using System;
using System.Globalization;

namespace game.KV
{
    /// <summary>
    /// Immutable process-start selection with canonical positive numeric player identities.
    /// </summary>
    internal sealed class KvRuntimeSelection
    {
        internal bool IsKV
        {
            get;
        }
        internal Uri Api
        {
            get;
        }

        private KvRuntimeSelection(bool isKV, Uri api)
        {
            IsKV = isKV;
            Api = api;
        }

        internal static string CompiledBackend
        {
            get
            {
#if USE_KV
                return "kv";
#else
                return "playfab";
#endif
            }
        }

        internal static KvRuntimeSelection CaptureForBuild(string api)
        {
            var backend = CompiledBackend;
            if (backend == "playfab")
            {
                return new KvRuntimeSelection(false, null);
            }
            if (!Uri.TryCreate(api, UriKind.Absolute, out var address) ||
                (address.Scheme != "http" && address.Scheme != "https") ||
                !string.IsNullOrEmpty(address.UserInfo) || !string.IsNullOrEmpty(address.Query) ||
                !string.IsNullOrEmpty(address.Fragment))
            {
                throw new ArgumentException("KV API address is invalid.", nameof(api));
            }
            return new KvRuntimeSelection(true, new Uri(address.AbsoluteUri.TrimEnd('/') + "/"));
        }

        internal bool TryAdmitPlayer(string requestedId, out string canonicalId)
        {
            canonicalId = null;
            if (!IsKV || !long.TryParse(requestedId, NumberStyles.None, CultureInfo.InvariantCulture, out var id) ||
                id <= 0)
            {
                return false;
            }
            canonicalId = id.ToString(CultureInfo.InvariantCulture);
            return true;
        }
    }
}