using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Numerics;

using Dalamud.Bindings.ImGui;
using Dalamud.Interface.Components;
using Dalamud.Interface.Internal.UiDebug.Browsing;
using Dalamud.Interface.Internal.UiDebug.Utility;
using Dalamud.Interface.Utility.Raii;

using FFXIVClientStructs.FFXIV.Component.GUI;

using static System.Globalization.NumberFormatInfo;

using static Dalamud.Bindings.ImGui.ImGuiCol;
using static Dalamud.Bindings.ImGui.ImGuiWindowFlags;
using static Dalamud.Interface.FontAwesomeIcon;
using static Dalamud.Interface.Internal.UiDebug.UiDebug;
using static Dalamud.Interface.UiBuilder;
using static Dalamud.Interface.Utility.ImGuiHelpers;
using static FFXIVClientStructs.FFXIV.Component.GUI.NodeFlags;

// ReSharper disable StructLacksIEquatable.Global

#pragma warning disable CS0659

namespace Dalamud.Interface.Internal.UiDebug;

/// <summary>
/// A tool that enables the user to select UI elements within the inspector by mousing over them onscreen.
/// </summary>
internal unsafe class ElementSelector : IDisposable
{
    private const int UnitListCount = 18;

    private readonly UiDebug uiDebug;

    private string addressSearchInput = string.Empty;

    private int index;

    /// <summary>
    /// Initializes a new instance of the <see cref="ElementSelector"/> class.
    /// </summary>
    /// <param name="uiDebug">The instance of <see cref="UiDebug"/> this Element Selector belongs to.</param>
    internal ElementSelector(UiDebug uiDebug)
    {
        this.uiDebug = uiDebug;
    }

    /// <summary>
    /// Gets or sets the results retrieved by the Element Selector.
    /// </summary>
    internal static nint[] SearchResults { get; set; } = [];

    /// <summary>
    /// Gets or sets a value governing the highlighting of nodes when found via search.
    /// </summary>
    internal static float Countdown { get; set; }

    /// <summary>
    /// Gets or sets a value indicating whether the window has scrolled down to the position of the search result.
    /// </summary>
    internal static bool Scrolled { get; set; }

    /// <summary>
    /// Gets or sets a value indicating whether the mouseover UI is currently active.
    /// </summary>
    internal bool Active { get; set; }

    /// <inheritdoc/>
    public void Dispose()
    {
        this.Active = false;
    }

    /// <summary>
    /// Draws the Element Selector and Address Search interface at the bottom of the sidebar.
    /// </summary>
    internal void DrawInterface()
    {
        using var ch = ImRaii.Child("###sidebar_elementSelector"u8, new(250, -1), true);

        if (ch.Success)
        {
            using (ImRaii.PushFont(IconFont))
            {
                using (ImRaii.PushColor(Text, new Vector4(1, 1, 0.2f, 1), this.Active))
                {
                    if (ImGui.Button($"{(char)ObjectUngroup}"))
                    {
                        this.Active = !this.Active;
                    }

                    if (Countdown > 0)
                    {
                        Countdown -= 1;
                        if (Countdown < 0)
                        {
                            Countdown = 0;
                        }
                    }
                }
            }

            if (ImGui.IsItemHovered())
            {
                ImGui.SetTooltip("Element Selector"u8);
            }

            ImGui.SameLine();

            ImGui.SetNextItemWidth(ImGui.GetContentRegionAvail().X - 32);
            ImGui.InputTextWithHint(
                "###addressSearchInput"u8,
                "Address Search"u8,
                ref this.addressSearchInput,
                18,
                ImGuiInputTextFlags.AutoSelectAll);
            ImGui.SameLine();

            if (ImGuiComponents.IconButton("###elemSelectorAddrSearch", Search) && nint.TryParse(
                    this.addressSearchInput,
                    NumberStyles.HexNumber | NumberStyles.AllowHexSpecifier,
                    InvariantInfo,
                    out var address))
            {
                this.PerformSearch(address);
            }
        }
    }

    /// <summary>
    /// Draws the Element Selector's search output within the main window.
    /// </summary>
    internal void DrawSelectorOutput()
    {
        ImGui.GetIO().WantCaptureKeyboard = true;
        ImGui.GetIO().WantCaptureMouse = true;
        ImGui.GetIO().WantTextInput = true;
        if (ImGui.IsKeyPressed(ImGuiKey.Escape))
        {
            this.Active = false;
            return;
        }

        ImGui.Text("ELEMENT SELECTOR"u8);
        ImGui.TextDisabled("Use the mouse to hover and identify UI elements, then click to jump to them in the inspector"u8);
        ImGui.TextDisabled("Use the scrollwheel to choose between overlapping elements"u8);
        ImGui.TextDisabled("Press ESCAPE to cancel"u8);
        ImGui.Spacing();

        var mousePos = ImGui.GetMousePos() - MainViewport.Pos;
        var addonResults = GetAtkUnitBaseAtPosition(mousePos);

        using (ImRaii.PushColor(WindowBg, new Vector4(0.5f)))
        {
            using var ch = ImRaii.Child("noClick"u8, new(800, 2000), false, NoInputs | NoBackground | NoScrollWithMouse);
            if (ch.Success)
            {
                using var gr = ImRaii.Group();
                Gui.PrintFieldValuePair("Mouse Position", $"{mousePos.X}, {mousePos.Y}");
                ImGui.Spacing();
                ImGui.Text("RESULTS:\n"u8);

                var i = 0;
                foreach (var a in addonResults)
                {
                    var name = a.Addon->NameString;
                    ImGui.Text($"[Addon] {name}");

                    using var indent = ImRaii.PushIndent(15.0f);
                    foreach (var n in a.Nodes)
                    {
                        var nSelected = i++ == this.index;

                        PrintNodeHeaderOnly(n.Node, nSelected, a.Addon);

                        if (nSelected && ImGui.IsMouseClicked(ImGuiMouseButton.Left))
                        {
                            this.Active = false;

                            this.uiDebug.SelectedAddonName = a.Addon->NameString;

                            var ptrList = new List<nint> { (nint)n.Node };

                            var nextNode = n.Node->ParentNode;
                            while (nextNode != null)
                            {
                                ptrList.Add((nint)nextNode);
                                nextNode = nextNode->ParentNode;
                            }

                            SearchResults = [.. ptrList];
                            Countdown = 100;
                            Scrolled = false;
                        }

                        if (nSelected)
                        {
                            n.NodeBounds.DrawFilled(new(1, 1, 0.2f, 1));
                        }
                    }
                }

                if (i != 0)
                {
                    this.index -= (int)ImGui.GetIO().MouseWheel;
                    while (this.index < 0)
                    {
                        this.index += i;
                    }

                    while (this.index >= i)
                    {
                        this.index -= i;
                    }
                }
            }
        }
    }

    private static List<AddonResult> GetAtkUnitBaseAtPosition(Vector2 position)
    {
        var addonResults = new List<AddonResult>();
        var unitListBaseAddr = GetUnitListBaseAddr();
        if (unitListBaseAddr == null)
        {
            return addonResults;
        }

        foreach (var unit in UnitListOptions)
        {
            var unitManager = &unitListBaseAddr[unit.Index];

            var safeCount = Math.Min(unitManager->Count, unitManager->Entries.Length);

            for (var i = 0; i < safeCount; i++)
            {
                var addon = unitManager->Entries[i].Value;

                if (addon == null || addon->RootNode == null)
                {
                    continue;
                }

                if (!addon->IsVisible || !addon->RootNode->NodeFlags.HasFlag(Visible))
                {
                    continue;
                }

                var addonResult = new AddonResult(addon, []);

                if (addonResults.Contains(addonResult))
                {
                    continue;
                }

                if (addon->X > position.X || addon->Y > position.Y)
                {
                    continue;
                }

                if (addon->X + addon->RootNode->Width < position.X)
                {
                    continue;
                }

                if (addon->Y + addon->RootNode->Height < position.Y)
                {
                    continue;
                }

                addonResult.Nodes.AddRange(GetNodeAtPosition(&addon->UldManager, position, true));
                addonResults.Add(addonResult);
            }
        }

        return [.. addonResults.OrderBy(static w => w.Area)];
    }

    private static List<NodeResult> GetNodeAtPosition(AtkUldManager* uldManager, Vector2 position, bool reverse)
    {
        var nodeResults = new List<NodeResult>();
        for (var i = 0; i < uldManager->NodeListCount; i++)
        {
            var node = uldManager->NodeList[i];

            var bounds = new NodeBounds(node);

            if (!bounds.ContainsPoint(position))
            {
                continue;
            }

            if ((int)node->Type >= 1000)
            {
                var compNode = (AtkComponentNode*)node;
                nodeResults.AddRange(GetNodeAtPosition(&compNode->Component->UldManager, position, false));
            }

            nodeResults.Add(new() { NodeBounds = bounds, Node = node });
        }

        if (reverse)
        {
            nodeResults.Reverse();
        }

        return nodeResults;
    }

    private static bool FindByAddress(AtkUnitBase* atkUnitBase, nint address)
    {
        if (atkUnitBase->RootNode == null)
        {
            return false;
        }

        if (!FindByAddress(atkUnitBase->RootNode, address, out var path))
        {
            return false;
        }

        Scrolled = false;
        SearchResults = path?.ToArray() ?? [];
        Countdown = 100;
        return true;
    }

    private static bool FindByAddress(AtkResNode* node, nint address, out List<nint>? path)
    {
        if (node == null)
        {
            path = null;
            return false;
        }

        if ((nint)node == address)
        {
            path = [(nint)node];
            return true;
        }

        if ((int)node->Type >= 1000)
        {
            var cNode = (AtkComponentNode*)node;

            if (cNode->Component != null)
            {
                if ((nint)cNode->Component == address)
                {
                    path = [(nint)node];
                    return true;
                }

                if (FindByAddress(cNode->Component->UldManager.RootNode, address, out path) && path != null)
                {
                    path.Add((nint)node);
                    return true;
                }
            }
        }

        if (FindByAddress(node->ChildNode, address, out path) && path != null)
        {
            path.Add((nint)node);
            return true;
        }

        if (FindByAddress(node->PrevSiblingNode, address, out path) && path != null)
        {
            return true;
        }

        path = null;
        return false;
    }

    private static void PrintNodeHeaderOnly(AtkResNode* node, bool selected, AtkUnitBase* addon)
    {
        if (addon == null)
        {
            return;
        }

        if (node == null)
        {
            return;
        }

        var tree = AddonTree.GetOrCreate(addon->NameString);
        if (tree == null)
        {
            return;
        }

        using (ImRaii.PushColor(Text, selected ? new Vector4(1, 1, 0.2f, 1) : new(0.6f, 0.6f, 0.6f, 1)))
        {
            ResNodeTree.GetOrCreate(node, tree).WriteTreeHeading();
        }
    }

    private void PerformSearch(nint address)
    {
        var unitListBaseAddr = GetUnitListBaseAddr();
        if (unitListBaseAddr == null)
        {
            return;
        }

        for (var i = 0; i < UnitListCount; i++)
        {
            var unitManager = &unitListBaseAddr[i];
            var safeCount = Math.Min(unitManager->Count, unitManager->Entries.Length);

            for (var j = 0; j < safeCount; j++)
            {
                var addon = unitManager->Entries[j].Value;
                if ((nint)addon == address || FindByAddress(addon, address))
                {
                    this.uiDebug.SelectedAddonName = addon->NameString;
                    return;
                }
            }
        }
    }

    /// <summary>
    /// An <see cref="AtkUnitBase"/> found by the Element Selector.
    /// </summary>
    internal struct AddonResult
    {
        /// <summary>The addon itself.</summary>
        internal AtkUnitBase* Addon;

        /// <summary>A list of nodes discovered within this addon by the Element Selector.</summary>
        internal List<NodeResult> Nodes;

        /// <summary>The calculated area of the addon's root node.</summary>
        internal float Area;

        /// <summary>
        /// Initializes a new instance of the <see cref="AddonResult"/> struct.
        /// </summary>
        /// <param name="addon">The addon found.</param>
        /// <param name="nodes">A list for documenting nodes found within the addon.</param>
        public AddonResult(AtkUnitBase* addon, List<NodeResult> nodes)
        {
            this.Addon = addon;
            this.Nodes = nodes;
            var rootNode = addon->RootNode;
            this.Area = rootNode != null ? rootNode->Width * rootNode->Height * rootNode->ScaleY * rootNode->ScaleX : 0;
        }

        /// <inheritdoc/>
        public override readonly bool Equals(object? obj)
        {
            if (obj is not AddonResult ar)
            {
                return false;
            }

            return (nint)this.Addon == (nint)ar.Addon;
        }
    }

    /// <summary>
    /// An <see cref="AtkResNode"/> found by the Element Selector.
    /// </summary>
    internal struct NodeResult
    {
        /// <summary>The node itself.</summary>
        internal AtkResNode* Node;

        /// <summary>A struct representing the perimeter of the node.</summary>
        internal NodeBounds NodeBounds;

        /// <inheritdoc/>
        public override readonly bool Equals(object? obj)
        {
            if (obj is not NodeResult nr)
            {
                return false;
            }

            return nr.Node == this.Node;
        }
    }
}