using System;
using AcDream.Core.Spells;

namespace AcDream.App.Spells;

/// <summary>
/// App-layer owner for retail cast intent. It validates the client-owned
/// selection rules, stops movement, and emits exactly one targeted or
/// untargeted request. ACE owns every gameplay result after that boundary.
/// </summary>
/// <remarks>
/// Port of <c>ClientMagicSystem::CastSpell</c> (0x00568040) and
/// <c>FreeHandsAndCastSpell</c> (0x00566EF0). This controller deliberately
/// does not consume mana/components or start local effects.
/// </remarks>
public sealed class SpellCastingController
{
    private readonly Spellbook _spellbook;
    private readonly Func<uint?> _selectedObject;
    private readonly Func<uint> _localPlayerId;
    private readonly Action _stopCompletely;
    private readonly Action<uint> _sendUntargeted;
    private readonly Action<uint, uint> _sendTargeted;
    private readonly Action<string> _displayMessage;
    private readonly Func<uint, SpellMetadata, bool> _targetCompatible;
    private readonly Func<uint, SpellMetadata, bool> _targetCompatibleSilent;
    private readonly Func<uint, bool> _hasRequiredComponents;
    private readonly Action _incrementBusy;
    private readonly Func<bool> _canSend;

    public SpellCastingController(
        Spellbook spellbook,
        Func<uint?> selectedObject,
        Func<uint> localPlayerId,
        Action stopCompletely,
        Action<uint> sendUntargeted,
        Action<uint, uint> sendTargeted,
        Action<string> displayMessage,
        Func<uint, SpellMetadata, bool>? targetCompatible = null,
        Func<uint, bool>? hasRequiredComponents = null,
        Action? incrementBusy = null,
        Func<bool>? canSend = null,
        Func<uint, SpellMetadata, bool>? targetCompatibleSilent = null)
    {
        _spellbook = spellbook ?? throw new ArgumentNullException(nameof(spellbook));
        _selectedObject = selectedObject ?? throw new ArgumentNullException(nameof(selectedObject));
        _localPlayerId = localPlayerId ?? throw new ArgumentNullException(nameof(localPlayerId));
        _stopCompletely = stopCompletely ?? throw new ArgumentNullException(nameof(stopCompletely));
        _sendUntargeted = sendUntargeted ?? throw new ArgumentNullException(nameof(sendUntargeted));
        _sendTargeted = sendTargeted ?? throw new ArgumentNullException(nameof(sendTargeted));
        _displayMessage = displayMessage ?? throw new ArgumentNullException(nameof(displayMessage));
        _targetCompatible = targetCompatible ?? ((_, _) => true);
        _targetCompatibleSilent = targetCompatibleSilent ?? _targetCompatible;
        _hasRequiredComponents = hasRequiredComponents ?? (_ => true);
        _incrementBusy = incrementBusy ?? (() => { });
        _canSend = canSend ?? (() => true);
    }

    public uint? LastRequestedSpellId { get; private set; }
    public uint? LastRequestedTargetId { get; private set; }

    public bool IsTargetReady(uint spellId)
    {
        if (!_spellbook.Knows(spellId)
            || !_spellbook.TryGetMetadata(spellId, out SpellMetadata spell))
            return false;
        if (spell.IsSelfTargeted || spell.IsUntargeted || spell.TargetMask == 0u)
            return true;
        return _selectedObject() is uint target and not 0u
            && _targetCompatibleSilent(target, spell);
    }

    public CastRequestResult Cast(uint spellId)
    {
        if (!_spellbook.Knows(spellId) || !_spellbook.TryGetMetadata(spellId, out SpellMetadata spell))
        {
            _displayMessage("You do not know that spell.");
            return CastRequestResult.UnknownSpell;
        }

        if (!_hasRequiredComponents(spellId))
        {
            _displayMessage("You do not have all of this spell's components.");
            return CastRequestResult.MissingComponents;
        }

        uint? target;
        bool untargeted;
        if (spell.IsSelfTargeted)
        {
            uint playerId = _localPlayerId();
            target = playerId == 0 ? null : playerId;
            untargeted = target is null;
        }
        else if (spell.IsUntargeted || spell.TargetMask == 0)
        {
            target = null;
            untargeted = true;
        }
        else
        {
            target = _selectedObject();
            untargeted = false;
            if (target is null or 0)
            {
                _displayMessage("You must select a suitable target.");
                return CastRequestResult.NoTarget;
            }
            if (!_targetCompatible(target.Value, spell))
                return CastRequestResult.IncompatibleTarget;
        }

        if (!_canSend())
        {
            _displayMessage("You cannot cast a spell right now.");
            return CastRequestResult.Unavailable;
        }

        try
        {
            _stopCompletely();
            LastRequestedSpellId = spellId;
            LastRequestedTargetId = target;
            if (untargeted)
                _sendUntargeted(spellId);
            else
                _sendTargeted(target!.Value, spellId);
            // FreeHandsAndCastSpell @ 0x00566EF0 increments the shared UI
            // busy reference only after Event_Cast has been emitted. The
            // matching server UseDone event decrements it.
            _incrementBusy();
        }
        catch
        {
            LastRequestedSpellId = null;
            LastRequestedTargetId = null;
            throw;
        }
        return CastRequestResult.Sent;
    }

    public void Reset()
    {
        LastRequestedSpellId = null;
        LastRequestedTargetId = null;
    }
}

public enum CastRequestResult
{
    Sent,
    UnknownSpell,
    NoTarget,
    IncompatibleTarget,
    MissingComponents,
    Unavailable,
}