using AcDream.App.UI;
using AcDream.App.UI.Layout;
namespace AcDream.App.Tests.UI.Layout;

public class ElementReaderTests
{
    // ── ToAnchors ────────────────────────────────────────────────────────────

    /// <summary>
    /// Edge value 4 = stretch (pinned to BOTH near AND far sides simultaneously).
    /// LeftEdge=4 → Left anchor; RightEdge=4 → Right anchor.
    /// TopEdge=1 → Top only (near-pin); BottomEdge=1 → near-pin (left/top axis), NOT Bottom.
    /// </summary>
    [Fact]
    public void EdgeFlagsToAnchors_LeftRight_Stretches()
    {
        // left=4 (stretch ⇒ Left), top=1 (near-pin ⇒ Top), right=4 (stretch ⇒ Right), bottom=1 (near-pin of bottom axis ⇒ not Bottom)
        var a = ElementReader.ToAnchors(left: 4, top: 1, right: 4, bottom: 1);
        Assert.True(a.HasFlag(AnchorEdges.Left));
        Assert.True(a.HasFlag(AnchorEdges.Right));
        Assert.False(a.HasFlag(AnchorEdges.Bottom));
    }

    /// <summary>
    /// Edge value 1 = pinned to the NEAR edge of that axis.
    /// For LeftEdge: near = Left. For TopEdge: near = Top.
    /// For RightEdge: value 1 means near-pin of the right axis → does NOT map to Right anchor.
    /// For BottomEdge: value 1 means near-pin of the bottom axis → does NOT map to Bottom anchor.
    /// </summary>
    [Fact]
    public void EdgeFlagsToAnchors_AllOnes_PinsTopLeftOnly()
    {
        // 1 everywhere: only Left and Top anchors set (near-pins). Right/Bottom are far edges and value 1 is near-pin.
        var a = ElementReader.ToAnchors(left: 1, top: 1, right: 1, bottom: 1);
        Assert.True(a.HasFlag(AnchorEdges.Left));
        Assert.True(a.HasFlag(AnchorEdges.Top));
        Assert.False(a.HasFlag(AnchorEdges.Right));
        Assert.False(a.HasFlag(AnchorEdges.Bottom));
    }

    /// <summary>
    /// Edge value 2 = pinned to the FAR edge of that axis.
    /// For RightEdge: far = Right anchor. For BottomEdge: far = Bottom anchor.
    /// For LeftEdge: value 2 means far-pin of the left axis → does NOT map to Left anchor.
    /// For TopEdge: value 2 means far-pin of the top axis → does NOT map to Top anchor.
    /// </summary>
    [Fact]
    public void EdgeFlagsToAnchors_AllTwos_PinsRightBottomOnly()
    {
        // 2 everywhere: only Right and Bottom anchors set (far-pins).
        var a = ElementReader.ToAnchors(left: 2, top: 2, right: 2, bottom: 2);
        Assert.False(a.HasFlag(AnchorEdges.Left));
        Assert.False(a.HasFlag(AnchorEdges.Top));
        Assert.True(a.HasFlag(AnchorEdges.Right));
        Assert.True(a.HasFlag(AnchorEdges.Bottom));
    }

    /// <summary>
    /// All-zero edge flags (prototype-only elements) fall back to Left|Top default.
    /// </summary>
    [Fact]
    public void EdgeFlagsToAnchors_AllZero_DefaultsToTopLeft()
    {
        var a = ElementReader.ToAnchors(left: 0, top: 0, right: 0, bottom: 0);
        Assert.Equal(AnchorEdges.Left | AnchorEdges.Top, a);
    }

    /// <summary>
    /// Value 3 = floating/centered between both far edges on that axis (format doc §4).
    /// The anchor mapping fires on near-pin (1) and stretch (4) for Left/Top, and on
    /// far-pin (2) and stretch (4) for Right/Bottom — value 3 matches none of these rules.
    /// Therefore all-3 edge flags contribute no anchor bits and fall through to the
    /// Left|Top default (pin top-left, fixed size).
    /// This test covers that corner case (element 0x100004A9 — expand-detail overlay).
    /// </summary>
    [Fact]
    public void EdgeFlagsToAnchors_ValueThree_FallsBackToTopLeft()
    {
        // value 3 doesn't match any anchor rule; falls back to Left|Top default.
        var a = ElementReader.ToAnchors(left: 3, top: 3, right: 3, bottom: 3);
        Assert.Equal(AnchorEdges.Left | AnchorEdges.Top, a);
    }

    // ── Merge ────────────────────────────────────────────────────────────────

    [Fact]
    public void Merge_BaseThenOverride_DerivedWins()
    {
        var base_ = new ElementInfo { Type = 0, FontDid = 0x40000000, Width = 150, Height = 16 };
        var derived = new ElementInfo { Type = 0, Width = 200 }; // overrides width, inherits font + height
        var merged = ElementReader.Merge(base_, derived);
        Assert.Equal(200, merged.Width);          // override
        Assert.Equal(16, merged.Height);          // inherited
        Assert.Equal(0x40000000u, merged.FontDid);// inherited
    }

    [Fact]
    public void Merge_DerivedHasFontDid_OverridesBase()
    {
        var base_ = new ElementInfo { FontDid = 0x40000000, Width = 100, Height = 10 };
        var derived = new ElementInfo { FontDid = 0x40000001, Width = 100 };
        var merged = ElementReader.Merge(base_, derived);
        Assert.Equal(0x40000001u, merged.FontDid);
    }

    [Fact]
    public void Merge_DerivedStateMediaOverridesBase()
    {
        var base_ = new ElementInfo();
        base_.StateMedia[""] = (0x06001000u, 1);
        base_.StateMedia["HideDetail"] = (0x06001001u, 1);

        var derived = new ElementInfo();
        derived.StateMedia[""] = (0x06002000u, 3); // overrides base default state

        var merged = ElementReader.Merge(base_, derived);
        // derived's "" overrides base's ""
        Assert.Equal((0x06002000u, 3), merged.StateMedia[""]);
        // base's "HideDetail" is kept (derived didn't provide it)
        Assert.Equal((0x06001001u, 1), merged.StateMedia["HideDetail"]);
    }

    [Fact]
    public void Merge_ChildrenComeFromDerived()
    {
        var base_ = new ElementInfo();
        base_.Children.Add(new ElementInfo { Id = 0x1u });

        var derived = new ElementInfo();
        derived.Children.Add(new ElementInfo { Id = 0x2u });

        var merged = ElementReader.Merge(base_, derived);
        // children must come from derived only
        Assert.Single(merged.Children);
        Assert.Equal(0x2u, merged.Children[0].Id);
    }
}