// Copyright (c) 2008-2023 the Urho3D project
// License: MIT

/// \file

#pragma once

#include "../GraphicsAPI/GraphicsDefs.h"
#include "../Resource/Resource.h"

namespace Urho3D
{

class ShaderVariation;

/// Lighting mode of a pass.
enum PassLightingMode
{
    LIGHTING_UNLIT = 0,
    LIGHTING_PERVERTEX,
    LIGHTING_PERPIXEL
};

/// %Material rendering pass, which defines shaders and render state.
class URHO3D_API Pass : public RefCounted
{
public:
    /// Construct.
    explicit Pass(const String& name);
    /// Destruct.
    ~Pass() override;

    /// Set blend mode.
    /// @property
    void SetBlendMode(BlendMode mode);
    /// Set culling mode override. By default culling mode is read from the material instead. Set the illegal culling mode MAX_CULLMODES to disable override again.
    /// @property
    void SetCullMode(CullMode mode);
    /// Set depth compare mode.
    /// @property
    void SetDepthTestMode(CompareMode mode);
    /// Set pass lighting mode, affects what shader variations will be attempted to be loaded.
    /// @property
    void SetLightingMode(PassLightingMode mode);
    /// Set depth write on/off.
    /// @property
    void SetDepthWrite(bool enable);
    /// Set alpha-to-coverage on/off.
    /// @property
    void SetAlphaToCoverage(bool enable);
    /// Set whether requires desktop level hardware.
    /// @property{set_desktop}
    void SetIsDesktop(bool enable);
    /// Set vertex shader name.
    /// @property
    void SetVertexShader(const String& name);
    /// Set pixel shader name.
    /// @property
    void SetPixelShader(const String& name);
    /// Set vertex shader defines. Separate multiple defines with spaces.
    /// @property
    void SetVertexShaderDefines(const String& defines);
    /// Set pixel shader defines. Separate multiple defines with spaces.
    /// @property
    void SetPixelShaderDefines(const String& defines);
    /// Set vertex shader define excludes. Use to mark defines that the shader code will not recognize, to prevent compiling redundant shader variations.
    /// @property
    void SetVertexShaderDefineExcludes(const String& excludes);
    /// Set pixel shader define excludes. Use to mark defines that the shader code will not recognize, to prevent compiling redundant shader variations.
    /// @property
    void SetPixelShaderDefineExcludes(const String& excludes);
    /// Reset shader pointers.
    void ReleaseShaders();
    /// Mark shaders loaded this frame.
    void MarkShadersLoaded(i32 frameNumber);

    /// Return pass name.
    const String& GetName() const { return name_; }

    /// Return pass index. This is used for optimal render-time pass queries that avoid map lookups.
    i32 GetIndex() const { return index_; }

    /// Return blend mode.
    /// @property
    BlendMode GetBlendMode() const { return blendMode_; }

    /// Return culling mode override. If pass is not overriding culling mode (default), the illegal mode MAX_CULLMODES is returned.
    /// @property
    CullMode GetCullMode() const { return cullMode_; }

    /// Return depth compare mode.
    /// @property
    CompareMode GetDepthTestMode() const { return depthTestMode_; }

    /// Return pass lighting mode.
    /// @property
    PassLightingMode GetLightingMode() const { return lightingMode_; }

    /// Return last shaders loaded frame number.
    i32 GetShadersLoadedFrameNumber() const { return shadersLoadedFrameNumber_; }

    /// Return depth write mode.
    /// @property
    bool GetDepthWrite() const { return depthWrite_; }

    /// Return alpha-to-coverage mode.
    /// @property
    bool GetAlphaToCoverage() const { return alphaToCoverage_; }

    /// Return whether requires desktop level hardware.
    /// @property
    bool IsDesktop() const { return isDesktop_; }

    /// Return vertex shader name.
    /// @property
    const String& GetVertexShader() const { return vertexShaderName_; }

    /// Return pixel shader name.
    /// @property
    const String& GetPixelShader() const { return pixelShaderName_; }

    /// Return vertex shader defines.
    /// @property
    const String& GetVertexShaderDefines() const { return vertexShaderDefines_; }

    /// Return pixel shader defines.
    /// @property
    const String& GetPixelShaderDefines() const { return pixelShaderDefines_; }

    /// Return vertex shader define excludes.
    /// @property
    const String& GetVertexShaderDefineExcludes() const { return vertexShaderDefineExcludes_; }

    /// Return pixel shader define excludes.
    /// @property
    const String& GetPixelShaderDefineExcludes() const { return pixelShaderDefineExcludes_; }

    /// Return vertex shaders.
    Vector<SharedPtr<ShaderVariation>>& GetVertexShaders() { return vertexShaders_; }

    /// Return pixel shaders.
    Vector<SharedPtr<ShaderVariation>>& GetPixelShaders() { return pixelShaders_; }

    /// Return vertex shaders with extra defines from the renderpath.
    Vector<SharedPtr<ShaderVariation>>& GetVertexShaders(const StringHash& extraDefinesHash);
    /// Return pixel shaders with extra defines from the renderpath.
    Vector<SharedPtr<ShaderVariation>>& GetPixelShaders(const StringHash& extraDefinesHash);
    /// Return the effective vertex shader defines, accounting for excludes. Called internally by Renderer.
    String GetEffectiveVertexShaderDefines() const;
    /// Return the effective pixel shader defines, accounting for excludes. Called internally by Renderer.
    String GetEffectivePixelShaderDefines() const;

private:
    /// Pass index.
    i32 index_;
    /// Blend mode.
    BlendMode blendMode_;
    /// Culling mode.
    CullMode cullMode_;
    /// Depth compare mode.
    CompareMode depthTestMode_;
    /// Lighting mode.
    PassLightingMode lightingMode_;
    /// Last shaders loaded frame number.
    i32 shadersLoadedFrameNumber_;
    /// Depth write mode.
    bool depthWrite_;
    /// Alpha-to-coverage mode.
    bool alphaToCoverage_;
    /// Require desktop level hardware flag.
    bool isDesktop_;
    /// Vertex shader name.
    String vertexShaderName_;
    /// Pixel shader name.
    String pixelShaderName_;
    /// Vertex shader defines.
    String vertexShaderDefines_;
    /// Pixel shader defines.
    String pixelShaderDefines_;
    /// Vertex shader define excludes.
    String vertexShaderDefineExcludes_;
    /// Pixel shader define excludes.
    String pixelShaderDefineExcludes_;
    /// Vertex shaders.
    Vector<SharedPtr<ShaderVariation>> vertexShaders_;
    /// Pixel shaders.
    Vector<SharedPtr<ShaderVariation>> pixelShaders_;
    /// Vertex shaders with extra defines from the renderpath.
    HashMap<StringHash, Vector<SharedPtr<ShaderVariation>>> extraVertexShaders_;
    /// Pixel shaders with extra defines from the renderpath.
    HashMap<StringHash, Vector<SharedPtr<ShaderVariation>>> extraPixelShaders_;
    /// Pass name.
    String name_;
};

/// %Material technique. Consists of several passes.
class URHO3D_API Technique : public Resource
{
    URHO3D_OBJECT(Technique, Resource);

    friend class Renderer;

public:
    /// Construct.
    explicit Technique(Context* context);
    /// Destruct.
    ~Technique() override;
    /// Register object factory.
    /// @nobind
    static void RegisterObject(Context* context);

    /// Load resource from stream. May be called from a worker thread. Return true if successful.
    bool BeginLoad(Deserializer& source) override;

    /// Set whether requires desktop level hardware.
    /// @property{set_desktop}
    void SetIsDesktop(bool enable);
    /// Create a new pass.
    Pass* CreatePass(const String& name);
    /// Remove a pass.
    void RemovePass(const String& name);
    /// Reset shader pointers in all passes.
    void ReleaseShaders();
    /// Clone the technique. Passes will be deep copied to allow independent modification.
    SharedPtr<Technique> Clone(const String& cloneName = String::EMPTY) const;

    /// Return whether requires desktop level hardware.
    /// @property
    bool IsDesktop() const { return isDesktop_; }

    /// Return whether technique is supported by the current hardware.
    /// @property
    bool IsSupported() const { return !isDesktop_ || desktopSupport_; }

    /// Return whether has a pass.
    bool HasPass(i32 passIndex) const
    {
        assert(passIndex >= 0);
        return passIndex < passes_.Size() && passes_[passIndex].Get() != nullptr;
    }

    /// Return whether has a pass by name. This overload should not be called in time-critical rendering loops; use a pre-acquired pass index instead.
    bool HasPass(const String& name) const;

    /// Return a pass, or null if not found.
    Pass* GetPass(i32 passIndex) const
    {
        assert(passIndex >= 0);
        return passIndex < passes_.Size() ? passes_[passIndex].Get() : nullptr;
    }

    /// Return a pass by name, or null if not found. This overload should not be called in time-critical rendering loops; use a pre-acquired pass index instead.
    Pass* GetPass(const String& name) const;

    /// Return a pass that is supported for rendering, or null if not found.
    Pass* GetSupportedPass(i32 passIndex) const
    {
        assert(passIndex >= 0);
        Pass* pass = passIndex < passes_.Size() ? passes_[passIndex].Get() : nullptr;
        return pass && (!pass->IsDesktop() || desktopSupport_) ? pass : nullptr;
    }

    /// Return a supported pass by name. This overload should not be called in time-critical rendering loops; use a pre-acquired pass index instead.
    Pass* GetSupportedPass(const String& name) const;

    /// Return number of passes.
    /// @property
    i32 GetNumPasses() const;
    /// Return all pass names.
    /// @property
    Vector<String> GetPassNames() const;
    /// Return all passes.
    /// @property
    Vector<Pass*> GetPasses() const;

    /// Return a clone with added shader compilation defines. Called internally by Material.
    SharedPtr<Technique> CloneWithDefines(const String& vsDefines, const String& psDefines);

    /// Return a pass type index by name. Allocate new if not used yet.
    static i32 GetPassIndex(const String& passName);

    /// Index for base pass. Initialized once GetPassIndex() has been called for the first time.
    static i32 basePassIndex;
    /// Index for alpha pass. Initialized once GetPassIndex() has been called for the first time.
    static i32 alphaPassIndex;
    /// Index for prepass material pass. Initialized once GetPassIndex() has been called for the first time.
    static i32 materialPassIndex;
    /// Index for deferred G-buffer pass. Initialized once GetPassIndex() has been called for the first time.
    static i32 deferredPassIndex;
    /// Index for per-pixel light pass. Initialized once GetPassIndex() has been called for the first time.
    static i32 lightPassIndex;
    /// Index for lit base pass. Initialized once GetPassIndex() has been called for the first time.
    static i32 litBasePassIndex;
    /// Index for lit alpha pass. Initialized once GetPassIndex() has been called for the first time.
    static i32 litAlphaPassIndex;
    /// Index for shadow pass. Initialized once GetPassIndex() has been called for the first time.
    static i32 shadowPassIndex;

private:
    /// Require desktop GPU flag.
    bool isDesktop_;
    /// Cached desktop GPU support flag.
    bool desktopSupport_;
    /// Passes.
    Vector<SharedPtr<Pass>> passes_;
    /// Cached clones with added shader compilation defines.
    HashMap<Pair<StringHash, StringHash>, SharedPtr<Technique>> cloneTechniques_;

    /// Pass index assignments.
    static HashMap<String, i32> passIndices;
};

}