using AcDream.App.UI.Layout;

namespace AcDream.App.Tests.UI.Layout;

/// <summary>
/// Pure logic tests for <see cref="OptionPage"/>/<see cref="BoolOptionRow"/> —
/// no DAT, no widgets, no runtime. Exercises a SYNTHETIC empty
/// <c>PlayerOptionPage</c>-shaped page (zero registered rows — a shape
/// Character/Chat/Config's pages briefly hold before OP4-6 register rows into
/// them) to pin the generic model-level "empty page" property, and a
/// synthetic 2-option page to prove Apply/Reset/Defaults' per-row semantics
/// before OP4-6 wire real DAT-backed rows into the same model.
///
/// <para>
/// NEITHER shape models the Gameplay tab. <c>gmGameplayOptionsUI</c>
/// (<c>acclient.h:55857</c>) derives from <c>UIElement_Field</c>, not
/// <c>OptionPage</c>/<c>PlayerOptionPage</c> at all — research doc
/// <c>2026-08-10-options-panel-structure.md</c> §6, mechanism review S1
/// (2026-08-11 fix round). <see cref="OptionsPanelControllerTests"/> pins
/// the Gameplay-specific consequence (its <see cref="OptionPage"/> instance
/// is constructed with <see cref="OptionPage.AfterApply"/> deliberately left
/// null, so it never flushes).
/// </para>
/// </summary>
public sealed class OptionPageModelTests
{
    // ── Empty page (a generic zero-row PlayerOptionPage-shaped page — NOT
    //    modeling Gameplay, which is not an OptionPage at all) ─────────────

    [Fact]
    public void EmptyPage_ChangedIsAlwaysFalse()
    {
        var page = new OptionPage();
        Assert.False(page.Changed);
    }

    [Fact]
    public void EmptyPage_ApplyResetDefaults_AreNoOps()
    {
        var page = new OptionPage();

        page.Apply();
        page.Reset();
        page.Defaults();

        Assert.Empty(page.Rows);
        Assert.False(page.Changed);
    }

    [Fact]
    public void EmptyPage_OnShownAndOnHidden_DoNotThrow()
    {
        var page = new OptionPage();

        page.OnShown();
        page.OnHidden();
    }

    [Fact]
    public void EmptyPlayerOptionPageShapedPage_WithAfterApplyWired_Apply_StillFlushes()
    {
        // Retail's PlayerOptionPage::SaveCurrentValues flushes the batched
        // module regardless of whether THIS page's own rows changed
        // anything — the module's dirty flag is global, not per-page. This
        // is a property of a page that IS AfterApply-wired (Character/Chat/
        // Config, briefly, before OP4-6 register their rows) — NOT of the
        // Gameplay tab, whose own OptionPage instance is constructed with
        // AfterApply left null (see OptionsPanelControllerTests).
        var page = new OptionPage();
        int flushCount = 0;
        page.AfterApply = () => flushCount++;

        page.Apply();

        Assert.Equal(1, flushCount);
    }

    [Fact]
    public void EmptyPlayerOptionPageShapedPage_WithAfterApplyWired_OnShown_StillFlushes()
    {
        var page = new OptionPage();
        int flushCount = 0;
        page.AfterApply = () => flushCount++;

        page.OnShown();

        Assert.Equal(1, flushCount);
    }

    [Fact]
    public void EmptyPage_WithNoAfterApplyWired_Apply_NeverFlushes()
    {
        // The Gameplay tab's own shape: AfterApply is null by construction
        // (OptionsPanelController), so Apply (fired by the initial default-
        // tab activation and every later tab entry) never publishes a flush.
        var page = new OptionPage { AfterApply = null };

        Exception? thrown = Record.Exception(page.Apply);

        Assert.Null(thrown);
    }

    [Fact]
    public void EmptyPage_ResetAndDefaults_DoNotInvokeAfterApply()
    {
        var page = new OptionPage();
        int flushCount = 0;
        page.AfterApply = () => flushCount++;

        page.Reset();
        page.Defaults();

        Assert.Equal(0, flushCount);
    }

    // ── BoolOptionRow leaf semantics (UIOption_Checkbox port) ───────────────

    [Fact]
    public void BoolOptionRow_SetCurrentValue_AppliesLiveImmediately_WithoutCommitting()
    {
        var applied = new List<bool>();
        var row = new BoolOptionRow(initial: false, defaultValue: false, apply: v => applied.Add(v));

        row.SetCurrentValue(true);

        Assert.True(row.Current);
        Assert.False(row.Saved); // NOT committed — SetCurrentValue never touches Saved.
        Assert.True(row.Changed);
        Assert.Equal([true], applied);
    }

    [Fact]
    public void BoolOptionRow_SaveCurrentValue_CommitsBaseline()
    {
        var row = new BoolOptionRow(initial: false, defaultValue: false);
        row.SetCurrentValue(true);

        row.SaveCurrentValue();

        Assert.True(row.Saved);
        Assert.False(row.Changed);
    }

    [Fact]
    public void BoolOptionRow_RestoreSavedValue_RevertsAndReapplies()
    {
        var applied = new List<bool>();
        var row = new BoolOptionRow(initial: false, defaultValue: false, apply: v => applied.Add(v));
        row.SetCurrentValue(true);
        applied.Clear();

        row.RestoreSavedValue();

        Assert.False(row.Current);
        Assert.False(row.Changed);
        Assert.Equal([false], applied);
    }

    [Fact]
    public void BoolOptionRow_RestoreDefaultValue_AppliesLiveWithoutCommitting()
    {
        var applied = new List<bool>();
        var row = new BoolOptionRow(initial: false, defaultValue: true, apply: v => applied.Add(v));

        row.RestoreDefaultValue();

        Assert.True(row.Current);
        Assert.False(row.Saved); // uncommitted — Changed re-arms Apply/Reset.
        Assert.True(row.Changed);
        Assert.Equal([true], applied);
    }

    // ── Synthetic 2-option page ──────────────────────────────────────────────

    private static (OptionPage Page, BoolOptionRow A, BoolOptionRow B) MakeTwoOptionPage()
    {
        var page = new OptionPage();
        var a = new BoolOptionRow(initial: true, defaultValue: true);
        var b = new BoolOptionRow(initial: false, defaultValue: true);
        page.Register(a);
        page.Register(b);
        return (page, a, b);
    }

    [Fact]
    public void TwoOptionPage_Changed_TrueWhenAnyRowChanged()
    {
        var (page, a, _) = MakeTwoOptionPage();
        Assert.False(page.Changed);

        a.SetCurrentValue(false);

        Assert.True(page.Changed);
    }

    [Fact]
    public void TwoOptionPage_Apply_CommitsEveryRowUnconditionally()
    {
        var (page, a, b) = MakeTwoOptionPage();
        a.SetCurrentValue(false); // a changed
        // b left at its initial (unchanged) value.

        page.Apply();

        Assert.False(page.Changed);
        Assert.True(a.Saved == a.Current);
        Assert.True(b.Saved == b.Current);
    }

    [Fact]
    public void TwoOptionPage_Reset_RevertsOnlyChangedRows()
    {
        var (page, a, b) = MakeTwoOptionPage();
        a.SetCurrentValue(false); // a: true -> false, changed
        // b stays at its initial false (unchanged, Saved == Current == false).

        page.Reset();

        Assert.True(a.Current); // reverted to its original saved baseline
        Assert.False(b.Current); // untouched — was never Changed
        Assert.False(page.Changed);
    }

    [Fact]
    public void TwoOptionPage_Defaults_RestoresEveryRow_WithoutCommitting()
    {
        var (page, a, b) = MakeTwoOptionPage();
        a.SetCurrentValue(false);
        page.Apply(); // commit a's change so Changed starts false

        page.Defaults();

        Assert.True(a.Current); // default is true
        Assert.True(b.Current); // default is true (was false)
        // Defaults never commits — b's baseline (Saved) is still its old
        // committed value (false), so Changed re-arms Apply/Reset.
        Assert.True(page.Changed);
    }

    [Fact]
    public void TwoOptionPage_OnHidden_RevertsUncommittedEdits()
    {
        var (page, a, _) = MakeTwoOptionPage();
        a.SetCurrentValue(false);

        page.OnHidden();

        Assert.True(a.Current);
        Assert.False(page.Changed);
    }

    [Fact]
    public void TwoOptionPage_OnShown_AppliesAndCommits()
    {
        var (page, a, _) = MakeTwoOptionPage();
        a.SetCurrentValue(false);

        page.OnShown();

        Assert.False(page.Changed);
        Assert.False(a.Saved != a.Current);
    }

    // ── OnOptionChanged seam (mechanism review S2, 2026-08-11 fix round) ────
    // PlayerOptionPage::OnOptionChanged @0x004F27D0: the sole Apply/Reset
    // enable-gate, run as the LAST statement of all three verbs
    // (0x004F2C95/0x004F2CE5/0x004F2D4A) plus once per live LED click via
    // UIOption::HandleDialogAndNotices @0x004EFB90.

    [Fact]
    public void OnOptionChanged_FiresAsLastStepOf_Apply()
    {
        var (page, a, _) = MakeTwoOptionPage();
        a.SetCurrentValue(false);
        var order = new List<string>();
        page.AfterApply = () => order.Add("afterApply");
        page.OnOptionChanged = () => order.Add("onOptionChanged");

        page.Apply();

        Assert.Equal(["afterApply", "onOptionChanged"], order);
    }

    [Fact]
    public void OnOptionChanged_FiresOnReset_EvenWithNoAfterApply()
    {
        var (page, a, _) = MakeTwoOptionPage();
        a.SetCurrentValue(false);
        int notifyCount = 0;
        page.OnOptionChanged = () => notifyCount++;

        page.Reset();

        Assert.Equal(1, notifyCount);
    }

    [Fact]
    public void OnOptionChanged_FiresOnDefaults()
    {
        var (page, _, _) = MakeTwoOptionPage();
        int notifyCount = 0;
        page.OnOptionChanged = () => notifyCount++;

        page.Defaults();

        Assert.Equal(1, notifyCount);
    }

    [Fact]
    public void OnOptionChanged_FiresOnEmptyPage_ForEveryVerb()
    {
        // Defaults is NEVER gated by retail's own OnOptionChanged override
        // (it never fetches the Defaults child id at all), but the page-
        // level notify still fires from EVERY verb regardless of row count
        // — the model doesn't special-case "which button retail happens to
        // gate" here, only the seam itself.
        var page = new OptionPage();
        int notifyCount = 0;
        page.OnOptionChanged = () => notifyCount++;

        page.Apply();
        page.Reset();
        page.Defaults();

        Assert.Equal(3, notifyCount);
    }

    [Fact]
    public void BoolOptionRow_SetCurrentValue_NotifiesAttachedPage()
    {
        // Retail's Apply(1)-only HandleDialogAndNotices path: a live LED
        // click reaches the page's OnOptionChanged directly, distinct from
        // (and in addition to) the per-row apply callback.
        var row = new BoolOptionRow(initial: false, defaultValue: false);
        int notifyCount = 0;
        row.AttachPageNotify(() => notifyCount++);

        row.SetCurrentValue(true);

        Assert.Equal(1, notifyCount);
    }

    [Fact]
    public void BoolOptionRow_RestoreSavedValueAndRestoreDefaultValue_DoNotNotifyAttachedPage()
    {
        // Apply(0) paths — retail's Reset/Defaults call these directly and
        // notify the page ONCE themselves at their own verb tail; a per-row
        // notify here would double-fire (or fire once per reverted row
        // instead of once per verb call).
        var row = new BoolOptionRow(initial: false, defaultValue: true);
        int notifyCount = 0;
        row.AttachPageNotify(() => notifyCount++);
        row.SetCurrentValue(true);
        notifyCount = 0; // drop the SetCurrentValue notify above

        row.RestoreSavedValue();
        row.RestoreDefaultValue();

        Assert.Equal(0, notifyCount);
    }

    [Fact]
    public void Register_AttachesPageNotify_SoSubsequentLiveEditsNotifyThePage()
    {
        var page = new OptionPage();
        var row = new BoolOptionRow(initial: false, defaultValue: false);
        int notifyCount = 0;
        page.OnOptionChanged = () => notifyCount++;

        page.Register(row);
        row.SetCurrentValue(true);

        Assert.Equal(1, notifyCount);
    }
}