package main

import "encoding/json"
import "fmt"
import "log"
import "net/http"
import "os"
import "slices"
import "strings"
import "sync/atomic"

func main() {
	password := os.Getenv("VRNP_PASSWORD")
	if len(password) == 0 {
		log.Fatal("Required environment variable VRNP_PASSWORD is not set")
	}

	clientAllowlist := strings.Split(os.Getenv("VRNP_CLIENT_ALLOWLIST"), ",")

	// Use round-robin to send incoming requests to different servers
	var efaClient atomic.Uint64
	var efaClients []EFAClient
	for _, efaClient := range allEfaClients {
		if len(clientAllowlist) != 0 && slices.Contains(clientAllowlist, efaClient.GetName()) {
			efaClients = append(efaClients, efaClient)
		}
	}

	http.HandleFunc("/departures", func(w http.ResponseWriter, r *http.Request) {
		user, pass, ok := r.BasicAuth()
		if !(ok && user == "admin" && pass == password) {
			w.Header().Set("WWW-Authenticate", "Basic realm=\"Access to departure API\"")
			http.Error(w, "You shall not pass", http.StatusUnauthorized)
			return
		}

		query := r.URL.Query()

		if query["stop_id"] == nil || len(query["stop_id"]) < 1 {
			http.Error(w, "Missing query parameter: stop_id", http.StatusBadRequest)
			return
		}
		stopId := query["stop_id"][0]

		/*
			var platform *string = nil
			if query["platform"] != nil && len(query["platform"]) != 0 {
				platform = &query["platform"][0]
			}
		*/

		c := efaClients[(efaClient.Add(1)-1)%uint64(len(efaClients))]
		departures, err := FetchDepartures(c, stopId)
		if err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
		// TODO: Filter for platform here

		// Does not handle multiple media types
		if r.Header.Get("Accept") == "application/json" {
			w.Header().Set("Content-Type", "application/json")
			json.NewEncoder(w).Encode(departures)
		} else {
			// plain text
			for _, d := range departures.Departures {
				fmt.Fprintf(w, "%2s %-11s %6s\n",
					d.Symbol[:min(2, len(d.Symbol))],
					d.Direction[:min(11, len(d.Direction))],
					d.Leaving,
				)
			}
		}
		return
	})
	log.Fatal(http.ListenAndServe(":8000", nil))
}