using System;
using System.Collections.Generic;
using Paca.Mobile.Core;
using Xunit;

namespace Paca.Tests.Core;

public class NetworkResilienceSupervisorGateTests
{
    [Fact]
    public void Gate265_NetworkResilienceSupervisor_PausesActiveDownloads_OnNetworkLoss()
    {
        var supervisor = new NetworkResilienceSupervisor();
        var item1 = new ResilientDownloadItem("id-1", "video1", ResilientDownloadState.Downloading);
        var item2 = new ResilientDownloadItem("id-2", "video2", ResilientDownloadState.Downloading);

        supervisor.RegisterItems(new[] { item1, item2 });

        // Network goes down
        supervisor.OnNetworkStatusChanged(isConnected: false);

        Assert.Equal(ResilientDownloadState.NetworkPaused, item1.State);
        Assert.Equal(ResilientDownloadState.NetworkPaused, item2.State);
    }

    [Fact]
    public void Gate266_NetworkResilienceSupervisor_AutomaticallyResumes_OnNetworkRestored()
    {
        var supervisor = new NetworkResilienceSupervisor();
        var item = new ResilientDownloadItem("id-1", "video1", ResilientDownloadState.Downloading);
        supervisor.RegisterItems(new[] { item });

        supervisor.OnNetworkStatusChanged(isConnected: false);
        Assert.Equal(ResilientDownloadState.NetworkPaused, item.State);

        // Network comes back up
        var resumedItems = supervisor.OnNetworkStatusChanged(isConnected: true);

        Assert.Equal(ResilientDownloadState.Downloading, item.State);
        Assert.Single(resumedItems);
        Assert.Equal("id-1", resumedItems[0].Id);
    }

    [Fact]
    public void Gate267_NetworkResilienceSupervisor_DoesNotResume_UserPausedItems()
    {
        var supervisor = new NetworkResilienceSupervisor();
        var userPausedItem = new ResilientDownloadItem("id-user", "video_paused", ResilientDownloadState.UserPaused);
        supervisor.RegisterItems(new[] { userPausedItem });

        // Network disconnect then reconnect
        supervisor.OnNetworkStatusChanged(isConnected: false);
        var resumed = supervisor.OnNetworkStatusChanged(isConnected: true);

        Assert.Equal(ResilientDownloadState.UserPaused, userPausedItem.State);
        Assert.Empty(resumed);
    }

    [Fact]
    public void Gate268_NetworkResilienceSupervisor_JitteredBackoff_CalculatesDelays()
    {
        var supervisor = new NetworkResilienceSupervisor();

        var delay1 = supervisor.GetJitteredDelayMs(itemIndex: 0, baseDelayMs: 500);
        var delay2 = supervisor.GetJitteredDelayMs(itemIndex: 1, baseDelayMs: 500);
        var delay3 = supervisor.GetJitteredDelayMs(itemIndex: 2, baseDelayMs: 500);

        Assert.True(delay1 >= 500);
        Assert.True(delay2 > delay1);
        Assert.True(delay3 > delay2);
    }
}