using System.Linq;
using AcDream.Core.Allegiance;
using Xunit;

namespace AcDream.Core.Tests.Allegiance;

public sealed class AllegianceTreeTests
{
    [Fact]
    public void SetMonarch_RegistersNode_FiresEvent()
    {
        var tree = new AllegianceTree();
        int changes = 0;
        tree.TreeChanged += () => changes++;

        tree.SetMonarch(0xAA, "Bael'Zharon");
        Assert.Equal(1, changes);
        Assert.Equal(0xAAu, tree.MonarchGuid);
        Assert.Equal(1, tree.NodeCount);
    }

    [Fact]
    public void UpsertNode_NewPatron_AddsToVassalList()
    {
        var tree = new AllegianceTree();
        tree.SetMonarch(0xAA, "Monarch");
        tree.UpsertNode(0xBB, "Vassal", patronGuid: 0xAA, rank: 1);

        var monarch = tree.Get(0xAA);
        Assert.NotNull(monarch);
        Assert.Contains(0xBBu, monarch!.VassalGuids);
    }

    [Fact]
    public void UpsertNode_RankClamp_CapsAt10()
    {
        var tree = new AllegianceTree();
        tree.SetMonarch(0xAA, "M");
        var node = tree.UpsertNode(0xBB, "V", 0xAA, rank: 50);
        Assert.Equal(10, node.Rank);
    }

    [Fact]
    public void RemoveNode_RemovesFromParentVassalList()
    {
        var tree = new AllegianceTree();
        tree.SetMonarch(0xAA, "M");
        tree.UpsertNode(0xBB, "V", 0xAA, 1);
        Assert.Single(tree.Get(0xAA)!.VassalGuids);

        tree.RemoveNode(0xBB);
        Assert.Empty(tree.Get(0xAA)!.VassalGuids);
    }

    [Fact]
    public void GetAncestors_WalksToMonarch()
    {
        var tree = new AllegianceTree();
        tree.SetMonarch(0xAA, "M");
        tree.UpsertNode(0xBB, "V", 0xAA, 1);
        tree.UpsertNode(0xCC, "VV", 0xBB, 2);
        tree.UpsertNode(0xDD, "VVV", 0xCC, 3);

        var chain = tree.GetAncestors(0xDD).Select(n => n.Name).ToArray();
        Assert.Equal(new[] { "VVV", "VV", "V", "M" }, chain);
    }

    [Fact]
    public void GetAncestors_HandlesCycleWithoutLooping()
    {
        // Corrupt data: defensive path. Treat a cycle as a stop.
        var tree = new AllegianceTree();
        tree.UpsertNode(0xAA, "A", patronGuid: 0xBB, rank: 1);
        tree.UpsertNode(0xBB, "B", patronGuid: 0xAA, rank: 1);   // cycle

        var walk = tree.GetAncestors(0xAA).Select(n => n.Guid).ToArray();
        Assert.Equal(2, walk.Length);   // visits each exactly once
    }

    [Fact]
    public void GetDescendants_BfsOrder()
    {
        var tree = new AllegianceTree();
        tree.SetMonarch(0xAA, "M");
        tree.UpsertNode(0xB0, "B0", 0xAA, 1);
        tree.UpsertNode(0xB1, "B1", 0xAA, 1);
        tree.UpsertNode(0xC0, "C0", 0xB0, 2);

        var bfs = tree.GetDescendants(0xAA).Select(n => n.Name).ToArray();
        Assert.Equal(new[] { "M", "B0", "B1", "C0" }, bfs);
    }

    [Fact]
    public void AllegianceMath_Passup_KnownCase()
    {
        // 1000 XP, loyalty 10, 100 real-time days, 100 in-game days.
        // loyaltyScale = (50 + 225) / 291 = 0.9450
        // ageScale     = 1 + (100/730)*(100/720) = 1 + 0.0190 = 1.0190
        // passup       = 1000 * 0.9450 * 1.0190 ≈ 963
        long passup = AllegianceMath.ComputePassup(1000, 10, 100, 100);
        Assert.InRange(passup, 960, 965);
    }

    [Fact]
    public void AllegianceMath_Passup_ZeroClamp()
    {
        // Negative XP shouldn't be possible; passup is clamped at 0.
        Assert.Equal(0, AllegianceMath.ComputePassup(-1000, 10, 0, 0));
    }
}