using System.Linq;
using Content.Client.UserInterface.ControlExtensions;
using Content.Client.UserInterface.Controls;
using Content.Client.UserInterface.Controls.FancyTree;
using Content.Client.UserInterface.RichText;
using Content.Client.UserInterface.Systems.Info;
using Content.Shared.Guidebook;
using Robust.Client.AutoGenerated;
using Robust.Client.UserInterface;
using Robust.Client.UserInterface.Controls;
using Robust.Client.UserInterface.XAML;
using Robust.Shared.ContentPack;
using Robust.Shared.Prototypes;

namespace Content.Client.Guidebook.Controls;

[GenerateTypedNameReferences]
public sealed partial class GuidebookWindow : FancyWindow, ILinkClickHandler, IAnchorClickHandler
{
    [Dependency] private DocumentParsingManager _parsingMan = default!;
    [Dependency] private IResourceManager _resourceManager = default!;

    private Dictionary<ProtoId<GuideEntryPrototype>, GuideEntry> _entries = [];

    private readonly ISawmill _sawmill;

    public ProtoId<GuideEntryPrototype>? Selected { get; private set; }


    public GuidebookWindow()
    {
        RobustXamlLoader.Load(this);
        IoCManager.InjectDependencies(this);
        _sawmill = Logger.GetSawmill("guidebook");

        Tree.OnSelectedItemChanged += OnSelectionChanged;
        TableOfContents.OnSelectedItemChanged += OnTableOfContentsSelectionChanged;

        SearchBar.OnTextChanged += _ =>
        {
            HandleFilter();
        };
    }

    public void HandleClick(string link)
    {
        if (!_entries.TryGetValue(link, out var entry))
            return;

        if (Tree.TryGetIndexFromMetadata(entry, out var index))
        {
            Tree.ExpandParentEntries(index.Value);
            Tree.SetSelectedIndex(index);
        }
        else
            ShowGuide(entry);
    }

    public void HandleAnchor(IPrototypeLinkControl prototypeLinkControl)
    {
        var prototype = prototypeLinkControl.LinkedPrototype;
        if (prototype == null)
            return;

        var (linkableControls, _) = GetLinkableControlsAndLinks(EntryContainer);
        foreach (var linkableControl in linkableControls)
        {
            if (linkableControl.RepresentedPrototype != prototype)
                continue;

            if (linkableControl is not Control control)
                return;

            // Check if the target item is currently filtered out
            if (!control.Visible)
                control.Visible = true;

            UserInterfaceManager.DeferAction(() =>
            {
                if (control.GetControlScrollPosition() is not { } position)
                    return;

                Scroll.HScrollTarget = position.X;
                Scroll.VScrollTarget = position.Y;
            });

            break;
        }
    }

    private void OnSelectionChanged(TreeItem? item)
    {
        if (item != null && item.Metadata is GuideEntry entry)
        {
            // do nothing if the guide is the same as the currently selected one
            if (entry.Id == Selected)
                return;

            ShowGuide(entry);

            var isRulesEntry = entry.RuleEntry;
            ReturnContainer.Visible = isRulesEntry;
            HomeButton.OnPressed += _ => ShowGuide(entry);
        }
        else
            ClearSelectedGuide();
    }

    private void OnTableOfContentsSelectionChanged(TreeItem? item)
    {
        if (item is null || item.Metadata is not Label entry)
            return;

        UserInterfaceManager.DeferAction(() =>
        {
            if (entry.GetControlScrollPosition() is not { } position)
                return;

            Scroll.HScrollTarget = position.X;
            Scroll.VScrollTarget = position.Y;
        });
    }

    public void ClearSelectedGuide()
    {
        Placeholder.Visible = true;
        EntryContainer.Visible = false;
        SearchContainer.Visible = false;
        EntryContainer.RemoveAllChildren();

        Selected = null;
    }

    private void ShowGuide(GuideEntry entry)
    {
        Scroll.SetScrollValue(default);
        Placeholder.Visible = false;
        EntryContainer.Visible = true;
        SearchBar.Text = "";
        EntryContainer.RemoveAllChildren();
        using var file = _resourceManager.ContentFileReadText(entry.Text);

        SearchContainer.Visible = entry.FilterEnabled;

        if (!_parsingMan.TryAddMarkup(EntryContainer, file.ReadToEnd()))
        {
            // The guidebook will automatically display the in-guidebook error if it fails

            _sawmill.Error($"Failed to parse contents of guide document {entry.Id}.");
        }

        Selected = entry.Id;

        var (linkableControls, linkControls) = GetLinkableControlsAndLinks(EntryContainer);

        HashSet<IPrototype> availablePrototypeLinks = [];
        foreach (var linkableControl in linkableControls)
        {
            var prototype = linkableControl.RepresentedPrototype;
            if (prototype != null)
                availablePrototypeLinks.Add(prototype);
        }

        foreach (var linkControl in linkControls)
        {
            var prototype = linkControl.LinkedPrototype;
            if (prototype != null && availablePrototypeLinks.Contains(prototype))
                linkControl.EnablePrototypeLink();
        }

        RepopulateTableOfContents();
    }

    private int? HeadingDepth(Label control)
    {
        if (control.StyleClasses.Contains("LabelHeadingBigger"))
            return 1;
        else if (control.StyleClasses.Contains("LabelHeading"))
            return 2;
        else if (control.StyleClasses.Contains("LabelKeyText"))
            return 3;

        return null;
    }

    private void RepopulateTableOfContents()
    {
        TableOfContents.Clear();

        var firstEntry = TableOfContents.AddItem(null);
        firstEntry.Label.Text = Loc.GetString("guidebook-toc-header");

        var labels = EntryContainer.GetControlOfType<Label>(true);
        var stack = new Stack<(TreeItem Item, int Depth)>();

        foreach (var label in labels)
        {
            if (HeadingDepth(label) is not { } depth)
                continue;

            while (stack.TryPeek(out var previous) && previous.Depth >= depth)
            {
                stack.Pop();
            }

            var item = stack.TryPeek(out var parent)
                ? TableOfContents.AddItem(parent.Item)
                : TableOfContents.AddItem(firstEntry);
            item.Label.Text = label.Text;
            item.Metadata = label;

            stack.Push((item, depth));
        }

        // Expand all entries, but collapse the first one
        TableOfContents.SetAllExpanded(true);
        firstEntry.SetExpanded(false);
    }

    /// <summary>
    /// Updates the guides used in the window.
    /// Returns whether the guides changed.
    /// </summary>
    public bool UpdateGuides(
        Dictionary<ProtoId<GuideEntryPrototype>, GuideEntry> entries,
        List<ProtoId<GuideEntryPrototype>>? rootEntries = null,
        ProtoId<GuideEntryPrototype>? forceRoot = null,
        ProtoId<GuideEntryPrototype>? selected = null)
    {
        // check if old and new entries are equal
        var sameAsLastUpdate = entries.Count != _entries.Count || !entries.All(_entries.Contains);
        if (sameAsLastUpdate)
        {
            _entries = entries;
            RepopulateTree(rootEntries, forceRoot);
            Split.State = SplitContainer.SplitState.Auto;
            if (entries.Count == 1)
            {
                TreeBox.Visible = false;
                Split.ResizeMode = SplitContainer.SplitResizeMode.NotResizable;
                selected = entries.Keys.First();
            }
            else
            {
                TreeBox.Visible = true;
                Split.ResizeMode = SplitContainer.SplitResizeMode.RespectChildrenMinSize;
            }
        }

        if (selected == null)
            ClearSelectedGuide();
        else
        {
            var item = Tree.Items.FirstOrDefault(x => x.Metadata is GuideEntry entry && entry.Id == selected);
            Tree.SetSelectedIndex(item?.Index);
        }

        return sameAsLastUpdate;
    }

    private IEnumerable<GuideEntry> GetSortedEntries(List<ProtoId<GuideEntryPrototype>>? rootEntries)
    {
        if (rootEntries == null)
        {
            HashSet<ProtoId<GuideEntryPrototype>> entries = [.. _entries.Keys];
            foreach (var entry in _entries.Values)
            {
                entries.ExceptWith(entry.Children);
            }

            rootEntries = [.. entries];
        }

        // Only roots need to be sorted.
        // As defined in the SS14 Dev Wiki, children are already sorted based on their child field order within their parent's prototype definition.
        // Roots are sorted by priority. If there is no defined priority for a root then it is by definition sorted undefined.
        return rootEntries
            .Select(rootEntryId => _entries[rootEntryId])
            .OrderBy(rootEntry => rootEntry.Priority)
            .ThenBy(rootEntry => Loc.GetString(rootEntry.Name));
    }

    private void RepopulateTree(List<ProtoId<GuideEntryPrototype>>? roots = null,
        ProtoId<GuideEntryPrototype>? forcedRoot = null)
    {
        Tree.Clear();

        HashSet<ProtoId<GuideEntryPrototype>> addedEntries = [];

        var parent = forcedRoot == null ? null : AddEntry(forcedRoot.Value, null, addedEntries);
        foreach (var entry in GetSortedEntries(roots))
        {
            AddEntry(entry.Id, parent, addedEntries);
        }

        Tree.SetAllExpanded(true);
    }

    private TreeItem? AddEntry(ProtoId<GuideEntryPrototype> id,
        TreeItem? parent,
        HashSet<ProtoId<GuideEntryPrototype>> addedEntries)
    {
        if (!_entries.TryGetValue(id, out var entry))
            return null;

        if (!addedEntries.Add(id))
        {
            // TODO GUIDEBOOK Maybe allow duplicate entries?
            // E.g., for adding medicine under both chemicals & the chemist job
            _sawmill.Error($"Adding duplicate guide entry: {id}");
            return null;
        }

        var rulesProto = UserInterfaceManager.GetUIController<InfoUIController>().GetCoreRuleEntry();
        if (entry.RuleEntry && entry.Id != rulesProto.Id)
            return null;

        var item = Tree.AddItem(parent);
        item.Metadata = entry;
        var name = Loc.GetString(entry.Name);
        item.Label.Text = name;

        foreach (var child in entry.Children)
        {
            AddEntry(child, item, addedEntries);
        }

        return item;
    }

    private void HandleFilter()
    {
        if (Tree.SelectedItem != null && Tree.SelectedItem.Metadata is GuideEntry entry && entry.FilterEnabled)
        {
            var foundElements = EntryContainer.GetSearchableControls();

            foreach (var element in foundElements)
            {
                element.SetHiddenState(true, SearchBar.Text.Trim());
            }
        }
    }

    private static (List<IPrototypeRepresentationControl>, List<IPrototypeLinkControl>) GetLinkableControlsAndLinks(Control parent)
    {
        List<IPrototypeRepresentationControl> linkableList = [];
        List<IPrototypeLinkControl> linkList = [];

        foreach (var child in parent.Children)
        {
            var hasChildren = child.ChildCount > 0;

            if (child is IPrototypeLinkControl linkChild)
                linkList.Add(linkChild);
            else if (child is IPrototypeRepresentationControl linkableChild)
                linkableList.Add(linkableChild);

            if (!hasChildren)
                continue;

            var (childLinkableList, childLinkList) = GetLinkableControlsAndLinks(child);

            linkableList.AddRange(childLinkableList);
            linkList.AddRange(childLinkList);
        }

        return (linkableList, linkList);
    }
}