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

namespace Paca.Tests.Core;

public class OfflineMediaPrefetcherGateTests
{
    private readonly List<string> _seriesPlaylist = new()
    {
        "ep-1", "ep-2", "ep-3", "ep-4", "ep-5"
    };

    [Fact]
    public void Gate389_OfflineMediaPrefetcher_DecidesToPrefetch_WhenThresholdAndConditionsMet()
    {
        var policy = new PrefetchPolicy(RequireWifi: true, MinBatteryPercent: 50, PlaybackProgressThresholdPercent: 70.0, MaxPrefetchCount: 2);
        var env = new DeviceEnvironmentStatus(IsWifiConnected: true, BatteryPercent: 80);

        // Currently watching ep-2 at 75% progress
        var decision = OfflineMediaPrefetcher.EvaluatePrefetchDecision(
            _seriesPlaylist, currentPlayingId: "ep-2", currentProgressPercent: 75.0, env, policy);

        Assert.True(decision.ShouldPrefetch);
        Assert.Equal(2, decision.ItemsToPrefetch.Count);
        Assert.Equal("ep-3", decision.ItemsToPrefetch[0]);
        Assert.Equal("ep-4", decision.ItemsToPrefetch[1]);
    }

    [Fact]
    public void Gate390_OfflineMediaPrefetcher_Waits_WhenProgressBelowThreshold()
    {
        var policy = new PrefetchPolicy(true, 50, 70.0, 2);
        var env = new DeviceEnvironmentStatus(true, 85);

        // Currently watching ep-1 at 40% progress (below 70%)
        var decision = OfflineMediaPrefetcher.EvaluatePrefetchDecision(
            _seriesPlaylist, "ep-1", 40.0, env, policy);

        Assert.False(decision.ShouldPrefetch);
        Assert.Empty(decision.ItemsToPrefetch);
        Assert.Contains("진행률", decision.ReasonMessage);
    }

    [Fact]
    public void Gate391_OfflineMediaPrefetcher_Blocks_OnCellularOrLowBattery()
    {
        var policy = new PrefetchPolicy(RequireWifi: true, MinBatteryPercent: 50, PlaybackProgressThresholdPercent: 70.0, MaxPrefetchCount: 2);

        // On cellular network
        var cellularEnv = new DeviceEnvironmentStatus(IsWifiConnected: false, BatteryPercent: 90);
        var decCellular = OfflineMediaPrefetcher.EvaluatePrefetchDecision(_seriesPlaylist, "ep-2", 80.0, cellularEnv, policy);
        Assert.False(decCellular.ShouldPrefetch);
        Assert.Contains("Wi-Fi", decCellular.ReasonMessage);

        // Low battery (30%)
        var lowBatteryEnv = new DeviceEnvironmentStatus(IsWifiConnected: true, BatteryPercent: 30);
        var decBattery = OfflineMediaPrefetcher.EvaluatePrefetchDecision(_seriesPlaylist, "ep-2", 80.0, lowBatteryEnv, policy);
        Assert.False(decBattery.ShouldPrefetch);
        Assert.Contains("배터리", decBattery.ReasonMessage);
    }

    [Fact]
    public void Gate392_OfflineMediaPrefetcher_HandlesEndOfPlaylistGracefully()
    {
        var policy = new PrefetchPolicy(true, 50, 70.0, 2);
        var env = new DeviceEnvironmentStatus(true, 90);

        // Watching the final episode (ep-5)
        var decision = OfflineMediaPrefetcher.EvaluatePrefetchDecision(
            _seriesPlaylist, "ep-5", 85.0, env, policy);

        Assert.False(decision.ShouldPrefetch);
        Assert.Empty(decision.ItemsToPrefetch);
        Assert.Contains("마지막", decision.ReasonMessage);
    }
}