using System;
using System.Collections.Generic;

namespace Vellum.Generator
{
    /// <summary>
    /// Holds the converters a compilation can save with, and the ones with something wrong.
    /// </summary>
    public sealed class ConverterList : IEquatable<ConverterList>
    {
        public readonly EquatableArray<ConverterModel> Usable;
        public readonly EquatableArray<ConverterModel> Problems;

        public ConverterList(EquatableArray<ConverterModel> usable, EquatableArray<ConverterModel> problems)
        {
            Usable = usable;
            Problems = problems;
        }

        /// <summary>
        /// Returns the name of each type something here converts, which is how a saved type finds its converter. A
        /// family isn't a converter of its base class, so it's not counted.
        /// </summary>
        public HashSet<string> ConvertedNames()
        {
            var returnMe = new HashSet<string>();
            foreach (ConverterModel converter in Usable.Items)
            {
                if (converter.FamilyBase == null)
                {
                    returnMe.Add(converter.ConvertedName);
                }
            }

            return returnMe;
        }

        /// <summary>
        /// Returns, for each type something here converts, the positions of its type arguments that its converter
        /// marks [Saveable]. The other arguments can be anything.
        /// </summary>
        public Dictionary<string, EquatableArray<int>> SaveableArguments()
        {
            var returnMe = new Dictionary<string, EquatableArray<int>>();
            foreach (ConverterModel converter in Usable.Items)
            {
                if (converter.FamilyBase == null)
                {
                    returnMe[converter.ConvertedName] = converter.SaveablePositions;
                }
            }

            return returnMe;
        }

        /// <summary>
        /// Returns the name of the base class of each family here, since a type derived from one is saved by it, with
        /// the positions of that class's type arguments that the family marks [Saveable].
        /// </summary>
        public Dictionary<string, EquatableArray<int>> FamilyBaseNames()
        {
            var returnMe = new Dictionary<string, EquatableArray<int>>();
            foreach (ConverterModel converter in Usable.Items)
            {
                if (converter.FamilyBase != null)
                {
                    returnMe[converter.FamilyBase] = converter.SaveablePositions;
                }
            }

            return returnMe;
        }

        /// <summary>
        /// Returns the name of the interface of each interface family here, with the name of each interface it
        /// extends.
        /// </summary>
        public Dictionary<string, EquatableArray<string>> InterfaceFamilies()
        {
            var returnMe = new Dictionary<string, EquatableArray<string>>();
            foreach (ConverterModel converter in Usable.Items)
            {
                if (converter.FamilyIsInterface)
                {
                    returnMe[converter.FamilyBase] = converter.FamilyExtends;
                }
            }

            return returnMe;
        }

        /// <summary>
        /// Returns the name of each assembly that defines the interface of an interface family here.
        /// </summary>
        public HashSet<string> InterfaceFamilyAssemblies()
        {
            var returnMe = new HashSet<string>();
            foreach (ConverterModel converter in Usable.Items)
            {
                if (converter.FamilyIsInterface)
                {
                    returnMe.Add(converter.FamilyBaseAssembly);
                }
            }

            return returnMe;
        }

        public bool Equals(ConverterList other)
        {
            return other != null && Usable.Equals(other.Usable) && Problems.Equals(other.Problems);
        }

        public override bool Equals(object obj)
        {
            return Equals(obj as ConverterList);
        }

        public override int GetHashCode()
        {
            return Usable.GetHashCode() * 31 + Problems.GetHashCode();
        }
    }
}