// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.

using System;
using System.Linq;
using System.Text;

namespace Microsoft.AspNetCore.Routing.Matchers
{
    internal class LinearSearchJumpTable : JumpTable
    {
        private readonly int _defaultDestination;
        private readonly int _exitDestination;
        private readonly (string text, int destination)[] _entries;

        public LinearSearchJumpTable(
            int defaultDestination,
            int exitDestination,
            (string text, int destination)[] entries)
        {
            _defaultDestination = defaultDestination;
            _exitDestination = exitDestination;
            _entries = entries;
        }

        public override int GetDestination(string path, PathSegment segment)
        {
            if (segment.Length == 0)
            {
                return _exitDestination;
            }

            var entries = _entries;
            for (var i = 0; i < entries.Length; i++)
            {
                var text = entries[i].text;
                if (segment.Length == text.Length &&
                    string.Compare(
                        path,
                        segment.Start,
                        text,
                        0,
                        segment.Length,
                        StringComparison.OrdinalIgnoreCase) == 0)
                {
                    return entries[i].destination;
                }
            }

            return _defaultDestination;
        }

        public override string DebuggerToString()
        {
            var builder = new StringBuilder();
            builder.Append("{ ");

            builder.Append(string.Join(", ", _entries.Select(e => $"{e.text}: {e.destination}")));

            builder.Append("$+: ");
            builder.Append(_defaultDestination);
            builder.Append(", ");

            builder.Append("$0: ");
            builder.Append(_defaultDestination);

            builder.Append(" }");

            return builder.ToString();
        }
    }
}