using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Runtime.InteropServices;
using HUD_Manager.Configuration;
using HUD_Manager.Structs;
using HUD_Manager.Tree;

namespace HUD_Manager {
    public class Hud {
        // Updated 5.45
        public const int InMemoryLayoutElements = 81;

        // Updated 5.45
        // Each element is 32 bytes in ADDON.DAT, but they're 36 bytes when loaded into memory.
        private const int LayoutSize = InMemoryLayoutElements * 36;

        // Updated 5.4
        private const int SlotOffset = 0x59e8;

        private delegate IntPtr GetFilePointerDelegate(byte index);

        private delegate uint SetHudLayoutDelegate(IntPtr filePtr, uint hudLayout, byte unk0, byte unk1);

        private readonly GetFilePointerDelegate? _getFilePointer;
        private readonly SetHudLayoutDelegate? _setHudLayout;

        private Plugin Plugin { get; }

        public Hud(Plugin plugin) {
            this.Plugin = plugin;
            var getFilePointerPtr = this.Plugin.SigScanner.ScanText("E8 ?? ?? ?? ?? 48 85 C0 74 14 83 7B 44 00");
            var setHudLayoutPtr = this.Plugin.SigScanner.ScanText("E8 ?? ?? ?? ?? 33 C0 EB 15");
            if (getFilePointerPtr != IntPtr.Zero) {
                this._getFilePointer = Marshal.GetDelegateForFunctionPointer<GetFilePointerDelegate>(getFilePointerPtr);
            }

            if (setHudLayoutPtr != IntPtr.Zero) {
                this._setHudLayout = Marshal.GetDelegateForFunctionPointer<SetHudLayoutDelegate>(setHudLayoutPtr);
            }
        }

        public IntPtr GetFilePointer(byte index) {
            return this._getFilePointer?.Invoke(index) ?? IntPtr.Zero;
        }

        public void SaveAddonData() {
            var saveMarker = this.GetFilePointer(0) + 0x3E;
            Marshal.WriteByte(saveMarker, 1);
        }

        public void SelectSlot(HudSlot slot, bool force = false) {
            if (this._setHudLayout == null) {
                return;
            }

            var file = this.GetFilePointer(0);
            // change the current slot so the game lets us pick one that's currently in use
            if (!force) {
                goto Return;
            }

            unsafe {
                var currentSlotPtr = (uint*) (this.GetDataPointer() + SlotOffset);
                // read the current slot
                var currentSlot = *currentSlotPtr;
                // if the current slot is the slot we want to change to, we can force a reload by
                // telling the game it's on a different slot and swapping back to the desired slot
                if (currentSlot == (uint) slot) {
                    var backupSlot = currentSlot;
                    if (backupSlot < 3) {
                        backupSlot += 1;
                    } else {
                        backupSlot = 0;
                    }

                    // back up this different slot
                    var backup = this.ReadLayout((HudSlot) backupSlot);
                    // change the current slot in memory
                    *currentSlotPtr = backupSlot;

                    // ask the game to change slot to our desired slot
                    // for some reason, this overwrites the current slot, so this is why we back up
                    this._setHudLayout.Invoke(file, (uint) slot, 0, 1);
                    // restore the backup
                    this.WriteLayout((HudSlot) backupSlot, backup, false);
                    return;
                }
            }

            Return:
            this._setHudLayout.Invoke(file, (uint) slot, 0, 1);
        }

        private IntPtr GetDataPointer() {
            var dataPtr = this.GetFilePointer(0) + 0x50;
            return Marshal.ReadIntPtr(dataPtr);
        }

        internal IntPtr GetDefaultLayoutPointer() {
            return this.GetDataPointer() + 0x1c4;
        }

        internal IntPtr GetLayoutPointer(HudSlot slot) {
            var slotNum = (int) slot;
            return this.GetDataPointer() + 0x2c58 + slotNum * LayoutSize;
        }

        public HudSlot GetActiveHudSlot() {
            var slotVal = Marshal.ReadInt32(this.GetDataPointer() + SlotOffset);

            if (!Enum.IsDefined(typeof(HudSlot), slotVal)) {
                throw new IOException($"invalid hud slot in FFXIV memory of ${slotVal}");
            }

            return (HudSlot) slotVal;
        }

        public Layout ReadLayout(HudSlot slot) {
            var slotPtr = this.GetLayoutPointer(slot);
            return Marshal.PtrToStructure<Layout>(slotPtr);
        }

        private void WriteLayout(HudSlot slot, Layout layout, bool reloadIfNecessary = true) {
            this.WriteLayout(slot, layout.ToDictionary(), reloadIfNecessary);
        }

        private void WriteLayout(HudSlot slot, IReadOnlyDictionary<ElementKind, Element> dict, bool reloadIfNecessary = true) {
            var slotPtr = this.GetLayoutPointer(slot);

            // update existing elements with saved data instead of wholesale overwriting
            var slotLayout = this.ReadLayout(slot);
            for (var i = 0; i < slotLayout.elements.Length; i++) {
                if (!dict.TryGetValue(slotLayout.elements[i].id, out var element)) {
                    continue;
                }

                // just replace the struct if all options are enabled
                if (element.Enabled == Element.AllEnabled) {
                    slotLayout.elements[i] = new RawElement(element);
                    continue;
                }

                // otherwise only replace the enabled options
                slotLayout.elements[i].UpdateEnabled(element);
            }

            Marshal.StructureToPtr(slotLayout, slotPtr, false);

            // copy directly over
            // Marshal.StructureToPtr(layout, slotPtr, false);

            if (!reloadIfNecessary) {
                return;
            }

            var currentSlot = this.GetActiveHudSlot();
            if (currentSlot == slot) {
                this.SelectSlot(currentSlot, true);
            }
        }

        private SavedLayout? GetEffectiveLayout(Guid id) {
            // find the node for this id
            var nodes = Node<SavedLayout>.BuildTree(this.Plugin.Config.Layouts);
            var node = nodes.Find(id);
            if (node == null) {
                return null;
            }

            var elements = new Dictionary<ElementKind, Element>();
            var windows = new Dictionary<string, Window>();

            // get the ancestors and their elements for this node
            foreach (var ancestor in node.Ancestors().Reverse()) {
                foreach (var element in ancestor.Value.Elements) {
                    if (element.Value.Enabled == Element.AllEnabled || !elements.ContainsKey(element.Key)) {
                        elements[element.Key] = element.Value.Clone();
                        continue;
                    }

                    elements[element.Key].UpdateEnabled(element.Value);
                }

                foreach (var window in ancestor.Value.Windows) {
                    if (window.Value.Enabled == Window.AllEnabled || !windows.ContainsKey(window.Key)) {
                        windows[window.Key] = window.Value.Clone();
                        continue;
                    }

                    windows[window.Key].UpdateEnabled(window.Value);
                }
            }

            // apply this node's elements
            foreach (var element in node.Value.Elements) {
                if (element.Value.Enabled == Element.AllEnabled || !elements.ContainsKey(element.Key)) {
                    elements[element.Key] = element.Value.Clone();
                    continue;
                }

                elements[element.Key].UpdateEnabled(element.Value);
            }

            foreach (var window in node.Value.Windows) {
                if (window.Value.Enabled == Window.AllEnabled || !windows.ContainsKey(window.Key)) {
                    windows[window.Key] = window.Value.Clone();
                    continue;
                }

                windows[window.Key].UpdateEnabled(window.Value);
            }

            return new SavedLayout($"Effective {id}", elements, windows, Guid.Empty);
        }

        public void WriteEffectiveLayout(HudSlot slot, Guid id) {
            var effective = this.GetEffectiveLayout(id);
            if (effective == null) {
                return;
            }

            this.WriteLayout(slot, effective.Elements);

            foreach (var window in effective.Windows) {
                this.Plugin.GameFunctions.SetAddonPosition(window.Key, window.Value.Position.X, window.Value.Position.Y);
            }
        }

        internal void ImportSlot(string name, HudSlot slot, bool save = true) {
            this.Import(name, this.Plugin.Hud.ReadLayout(slot), save);
        }

        private void Import(string name, Layout layout, bool save = true) {
            var guid = this.Plugin.Config.Layouts.FirstOrDefault(kv => kv.Value.Name == name).Key;
            guid = guid != default ? guid : Guid.NewGuid();

            this.Plugin.Config.Layouts[guid] = new SavedLayout(name, layout);
            if (save) {
                this.Plugin.Config.Save();
            }
        }
    }

    public enum HudSlot {
        One = 0,
        Two = 1,
        Three = 2,
        Four = 3,
    }

    public class Vector2<T> {
        public T X { get; set; }
        public T Y { get; set; }

        public Vector2(T x, T y) {
            this.X = x;
            this.Y = y;
        }
    }
}