Stairs/src/server/geocode.cpp

/*
 * Stairs
 * Copyright 2017 (c) Mark van Renswoude
 *
 * https://git.x2software.net/pub/Stairs
*/
#include "geocode.h"
#include <ESP8266WiFi.h>
#include <ESPAsyncTCP.h>

#include "../debug.h"
#include "../secret.h"


struct ResponseBuffer
{
  void* data;
  size_t length;
  ResponseBuffer* next;
};


String urlencode(const String url)
{
  String encoded;

  for (int i = 0; i < url.length(); i++)
  {
    char c = url.charAt(i);
    if (c == 0x20)
      encoded += "%20";
    else if (isalnum(c))
      encoded += c;
    else
    {
      encoded += "%";
      if (c < 0x10) encoded += "0";
      encoded += String(c, HEX);
    }
  }

  return encoded;
}


void memcpy_unaligned(void* dest, void* source, size_t length)
{
  uint8_t* destChar = (uint8_t*)dest;
  uint8_t* sourceChar = (uint8_t*)source;

  while (length > 0)
  {
    *destChar = *sourceChar;

    sourceChar++;
    destChar++;
    length--;
  }
}


void handleGetLatLong(AsyncWebServerRequest *request)
{
  _dln("API :: get lat long");

  AsyncWebParameter* addressParam = request->getParam("address");
  if (addressParam == nullptr)
  {
    request->send(400);
    return;
  }

  String address = addressParam->value();
  if (!address.length())
  {
    request->send(400);
    return;
  }

  AsyncClient* httpClient = new AsyncClient();
  httpClient->onError([&](void* arg, AsyncClient* client, int error)
  {
    _dln("API :: get lat long: OnError");
    request->send(500);
    delete client;
  });


  httpClient->onConnect([&](void * arg, AsyncClient* client)
  {
    client->onError(nullptr, nullptr);
    ResponseBuffer* responseData = nullptr;

    client->onData([&](void* arg, AsyncClient* c, void* data, size_t len)
    {
      _dln("> OnData");
      // Store all received chunks in a linked list
      ResponseBuffer* next = new ResponseBuffer;
      next->data = malloc(len);
      memcpy_unaligned(next->data, data, len);
      next->length = len;
      next->next = nullptr;

      if (responseData == nullptr)
        responseData = next;
      else
      {
        ResponseBuffer* prev = responseData;
        while (prev->next != nullptr)
          prev = prev->next;

        prev->next = next;
      }
      _dln("< OnData");
    });

    client->onDisconnect([&](void* arg, AsyncClient* c)
    {
      _dln("> OnDisconnect");
      if (responseData == nullptr)
      {
        request->send(500);
        return;
      }

      // Send back the linked list using a chunked response
      ResponseBuffer* sendChunk = responseData;
      size_t sendOffset = 0;

      AsyncWebServerResponse *response = request->beginChunkedResponse("application/json", [&](uint8_t *buffer, size_t maxLen, size_t index) -> size_t
      {
        _dln("> ChunkedResponse");
        if (sendOffset >= sendChunk->length)
        {
          // End of the chunk, go to the next one
          sendChunk = sendChunk->next;
          sendOffset = 0;
        }

        if (sendChunk == nullptr)
        {
          // We sent the last one, clean up the linked list
          ResponseBuffer* next;
          while (responseData != nullptr)
          {
            next = responseData->next;

            free(responseData->data);
            delete responseData;

            responseData = next;
          }

          return 0;
        }

        if (maxLen >= sendChunk->length - sendOffset)
        {
          // Send the remainder of the chunk
          memcpy_unaligned(buffer, (uint8_t*)sendChunk->data + sendOffset, sendChunk->length - sendOffset);
          sendOffset = sendChunk->length;
        }
        else
        {
          memcpy_unaligned(buffer, (uint8_t*)sendChunk->data + sendOffset, maxLen);
          sendOffset += maxLen;
        }
        _dln("< ChunkedResponse");
      });
      request->send(response);

      delete c;
      _dln("< OnDisconnect");
    });

    #ifdef SecretsPresent
    String url = "/maps/api/geocode/json?address=" + urlencode(address) + "&key=" + urlencode(GoogleAPIKey);
    #else
    String url = "/maps/api/geocode/json?address=" + urlencode(address);
    #endif

    client->write(String("GET " + url + " HTTP/1.0\r\nHost: maps.googleapis.com\n\r\n").c_str());
  });


  if (!httpClient->connect("maps.googleapis.com", 443, true))
  {
    _dln("API :: get lat long: failed to connect to Google API");
    delete httpClient;

    request->send(500);
  }
}



void registerGeocodeRoutes(AsyncWebServer* server)
{
  server->on("/api/geo/latlong", HTTP_GET, handleGetLatLong);
}