using System.Globalization;

namespace CanonSharp.Common.LexicalAnalyzer;

public class LexicalToken : IEquatable<LexicalToken>
{
    private readonly Guid _tokenId;

    public RegularExpression Expression { get; }

    public int Priority { get; }

    public LexicalToken(RegularExpression expression, int priority)
    {
        _tokenId = Guid.NewGuid();
        Expression = expression;
        Priority = priority;
        LiteralValue = string.Empty;
    }

    internal LexicalToken(LexicalToken definition, string literalValue)
    {
        _tokenId = definition._tokenId;
        Expression = definition.Expression;
        Priority = definition.Priority;
        LiteralValue = literalValue;
    }

    public string LiteralValue { get; }

    public bool Equals(LexicalToken? other) => other is not null && _tokenId == other._tokenId;

    public override bool Equals(object? obj) => obj is LexicalToken other && Equals(other);

    public override int GetHashCode() => _tokenId.GetHashCode();

    public static bool operator ==(LexicalToken a, LexicalToken b) => a.Equals(b);

    public static bool operator !=(LexicalToken a, LexicalToken b) => !(a == b);

    /// <summary>
    /// 匹配所有的空白字符
    /// </summary>
    public static readonly LexicalToken WhiteSpace = new(
        RegularExpression.Alternate(
            RegularExpression.CharSetOf(c => char.GetUnicodeCategory(c) == UnicodeCategory.SpaceSeparator),
            RegularExpression.CharSetOf("\u0009\u000B\u000C")), int.MinValue);

    /// <summary>
    /// 匹配所有的换行符
    /// </summary>
    public static readonly LexicalToken LineBreaker = new(
        RegularExpression.Alternate(
            RegularExpression.CharSetOf("\u000D\u000A\u0085\u2028\u2029"),
            RegularExpression.String("\r\n")), int.MinValue);
}