using System.Text.Json;
using Serilog.Events;
using YZWater.Core.Models;
using YZWater.Core.Services;

namespace YZWater.Core.Tests.Services;

/// <summary>
/// 日志级别运行时开关的回归测试。
/// 背景：轮询诊断降到 Debug 之后，如果级别不可调，现场遇到"某个值不对"就没有任何手段
/// 把它临时开回来取证，只能停下来重新发布 —— 降级就变成了丢能力。
/// </summary>
// 本类会改 LogService.MinimumLevel（静态），必须与同样改它的测试类串行，否则默认值断言偶发失败
[Collection("Serilog minimum level")]
public class LogLevelSwitchTests : IDisposable
{
    private readonly LogEventLevel _original = LogService.MinimumLevel;

    [Fact]
    public void Default_MinimumLevel_IsInformation()
    {
        Assert.Equal(LogEventLevel.Information, _original);
    }

    [Fact]
    public void ApplyMinimumLevel_Debug_TakesEffect()
    {
        LogService.ApplyMinimumLevel("Debug");

        Assert.Equal(LogEventLevel.Debug, LogService.MinimumLevel);
    }

    [Fact]
    public void ApplyMinimumLevel_IsCaseInsensitive()
    {
        LogService.ApplyMinimumLevel("warning");

        Assert.Equal(LogEventLevel.Warning, LogService.MinimumLevel);
    }

    [Theory]
    [InlineData(null)]
    [InlineData("")]
    [InlineData("   ")]
    [InlineData("banana")]
    [InlineData("Infos")]
    public void ApplyMinimumLevel_InvalidValue_KeepsCurrentLevel(string? level)
    {
        LogService.ApplyMinimumLevel("Debug");
        var before = LogService.MinimumLevel;

        LogService.ApplyMinimumLevel(level);

        Assert.Equal(before, LogService.MinimumLevel);
    }

    [Theory]
    [InlineData("Debug", true)]
    [InlineData("debug", true)]
    [InlineData("Information", true)]
    [InlineData("Verbose", true)]
    [InlineData("Fatal", true)]
    [InlineData("Trace", false)]
    // 手改配置文件容易多敲空格，Enum.TryParse 本身容忍首尾空白 —— 这里把它钉住
    [InlineData("Debug ", true)]
    [InlineData(" Debug", true)]
    public void TryParseLevel_MatchesSerilogVocabulary(string level, bool expected)
    {
        Assert.Equal(expected, LogService.TryParseLevel(level, out _));
    }

    [Fact]
    public void SystemConfig_LogKnobs_DefaultToProductionValues()
    {
        var config = new SystemConfig();

        Assert.Equal("Information", config.MinimumLogLevel);
        Assert.Equal(60, config.LogSnapshotIntervalSeconds);
    }

    [Fact]
    public void SystemConfig_LogKnobs_RoundTripThroughJson()
    {
        // 现场排障就是改这两行文本，键名必须能被反序列化认出来
        const string json = """{"MinimumLogLevel":"Debug","LogSnapshotIntervalSeconds":10}""";

        var config = JsonSerializer.Deserialize<SystemConfig>(json);

        Assert.Equal("Debug", config?.MinimumLogLevel);
        Assert.Equal(10, config?.LogSnapshotIntervalSeconds);
    }

    [Fact]
    public void PlcPollingService_SnapshotInterval_DefaultsTo60Seconds()
    {
        // 0 会让快照静默关闭，默认值必须是有证据的那一档
        Assert.Equal(60, PlcPollingService.Instance.LogSnapshotIntervalSeconds);
    }

    public void Dispose() => LogService.ApplyMinimumLevel(_original.ToString());
}