using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;

namespace ShrinkModFramework
{
    /// <summary>Maven 风格区间/并集；裸版本表示最低版本。版本比较沿用框架规则，数字尾部零等价。</summary>
    public sealed class ShrinkModVersionRange
    {
        private readonly List<Func<string, bool>> _ranges = new();
        private ShrinkModVersionRange() { }

        public static ShrinkModVersionRange Parse(string expression)
        {
            var result = new ShrinkModVersionRange();
            if (string.IsNullOrWhiteSpace(expression)) return result;
            var text = expression.Trim();
            if (text[0] != '[' && text[0] != '(')
            {
                ValidateVersion(text);
                result._ranges.Add(version => ShrinkVersionUtility.Compare(version, text) >= 0);
                return result;
            }
            while (text.Length > 0)
            {
                var end = text.IndexOfAny(new[] { ']', ')' });
                if (end < 0 || (text[0] != '[' && text[0] != '(')) throw Invalid(expression);
                var lowerInclusive = text[0] == '[';
                var upperInclusive = text[end] == ']';
                var bounds = text.Substring(1, end - 1).Split(',');
                string lower, upper;
                if (bounds.Length == 1)
                {
                    if (!lowerInclusive || !upperInclusive) throw Invalid(expression);
                    lower = upper = bounds[0].Trim();
                    ValidateVersion(lower);
                }
                else if (bounds.Length == 2)
                {
                    lower = bounds[0].Trim(); upper = bounds[1].Trim();
                    if (lower.Length > 0) ValidateVersion(lower);
                    if (upper.Length > 0) ValidateVersion(upper);
                    if ((lower.Length == 0 && lowerInclusive) || (upper.Length == 0 && upperInclusive))
                        throw Invalid(expression);
                    if (lower.Length > 0 && upper.Length > 0)
                    {
                        var comparison = ShrinkVersionUtility.Compare(lower, upper);
                        if (comparison > 0 || (comparison == 0 && (!lowerInclusive || !upperInclusive))) throw Invalid(expression);
                    }
                }
                else throw Invalid(expression);
                result._ranges.Add(version =>
                    (lower.Length == 0 || (lowerInclusive ? ShrinkVersionUtility.Compare(version, lower) >= 0 : ShrinkVersionUtility.Compare(version, lower) > 0)) &&
                    (upper.Length == 0 || (upperInclusive ? ShrinkVersionUtility.Compare(version, upper) <= 0 : ShrinkVersionUtility.Compare(version, upper) < 0)));
                text = text.Substring(end + 1).Trim();
                if (text.Length == 0) break;
                if (text[0] != ',' || text.Length == 1) throw Invalid(expression);
                text = text.Substring(1).Trim();
                if (text.Length == 0) throw Invalid(expression);
            }
            return result;
        }

        public bool Contains(string version)
        {
            ValidateVersion(version);
            return _ranges.Count == 0 || _ranges.Any(range => range(version));
        }

        private static void ValidateVersion(string version)
        {
            if (string.IsNullOrWhiteSpace(version) || !Regex.IsMatch(version, @"^[0-9]+(?:[.][0-9]+)*(?:[-+][A-Za-z0-9.-]+)?$"))
                throw Invalid(version);
        }
        private static FormatException Invalid(string value) => new FormatException($"Invalid mod version range: '{value}'.");
    }
}