using System.Collections.Generic;
using System.Linq;

namespace Deltares.Maps
{
    public static class GeometryRepositoryExtensions
    {
        /// <summary>
        ///     Determines if lines in the source repository have an intersection with lines in the target repository,
        ///     the result is grouped by the count of intersection points
        /// </summary>
        /// <param name="sourceRepository"></param>
        /// <param name="targetRepository"></param>
        /// <returns>
        ///     A list of target and source geometries and the calculated intersection points grouped by the count of
        ///     intersection points
        /// </returns>
        public static IEnumerable<IGrouping<int, IntersectionResult>> GetIntersectionPoints(
            this IFeatureRepository sourceRepository, IFeatureRepository targetRepository)
        {
            /*
            var results = from source in sourceRepository.Features
                          from target in targetRepository.Query(source)
                          let intersectionPoints = target.Geometry.Intersection(source.Geometry)
                          select new IntersectionResult()
                                     {
                                         Source = source,
                                         Target = target,
                                         IntersectionPoints = intersectionPoints.Coordinates
                                     };
*/

            var results = new List<IntersectionResult>();
            foreach (IFeature source in sourceRepository.Features)
            {
                foreach (IFeature target in targetRepository.Query(source))
                {
                    results.Add(new IntersectionResult
                    {
                        Source = source,
                        Target = target,
                        IntersectionPoints = target.Geometry.Intersection(source.Geometry).Coordinates
                    });
                }
            }

            return from result in results
                group result by result.IntersectionPoints.Count();
        }

        public static IEnumerable<IntersectionResult> GetResultsHavingCount(
            this IEnumerable<IGrouping<int, IntersectionResult>> results, int count)
        {
            IGrouping<int, IntersectionResult> havingKey = results.FirstOrDefault(r => r.Key == count);
            return havingKey == null ? new List<IntersectionResult>() : havingKey.Select(r => r);
        }
    }
}