import std/[httpclient, cookies, uri, files, paths, syncio, cgi, times, strutils, tables, json]
import std/math
import std/times
import pkg/htmlparser
import std/xmltree  # To use '$' for XmlNode
import std/strtabs  # To access XmlAttributes
import std/strutils # To use cmpIgnoreCase

var tokenFile = Path("/tmp/csrf-token")
var csrf: JsonNode 

var dbregioClient = newHttpClient()

var verkehrslageClient = newHttpClient()
verkehrslageClient.headers["db-api-key"] = "32a84ba3-de45-46b3-a580-e3cac9591981"
verkehrslageClient.headers["db-client-id"] = "ris-api"

proc calcDistMeters(lat1, lon1, lat2, lon2: float): float = 
  var R = 6371000.0;
  var dLat = ((lat2 - lat1) * PI) / 180
  var dLon = ((lon2 - lon1) * PI) / 180
  var a =
    sin(dLat / 2) * sin(dLat / 2) +
    cos((lat1 * PI) / 180) *
      cos((lat2 * PI) / 180) *
      sin(dLon / 2) *
      sin(dLon / 2);
  result = (
    R * 2.0 * arctan2(
      sqrt(a),
      sqrt(1 - a)
    )
  )

proc getCsrfToken() =
  if not fileExists(tokenFile):
    var response = dbregioClient.request("https://wifi-landingpage.dbregio.de/", HttpGet)
    var html = parseHtml(response.bodyStream)
    var cookieJar = parseCookies(response.headers["set-cookie"])

    for meta in html.findAll("meta"):
        if (meta.attrs.hasKey "name") and (meta.attrs["name"] == "csrf-token"):
          csrf = %* {
            "token": meta.attrs["content"],
            "cookie": cookieJar["__Host-csrf"],
          }
          writeFile($tokenFile, $csrf)
  else:
    csrf = parseFile($tokenFile)
  
  dbregioClient.headers["Cookie"] = "__Host-csrf=" & $csrf["cookie"]
  dbregioClient.headers["Csrf-Token"] = $csrf["token"]

proc risStationsRequest(endpoint: string, params: openArray[(string, string)]): JsonNode = 
  var response = verkehrslageClient.request(parseUri("https://verkehrslage.bahnhof.de/api/stations") / endpoint ? params)
  result = parseJson(response.body)

proc risBoardsRequest(endpoint: string, params: openArray[(string, string)]): JsonNode = 
  var response = dbregioClient.request(parseUri("https://wifi-landingpage.dbregio.de/api/boards") / endpoint ? params)

  if response.code != Http200:
    removeFile(tokenFile)
    getCsrfToken()
    response = dbregioClient.request(parseUri("https://wifi-landingpage.dbregio.de/api/boards") / endpoint ? params)

  result = parseJson(response.body)

proc risJourneysRequest(id: string, params: openArray[(string, string)]): JsonNode = 
  var response = dbregioClient.request(parseUri("https://wifi-landingpage.dbregio.de/api/journeys") / id ? params)

  if response.code != Http200:
    removeFile(tokenFile)
    getCsrfToken()
    response = dbregioClient.request(parseUri("https://wifi-landingpage.dbregio.de/api/journeys") / id ? params)

  result = parseJson(response.body)

proc getStations(lat, lon: float, limit: int = 3, radius: int = 500): JsonNode = 
  var response = risStationsRequest("/stop-places/by-position", @[
    ("groupBy", "SALES"),
    ("latitude", $lat),
    ("longitude", $lon),
    ("radius", $radius),
    ("limit", $limit),
  ])

  result = newJArray()
  for station in items(response["stopPlaces"]):
    var name: string
    if station["names"]["DE"].hasKey("speechShort"):
      name = station["names"]["DE"]["speechShort"].getStr()
    else:
      name = station["names"]["DE"]["nameLong"].getStr()
      
    result.add(%* {
      "name": name,
      "id":   station["evaNumber"],
      "dist": (int)round(calcDistMeters(
        lat,
        lon,
        station["position"]["latitude"].getFloat(),
        station["position"]["longitude"].getFloat(),
      )),
    })

proc getDepartures(evaId: string, limit: int = 10, duration: int = 60): JsonNode =
  var response = risBoardsRequest("/public/departures/" & evaId, @[
    ("includeStationGroup", "true"),
    ("maxViaStops", "0"),
    ("sortBy", "TIME"),
    ("duration", $duration)
  ])
  
  result = newJArray()
  for departure in items(response["departures"]):
    var direction: string

    if departure["transport"]["direction"]["text"].getStr() != "":
      direction = departure["transport"]["direction"]["text"].getStr()
    else:
      direction = departure["transport"]["direction"]["stopPlaces"][0]["name"].getStr()

    result.add(%* {
      "id": departure["transport"]["journeyID"],
      "type": departure["transport"]["type"],
      "category": departure["transport"]["category"],
      "line": departure["transport"]["line"],
      "direction": direction,
      "platform": departure["platform"],
      "time": toUnix(parse(departure["timeSchedule"].getStr(), "yyyy-MM-dd'T'HH:mm:sszzz").toTime()),
      "delay": inSeconds(parse(departure["time"].getStr(), "yyyy-MM-dd'T'HH:mm:sszzz") -  parse(departure["timeSchedule"].getStr(), "yyyy-MM-dd'T'HH:mm:sszzz")),
      "canceled": departure["canceled"]
    })

    if (result.len == limit):
      break

proc getRoute(id: string): JsonNode =
  var response = risJourneysRequest(id, @[
    ("separateCancelled", "true")
  ])

  result = %* [
    {
      "id": response["events"][0]["stopPlace"]["evaNumber"],
      "name": response["events"][0]["stopPlace"]["name"],
      "platform": response["events"][0]["platform"],
      "time": toUnix(parse(response["events"][0]["timeSchedule"].getStr(), "yyyy-MM-dd'T'HH:mm:sszzz").toTime()),
      "delay": inSeconds(parse(response["events"][0]["time"].getStr(), "yyyy-MM-dd'T'HH:mm:sszzz") -  parse(response["events"][0]["timeSchedule"].getStr(), "yyyy-MM-dd'T'HH:mm:sszzz")),
      "canceled": false,
    }
  ]
  var elemNum = 0
  for event in items(response["events"]):
    if (event["type"].getStr() == "DEPARTURE") or (response["events"].len == elemNum):
      result.add(%* {
        "id": event["stopPlace"]["evaNumber"],
        "name": event["stopPlace"]["name"],
        "platform": event["platform"],
        "time": toUnix(parse(event["timeSchedule"].getStr(), "yyyy-MM-dd'T'HH:mm:sszzz").toTime()),
        "delay": inSeconds(parse(event["time"].getStr(), "yyyy-MM-dd'T'HH:mm:sszzz") -  parse(event["timeSchedule"].getStr(), "yyyy-MM-dd'T'HH:mm:sszzz")),
        "canceled": false,
      })
      elemNum = elemNum+1

getCsrfToken()
var params = readData()

write(stdout, "Content-Type: application/json; charset=UTF-8\n")
write(stdout, "Cache-Control: no-store, must-revalidate\n")
write(stdout, "Pragma: no-cache\n")
write(stdout, "Expires: 0\n")
write(stdout, "\n")

if params["get"] == "stations":
  write(stdout, $getStations(
    parseFloat(params["lat"]),
    parseFloat(params["lon"]),
    parseInt(params.getOrDefault("limit", "5")),
    parseInt(params.getOrDefault("radius", "750")),
  ))

if params["get"] == "departures":
  write(stdout, $getDepartures(
    params["evaId"],
    parseInt(params["limit"]),
    parseInt(params.getOrDefault("duration", "30")),
  ))

if params["get"] == "route":
  write(stdout, $getRoute(
    params["id"],
  ))