using System.ComponentModel.DataAnnotations;
using System.Text.RegularExpressions;

namespace RhSolutions.Api.Models
{
    public class Sku
    {
        private const string matchPattern = @"([1\D]|\b)(?<Article>\d{6})([1\s-]|)(?<Variant>\d{3})\b";
        private string? _article;
        private string? _variant;

        public Sku(string article, string variant)
        {
            Article = article;
            Variant = variant;
        }

        [Key]
        public string Id
        {
            get
            {
                return $"1{Article}1{Variant}";
            }
            set
            {
                if (TryParse(value, out IEnumerable<Sku> skus))
                {
                    if (skus.Count() > 1)
                    {
                        throw new ArgumentException($"More than one valid sku detected: {value}");
                    }
                    else
                    {
                        this.Article = skus.First().Article;
                        this.Variant = skus.First().Variant;
                    }
                }
                else
                {
                    throw new ArgumentException($"Invalid sku input: {value}");
                }
            }
        }
        public string? Article
        {
            get
            {
                return _article;
            }
            set
            {
                if (value == null || value.Length != 6 || value.Where(c => char.IsDigit(c)).Count() != 6)
                {
                    throw new ArgumentException($"Wrong Article: {Article}");
                }
                else
                {
                    _article = value;
                }
            }
        }
        public string? Variant
        {
            get
            {
                return _variant;
            }
            set
            {
                if (value == null || value.Length != 3 || value.Where(c => char.IsDigit(c)).Count() != 3)
                {
                    throw new ArgumentException($"Wrong Variant: {Variant}");
                }
                else _variant = value;
            }
        }
        public static IEnumerable<Sku> GetValidSkus(string line)
        {
            MatchCollection matches = Regex.Matches(line, matchPattern);
            if (matches.Count == 0)
            {
                yield break;
            }
            else
            {
                foreach (Match m in matches)
                {
                    yield return new Sku(m.Groups["Article"].Value, m.Groups["Variant"].Value);
                }
            }
        }

        public static bool TryParse(string line, out IEnumerable<Sku> skus)
        {
            MatchCollection matches = Regex.Matches(line, matchPattern);
            if (matches.Count == 0)
            {
                skus = Enumerable.Empty<Sku>();
                return false;
            }

            else
            {
                skus = GetValidSkus(line);
                return true;
            }
        }

        public override bool Equals(object? obj)
        {
            return obj is Sku sku &&
                   Article!.Equals(sku.Article) &&
                   Variant!.Equals(sku.Variant);
        }

        public override int GetHashCode()
        {
            return HashCode.Combine(Article, Variant);
        }

        public override string ToString()
        {
            return $"1{Article}1{Variant}";
        }
    }
}