public async Task <string> ReadFromCache(DecimalCoordinatePairModel coordinateModel)
{
var folderName = GetFolderName(coordinateModel.Latitude);
if (!folderName.Exists())
{
return(null);
}
var fileName = GetFileName(folderName, coordinateModel.Latitude);
if (!fileName.Exists())
{
return(null);
}
var fileContents = await fileName.ReadJson <List <ReverseGeocodeModel> >();
if (fileContents.Exists(entry => entry.Longitude == coordinateModel.Longitude))
{
return(fileContents.Single(entry => entry.Longitude == coordinateModel.Longitude).LocationText);
}
return(null);
}
public async Task SaveToCache(DecimalCoordinatePairModel coordinateModel, string locationText)
{
var folderName = GetFolderName(coordinateModel.Latitude);
if (!folderName.Exists())
{
Directory.CreateDirectory(folderName);
await UpdateCacheDirectory(folderName);
}
var entry = new ReverseGeocodeModel {
Latitude = coordinateModel.Latitude, Longitude = coordinateModel.Longitude, LocationText = locationText,
};
var fileName = GetFileName(folderName, coordinateModel.Latitude);
if (!fileName.Exists())
{
var entries = new List <ReverseGeocodeModel> {
entry
};
await fileName.WriteJson(entries);
}
var fileContents = await fileName.ReadJson <List <ReverseGeocodeModel> >();
if (!fileContents.Exists(fc => fc.Longitude == coordinateModel.Longitude))
{
fileContents.Add(entry);
await fileName.WriteJson(fileContents);
}
}
private async Task <string> CallReverseGeocodeApi(DecimalCoordinatePairModel coordinateModel)
{
var url = $"https://maps.googleapis.com/maps/api/geocode/json?latlng={coordinateModel.Latitude},{coordinateModel.Longitude}&language=ja&key={apiKey}";
var client = new HttpClient();
var response = await client.GetAsync(url);
var jsonResponse = await response.Content.ReadAsStringAsync();
dynamic obj = JsonConvert.DeserializeObject(jsonResponse);
var result = $"{obj.results[0].address_components[2].long_name} {obj.results[0].address_components[3].long_name} {obj.results[0].address_components[5].long_name}";
return(result);
}
public async Task <string> ReverseGeocode(DecimalCoordinatePairModel coordinateModel)
{
var helper = new CacheHelper("./");
var cachedLocationText = await helper.ReadFromCache(coordinateModel);
if (string.IsNullOrWhiteSpace(cachedLocationText))
{
var locationText = await CallReverseGeocodeApi(coordinateModel);
await helper.SaveToCache(coordinateModel, locationText);
return(locationText);
}
return(cachedLocationText);
}
