using Jellyfin.Plugin.Multilang.Services;

namespace Jellyfin.Plugin.Multilang.Tests;

public sealed class ItemsProxyCacheTests
{
    [Fact]
    public void PolicyChangesInvalidateCachedDataAndOldInFlightWrites()
    {
        var cache = new ItemsProxyCache();
        var generation = cache.ObserveUserPolicy("user", "all libraries");
        Store(cache, "key");
        Assert.Equal(generation, cache.ObserveUserPolicy("user", "all libraries"));
        Assert.True(cache.TryGet("key", TimeSpan.FromMinutes(1), out _));
        Assert.True(cache.ObserveUserPolicy("user", "no libraries") > generation);
        Assert.False(cache.TryGet("key", TimeSpan.FromMinutes(1), out _));
        Assert.False(cache.Store("key", "user", "/Items", 1, "body", "application/json", 1, 100, TimeSpan.FromMinutes(1), generation));
    }

    [Fact]
    public void StoreRetrievesAndClearsCachedResponses()
    {
        var cache = new ItemsProxyCache();

        Assert.True(Store(cache, "key"));
        Assert.True(cache.TryGet("key", TimeSpan.FromMinutes(1), out var response));
        Assert.Equal("body-key", response.Body);
        Assert.Equal(1, response.ItemCount);

        cache.ClearAll();

        Assert.False(cache.TryGet("key", TimeSpan.FromMinutes(1), out _));
    }

    [Fact]
    public void MicroCacheServesFastResponsesAndIsInvalidatedWithTheMainCache()
    {
        var cache = new ItemsProxyCache();

        Assert.True(cache.StoreMicro("key", "user", "/Items", 1, "micro", "application/json", 1, 1024));
        Assert.True(cache.TryGet("key", TimeSpan.FromMinutes(1), out var response));
        Assert.Equal("micro", response.Body);

        cache.ClearAll();

        Assert.False(cache.TryGet("key", TimeSpan.FromMinutes(1), out _));
    }

    [Fact]
    public void StoreEvictsTheOldestEntryWhenCapacityIsExceeded()
    {
        var cache = new ItemsProxyCache();

        Assert.True(Store(cache, "first", body: "1111", maxBytes: 6));
        Thread.Sleep(10);
        Assert.True(Store(cache, "second", body: "2222", maxBytes: 6));

        Assert.False(cache.TryGet("first", TimeSpan.FromMinutes(1), out _));
        Assert.True(cache.TryGet("second", TimeSpan.FromMinutes(1), out _));
    }

    [Fact]
    public void StoreEntriesExpireAtTheConfiguredTtl()
    {
        var cache = new ItemsProxyCache();

        Assert.True(Store(cache, "key", ttl: TimeSpan.FromMilliseconds(1)));
        Thread.Sleep(20);

        Assert.False(cache.TryGet("key", TimeSpan.FromMilliseconds(1), out _));
    }

    [Fact]
    public void StoreRejectsResponsesLargerThanTheConfiguredLimit()
    {
        var cache = new ItemsProxyCache();

        Assert.False(Store(cache, "key", body: "12345", maxBytes: 4));
        Assert.False(cache.TryGet("key", TimeSpan.FromMinutes(1), out _));
    }

    private static bool Store(
        ItemsProxyCache cache,
        string key,
        int itemCount = 1,
        string? body = null,
        long maxBytes = 1024,
        TimeSpan? ttl = null)
        => cache.Store(
            key,
            "user",
            "/Items",
            itemCount,
            body ?? "body-" + key,
            "application/json",
            100,
            maxBytes,
            ttl ?? TimeSpan.FromMinutes(1));

    [Fact]
    public void MicroAndMainEntriesShareOneBudget()
    {
        var cache = new ItemsProxyCache();
        Assert.True(Store(cache, "main", body: "1111", maxBytes: 6));
        Assert.True(cache.StoreMicro("micro1", "user", "/Items", 1, "2222", "application/json", 1, 6));
        Assert.False(cache.TryGet("main", TimeSpan.FromMinutes(1), out _));
        Assert.True(cache.StoreMicro("micro2", "user", "/Items", 1, "3333", "application/json", 1, 6));
        Assert.False(cache.TryGet("micro1", TimeSpan.FromMinutes(1), out _));
        Assert.True(cache.TryGet("micro2", TimeSpan.FromMinutes(1), out _));
    }

    [Fact]
    public void InvalidationRejectsStaleInFlightWrites()
    {
        var cache = new ItemsProxyCache();
        var generation = cache.Generation;
        cache.ClearAll();
        Assert.False(cache.Store("key", "user", "/Items", 1, "body", "application/json", 1, 100, TimeSpan.FromMinutes(1), generation));
        Assert.False(cache.StoreMicro("key", "user", "/Items", 1, "body", "application/json", 1, 100, generation));
    }

    [Fact]
    public void ClearingOneUserPreservesOtherUsersCachedResponses()
    {
        var cache = new ItemsProxyCache();
        Store(cache, "one");
        cache.Store("two", "other", "/Items", 1, "body", "application/json", 1, 100, TimeSpan.FromMinutes(1));
        cache.ClearUser("user");
        Assert.False(cache.TryGet("one", TimeSpan.FromMinutes(1), out _));
        Assert.True(cache.TryGet("two", TimeSpan.FromMinutes(1), out _));
    }
}