namespace DynamicBibleUtility.Geolocation;

/// <summary>
/// An index of Bible location data by Strong's numbers.
/// Strong's numbers tend to be more useful for lookups in the Dynamic Bible app
/// due to how they're integrated into the rest of the app and can help more clearly
/// define a particular location.
/// This class maintains a simple lookup of Strong's numbers to location names
/// in addition to a lookup that includes the full location data.
/// </summary>
public class BibleLocationIndexByStrongsNumbers
{
    /// <summary>
    /// A mapping of Strong's numbers to normalized location names.
    /// A Strong's number may refer to multiple locations.
    /// </summary>
    public readonly IDictionary<string, List<string>> StrongsNumberToLocationNameLookup = new Dictionary<string, List<string>>();

    /// <summary>
    /// A mapping of Strong's numbers to full location data (in JSON format).
    /// A Strong's number may refer to multiple locations.
    /// </summary>
    public readonly IDictionary<string, List<dynamic>> StrongsNumberToLocationLookup = new Dictionary<string, List<dynamic>>();

    /// <summary>
    /// Creates the index from the provided locations.
    /// </summary>
    /// <param name="locations">The locations to put in the index.</param>
    /// <exception cref="System.NullReferenceException">Thrown if the locations are null.</exception>
    public BibleLocationIndexByStrongsNumbers(IEnumerable<BibleLocationReference> locations)
    {
        // INDEX THE LOCATIONS BY STRONG'S NUMBERS.
        foreach (var location in locations)
        {
            // DON'T INDEX THE LOCATION IF IT HAS GEOGRAPHIC COORDINATES.
            // The information currently isn't useful without these coordinates.
            if (!location.HasGeographicCoordinates)
            {
                continue;
            }

            // DON'T INDEX THE LOCATION IF IT DOESN'T HAVE ANY STRONG'S NUMBERS.
            var location_has_strongs_numbers = location.StrongsNumbers.Any();
            if (!location_has_strongs_numbers)
            {
                continue;
            }

            // INDEX THE LOCATION BY STRONG'S NUMBERS.
            foreach (var strongs_number in location.StrongsNumbers)
            {
                // MAKE SURE EXISTING COLLECTIONS EXIST FOR THE STRONG'S NUMBER.
                var strongs_number_exists_in_index = StrongsNumberToLocationLookup.ContainsKey(strongs_number);
                if (!strongs_number_exists_in_index)
                {
                    StrongsNumberToLocationNameLookup[strongs_number] = [];
                    StrongsNumberToLocationLookup[strongs_number] = [];
                }

                // CONVERT THE LOCATION TO JSON FORMAT.
                // Since the location data needs to be converted to JSON in different
                // scenarios with different properties serialized, there's not an easy
                // way to simply mark which fields should/shouldn't be serialized in
                // all situations.  While a custom JSON converter could be used,
                // creating a dynamic object here seemed simpler.  In this scenario,
                // the Strong's number doesn't need to be included in the member data
                // since it already serves as the key in the lookup.
                dynamic converted_location = new
                {
                    name = location.Name,
                    lat = location.Latitude,
                    lon = location.Longitude,
                    vss = location.VerseReferenceStrings,
                };

                // INDEX THE LOCATION BY STRONG'S NUMBER.
                // Indices with just the location name and full location data are maintained.
                StrongsNumberToLocationNameLookup[strongs_number].Add(location.Name);
                StrongsNumberToLocationLookup[strongs_number].Add(converted_location);
            }
        }
    }
}