#nullable enable

using System;
using System.Linq;
using Godot;
using SideScrollerGame.Content.Samples;
using SideScrollerGame.Debug.Commands;

namespace SideScrollerGame.Debug;

public partial class DebugCommandNode : Node
{
    public override void _Ready()
    {
        ProcessMode = ProcessModeEnum.Always;
        _ = Service;
        ApplyEngineState();
    }

    public override void _Process(double delta)
    {
        if (m_PendingFrameStep)
        {
            GetTree().Paused = State.IsPaused;
            m_PendingFrameStep = false;
            return;
        }

        if (State.FrameStepRequestCount <= m_AppliedFrameStepCount)
        {
            return;
        }

        m_AppliedFrameStepCount = State.FrameStepRequestCount;
        GetTree().Paused = false;
        m_PendingFrameStep = true;
    }

    public void Initialize(DebugSettings settings)
    {
        m_Service = new DebugCommandService(SampleContent.CreateRegistry(), settings.Seed);
        m_Service.StateChanged += _ => ApplyEngineState();
        GD.Seed((ulong)settings.Seed);
        ApplyEngineState();
    }

    public DebugCommandResult Execute(DebugCommandId commandId, string? argument = null)
    {
        DebugCommandResult result = Service.Execute(commandId, argument);
        if (!result.Succeeded)
        {
            return result;
        }

        if (commandId == DebugCommandId.SetSeed && int.TryParse(argument, out int seed))
        {
            GD.Seed((ulong)seed);
        }
        else if (commandId == DebugCommandId.ReloadScene)
        {
            ReloadScene();
        }

        return result;
    }

    public DebugCommandService Service
    {
        get
        {
            if (m_Service is null)
            {
                m_Service = new DebugCommandService(SampleContent.CreateRegistry(), 1);
                m_Service.StateChanged += _ => ApplyEngineState();
            }

            return m_Service;
        }
    }

    private DebugRuntimeState State => Service.State;

    private void ApplyEngineState()
    {
        Engine.TimeScale = State.TimeScale;
        if (!m_PendingFrameStep)
        {
            GetTree().Paused = State.IsPaused;
        }
    }

    private void ReloadScene()
    {
        if (IsHeadlessSmokeScript())
        {
            return;
        }

        GetTree().ReloadCurrentScene();
    }

    private static bool IsHeadlessSmokeScript()
    {
        return DisplayServer.GetName().Equals("headless", StringComparison.OrdinalIgnoreCase) && OS.GetCmdlineUserArgs().Any(argument => argument.Equals("--debug-script=foundation-smoke", StringComparison.OrdinalIgnoreCase));
    }

    private DebugCommandService? m_Service;
    private int m_AppliedFrameStepCount;
    private bool m_PendingFrameStep;
}