public LogisticCenter LogisticCenter()
{
var logisticCetner = _context.LogisticCenter.FirstOrDefault();
var newCenter = new LogisticCenter();
if (logisticCetner != null)
{
// check timestamps on last road update and last logistic center generation so we know if we should do all the logic
if (_context.Roads.OrderByDescending(x => x.UpdateDate).First().UpdateDate < logisticCetner.UpdatedDate)
{
newCenter = new LogisticCenter {
Id = logisticCetner.Id, Name = logisticCetner.Name
};
return(newCenter);
}
else
{
newCenter = GenerateLogisticCenter();
if (newCenter == null)
{
// could make custom exception
throw new ArgumentException("Something went wrong when generating a logistic center.");
}
else
{
logisticCetner.Name = newCenter.Name;
_context.LogisticCenter.Update(logisticCetner);
_context.SaveChangesAsync();
}
return(newCenter);
}
}
else
{
newCenter = GenerateLogisticCenter();
if (newCenter == null)
{
// could make custom exception
throw new ArgumentException("Something went wrong when generating a logistic center.");
}
var logisticCenterEntity = new LogisticCenterEntity()
{
Name = newCenter.Name,
UpdatedDate = DateTime.Now
};
_context.LogisticCenter.Add(logisticCenterEntity);
_context.SaveChanges();
return(newCenter);
}
}
private LogisticCenter GenerateLogisticCenter()
{
var logisticCenterName = new LogisticCenter();
if (_context.Roads.Any())
{
var cities = _context.Cities.Include(x => x.RoadFrom).Include(x => x.To);
// collection to store how many times a city has been marked as "furthest" from another city in the map
Dictionary <CityEntity, int> furthestCityIds = new Dictionary <CityEntity, int>();
//find furthest city for each city we have in db that has roads
foreach (var city in cities)
{
if (city.RoadFrom.Count == 0)
{
continue;
}
int totalDistance = 0;
List <CityEntity> visited = new List <CityEntity>();
visited.Add(city);
foreach (var road in city.RoadFrom)
{
if (visited.Contains(road.To) == false)
{
// using depth first search and keeping track of the distance to the bottom(a.k.a furthest) most city in the search.
DFS(road.To, road.Distance, furthestCityIds, totalDistance, visited);
}
}
}
// Find the most common furthest city
KeyValuePair <CityEntity, int> max = new KeyValuePair <CityEntity, int>(new CityEntity(), 0);
foreach (var city in furthestCityIds)
{
if (city.Value > max.Value)
{
max = city;
}
}
// we found our furthest city in max. Now lets find the logistic center.
// this will be the city that has the shortest road to max.
logisticCenterName.Name = cities.First(x => x.Name == max.Key.Name).To.OrderBy(r => r.Distance).First().From.Name;
}
return(logisticCenterName);
}
public LogisticCenter GetLogisticCenter()
{
var logCenterName = new LogisticCenter()
{
Id = 1, Name = "Not Generated"
};
var center = _context.LogisticCenter.FirstOrDefault();
if (center != null)
{
logCenterName.Name = center.Name;
logCenterName.Id = center.Id;
}
return(logCenterName);
}
public async Task SetLocation(string cityName)
{
City city = await this.cities.GetByNameAsync(cityName);
if (city != null)
{
LogisticCenter lc = await this.Db.LogisticCenters.FirstOrDefaultAsync();
if (lc == null)
{
lc = new LogisticCenter
{
City = city
};
await this.Db.LogisticCenters.AddAsync(lc);
}
else
{
lc.City = city;
}
await this.Db.SaveChangesAsync();
}
}
public async Task <string> GetCurrent()
{
LogisticCenter result = await this.Db.LogisticCenters.Include(lc => lc.City).FirstOrDefaultAsync();
return(result?.City?.Name);
}
