using System.Diagnostics;
using System.Runtime.InteropServices;
using RobotAndDonkey.Game.Execution.Results;
using RobotAndDonkey.Game.GameState;
using RobotAndDonkey.Game.Intents;

namespace RobotAndDonkey.Game.Modifiers;

public class ModifierStack
{
    public void Push(Entity entity)
    {
        m_Stack.Push((entity, entity.Modifiers));
    }

    public void Pop()
    {
        _ = m_Stack.Pop();
    }

    private IEnumerable<(Entity Owner, Modifier Modifier)> GetModifiers()
    {
        foreach (var (owner, modifiers) in m_Stack)
        {
            foreach (var modifier in modifiers)
            {
                if (modifier.DebuffSources.Count == 0)
                    yield return (owner, modifier);
            }
        }
    }

    public void Execute(Guid requestId, CoreLoop coreLoop, List<Intent> intents, List<Result> results, bool force, bool verbose)
    {
        var newIntents = new List<Intent>();
        var index = 0;
        do
        {
            var currentIntents = intents[index..];
            var modifiableIntents = currentIntents.Where(i => !i.Immune).ToArray();
            foreach (var (owner, modifier) in GetModifiers())
            {
                if (modifier.DebuffSources.Count == 0)
                {
                    if (verbose)
                        Debug.WriteLine($"Before {modifier}");
                    modifier.Before(requestId, modifiableIntents, coreLoop, owner, newIntents, results);
                }
            }

            foreach (var intent in currentIntents)
            {
                var isValid = intent.IsValid(coreLoop);
                if (force || isValid)
                {
                    if (verbose)
                        Debug.WriteLine($"Run {(isValid ? "Valid" : "Invalid")} intent: {intent}");
                    intent.Run(requestId, coreLoop, newIntents, results);
                }
            }

            foreach (var (owner, modifier) in GetModifiers())
            {
                if (modifier.DebuffSources.Count == 0)
                {
                    if (verbose)
                        Debug.WriteLine($"After {modifier}");
                    modifier.After(requestId, modifiableIntents, coreLoop, owner, newIntents, results);
                }
            }

            index = intents.Count;
            intents.AddRange(newIntents);
            newIntents.Clear();
        } while (index < intents.Count);
    }

    private readonly Stack<(Entity Owner, IReadOnlyList<Modifier> Modifiers)> m_Stack = [];
}