.WithLimitHandler(func(w http.ResponseWriter, r *http.Request) {
				w.Header().Set("Content-Type", "application/json")
				w.WriteHeader(http.StatusTooManyRequests)
				err := json.NewEncoder(w).Encode(
					internal.Response{
						HTTPResponse: http.StatusTooManyRequests,
						Message:      "API rate limit exceded",
					})
				if err != nil {
					internalServerError(w, r, "internal server error")

					return
				}
			}),
		))
		api.Use(jwtauth.Verifier(tokenAuth))

		api.Use(jwtauth.Authenticator)
		api.With(setDBMiddleware).Post("/upload", ReceiveFile)
		api.With(setDBMiddleware).Post("/parse", ParseZoneFiles)
	})

	// Open routes
	api.Group(func(api chi.Router) {
		api.Use(httprate.Limit(
			5,             // requests
			5*time.Second, // per duration
			httprate.WithKeyFuncs(httprate.KeyByIP, httprate.KeyByEndpoint),
			httprate.WithLimitHandler(func(w http.ResponseWriter, r *http.Request) {
				w.Header().Set("Content-Type", "application/json")
				w.WriteHeader(http.StatusTooManyRequests)
				err := json.NewEncoder(w).Encode(
					internal.Response{
						HTTPResponse: http.StatusTooManyRequests,
						Message:      "API rate limit exceded",
					})
				if err != nil {
					internalServerError(w, r, "internal server error")

					return
				}
			}),
		))
		api.Use(setDBMiddleware)
		api.With(setDBMiddleware).Post("/create", NewUser)
		api.With(setDBMiddleware).Post("/login", Login)
		api.Post("/logout", Logout)
	})

	return api
}