// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

using System.Globalization;

namespace System.Net.Cache
{
    public class HttpRequestCachePolicy : RequestCachePolicy
    {
        private readonly DateTime _lastSyncDateUtc = DateTime.MinValue;
        private readonly TimeSpan _maxAge = TimeSpan.MaxValue;
        private readonly TimeSpan _minFresh = TimeSpan.MinValue;
        private readonly TimeSpan _maxStale = TimeSpan.MinValue;

        public HttpRequestCachePolicy() : this(HttpRequestCacheLevel.Default)
        {
        }

        public HttpRequestCachePolicy(HttpRequestCacheLevel level) : base(MapLevel(level))
        {
            Level = level;
        }

        public HttpRequestCachePolicy(HttpCacheAgeControl cacheAgeControl, TimeSpan ageOrFreshOrStale) : this(HttpRequestCacheLevel.Default)
        {
            switch (cacheAgeControl)
            {
                case HttpCacheAgeControl.MinFresh:
                    _minFresh = ageOrFreshOrStale;
                    break;
                case HttpCacheAgeControl.MaxAge:
                    _maxAge = ageOrFreshOrStale;
                    break;
                case HttpCacheAgeControl.MaxStale:
                    _maxStale = ageOrFreshOrStale;
                    break;
                default:
                    throw new ArgumentException(SR.Format(SR.net_invalid_enum, nameof(HttpCacheAgeControl)), nameof(cacheAgeControl));
            }
        }

        public HttpRequestCachePolicy(HttpCacheAgeControl cacheAgeControl, TimeSpan maxAge, TimeSpan freshOrStale) : this(HttpRequestCacheLevel.Default)
        {
            switch (cacheAgeControl)
            {
                case HttpCacheAgeControl.MinFresh:
                    _minFresh = freshOrStale;
                    break;
                case HttpCacheAgeControl.MaxAge:
                    _maxAge = maxAge;
                    break;
                case HttpCacheAgeControl.MaxStale:
                    _maxStale = freshOrStale;
                    break;
                case HttpCacheAgeControl.MaxAgeAndMinFresh:
                    _maxAge = maxAge;
                    _minFresh = freshOrStale;
                    break;
                case HttpCacheAgeControl.MaxAgeAndMaxStale:
                    _maxAge = maxAge;
                    _maxStale = freshOrStale;
                    break;
                default:
                    throw new ArgumentException(SR.Format(SR.net_invalid_enum, nameof(HttpCacheAgeControl)), nameof(cacheAgeControl));
            }
        }

        public HttpRequestCachePolicy(DateTime cacheSyncDate) :
            this(HttpRequestCacheLevel.Default)
        {
            _lastSyncDateUtc = cacheSyncDate.ToUniversalTime();
        }

        public HttpRequestCachePolicy(HttpCacheAgeControl cacheAgeControl, TimeSpan maxAge, TimeSpan freshOrStale, DateTime cacheSyncDate) :
            this(cacheAgeControl, maxAge, freshOrStale)
        {
            _lastSyncDateUtc = cacheSyncDate.ToUniversalTime();
        }

        public new HttpRequestCacheLevel Level { get; }

        public DateTime CacheSyncDate =>
            _lastSyncDateUtc == DateTime.MinValue || _lastSyncDateUtc == DateTime.MaxValue ?
                _lastSyncDateUtc :
                _lastSyncDateUtc.ToLocalTime();

        public TimeSpan MaxAge => _maxAge;

        public TimeSpan MinFresh => _minFresh;

        public TimeSpan MaxStale => _maxStale;

        public override string ToString()
        {
            return "Level:" + Level.ToString() +
                (_maxAge == TimeSpan.MaxValue ? string.Empty : " MaxAge:" + _maxAge.ToString()) +
                (_minFresh == TimeSpan.MinValue ? string.Empty : " MinFresh:" + _minFresh.ToString()) +
                (_maxStale == TimeSpan.MinValue ? string.Empty : " MaxStale:" + _maxStale.ToString()) +
                (CacheSyncDate == DateTime.MinValue ? string.Empty : " CacheSyncDate:" + CacheSyncDate.ToString(CultureInfo.CurrentCulture));
        }

        private static RequestCacheLevel MapLevel(HttpRequestCacheLevel level)
        {
            if (level <= HttpRequestCacheLevel.NoCacheNoStore)
            {
                return (RequestCacheLevel)level;
            }

            if (level == HttpRequestCacheLevel.CacheOrNextCacheOnly)
            {
                return RequestCacheLevel.CacheOnly;
            }

            if (level == HttpRequestCacheLevel.Refresh)
            {
                return RequestCacheLevel.Reload;
            }

            throw new ArgumentOutOfRangeException(nameof(level));
        }
    }
}