using System;
using System.Collections.Generic;
using System.Linq;
using System.Numerics;
using AcDream.App.UI;
using AcDream.App.UI.Layout;
using Xunit;

namespace AcDream.App.Tests.UI.Layout;

/// <summary>
/// Unit tests for <see cref="SelectedObjectController"/> — the
/// <c>gmToolbarUI::HandleSelectionChanged</c> + <c>RecvNotice_UpdateObjectHealth</c>
/// analogue (<c>acclient_2013_pseudo_c.txt:198635</c> / <c>:196213</c>).
///
/// <para>
/// Key behavior under test: the Health meter is <b>UpdateHealth-driven</b> — it becomes
/// visible only when real health is known for the selected guid (a <c>HealthChanged</c>
/// fires for it, or it is already cached at select time via <c>hasHealth</c>). Selecting a
/// target does NOT show the meter on its own. This matches retail: a friendly NPC you have
/// not assessed shows name-only; a monster's bar appears after damage / assess.
/// </para>
/// </summary>
public class SelectedObjectControllerTests
{
    // ── Shared layout ────────────────────────────────────────────────────────

    private static (
        ImportedLayout layout,
        UiPanel nameEl,
        UiDatElement overlayEl,
        UiMeter healthMeterEl)
    FakeLayout()
    {
        var dict = new Dictionary<uint, UiElement>();
        var root = new UiPanel();

        var nameEl = new UiPanel { Width = 100, Height = 20 };
        dict[SelectedObjectController.NameId] = nameEl;
        root.AddChild(nameEl);

        var overlayInfo = new ElementInfo
        {
            Id   = SelectedObjectController.OverlayId,
            Type = 3,
            StateMedia =
            {
                [""]                    = (0x06000001u, 3),
                ["ObjectSelected"]      = (0x06001937u, 3),
                ["StackedItemSelected"] = (0x06004CF4u, 3),
            },
        };
        var overlayEl = new UiDatElement(overlayInfo, _ => (0u, 0, 0));
        dict[SelectedObjectController.OverlayId] = overlayEl;
        root.AddChild(overlayEl);

        var healthMeterEl = new UiMeter { Width = 100, Height = 10, Visible = true };
        dict[SelectedObjectController.HealthMeterId] = healthMeterEl;
        root.AddChild(healthMeterEl);

        return (new ImportedLayout(root, dict), nameEl, overlayEl, healthMeterEl);
    }

    // ── Recording delegates ──────────────────────────────────────────────────

    private sealed class Harness
    {
        public Action<uint?>? SelectionHandler;
        public Action<uint, float>? HealthHandler;
        public readonly List<uint> QueryHealthCalls = new();

        public readonly Dictionary<uint, bool>   HealthTargetMap = new();
        public readonly Dictionary<uint, string> NameMap         = new();
        public readonly Dictionary<uint, float>  HealthMap       = new();
        public readonly Dictionary<uint, bool>   HasHealthMap    = new();
        public readonly Dictionary<uint, uint>   StackMap        = new();

        public void FireSelection(uint? g) => SelectionHandler?.Invoke(g);
        public void FireHealth(uint g, float pct) => HealthHandler?.Invoke(g, pct);

        public SelectedObjectController Bind(ImportedLayout layout, UiDatFont? datFont = null)
            => SelectedObjectController.Bind(
                layout,
                subscribeSelectionChanged: h => SelectionHandler = h,
                subscribeHealthChanged:    h => HealthHandler = h,
                isHealthTarget:  g => HealthTargetMap.TryGetValue(g, out var v) && v,
                name:            g => NameMap.TryGetValue(g, out var v) ? v : null,
                healthPercent:   g => HealthMap.TryGetValue(g, out var v) ? v : 1f,
                hasHealth:       g => HasHealthMap.TryGetValue(g, out var v) && v,
                stackSize:       g => StackMap.TryGetValue(g, out var v) ? v : 0u,
                sendQueryHealth: g => QueryHealthCalls.Add(g),
                datFont:         datFont);
    }

    // ── B1: Bind initialisation ──────────────────────────────────────────────

    [Fact]
    public void Bind_healthMeterHidden_nameTextChildAttached_nameFloatedOnTop()
    {
        var (layout, nameEl, _, healthMeterEl) = FakeLayout();
        new Harness().Bind(layout);

        Assert.False(healthMeterEl.Visible, "health meter must be Visible=false immediately after Bind");

        var textChild = nameEl.Children.OfType<UiText>().SingleOrDefault();
        Assert.NotNull(textChild);
        Assert.True(textChild!.Centered,            "name UiText must be Centered");
        Assert.True(textChild.ClickThrough,         "name UiText must be ClickThrough");
        Assert.False(textChild.AcceptsFocus,        "AcceptsFocus must be false on name label");
        Assert.False(textChild.IsEditControl,       "IsEditControl must be false on name label");
        Assert.False(textChild.CapturesPointerDrag, "CapturesPointerDrag must be false on name label");

        // The name element must be floated to the top of the strip's z-order so it draws
        // OVER the overlay frame and the health bar (retail draws the name over the bar).
        Assert.True(nameEl.ZOrder > 1000, "name element must be floated above the overlay/meter z-order");
    }

    [Fact]
    public void Bind_nameLinesProvider_yieldsEmpty_whenNothingSelected()
    {
        var (layout, nameEl, _, _) = FakeLayout();
        new Harness().Bind(layout);

        var textChild = nameEl.Children.OfType<UiText>().Single();
        Assert.Empty(textChild.LinesProvider());
    }

    // ── H1: Select a health target — meter does NOT show on select alone ─────

    [Fact]
    public void SelectHealthTarget_unknownHealth_meterStaysHidden_queryFired_nameAndOverlaySet()
    {
        const uint Guid = 0xAA01u;
        const string ExpectedName = "Drudge Prowler";

        var (layout, nameEl, overlayEl, healthMeterEl) = FakeLayout();
        var h = new Harness();
        h.HealthTargetMap[Guid] = true;
        h.NameMap[Guid] = ExpectedName;
        h.StackMap[Guid] = 1u;            // ObjectSelected
        // HasHealthMap[Guid] not set → false (no health known yet)
        h.Bind(layout);

        h.FireSelection(Guid);

        // Health not yet known → meter must stay hidden (retail: shows on UpdateHealth).
        Assert.False(healthMeterEl.Visible,
            "meter must stay hidden on select when no health is known yet");
        // But QueryHealth is sent (retail Event_QueryHealth on select for a health target).
        Assert.Single(h.QueryHealthCalls);
        Assert.Equal(Guid, h.QueryHealthCalls[0]);
        Assert.Equal("ObjectSelected", overlayEl.ActiveState);

        var lines = nameEl.Children.OfType<UiText>().Single().LinesProvider();
        Assert.Single(lines);
        Assert.Equal(ExpectedName, lines[0].Text);
        Assert.Equal(new Vector4(1f, 1f, 1f, 1f), lines[0].Color);
    }

    // ── H1b: Health arrives for the selected guid → meter appears ───────────

    [Fact]
    public void HealthChanged_forSelectedGuid_showsMeter()
    {
        const uint Guid = 0xAA02u;

        var (layout, _, _, healthMeterEl) = FakeLayout();
        var h = new Harness();
        h.HealthTargetMap[Guid] = true;
        h.NameMap[Guid] = "Drudge Slinker";
        h.Bind(layout);

        h.FireSelection(Guid);
        Assert.False(healthMeterEl.Visible, "hidden until health arrives");

        // Simulate UpdateHealth (0x01C0) for the selected guid.
        h.FireHealth(Guid, 0.6f);
        Assert.True(healthMeterEl.Visible, "meter must appear when health arrives for the selected guid");
    }

    [Fact]
    public void HealthChanged_forOtherGuid_doesNotShowMeter()
    {
        const uint Sel = 0xAA03u, Other = 0xBB03u;

        var (layout, _, _, healthMeterEl) = FakeLayout();
        var h = new Harness();
        h.HealthTargetMap[Sel] = true;
        h.HealthTargetMap[Other] = true;
        h.NameMap[Sel] = "Selected";
        h.Bind(layout);

        h.FireSelection(Sel);
        h.FireHealth(Other, 0.5f);   // health for a DIFFERENT entity

        Assert.False(healthMeterEl.Visible, "health for a non-selected guid must not show the meter");
    }

    // ── H1c: Already-known health → meter shows immediately on select ───────

    [Fact]
    public void SelectHealthTarget_alreadyKnownHealth_meterVisibleImmediately()
    {
        const uint Guid = 0xAA04u;

        var (layout, _, _, healthMeterEl) = FakeLayout();
        var h = new Harness();
        h.HealthTargetMap[Guid] = true;
        h.HasHealthMap[Guid] = true;     // health already cached (e.g. previously assessed)
        h.HealthMap[Guid] = 0.9f;
        h.NameMap[Guid] = "Olthoi";
        h.Bind(layout);

        h.FireSelection(Guid);
        Assert.True(healthMeterEl.Visible,
            "meter must show immediately when health is already known for the target");
    }

    // ── H2: Stacked item ─────────────────────────────────────────────────────

    [Fact]
    public void SelectStackedItem_overlayStackedItemSelected_meterHidden()
    {
        const uint Guid = 0xBB02u;

        var (layout, _, overlayEl, healthMeterEl) = FakeLayout();
        var h = new Harness();
        h.HealthTargetMap[Guid] = false;
        h.NameMap[Guid] = "Heal Kits";
        h.StackMap[Guid] = 5u;            // stackSize > 1
        h.Bind(layout);

        h.FireSelection(Guid);

        Assert.Equal("StackedItemSelected", overlayEl.ActiveState);
        Assert.False(healthMeterEl.Visible);
    }

    // ── H3: Non-health target (friendly NPC / scenery / Door) ───────────────

    [Fact]
    public void SelectNonHealthTarget_meterHidden_noQuery_nameSet()
    {
        const uint Guid = 0xCC03u;
        const string ExpectedName = "Town Crier";

        var (layout, nameEl, overlayEl, healthMeterEl) = FakeLayout();
        var h = new Harness();
        h.HealthTargetMap[Guid] = false;
        h.NameMap[Guid] = ExpectedName;
        h.Bind(layout);

        h.FireSelection(Guid);

        Assert.False(healthMeterEl.Visible, "meter must stay hidden for a non-health target");
        Assert.Empty(h.QueryHealthCalls);
        Assert.Equal("ObjectSelected", overlayEl.ActiveState);

        var lines = nameEl.Children.OfType<UiText>().Single().LinesProvider();
        Assert.Single(lines);
        Assert.Equal(ExpectedName, lines[0].Text);
    }

    // ── H4: Deselect clears the strip ────────────────────────────────────────

    [Fact]
    public void SelectNull_clearsStrip()
    {
        const uint Guid = 0xDD04u;

        var (layout, nameEl, overlayEl, healthMeterEl) = FakeLayout();
        var h = new Harness();
        h.HealthTargetMap[Guid] = true;
        h.HasHealthMap[Guid] = true;        // so the meter is shown on select
        h.HealthMap[Guid] = 0.5f;
        h.NameMap[Guid] = "Wolf";
        h.Bind(layout);

        h.FireSelection(Guid);
        Assert.True(healthMeterEl.Visible);

        h.FireSelection(null);

        Assert.False(healthMeterEl.Visible, "meter must be hidden after deselect");
        Assert.Equal("", overlayEl.ActiveState);
        Assert.Empty(nameEl.Children.OfType<UiText>().Single().LinesProvider());
    }

    // ── H5: Re-select a different guid ───────────────────────────────────────

    [Fact]
    public void ReSelect_differentGuid_clearsFirstThenAppliesSecond()
    {
        const uint GuidA = 0xEE05u, GuidB = 0xFF06u;

        var (layout, nameEl, overlayEl, healthMeterEl) = FakeLayout();
        var h = new Harness();
        h.HealthTargetMap[GuidA] = true;  h.HealthTargetMap[GuidB] = false;
        h.HasHealthMap[GuidA] = true;     // A shows its bar on select
        h.NameMap[GuidA] = "Bandit";      h.NameMap[GuidB] = "Chest";
        h.HealthMap[GuidA] = 1.0f;
        h.Bind(layout);

        h.FireSelection(GuidA);
        Assert.True(healthMeterEl.Visible);
        Assert.Single(h.QueryHealthCalls);

        h.FireSelection(GuidB);

        Assert.False(healthMeterEl.Visible, "meter must clear when switching to a non-health target");
        Assert.Equal("ObjectSelected", overlayEl.ActiveState);
        Assert.Single(h.QueryHealthCalls);   // B is not a health target → no extra query

        var lines = nameEl.Children.OfType<UiText>().Single().LinesProvider();
        Assert.Single(lines);
        Assert.Equal("Chest", lines[0].Text);
    }

    // ── H6: Overlay flash reverts after the flash window (Tick) ─────────────

    [Fact]
    public void Tick_revertsOverlayFlash_afterDuration()
    {
        const uint Guid = 0xAB06u;

        var (layout, _, overlayEl, _) = FakeLayout();
        var h = new Harness();
        h.HealthTargetMap[Guid] = false;
        h.NameMap[Guid] = "Lever";
        var c = h.Bind(layout);

        h.FireSelection(Guid);
        Assert.Equal("ObjectSelected", overlayEl.ActiveState);

        // A small tick before the window elapses → still flashing.
        c.Tick(0.1);
        Assert.Equal("ObjectSelected", overlayEl.ActiveState);

        // Tick past the 0.25s window → overlay reverts to blank.
        c.Tick(0.2);
        Assert.Equal("", overlayEl.ActiveState);
    }

    // ── H7: Partial layout (missing elements) ────────────────────────────────

    [Fact]
    public void PartialLayout_noElements_doesNotThrow()
    {
        var root = new UiPanel();
        var layout = new ImportedLayout(root, new Dictionary<uint, UiElement>());

        var h = new Harness();
        h.HealthTargetMap[0x12345678u] = true;
        h.NameMap[0x12345678u] = "Something";
        var c = h.Bind(layout);

        Assert.NotNull(h.SelectionHandler);
        Assert.Null(Record.Exception(() => h.FireSelection(0x12345678u)));
        Assert.Null(Record.Exception(() => h.FireHealth(0x12345678u, 0.5f)));
        Assert.Null(Record.Exception(() => c.Tick(0.5)));
        Assert.Null(Record.Exception(() => h.FireSelection(null)));

        Assert.Single(h.QueryHealthCalls);
        Assert.Equal(0x12345678u, h.QueryHealthCalls[0]);
    }

    // ── H8: Fill reflects live health; returns 0 when nothing selected ──────

    [Fact]
    public void HealthMeterFill_reflectsLiveHealthPercent()
    {
        const uint Guid = 0xAA07u;

        var (layout, _, _, healthMeterEl) = FakeLayout();
        var h = new Harness();
        h.HealthTargetMap[Guid] = true;
        h.NameMap[Guid] = "Arwic Banderling";
        h.HealthMap[Guid] = 0.5f;
        h.Bind(layout);

        h.FireSelection(Guid);
        Assert.Equal(0.5f, healthMeterEl.Fill());

        h.HealthMap[Guid] = 0.25f;        // server updates health
        Assert.Equal(0.25f, healthMeterEl.Fill());
    }

    [Fact]
    public void HealthMeterFill_returnsZero_whenNothingSelected()
    {
        const uint Guid = 0xAA08u;

        var (layout, _, _, healthMeterEl) = FakeLayout();
        var h = new Harness();
        h.HealthTargetMap[Guid] = true;
        h.NameMap[Guid] = "Spider";
        h.HealthMap[Guid] = 0.8f;
        h.Bind(layout);

        h.FireSelection(Guid);
        Assert.Equal(0.8f, healthMeterEl.Fill());

        h.FireSelection(null);
        Assert.Equal(0f, healthMeterEl.Fill() ?? 0f);
    }
}