using System;
using System.Collections.Generic;
using ServiceStack.Text;

#if !NET6_0_OR_GREATER
using ServiceStack.Extensions;
#endif

namespace ServiceStack;

public class Command
{
    public string Name { get; set; }

    public ReadOnlyMemory<char> Original { get; set; }

    public List<ReadOnlyMemory<char>> Args { get; internal set; } = new();

    public ReadOnlyMemory<char> Suffix { get; set; }

    public int IndexOfMethodEnd(ReadOnlyMemory<char> commandsString, int pos)
    {
        //finding end of suffix, e.g: 'SUM(*) Total' or 'SUM(*) as Total'
        var endPos = pos;
        var cmdSpan = commandsString.Span;
        while (cmdSpan.Length > endPos && char.IsWhiteSpace(cmdSpan[endPos]))
            endPos++;

        if (cmdSpan.Length > endPos && cmdSpan.IndexOf("as ", endPos) == endPos)
            endPos += "as ".Length;

        while (cmdSpan.Length > endPos && char.IsWhiteSpace(cmdSpan[endPos]))
            endPos++;

        while (cmdSpan.Length > endPos &&
               char.IsLetterOrDigit(cmdSpan[endPos]))
            endPos++;

        this.Suffix = commandsString.Slice(pos, endPos - pos).TrimEnd();

        return endPos;
    }

    //Output different format for debugging to verify command was parsed correctly
    public virtual string ToDebugString()
    {
        var sb = StringBuilderCacheAlt.Allocate();
        foreach (var arg in Args)
        {
            if (sb.Length > 0)
                sb.Append('|');
            sb.Append(arg);
        }

        return $"[{Name}:{StringBuilderCacheAlt.ReturnAndFree(sb)}]{Suffix}";
    }

    public override string ToString()
    {
        var sb = StringBuilderCacheAlt.Allocate();
        foreach (var arg in Args)
        {
            if (sb.Length > 0)
                sb.Append(',');
            sb.Append(arg);
        }

        return $"{Name}({StringBuilderCacheAlt.ReturnAndFree(sb)}){Suffix}";
    }

    public ReadOnlyMemory<char> AsMemory() => ToString().AsMemory();
}