using System;
using System.Numerics;
using AcDream.Core.Social;

namespace AcDream.App.UI.Layout;

/// <summary>
/// Campaign FA slice FA3, D1: the Friends page's read-only roster — names
/// only, bound directly to the J4.1 <see cref="FriendsState"/> owner
/// (<c>RuntimeCommunicationState.Friends</c>). Rebuilds on
/// <see cref="FriendsState.Revision"/> change; polled every frame from
/// <see cref="SocialPanelController.Tick"/> WHILE THE PANEL IS VISIBLE
/// (cheap — a single <see langword="long"/> comparison when nothing
/// changed; see the scrollbar/rebuild-discipline paragraph below for the
/// fix-round visibility gate).
///
/// <para>
/// <b>Actions LIVE as of 2026-08-13 (AD-79 retired for this page).</b>
/// Add (name box → <c>0x0018</c>), Remove (selected row → <c>0x0017</c>),
/// and Appear Offline (CharacterOption <c>0x27</c> via the immediate
/// <c>0x0005</c> auto-save) are wired through <see cref="Actions"/> — the
/// wire beneath existed end-to-end all along
/// (docs/research/2026-08-13-social-wire-completion.md §4). Send Tell
/// (<c>0x10000516</c>) remains the one inert button — not in the
/// 2026-08-13 order and needing the chat-tell seam; tracked in AD-79's
/// remainder.
/// </para>
///
/// <para>
/// Row template <c>0x2100005D</c>/<c>0x10000519</c> (FA3 live-mount probe);
/// <see cref="SocialPanelRowText.FindDeepest"/> resolves the row's own
/// name-text leaf — see that class's doc for why the deepest match is used
/// (gmFriendsUI is outside this campaign's decompiled scope).
/// </para>
///
/// <para>
/// <b>Scrollbar (fix-round blast MF-1; FA4 carry-forward 3).</b> The
/// ListBox <c>0x10000517</c> authors a direct sibling scrollbar,
/// <c>0x10000518</c> — wired to <see cref="UiTemplateListBox.Scroll"/> the
/// SAME way every other <c>UiTemplateListBox</c> consumer wires its own
/// scrollbar. Resolved via the built <see cref="UiTemplateListBox.ScrollbarElementId"/>
/// (dat property <c>0x72</c>, populated by <see cref="ElementReader"/>)
/// rather than the hardcoded literal a prior revision of this file used —
/// same "prefer the DAT field over a duplicated constant" fix
/// <c>ConfigOptionsPageController.Bind</c> already applied (OP6 review N2,
/// <c>feedback_prefer_dat_field_over_geometry</c>), scoped to this page's
/// own subtree so a flat lookup can't grab a same-id sibling on another
/// page. Without it the list has NO wheel fallback
/// (<see cref="UiScrollablePanel"/> has no wheel handler) and is completely
/// unreachable past the box's visible extent.
/// </para>
///
/// <para>
/// <b>Rebuild discipline (fix-round blast SF-2/SF-3).</b> <see cref="Refresh"/>
/// only advances <see cref="_lastRevision"/> after a successful rebuild — a
/// transient resolver miss (<see cref="UiTemplateListBox.AddItemFromTemplateList"/>
/// returning null) leaves the revision UNCONSUMED so the next
/// <see cref="Tick"/> retries instead of latching an empty list until the
/// NEXT server-side change. <see cref="SocialPanelController"/> also gates
/// this controller's <see cref="Tick"/> on the panel's own visibility (its
/// <c>IRetainedPanelController.OnShown</c>/<c>OnHidden</c> hooks) — the
/// per-row template resolve takes the shared DAT lock, so no rebuild work
/// runs while the panel is closed.
/// </para>
/// </summary>
public sealed class SocialFriendsPageController
{
    private const uint ListBoxId = 0x10000517u;
    // 2026-08-13 gate (AD-79 retirement): the authored action widgets, roles
    // probe-verified against the live DAT (ProbeSocialClickRouting label
    // dump): Add / Remove / Send Tell buttons, the Appear Offline checkbox,
    // and the name edit box gmFriendsUI's own Add path reads
    // (Request_AddFriend @0x0048D240 reads the box, sends 0x0018, clears it).
    private const uint AddButtonId = 0x10000514u;
    private const uint RemoveButtonId = 0x10000515u;
    private const uint AppearOfflineCheckboxId = 0x1000052Cu;
    private const uint NameFieldId = 0x1000051Bu;

    /// <summary>The live wire seams (2026-08-13, AD-79 retired): every
    /// command below already existed end-to-end (builders, WorldSession
    /// sends, Runtime commands, inbound parsers —
    /// docs/research/2026-08-13-social-wire-completion.md §4); this page was
    /// the only missing link. AppearOffline is CharacterOption 0x27 riding
    /// the immediate 0x0005 auto-save — ACE pushes FriendStatusChanged to
    /// everyone who friended you (its §1.4).</summary>
    public sealed record Actions(
        Action<string> AddFriend,
        Action<uint> RemoveFriend,
        Func<bool> CurrentAppearOffline,
        Action<bool> SetAppearOffline);

    private readonly UiTemplateListBox _listBox;
    private readonly FriendsState _friends;
    private readonly Actions? _actions;
    private readonly UiField? _nameField;
    private readonly UiButton? _appearOfflineCheckbox;
    private long _lastRevision = long.MinValue;
    private uint _selectedFriendGuid;

    private SocialFriendsPageController(
        UiTemplateListBox listBox,
        FriendsState friends,
        Actions? actions,
        UiField? nameField,
        UiButton? appearOfflineCheckbox)
    {
        _listBox = listBox;
        _friends = friends;
        _actions = actions;
        _nameField = nameField;
        _appearOfflineCheckbox = appearOfflineCheckbox;
    }

    public static SocialFriendsPageController? Bind(
        UiElement pageRoot,
        FriendsState friends,
        Func<uint, uint, UiElement?> templateResolver,
        Actions? actions = null)
    {
        ArgumentNullException.ThrowIfNull(pageRoot);
        ArgumentNullException.ThrowIfNull(friends);
        ArgumentNullException.ThrowIfNull(templateResolver);

        if (UiElement.FindDescendant(pageRoot, ListBoxId) is not UiTemplateListBox listBox)
        {
            Console.WriteLine(
                $"[D.2b] SocialFriendsPageController: ListBox 0x{ListBoxId:X8} not "
                + "found — Friends page will not populate.");
            return null;
        }
        listBox.TemplateResolver = templateResolver;

        uint scrollbarElementId = listBox.ScrollbarElementId;
        UiElement? scrollbarElement = scrollbarElementId == 0
            ? null
            : UiElement.FindDescendant(pageRoot, scrollbarElementId);
        if (scrollbarElement is UiScrollbar scrollbar)
            scrollbar.Model = listBox.Scroll;
        else
            Console.WriteLine(
                $"[D.2b] SocialFriendsPageController: scrollbar 0x{scrollbarElementId:X8} "
                + "not found — the Friends list will not scroll.");

        var nameField = UiElement.FindDescendant(pageRoot, NameFieldId) as UiField;
        var appearOffline = UiElement.FindDescendant(pageRoot, AppearOfflineCheckboxId) as UiButton;
        var controller = new SocialFriendsPageController(
            listBox, friends, actions, nameField, appearOffline);
        controller.WireActions(pageRoot);
        controller.Refresh();
        return controller;
    }

    private void WireActions(UiElement pageRoot)
    {
        if (_actions is not { } actions) return;   // fixture callers stay inert

        if (UiElement.FindDescendant(pageRoot, AddButtonId) is UiButton add)
            add.OnClick = () =>
            {
                string name = _nameField?.Text?.Trim() ?? string.Empty;
                if (string.IsNullOrWhiteSpace(name)) return;
                actions.AddFriend(name);
                // Retail clears the edit box on send (Request_AddFriend
                // @0x0048D240's own post-send clear).
                _nameField?.SetText(string.Empty);
            };

        if (UiElement.FindDescendant(pageRoot, RemoveButtonId) is UiButton remove)
            remove.OnClick = () =>
            {
                if (_selectedFriendGuid != 0u)
                    actions.RemoveFriend(_selectedFriendGuid);
            };

        if (_appearOfflineCheckbox is { } checkbox)
        {
            // The same ToggleBehavior mirror discipline as the fellowship/
            // allegiance checkboxes (the 2026-08-13 double-toggle fix).
            checkbox.SuppressSelfToggle = true;
            checkbox.OnClick = () =>
                actions.SetAppearOffline(!actions.CurrentAppearOffline());
        }
    }

    public void Tick()
    {
        if (_actions is { } actions && _appearOfflineCheckbox is { } checkbox)
            checkbox.Selected = actions.CurrentAppearOffline();

        long revision = _friends.Revision;
        if (revision == _lastRevision) return;
        Refresh();
    }

    /// <summary>The row template's LEFT name cell (template layout
    /// 0x2100005D root 0x10000519). Its <c>Online</c>/<c>Offline</c>
    /// PassToChildren states cascade into the RIGHT status grandchild
    /// 0x1000051F, which authors the per-state 'Online'/'Offline' strings
    /// and colors (retail's green Online) — installed-DAT probe 2026-08-14,
    /// retail's <c>gmFriendsUI</c> row shape.</summary>
    private const uint RowNameTextId = 0x1000051Au;
    private const uint OnlineStateId = 0x10000054u;
    private const uint OfflineStateId = 0x10000055u;

    private void Refresh()
    {
        long revision = _friends.Revision;
        _listBox.Flush();
        bool allRowsResolved = true;
        bool selectedStillPresent = false;
        foreach (FriendEntry friend in _friends.Snapshot())
        {
            UiElement? row = _listBox.AddItemFromTemplateList(0);
            if (row is null) { allRowsResolved = false; continue; }
            if (friend.Id == _selectedFriendGuid) selectedStillPresent = true;
            // 2026-08-14 friends gate ("detects online/offline but the list
            // does not update"): the old FindDeepest binding wrote the NAME
            // into the STATUS cell (the deepest text IS the status
            // grandchild) and never flipped the authored state machine, so
            // the status column never showed anything. Bind the name to its
            // own cell and flip the authored Online/Offline state — the
            // cascade swaps the status cell's authored string + color.
            if (UiElement.FindDescendant(row, RowNameTextId) is UiText nameText)
            {
                string name = friend.Name;
                uint guid = friend.Id;
                nameText.LinesProvider = () => [new UiText.Line(name, Vector4.One)];
                // 2026-08-13 gate: row click selects the friend the Remove
                // button acts on (UiText.OnClick clears the display-text
                // ClickThrough default — see its doc).
                nameText.OnClick = () => _selectedFriendGuid = guid;
                nameText.TrySetRetailState(
                    friend.Online ? OnlineStateId : OfflineStateId);
            }
            else
            {
                allRowsResolved = false;
            }
        }
        if (!selectedStillPresent) _selectedFriendGuid = 0u;
        // SF-3: only latch the revision once the rebuild actually reflects it —
        // a resolver miss must not silently swallow a future revision bump.
        if (allRowsResolved) _lastRevision = revision;
    }
}