using System;
using System.Collections.Generic;
using System.Runtime.InteropServices;
using Dalamud.Game;
using Dalamud.Game.Gui.PartyFinder.Types;
using Dalamud.Hooking;
using Dalamud.Plugin.Services;

namespace XivCommon.Functions;

/// <summary>
/// A class containing Party Finder functionality
/// </summary>
public class PartyFinder : IDisposable {
    private static class Signatures {
        internal const string RequestListings = "48 89 5C 24 ?? 48 89 74 24 ?? 57 48 83 EC 40 0F 10 81";
        internal const string JoinCrossParty = "E8 ?? ?? ?? ?? 41 0F B7 07 49 8B CC";
    }

    private delegate byte RequestPartyFinderListingsDelegate(IntPtr agent, byte categoryIdx);

    private delegate IntPtr JoinPfDelegate(IntPtr manager, IntPtr a2, int type, IntPtr packetData, uint a5);

    private RequestPartyFinderListingsDelegate? RequestPartyFinderListings { get; }
    private Hook<RequestPartyFinderListingsDelegate>? RequestPfListingsHook { get; }
    private Hook<JoinPfDelegate>? JoinPfHook { get; }

    /// <summary>
    /// The delegate for party join events.
    /// </summary>
    public delegate void JoinPfEventDelegate(PartyFinderListing listing);

    /// <summary>
    /// <para>
    /// The event that is fired when the player joins a <b>cross-world</b> party via Party Finder.
    /// </para>
    /// <para>
    /// Requires the <see cref="Hooks.PartyFinderJoins"/> hook to be enabled.
    /// </para>
    /// </summary>
    public event JoinPfEventDelegate? JoinParty;

    private IPartyFinderGui PartyFinderGui { get; }
    private bool JoinsEnabled { get; }
    private bool ListingsEnabled { get; }
    private IntPtr PartyFinderAgent { get; set; } = IntPtr.Zero;
    private Dictionary<uint, PartyFinderListing> Listings { get; } = new();
    private int LastBatch { get; set; } = -1;

    /// <summary>
    /// <para>
    /// The current Party Finder listings that have been displayed.
    /// </para>
    /// <para>
    /// This dictionary is cleared and updated each time the Party Finder is requested, and it only contains the category selected in the Party Finder addon.
    /// </para>
    /// <para>
    /// Keys are the listing ID for fast lookup by ID. Values are the listing itself.
    /// </para>
    /// </summary>
    public IReadOnlyDictionary<uint, PartyFinderListing> CurrentListings => this.Listings;

    internal PartyFinder(ISigScanner scanner, IPartyFinderGui partyFinderGui, IGameInteropProvider interop, Hooks hooks) {
        this.PartyFinderGui = partyFinderGui;

        this.ListingsEnabled = hooks.HasFlag(Hooks.PartyFinderListings);
        this.JoinsEnabled = hooks.HasFlag(Hooks.PartyFinderJoins);

        if (this.ListingsEnabled || this.JoinsEnabled) {
            this.PartyFinderGui.ReceiveListing += this.ReceiveListing;
        }

        if (scanner.TryScanText(Signatures.RequestListings, out var requestPfPtr, "Party Finder listings")) {
            this.RequestPartyFinderListings = Marshal.GetDelegateForFunctionPointer<RequestPartyFinderListingsDelegate>(requestPfPtr);

            if (this.ListingsEnabled) {
                this.RequestPfListingsHook = interop.HookFromAddress<RequestPartyFinderListingsDelegate>(requestPfPtr, this.OnRequestPartyFinderListings);
                this.RequestPfListingsHook.Enable();
            }
        }

        if (this.JoinsEnabled && scanner.TryScanText(Signatures.JoinCrossParty, out var joinPtr, "Party Finder joins")) {
            this.JoinPfHook = interop.HookFromAddress<JoinPfDelegate>(joinPtr, this.JoinPfDetour);
            this.JoinPfHook.Enable();
        }
    }

    /// <inheritdoc />
    public void Dispose() {
        this.PartyFinderGui.ReceiveListing -= this.ReceiveListing;
        this.JoinPfHook?.Dispose();
        this.RequestPfListingsHook?.Dispose();
    }

    private void ReceiveListing(PartyFinderListing listing, PartyFinderListingEventArgs args) {
        if (args.BatchNumber != this.LastBatch) {
            this.Listings.Clear();
        }

        this.LastBatch = args.BatchNumber;

        this.Listings[listing.Id] = listing;
    }

    private byte OnRequestPartyFinderListings(IntPtr agent, byte categoryIdx) {
        this.PartyFinderAgent = agent;
        return this.RequestPfListingsHook!.Original(agent, categoryIdx);
    }

    private IntPtr JoinPfDetour(IntPtr manager, IntPtr a2, int type, IntPtr packetData, uint a5) {
        // Updated: 5.5
        const int idOffset = -0x20;

        var ret = this.JoinPfHook!.Original(manager, a2, type, packetData, a5);

        if (this.JoinParty == null || (JoinType) type != JoinType.PartyFinder || packetData == IntPtr.Zero) {
            return ret;
        }

        try {
            var id = (uint) Marshal.ReadInt32(packetData + idOffset);
            if (this.Listings.TryGetValue(id, out var listing)) {
                this.JoinParty?.Invoke(listing);
            }
        } catch (Exception ex) {
            Logger.Log.Error(ex, "Exception in PF join detour");
        }

        return ret;
    }

    /// <summary>
    /// <para>
    /// Refresh the Party Finder listings. This does not open the Party Finder.
    /// </para>
    /// <para>
    /// This maintains the currently selected category.
    /// </para>
    /// </summary>
    /// <exception cref="InvalidOperationException">If the <see cref="Hooks.PartyFinderListings"/> hook is not enabled or if the signature for this function could not be found</exception>
    public void RefreshListings() {
        if (this.RequestPartyFinderListings == null) {
            throw new InvalidOperationException("Could not find signature for Party Finder listings");
        }

        if (!this.ListingsEnabled) {
            throw new InvalidOperationException("PartyFinder hooks are not enabled");
        }

        // Updated 6.0
        const int categoryOffset = 11_031;

        if (this.PartyFinderAgent == IntPtr.Zero) {
            return;
        }

        var categoryIdx = Marshal.ReadByte(this.PartyFinderAgent + categoryOffset);
        this.RequestPartyFinderListings(this.PartyFinderAgent, categoryIdx);
    }
}

internal enum JoinType : byte {
    /// <summary>
    /// Join via invite or party conversion.
    /// </summary>
    Normal = 0,

    /// <summary>
    /// Join via Party Finder.
    /// </summary>
    PartyFinder = 1,

    Unknown2 = 2,

    /// <summary>
    /// Remain in cross-world party after leaving a duty.
    /// </summary>
    LeaveDuty = 3,

    Unknown4 = 4,
}