/* Copyright (C) 2023 Wildfire Games.
 * This file is part of 0 A.D.
 *
 * 0 A.D. is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 2 of the License, or
 * (at your option) any later version.
 *
 * 0 A.D. is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with 0 A.D.  If not, see <http://www.gnu.org/licenses/>.
 */

#ifndef INCLUDED_MINIMAPTEXTURE
#define INCLUDED_MINIMAPTEXTURE

#include "graphics/Color.h"
#include "graphics/ShaderTechniquePtr.h"
#include "graphics/Texture.h"
#include "maths/Vector2D.h"
#include "renderer/backend/IDeviceCommandContext.h"
#include "renderer/backend/IShaderProgram.h"
#include "renderer/backend/ITexture.h"
#include "renderer/VertexArray.h"

#include <memory>
#include <string>
#include <unordered_map>
#include <vector>

class CLOSTexture;
class CSimulation2;
class CTerrain;
class CTerritoryTexture;

class CMiniMapTexture
{
	NONCOPYABLE(CMiniMapTexture);
public:
	CMiniMapTexture(Renderer::Backend::IDevice* device, CSimulation2& simulation);
	~CMiniMapTexture();

	/**
	 * Marks the texture as dirty if it's old enough to redraw it on Render.
	 */
	void Update(const float deltaRealTime);

	/**
	 * Redraws the texture if it's dirty.
	 */
	void Render(
		Renderer::Backend::IDeviceCommandContext* deviceCommandContext,
		CLOSTexture& losTexture, CTerritoryTexture& territoryTexture);

	const CTexturePtr& GetTexture() const { return m_FinalTexture; }

	bool IsFlipped() const { return m_Flipped; }

	/**
	 * @return The maximum height for unit passage in water.
	 */
	static float GetShallowPassageHeight();

	struct Icon
	{
		CTexturePtr texture;
		CColor color;
		CVector2D worldPosition;
		float halfSize;
	};
	// Returns icons for corresponding entities on the minimap texture.
	const std::vector<Icon>& GetIcons() { return m_Icons; }

private:
	void CreateTextures(
		Renderer::Backend::IDeviceCommandContext* deviceCommandContext,
		const CTerrain& terrain);
	void DestroyTextures();
	void RebuildTerrainTexture(
		Renderer::Backend::IDeviceCommandContext* deviceCommandContext,
		const CTerrain& terrain);
	void RenderFinalTexture(
		Renderer::Backend::IDeviceCommandContext* deviceCommandContext,
		CLOSTexture& losTexture, CTerritoryTexture& territoryTexture);
	void UpdateAndUploadEntities(
		Renderer::Backend::IDeviceCommandContext* deviceCommandContext,
		const float entityRadius, const double& currentTime);
	void DrawEntities(
		Renderer::Backend::IDeviceCommandContext* deviceCommandContext,
		const float entityRadius);

	CSimulation2& m_Simulation;

	bool m_TerrainTextureDirty = true;
	bool m_FinalTextureDirty = true;
	double m_LastFinalTextureUpdate = 0.0;
	bool m_Flipped = false;

	// minimap texture handles
	std::unique_ptr<Renderer::Backend::ITexture> m_TerrainTexture;

	CTexturePtr m_FinalTexture;

	std::unique_ptr<Renderer::Backend::IFramebuffer>
		m_FinalTextureFramebuffer;

	// texture data
	std::unique_ptr<u32[]> m_TerrainData;

	// map size
	ssize_t m_MapSize = 0;

	// Maximal water height to allow the passage of a unit (for underwater shallows).
	float m_ShallowPassageHeight = 0.0f;
	float m_WaterHeight = 0.0f;

	Renderer::Backend::IVertexInputLayout* m_QuadVertexInputLayout = nullptr;
	Renderer::Backend::IVertexInputLayout* m_EntitiesVertexInputLayout = nullptr;

	VertexIndexArray m_IndexArray;
	VertexArray m_VertexArray;
	VertexArray::Attribute m_AttributePos;
	VertexArray::Attribute m_AttributeColor;

	bool m_UseInstancing = false;
	// Vertex data if instancing is supported.
	VertexArray m_InstanceVertexArray;
	VertexArray::Attribute m_InstanceAttributePosition;

	CShaderTechniquePtr m_TerritoryTechnique;

	size_t m_EntitiesDrawn = 0;

	double m_PingDuration = 25.0;
	double m_HalfBlinkDuration = 0.0;
	double m_NextBlinkTime = 0.0;
	bool m_BlinkState = false;

	std::vector<Icon> m_Icons;
	// We store the map as a member to avoid redundant reallocations on each
	// update. We use a grid approach to combine icons by distance.
	struct CellIconKey
	{
		std::string path;
		u8 r, g, b;
	};
	struct CellIconKeyHash
	{
		size_t operator()(const CellIconKey& key) const;
	};
	struct CellIconKeyEqual
	{
		bool operator()(const CellIconKey& lhs, const CellIconKey& rhs) const;
	};
	struct CellIcon
	{
		// TODO: use CVector2DI.
		u16 gridX, gridY;
		float halfSize;
		CVector2D worldPosition;
	};
	std::unordered_map<CellIconKey, std::vector<CellIcon>, CellIconKeyHash, CellIconKeyEqual> m_IconsCache;
};

#endif // INCLUDED_MINIMAPTEXTURE