//********************************** Banshee Engine (www.banshee3d.com) **************************************************//
//**************** Copyright (c) 2016 Marko Pintera (marko.pintera@gmail.com). All rights reserved. **********************//
#pragma once

#include "BsVulkanPrerequisites.h"
#include "BsCommandBuffer.h"
#include "BsVulkanRenderAPI.h"
#include "BsVulkanResource.h"
#include "BsVulkanGpuPipelineState.h"

namespace bs
{
	class VulkanImage;
	/** @addtogroup Vulkan
	 *  @{
	 */

	class VulkanCmdBuffer;

#define BS_MAX_VULKAN_CB_PER_QUEUE_FAMILY BS_MAX_QUEUES_PER_TYPE * 32

	/** Pool that allocates and distributes Vulkan command buffers. */
	class VulkanCmdBufferPool
	{
	public:
		VulkanCmdBufferPool(VulkanDevice& device);
		~VulkanCmdBufferPool();

		/** 
		 * Attempts to find a free command buffer, or creates a new one if not found. Caller must guarantee the provided
		 * queue family is valid. 
		 */
		VulkanCmdBuffer* getBuffer(UINT32 queueFamily, bool secondary);

	private:
		/** Command buffer pool and related information. */
		struct PoolInfo
		{
			VkCommandPool pool = VK_NULL_HANDLE;
			VulkanCmdBuffer* buffers[BS_MAX_VULKAN_CB_PER_QUEUE_FAMILY];
			UINT32 queueFamily = -1;
		};

		/** Creates a new command buffer. */
		VulkanCmdBuffer* createBuffer(UINT32 queueFamily, bool secondary);

		VulkanDevice& mDevice;
		UnorderedMap<UINT32, PoolInfo> mPools;
		UINT32 mNextId;
	};

	/** Determines where are the current descriptor sets bound to. */
	enum class DescriptorSetBindFlag
	{
		None = 0,
		Graphics = 1 << 0,
		Compute = 1 << 1
	};

	typedef Flags<DescriptorSetBindFlag> DescriptorSetBindFlags;
	BS_FLAGS_OPERATORS(DescriptorSetBindFlag)

	/** 
	 * Represents a direct wrapper over an internal Vulkan command buffer. This is unlike VulkanCommandBuffer which is a
	 * higher level class, and it allows for re-use by internally using multiple low-level command buffers.
	 */
	class VulkanCmdBuffer
	{
		/** Possible states a command buffer can be in. */
		enum class State
		{
			/** Buffer is ready to be re-used. */
			Ready,
			/** Buffer is currently recording commands, but isn't recording a render pass. */
			Recording,
			/** Buffer is currently recording render pass commands. */
			RecordingRenderPass,
			/** Buffer is done recording but hasn't been submitted. */
			RecordingDone,
			/** Buffer is done recording and is currently submitted on a queue. */
			Submitted
		};

	public:
		VulkanCmdBuffer(VulkanDevice& device, UINT32 id, VkCommandPool pool, UINT32 queueFamily, bool secondary);
		~VulkanCmdBuffer();

		/** Returns an unique identifier of this command buffer. */
		UINT32 getId() const { return mId; }

		/** Returns the index of the queue family this command buffer is executing on. */
		UINT32 getQueueFamily() const { return mQueueFamily; }

		/** Returns the index of the device this command buffer will execute on. */
		UINT32 getDeviceIdx() const;

		/** Makes the command buffer ready to start recording commands. */
		void begin();

		/** Ends command buffer command recording (as started with begin()). */
		void end();

		/** Begins render pass recording. Must be called within begin()/end() calls. */
		void beginRenderPass();

		/** Ends render pass recording (as started with beginRenderPass(). */
		void endRenderPass();

		/** 
		 * Submits the command buffer for execution. 
		 * 
		 * @param[in]	queue		Queue to submit the command buffer on.
		 * @param[in]	queueIdx	Index of the queue the command buffer was submitted on. Note that this may be different
		 *							from the actual VulkanQueue index since multiple command buffer queue indices can map
		 *							to the same queue.
		 * @param[in]	syncMask	Mask that controls which other command buffers does this command buffer depend upon
		 *							(if any). See description of @p syncMask parameter in RenderAPICore::executeCommands().
		 */
		void submit(VulkanQueue* queue, UINT32 queueIdx, UINT32 syncMask);

		/** Returns the handle to the internal Vulkan command buffer wrapped by this object. */
		VkCommandBuffer getHandle() const { return mCmdBuffer; }

		/** Returns a fence that can be used for tracking when the command buffer is done executing. */
		VkFence getFence() const { return mFence; }

		/** 
		 * Returns a semaphore that may be used for synchronizing execution between command buffers executing on different 
		 * queues. 
		 */
		VkSemaphore getSemaphore() const { return mSemaphore; }

		/** Returns true if the command buffer is currently being processed by the device. */
		bool isSubmitted() const { return mState == State::Submitted; }

		/** Returns true if the command buffer is currently recording (but not within a render pass). */
		bool isRecording() const { return mState == State::Recording; }

		/** Returns true if the command buffer is ready to be submitted to a queue. */
		bool isReadyForSubmit() const { return mState == State::RecordingDone; }

		/** Returns true if the command buffer is currently recording a render pass. */
		bool isInRenderPass() const { return mState == State::RecordingRenderPass; }

		/** Returns a counter that gets incremented whenever the command buffer is done executing. */
		UINT32 getFenceCounter() const { return mFenceCounter; }

		/** Checks the internal fence and changes command buffer state if done executing. */
		void refreshFenceStatus();

		/** 
		 * Lets the command buffer know that the provided resource has been queued on it, and will be used by the
		 * device when the command buffer is submitted. If a resource is an image or a buffer use the more specific
		 * registerResource() overload.
		 */
		void registerResource(VulkanResource* res, VulkanUseFlags flags);

		/** 
		 * Lets the command buffer know that the provided image resource has been queued on it, and will be used by the
		 * device when the command buffer is submitted.
		 */
		void registerResource(VulkanImage* res, VkAccessFlags accessFlags, VkImageLayout layout, 
			VulkanUseFlags flags, bool isFBAttachment = false);

		/** 
		 * Lets the command buffer know that the provided image resource has been queued on it, and will be used by the
		 * device when the command buffer is submitted. 
		 */
		void registerResource(VulkanBuffer* res, VkAccessFlags accessFlags, VulkanUseFlags flags);

		/** 
		 * Lets the command buffer know that the provided framebuffer resource has been queued on it, and will be used by
		 * the device when the command buffer is submitted.
		 */
		void registerResource(VulkanFramebuffer* res, VulkanUseFlags flags);

		/************************************************************************/
		/* 								COMMANDS	                     		*/
		/************************************************************************/

		/** 
		 * Assigns a render target the the command buffer. This render target's framebuffer and render pass will be used
		 * when beginRenderPass() is called. Command buffer must not be currently recording a render pass.
		 */
		void setRenderTarget(const SPtr<RenderTargetCore>& rt, bool readOnlyDepthStencil, RenderSurfaceMask loadMask);

		/** Clears the entirety currently bound render target. */
		void clearRenderTarget(UINT32 buffers, const Color& color, float depth, UINT16 stencil, UINT8 targetMask);

		/** Clears the viewport portion of the currently bound render target. */
		void clearViewport(UINT32 buffers, const Color& color, float depth, UINT16 stencil, UINT8 targetMask);

		/** Assigns a pipeline state to use for subsequent draw commands. */
		void setPipelineState(const SPtr<GraphicsPipelineStateCore>& state);

		/** Assigns a pipeline state to use for subsequent dispatch commands. */
		void setPipelineState(const SPtr<ComputePipelineStateCore>& state);

		/** Assign GPU params to the GPU programs bound by the pipeline state. */
		void setGpuParams(const SPtr<GpuParamsCore>& gpuParams);

		/** Sets the current viewport which determine to which portion of the render target to render to. */
		void setViewport(const Rect2& area);

		/** 
		 * Sets the scissor rectangle area which determines in which area if the viewport are the fragments allowed to be
		 * generated. Only relevant if enabled on the pipeline state.
		 */
		void setScissorRect(const Rect2I& area);

		/** Sets a stencil reference value that will be used for comparisons in stencil operations, if enabled. */
		void setStencilRef(UINT32 value);

		/** Changes how are primitives interpreted as during rendering. */
		void setDrawOp(DrawOperationType drawOp);

		/** Sets one or multiple vertex buffers that will be used for subsequent draw() or drawIndexed() calls. */
		void setVertexBuffers(UINT32 index, SPtr<VertexBufferCore>* buffers, UINT32 numBuffers);

		/** Sets an index buffer that will be used for subsequent drawIndexed() calls. */
		void setIndexBuffer(const SPtr<IndexBufferCore>& buffer);

		/** Sets a declaration that determines how are vertex buffer contents interpreted. */
		void setVertexDeclaration(const SPtr<VertexDeclarationCore>& decl);

		/** Executes a draw command using the currently bound graphics pipeline, vertex buffer and render target. */
		void draw(UINT32 vertexOffset, UINT32 vertexCount, UINT32 instanceCount);

		/** Executes a draw command using the currently bound graphics pipeline, index & vertex buffer and render target. */
		void drawIndexed(UINT32 startIndex, UINT32 indexCount, UINT32 vertexOffset, UINT32 instanceCount);

		/** Executes a dispatch command using the currently bound compute pipeline. */
		void dispatch(UINT32 numGroupsX, UINT32 numGroupsY, UINT32 numGroupsZ);

	private:
		friend class VulkanCmdBufferPool;
		friend class VulkanCommandBuffer;

		/** Contains information about a single Vulkan resource bound/used on this command buffer. */
		struct ResourceUseHandle
		{
			bool used;
			VulkanUseFlags flags;
		};

		/** Contains information about a single Vulkan buffer resource bound/used on this command buffer. */
		struct BufferInfo
		{
			VkAccessFlags accessFlags;
			ResourceUseHandle useHandle;
		};

		/** Contains information about a single Vulkan image resource bound/used on this command buffer. */
		struct ImageInfo
		{
			VkAccessFlags accessFlags;
			VkImageSubresourceRange range;
			ResourceUseHandle useHandle;

			// Only relevant for layout transitions
			VkImageLayout currentLayout;
			VkImageLayout requiredLayout;
			VkImageLayout finalLayout;

			bool isFBAttachment : 1;
			bool isShaderInput : 1;
		};

		/** Checks if all the prerequisites for rendering have been made (e.g. render target and pipeline state are set. */
		bool isReadyForRender();

		/** Binds the current graphics pipeline to the command buffer. Returns true if bind was successful. */
		bool bindGraphicsPipeline();

		/** Binds any dynamic states to the pipeline, as required. 
		 *
		 * @param[in]	forceAll	If true all states will be bound. If false only states marked as dirty will be bound.
		 */
		void bindDynamicStates(bool forceAll);

		/** Clears the specified area of the currently bound render target. */
		void clearViewport(const Rect2I& area, UINT32 buffers, const Color& color, float depth, UINT16 stencil, 
			UINT8 targetMask);

		UINT32 mId;
		UINT32 mQueueFamily;
		State mState;
		VulkanDevice& mDevice;
		VkCommandPool mPool;
		VkCommandBuffer mCmdBuffer;
		VkFence mFence;
		VkSemaphore mSemaphore;
		UINT32 mFenceCounter;

		VulkanFramebuffer* mFramebuffer;
		VkSemaphore mPresentSemaphore;
		UINT32 mRenderTargetWidth;
		UINT32 mRenderTargetHeight;
		bool mRenderTargetDepthReadOnly;
		RenderSurfaceMask mRenderTargetLoadMask;

		UnorderedMap<VulkanResource*, ResourceUseHandle> mResources;
		UnorderedMap<VulkanResource*, UINT32> mImages;
		UnorderedMap<VulkanResource*, BufferInfo> mBuffers;
		Vector<ImageInfo> mImageInfos;
		UINT32 mGlobalQueueIdx;

		SPtr<VulkanGraphicsPipelineStateCore> mGraphicsPipeline;
		SPtr<VulkanComputePipelineStateCore> mComputePipeline;
		SPtr<VertexDeclarationCore> mVertexDecl;
		Rect2 mViewport;
		Rect2I mScissor;
		UINT32 mStencilRef;
		DrawOperationType mDrawOp;
		UINT32 mNumBoundDescriptorSets;
		bool mGfxPipelineRequiresBind : 1;
		bool mCmpPipelineRequiresBind : 1;
		bool mViewportRequiresBind : 1;
		bool mStencilRefRequiresBind : 1;
		bool mScissorRequiresBind : 1;
		DescriptorSetBindFlags mDescriptorSetsBindState;

		VkSemaphore mSemaphoresTemp[BS_MAX_UNIQUE_QUEUES + 1]; // +1 for present semaphore
		VkBuffer mVertexBuffersTemp[BS_MAX_BOUND_VERTEX_BUFFERS];
		VkDeviceSize mVertexBufferOffsetsTemp[BS_MAX_BOUND_VERTEX_BUFFERS];
		VkDescriptorSet* mDescriptorSetsTemp;
		UnorderedMap<UINT32, TransitionInfo> mTransitionInfoTemp;
		Vector<VkImageMemoryBarrier> mLayoutTransitionBarriersTemp;
		UnorderedMap<VulkanImage*, UINT32> mQueuedLayoutTransitions;
	};

	/** CommandBuffer implementation for Vulkan. */
	class VulkanCommandBuffer : public CommandBuffer
	{
	public:
		/** 
		 * Submits the command buffer for execution. 
		 * 
		 * @param[in]	syncMask	Mask that controls which other command buffers does this command buffer depend upon
		 *							(if any). See description of @p syncMask parameter in RenderAPICore::executeCommands().
		 */
		void submit(UINT32 syncMask);

		/** 
		 * Returns the internal command buffer. 
		 * 
		 * @note	This buffer will change after a submit() call.
		 */
		VulkanCmdBuffer* getInternal() const { return mBuffer; }

	private:
		friend class VulkanCommandBufferManager;

		VulkanCommandBuffer(VulkanDevice& device, GpuQueueType type, UINT32 deviceIdx, UINT32 queueIdx,
			bool secondary);

		/** 
		 * Tasks the command buffer to find a new internal command buffer. Call this after the command buffer has been
		 * submitted to a queue (it's not allowed to be used until the queue is done with it).
		 */
		void acquireNewBuffer();

		VulkanCmdBuffer* mBuffer;
		VulkanDevice& mDevice;
		VulkanQueue* mQueue;
		UINT32 mIdMask;
	};

	/** @} */
}