namespace Invercargill {

    public class EnumerableInfo {

        public int? count { get; private set; }
        public Type enumerable_type { get; private set; }
        public Type element_type { get; private set; }
        public EnumerableCategory category { get; private set; }
        public Enumerable<EnumerableInfo> sources { get; private set; }
        public Enumerable<EnumerableInfo> ultimate_sources { get; private set; }

        public EnumerableInfo(int? count, Type enumerable_type, Type value_type, EnumerableCategory category, ReadOnlyCollection<EnumerableInfo> sources, Enumerable<EnumerableInfo> ultimate_sources) {
            this.count = count;
            this.enumerable_type = enumerable_type;
            this.element_type = value_type;
            this.category = category;
            this.sources = sources;
            this.ultimate_sources = ultimate_sources.cache();
        }

        public EnumerableInfo.infer(Enumerable enumerable, EnumerableCategory category, Enumerable<Enumerable> sources) {
            this.count = enumerable.peek_count();
            this.enumerable_type = enumerable.get_type();
            this.element_type = enumerable.element_type;
            this.category = category;
            this.sources = sources.select<EnumerableInfo>(s => s.get_info()).to_series().seal();
            this.ultimate_sources = this.sources
                .where(s => s.ultimate_sources.no())
                .concat(this.sources.select_many(s => s.ultimate_sources));
        }

        public EnumerableInfo.infer_single(Enumerable enumerable, EnumerableCategory category, Enumerable source) {
            this.count = enumerable.peek_count();
            this.enumerable_type = enumerable.get_type();
            this.element_type = enumerable.element_type;
            this.category = category;
            var source_info = source.get_info();
            this.sources = single(source_info);
            this.ultimate_sources = source_info.sources.any() ? source_info.ultimate_sources : single(source_info);
        }

        public EnumerableInfo.infer_ultimate(Enumerable enumerable, EnumerableCategory category) {
            this.count = enumerable.peek_count();
            this.enumerable_type = enumerable.get_type();
            this.element_type = enumerable.element_type;
            this.category = category;
            this.sources = empty<EnumerableInfo>();
            this.ultimate_sources = this.sources;
        }

    }

    public enum EnumerableCategory {
        IN_MEMORY,
        EXTERNAL,
        COMPUTED,
        CACHED,
        PROXY;
    }

}