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. Campaign OP slice OP3 ships the model
/// against an EMPTY page (the Gameplay tab has no options at all — research
/// doc <c>2026-08-10-options-panel-structure.md</c> §6); this file also
/// exercises 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.
/// </summary>
public sealed class OptionPageModelTests
{
    // ── Empty page (the Gameplay tab's own shape) ───────────────────────────

    [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 EmptyPage_Apply_StillInvokesAfterApply()
    {
        // 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.
        var page = new OptionPage();
        int flushCount = 0;
        page.AfterApply = () => flushCount++;

        page.Apply();

        Assert.Equal(1, flushCount);
    }

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

        page.OnShown();

        Assert.Equal(1, flushCount);
    }

    [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);
    }
}