using System;
using UnityEngine.Rendering;
using UnityEngine.Profiling;

namespace UnityEngine.Experimental.Rendering
{
    public struct ProfilingSample : IDisposable
    {
        readonly CommandBuffer m_Cmd;
        readonly string m_Name;

        bool m_Disposed;
        CustomSampler m_Sampler;

        public ProfilingSample(CommandBuffer cmd, string name, CustomSampler sampler = null)
        {
            m_Cmd = cmd;
            m_Name = name;
            m_Disposed = false;
            cmd.BeginSample(name);
            m_Sampler = sampler;
            if (m_Sampler != null)
                m_Sampler.Begin();
        }

        // Shortcut to string.Format() using only one argument (reduces Gen0 GC pressure)
        public ProfilingSample(CommandBuffer cmd, string format, object arg) : this(cmd, string.Format(format, arg))
        {
        }

        // Shortcut to string.Format() with variable amount of arguments - for performance critical
        // code you should pre-build & cache the marker name instead of using this
        public ProfilingSample(CommandBuffer cmd, string format, params object[] args) : this(cmd, string.Format(format, args))
        {
        }

        public void Dispose()
        {
            Dispose(true);
        }

        // Protected implementation of Dispose pattern.
        void Dispose(bool disposing)
        {
            if (m_Disposed)
                return;

            // As this is a struct, it could have been initialized using an empty constructor so we
            // need to make sure `cmd` isn't null to avoid a crash. Switching to a class would fix
            // this but will generate garbage on every frame (and this struct is used quite a lot).
            if (disposing && m_Cmd != null)
            {
                m_Cmd.EndSample(m_Name);
                if (m_Sampler != null)
                    m_Sampler.End();
            }

            m_Disposed = true;
        }
    }
}