using Fleet.Core;
using Microsoft.Extensions.Time.Testing;
using Monitor.Backend.Analysis;
using Monitor.Backend.Application;
using Monitor.Protocol;

namespace Monitor.Backend.Tests;

/// <summary>时间段、步长与数据源的规划：与 docs/query.md 里的表格逐行对应。</summary>
public sealed class QueryPlanningTests
{
    private const long Second = 1000;
    private const long Minute = 60 * Second;
    private const long Hour = 60 * Minute;
    private const long Day = 24 * Hour;

    private static readonly long s_now = new DateTimeOffset(2026, 10, 3, 12, 34, 56, TimeSpan.Zero).ToUnixTimeMilliseconds();

    private readonly BackendOptions _options = new();

    private RangeResolver Resolver => new(_options);

    private SourcePlanner Planner => new(_options);

    private QueryRange Resolve(string range, string? step = null)
    {
        Result<QueryRange> result = Resolver.Resolve(new RangeRequest(range, null, null, step, null), s_now);
        Assert.True(result.IsSuccess, result.IsSuccess ? "" : result.Error.Message);
        return result.Value;
    }

    [Theory]
    [InlineData("5m", "1s", 300)]
    [InlineData("15m", "2s", 450)]
    [InlineData("30m", "5s", 360)]
    [InlineData("1h", "5s", 720)]
    [InlineData("6h", "30s", 720)]
    [InlineData("24h", "2m", 720)]
    [InlineData("7d", "15m", 672)]
    [InlineData("30d", "1h", 720)]
    [InlineData("90d", "3h", 720)]
    public void AutoStep_MatchesTheDocumentedTable(string range, string step, int points)
    {
        QueryRange resolved = Resolve(range);
        Assert.Equal(step, Steps.Format(resolved.StepMs));
        Assert.InRange(resolved.Points - points, 0, 1); // 对齐到步长的整数倍，可能多出一个不完整的桶
    }

    [Theory]
    [InlineData("5m", "hot")]
    [InlineData("15m", "hot")]
    [InlineData("30m", "hot")]
    [InlineData("1h", "hot")]
    [InlineData("6h", "10s")]
    [InlineData("24h", "1m")]
    [InlineData("7d", "5m")]
    [InlineData("30d", "1h")]
    [InlineData("90d", "1h")]
    public void SourceSelection_MatchesTheDocumentedTable(string range, string source)
    {
        QueryRange resolved = Resolve(range);
        SourcePlan plan = Planner.Plan(resolved, s_now, hotReady: true);
        Assert.Equal(source, plan.Name);
        Assert.False(plan.Degraded);
        Assert.Equal(resolved.StepMs, plan.StepMs);
    }

    [Fact]
    public void WhenTheHotLayerIsNotReady_FineStepsOverRecentDataComeFromRawChunks()
    {
        SourcePlan plan = Planner.Plan(Resolve("5m"), s_now, hotReady: false);
        Assert.Equal("raw", plan.Name);

        // 区间超过 15 分钟就不现算，降级到 10 s 层
        SourcePlan degraded = Planner.Plan(Resolve("1h", step: "5s"), s_now, hotReady: false);
        Assert.Equal("10s", degraded.Name);
        Assert.True(degraded.Degraded);
        Assert.Equal(10 * Second, degraded.StepMs);
    }

    [Fact]
    public void StepsThatNoLayerCanServe_AreDegradedAndSnappedToACommonStep()
    {
        // 15 s 不能整除 10 s 层的宽度，而且已经超出热层
        QueryRange old = Resolver.Resolve(new RangeRequest(null, DateTimeOffset.FromUnixTimeMilliseconds(s_now - (3 * Hour)), DateTimeOffset.FromUnixTimeMilliseconds(s_now - (2 * Hour)), "15s", null), s_now).Value;
        SourcePlan plan = Planner.Plan(old, s_now, hotReady: true);
        Assert.Equal(("10s", true, "30s"), (plan.Name, plan.Degraded, Steps.Format(plan.StepMs)));
        Assert.Equal(30 * Second, old.WithStep(plan.StepMs).StepMs);
        Assert.Equal(0, old.WithStep(plan.StepMs).FromMs % plan.StepMs);

        // 超出 10 s 层的保留期（48 小时），1 分钟步长改用 1 分钟层（不降级：1m 层能整除）
        QueryRange week = Resolver.Resolve(new RangeRequest(null, DateTimeOffset.FromUnixTimeMilliseconds(s_now - (3 * Day)), DateTimeOffset.FromUnixTimeMilliseconds(s_now - (3 * Day) + Hour), "10s", null), s_now).Value;
        SourcePlan expired = Planner.Plan(week, s_now, hotReady: true);
        Assert.True(expired.Degraded, "the 10 s layer only keeps 48 hours");
        Assert.Equal("1m", expired.Name);
        Assert.Equal(Minute, expired.StepMs);
    }

    [Fact]
    public void RangeResolver_AlignsBucketsAndMarksPartialEdges()
    {
        long from = s_now - (s_now % Minute) + (13 * Second);
        long to = from + (4 * Minute) + (7 * Second);
        QueryRange range = Resolver.Resolve(new RangeRequest(null, DateTimeOffset.FromUnixTimeMilliseconds(from), DateTimeOffset.FromUnixTimeMilliseconds(to), "1m", null), s_now).Value;

        Assert.Equal(0, range.FromMs % Minute);
        Assert.Equal(0, range.ToMs % Minute);
        Assert.Equal(5, range.Points);
        Assert.True(range.FirstPartial);
        Assert.True(range.LastPartial);
        Assert.False(range.IsRelative);

        QueryRange aligned = Resolver.Resolve(new RangeRequest(null, DateTimeOffset.FromUnixTimeMilliseconds(range.FromMs), DateTimeOffset.FromUnixTimeMilliseconds(range.ToMs), "1m", null), s_now).Value;
        Assert.False(aligned.FirstPartial);
        Assert.False(aligned.LastPartial);
    }

    [Theory]
    [InlineData("0m")]
    [InlineData("-5m")]
    [InlineData("5")]
    [InlineData("5x")]
    [InlineData("m")]
    [InlineData("99999999d")]
    [InlineData("1000d")]
    public void RangeResolver_RejectsMalformedAndAbsurdRanges(string range)
    {
        Result<QueryRange> result = Resolver.Resolve(new RangeRequest(range, null, null, null, null), s_now);
        Assert.False(result.IsSuccess);
        Assert.Contains(result.Error.Code, new[] { MonitorErrors.InvalidRange, MonitorErrors.RangeTooLarge });
    }

    [Fact]
    public void RangeResolver_EnforcesThePointLimit_AndSuggestsAStep()
    {
        Result<QueryRange> result = Resolver.Resolve(new RangeRequest("30d", null, null, "1m", null), s_now);
        Assert.Equal(MonitorErrors.RangeTooLarge, result.Error.Code);
        Assert.Contains("step=", result.Error.Message);
        Assert.Equal(MonitorErrors.InvalidStep, Resolver.Resolve(new RangeRequest("1h", null, null, "7s", null), s_now).Error.Code);
        Assert.Equal(MonitorErrors.InvalidRange, Resolver.Resolve(new RangeRequest(null, DateTimeOffset.FromUnixTimeMilliseconds(s_now), DateTimeOffset.FromUnixTimeMilliseconds(s_now), null, null), s_now).Error.Code);
        Assert.Equal(MonitorErrors.ValidationFailed, Resolver.Resolve(new RangeRequest("1h", DateTimeOffset.FromUnixTimeMilliseconds(s_now - Hour), null, null, null), s_now).Error.Code);
    }

    [Fact]
    public void OnlyUtcIsSupported_OtherTimeZonesAreRejectedInsteadOfSilentlyIgnored()
    {
        Assert.True(Resolver.Resolve(new RangeRequest("1h", null, null, null, "UTC"), s_now).IsSuccess);
        Assert.True(Resolver.Resolve(new RangeRequest("1h", null, null, null, null), s_now).IsSuccess);
        Result<QueryRange> shanghai = Resolver.Resolve(new RangeRequest("7d", null, null, "1d", "Asia/Shanghai"), s_now);
        Assert.Equal(MonitorErrors.ValidationFailed, shanghai.Error.Code);
        Assert.IsType<ValidationError>(shanghai.Error);
    }

    [Fact]
    public void RelativeRanges_AreLive_AbsoluteOnesAreNot()
    {
        Assert.True(Resolve("15m").IsRelative);
        QueryRange fromOnly = Resolver.Resolve(new RangeRequest(null, DateTimeOffset.FromUnixTimeMilliseconds(s_now - Hour), null, null, null), s_now).Value;
        Assert.True(fromOnly.IsRelative); // 没有 to：to = now，可以跟随实时数据
    }

    [Fact]
    public void Steps_ParseFormatAndSnap()
    {
        foreach (long step in Steps.Common)
        {
            Assert.True(Steps.TryParse(Steps.Format(step), out long parsed));
            Assert.Equal(step, parsed);
        }

        Assert.False(Steps.TryParse("3s", out _));
        Assert.Equal(30 * Second, Steps.Snap(15 * Second, 10 * Second));
        Assert.Equal(5 * Minute, Steps.Snap(Minute, 5 * Minute));
        Assert.Equal(-60_000, Steps.FloorTo(-1, Minute));
        Assert.Equal(0, Steps.CeilTo(0, Minute));
        Assert.Equal(Minute, Steps.CeilTo(1, Minute));
    }

    [Fact]
    public void BucketedRows_MergeExactly_AndDoNotMutateTheirSources()
    {
        QueryRange range = Resolve("5m", "1m");
        var first = new MetricSet();
        first.GetOrAdd("c", AccKind.Counter).Add(3);
        ((HistogramAcc)first.GetOrAdd("h", AccKind.Histogram)).Add(10);
        var second = new MetricSet();
        second.GetOrAdd("c", AccKind.Counter).Add(4);
        ((HistogramAcc)second.GetOrAdd("h", AccKind.Histogram)).Add(20);

        BucketedRows rows = BucketedRows.Create(
            [new SourceRow(range.FromMs, first, false), new SourceRow(range.FromMs + (10 * Second), second, false), new SourceRow(range.FromMs - Minute, first, false), new SourceRow(range.ToMs, first, false)], range);

        Assert.Equal(range.Points, rows.T.Length);
        Assert.Equal(2, rows.RowCounts[0]);
        Assert.Equal(7UL, ((CounterAcc)rows.Sets[0]!.Items["c"]).Value);
        Assert.Equal(2UL, ((HistogramAcc)rows.Sets[0]!.Items["h"]).Count);
        Assert.Equal(3UL, ((CounterAcc)first.Items["c"]).Value); // 源行没有被改动
        Assert.Equal(2, rows.TotalRows); // 区间之外的行被忽略
        Assert.Null(rows.Sets[1]);
    }

    [Fact]
    public void MetricSelection_ResolvesPresetsAndScores_AndRejectsUnknownIds()
    {
        MetricSelection selection = MetricSelection.Resolve("rtt.p95,score.mc", "udp,scores", 100).Value;
        Assert.Contains("loss.total", selection.ExportIds);
        Assert.Contains("mc", selection.ScoreModelIds);
        Assert.Equal(4, selection.ScoreModelIds.Count);
        Assert.Equal(selection.ExportIds.Count, selection.ExportIds.Distinct().Count());
        Assert.True(selection.WantsScores);

        Assert.Equal(MonitorErrors.UnknownMetric, MetricSelection.Resolve("nope", null, 100).Error.Code);
        Assert.Equal(MonitorErrors.UnknownMetric, MetricSelection.Resolve("score.nope", null, 100).Error.Code);
        Assert.Equal(MonitorErrors.UnknownPreset, MetricSelection.Resolve(null, "nope", 100).Error.Code);
        Assert.Equal(MonitorErrors.TooManyMetrics, MetricSelection.Resolve(null, "udp", 3).Error.Code);
    }

    [Fact]
    public void LoginRateLimiter_AllowsABurst_ThenBlocksUntilTheWindowSlides()
    {
        var time = new FakeTimeProvider(DateTimeOffset.UnixEpoch);
        var limiter = new LoginRateLimiter(new BackendOptions { LoginAttemptsPerMinute = 3 }, time);

        for (int i = 0; i < 3; i++)
        {
            Assert.True(limiter.TryAcquire("1.2.3.4", out _));
            time.Advance(TimeSpan.FromSeconds(10));
        }

        Assert.False(limiter.TryAcquire("1.2.3.4", out int retry)); // 已过 30 秒，最早的一次还要 30 秒才滑出窗口
        Assert.InRange(retry, 29, 31);
        Assert.True(limiter.TryAcquire("5.6.7.8", out _), "another source is independent");

        time.Advance(TimeSpan.FromSeconds(31));
        Assert.True(limiter.TryAcquire("1.2.3.4", out _));
        limiter.Prune();
        time.Advance(TimeSpan.FromMinutes(2));
        limiter.Prune();
        Assert.True(limiter.TryAcquire("1.2.3.4", out _));
    }
}