//
// Copyright 2016 Pixar
//
// Licensed under the Apache License, Version 2.0 (the "Apache License")
// with the following modification; you may not use this file except in
// compliance with the Apache License and the following modification to it:
// Section 6. Trademarks. is deleted and replaced with:
//
// 6. Trademarks. This License does not grant permission to use the trade
//    names, trademarks, service marks, or product names of the Licensor
//    and its affiliates, except as required to comply with Section 4(c) of
//    the License and to reproduce the content of the NOTICE file.
//
// You may obtain a copy of the Apache License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the Apache License with the above modification is
// distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied. See the Apache License for the specific
// language governing permissions and limitations under the Apache License.
//
#ifndef USDSHADE_GENERATED_SHADER_H
#define USDSHADE_GENERATED_SHADER_H

/// \file usdShade/shader.h

#include "pxr/pxr.h"
#include "pxr/usd/usdShade/api.h"
#include "pxr/usd/usd/typed.h"
#include "pxr/usd/usd/prim.h"
#include "pxr/usd/usd/stage.h"
#include "pxr/usd/usdShade/tokens.h"

#include "pxr/usd/usdShade/input.h"
#include "pxr/usd/usdShade/output.h"
#include "pxr/usd/ndr/declare.h"
#include "pxr/usd/sdr/shaderNode.h"

#include "pxr/base/vt/value.h"

#include "pxr/base/gf/vec3d.h"
#include "pxr/base/gf/vec3f.h"
#include "pxr/base/gf/matrix4d.h"

#include "pxr/base/tf/token.h"
#include "pxr/base/tf/type.h"

PXR_NAMESPACE_OPEN_SCOPE

class SdfAssetPath;

// -------------------------------------------------------------------------- //
// SHADER                                                                     //
// -------------------------------------------------------------------------- //

/// \class UsdShadeShader
///
/// Base class for all USD shaders. Shaders are the building blocks
/// of shading networks. While UsdShadeShader objects are not target specific,
/// each renderer or application target may derive its own renderer-specific 
/// shader object types from this base, if needed.
/// 
/// Objects of this class generally represent a single shading object, whether
/// it exists in the target renderer or not. For example, a texture, a fractal,
/// or a mix node.
/// 
/// The main property of this class is the info:id token, which uniquely 
/// identifies the type of this node. The id resolution into a renderable 
/// shader target is deferred to the consuming application.
/// 
/// The purpose of representing them in Usd is two-fold:
/// \li To represent, via "connections" the topology of the shading network
/// that must be reconstructed in the renderer. Facilities for authoring and 
/// manipulating connections are encapsulated in the Has-A schema 
/// UsdShadeConnectableAPI.
/// \li To present a (partial or full) interface of typed input parameters 
/// whose values can be set and overridden in Usd, to be provided later at 
/// render-time as parameter values to the actual render shader objects. Shader 
/// input parameters are encapsulated in the property schema UsdShadeInput.
/// 
///
/// For any described attribute \em Fallback \em Value or \em Allowed \em Values below
/// that are text/tokens, the actual token is published and defined in \ref UsdShadeTokens.
/// So to set an attribute to the value "rightHanded", use UsdShadeTokens->rightHanded
/// as the value.
///
class UsdShadeShader : public UsdTyped
{
public:
    /// Compile time constant representing what kind of schema this class is.
    ///
    /// \sa UsdSchemaType
    static const UsdSchemaType schemaType = UsdSchemaType::ConcreteTyped;

    /// Construct a UsdShadeShader on UsdPrim \p prim .
    /// Equivalent to UsdShadeShader::Get(prim.GetStage(), prim.GetPath())
    /// for a \em valid \p prim, but will not immediately throw an error for
    /// an invalid \p prim
    explicit UsdShadeShader(const UsdPrim& prim=UsdPrim())
        : UsdTyped(prim)
    {
    }

    /// Construct a UsdShadeShader on the prim held by \p schemaObj .
    /// Should be preferred over UsdShadeShader(schemaObj.GetPrim()),
    /// as it preserves SchemaBase state.
    explicit UsdShadeShader(const UsdSchemaBase& schemaObj)
        : UsdTyped(schemaObj)
    {
    }

    /// Destructor.
    USDSHADE_API
    virtual ~UsdShadeShader();

    /// Return a vector of names of all pre-declared attributes for this schema
    /// class and all its ancestor classes.  Does not include attributes that
    /// may be authored by custom/extended methods of the schemas involved.
    USDSHADE_API
    static const TfTokenVector &
    GetSchemaAttributeNames(bool includeInherited=true);

    /// Return a UsdShadeShader holding the prim adhering to this
    /// schema at \p path on \p stage.  If no prim exists at \p path on
    /// \p stage, or if the prim at that path does not adhere to this schema,
    /// return an invalid schema object.  This is shorthand for the following:
    ///
    /// \code
    /// UsdShadeShader(stage->GetPrimAtPath(path));
    /// \endcode
    ///
    USDSHADE_API
    static UsdShadeShader
    Get(const UsdStagePtr &stage, const SdfPath &path);

    /// Attempt to ensure a \a UsdPrim adhering to this schema at \p path
    /// is defined (according to UsdPrim::IsDefined()) on this stage.
    ///
    /// If a prim adhering to this schema at \p path is already defined on this
    /// stage, return that prim.  Otherwise author an \a SdfPrimSpec with
    /// \a specifier == \a SdfSpecifierDef and this schema's prim type name for
    /// the prim at \p path at the current EditTarget.  Author \a SdfPrimSpec s
    /// with \p specifier == \a SdfSpecifierDef and empty typeName at the
    /// current EditTarget for any nonexistent, or existing but not \a Defined
    /// ancestors.
    ///
    /// The given \a path must be an absolute prim path that does not contain
    /// any variant selections.
    ///
    /// If it is impossible to author any of the necessary PrimSpecs, (for
    /// example, in case \a path cannot map to the current UsdEditTarget's
    /// namespace) issue an error and return an invalid \a UsdPrim.
    ///
    /// Note that this method may return a defined prim whose typeName does not
    /// specify this schema class, in case a stronger typeName opinion overrides
    /// the opinion at the current EditTarget.
    ///
    USDSHADE_API
    static UsdShadeShader
    Define(const UsdStagePtr &stage, const SdfPath &path);

protected:
    /// Returns the type of schema this class belongs to.
    ///
    /// \sa UsdSchemaType
    USDSHADE_API
    UsdSchemaType _GetSchemaType() const override;

private:
    // needs to invoke _GetStaticTfType.
    friend class UsdSchemaRegistry;
    USDSHADE_API
    static const TfType &_GetStaticTfType();

    static bool _IsTypedSchema();

    // override SchemaBase virtuals.
    USDSHADE_API
    const TfType &_GetTfType() const override;

public:
    // --------------------------------------------------------------------- //
    // IMPLEMENTATIONSOURCE 
    // --------------------------------------------------------------------- //
    /// Specifies the attribute that should be consulted to get the 
    /// shader's implementation or its source code.
    /// 
    /// * If set to "id", the "info:id" attribute's value is used to 
    /// determine the shader source from the shader registry.
    /// * If set to "sourceAsset", the resolved value of the "info:sourceAsset" 
    /// attribute corresponding to the desired implementation (or source-type)
    /// is used to locate the shader source.  A source asset file may also
    /// specify multiple shader definitions, so there is an optional attribute
    /// "info:sourceAsset:subIdentifier" whose value should be used to indicate
    /// a particular shader definition from a source asset file.
    /// * If set to "sourceCode", the value of "info:sourceCode" attribute 
    /// corresponding to the desired implementation (or source type) is used as 
    /// the shader source.
    /// 
    ///
    /// | ||
    /// | -- | -- |
    /// | Declaration | `uniform token info:implementationSource = "id"` |
    /// | C++ Type | TfToken |
    /// | \ref Usd_Datatypes "Usd Type" | SdfValueTypeNames->Token |
    /// | \ref SdfVariability "Variability" | SdfVariabilityUniform |
    /// | \ref UsdShadeTokens "Allowed Values" | id, sourceAsset, sourceCode |
    USDSHADE_API
    UsdAttribute GetImplementationSourceAttr() const;

    /// See GetImplementationSourceAttr(), and also 
    /// \ref Usd_Create_Or_Get_Property for when to use Get vs Create.
    /// If specified, author \p defaultValue as the attribute's default,
    /// sparsely (when it makes sense to do so) if \p writeSparsely is \c true -
    /// the default for \p writeSparsely is \c false.
    USDSHADE_API
    UsdAttribute CreateImplementationSourceAttr(VtValue const &defaultValue = VtValue(), bool writeSparsely=false) const;

public:
    // --------------------------------------------------------------------- //
    // ID 
    // --------------------------------------------------------------------- //
    /// The id is an identifier for the type or purpose of the 
    /// shader. E.g.: Texture or FractalFloat.
    /// The use of this id will depend on the render target: some will turn it
    /// into an actual shader path, some will use it to generate shader source 
    /// code dynamically.
    /// 
    /// \sa SetShaderId()
    /// 
    ///
    /// | ||
    /// | -- | -- |
    /// | Declaration | `uniform token info:id` |
    /// | C++ Type | TfToken |
    /// | \ref Usd_Datatypes "Usd Type" | SdfValueTypeNames->Token |
    /// | \ref SdfVariability "Variability" | SdfVariabilityUniform |
    USDSHADE_API
    UsdAttribute GetIdAttr() const;

    /// See GetIdAttr(), and also 
    /// \ref Usd_Create_Or_Get_Property for when to use Get vs Create.
    /// If specified, author \p defaultValue as the attribute's default,
    /// sparsely (when it makes sense to do so) if \p writeSparsely is \c true -
    /// the default for \p writeSparsely is \c false.
    USDSHADE_API
    UsdAttribute CreateIdAttr(VtValue const &defaultValue = VtValue(), bool writeSparsely=false) const;

public:
    // ===================================================================== //
    // Feel free to add custom code below this line, it will be preserved by 
    // the code generator. 
    //
    // Just remember to: 
    //  - Close the class declaration with }; 
    //  - Close the namespace with PXR_NAMESPACE_CLOSE_SCOPE
    //  - Close the include guard with #endif
    // ===================================================================== //
    // --(BEGIN CUSTOM CODE)--

    /// Constructor that takes a ConnectableAPI object.
    /// Allow implicit (auto) conversion of UsdShadeShader to 
    /// UsdShadeConnectableAPI, so that a shader can be passed into any function
    /// that accepts a ConnectableAPI.
    USDSHADE_API
    UsdShadeShader(const UsdShadeConnectableAPI &connectable);

    /// Contructs and returns a UsdShadeConnectableAPI object with this shader.
    ///
    /// Note that most tasks can be accomplished without explicitly constructing 
    /// a UsdShadeConnectable API, since connection-related API such as
    /// UsdShadeConnectableAPI::ConnectToSource() are static methods, and 
    /// UsdShadeShader will auto-convert to a UsdShadeConnectableAPI when 
    /// passed to functions that want to act generically on a connectable
    /// UsdShadeConnectableAPI object.
    USDSHADE_API
    UsdShadeConnectableAPI ConnectableAPI() const;

    // -------------------------------------------------------------------------
    /// \name Outputs API
    ///
    /// Outputs represent a typed attribute on a shader or node-graph whose value 
    /// is computed externally. 
    /// 
    /// When they exist on a node-graph, they are connectable and are typically 
    /// connected to the output of a shader within the node-graph.
    /// 
    /// @{
        
    /// Create an output which can either have a value or can be connected.
    /// The attribute representing the output is created in the "outputs:" 
    /// namespace. Outputs on a shader cannot be connected, as their 
    /// value is assumed to be computed externally.
    /// 
    USDSHADE_API
    UsdShadeOutput CreateOutput(const TfToken& name,
                                const SdfValueTypeName& typeName);

    /// Return the requested output if it exists.
    /// 
    USDSHADE_API
    UsdShadeOutput GetOutput(const TfToken &name) const;

    /// Outputs are represented by attributes in the "outputs:" namespace.
    /// 
    USDSHADE_API
    std::vector<UsdShadeOutput> GetOutputs() const;

    /// @}

    // ------------------------------------------------------------------------- 

    /// \name Inputs API
    ///
    /// Inputs are connectable attribute with a typed value. 
    /// 
    /// On shaders, the shader parameters are encoded as inputs. On node-graphs,
    /// interface attributes are represented as inputs.
    /// 
    /// @{
        
    /// Create an input which can either have a value or can be connected.
    /// The attribute representing the input is created in the "inputs:" 
    /// namespace. Inputs on both shaders and node-graphs are connectable.
    /// 
    USDSHADE_API
    UsdShadeInput CreateInput(const TfToken& name,
                              const SdfValueTypeName& typeName);

    /// Return the requested input if it exists.
    /// 
    USDSHADE_API
    UsdShadeInput GetInput(const TfToken &name) const;

    /// Inputs are represented by attributes in the "inputs:" namespace.
    /// 
    USDSHADE_API
    std::vector<UsdShadeInput> GetInputs() const;

    /// @}

    // -------------------------------------------------------------------------

    /// \anchor UsdShadeShader_ImplementationSource
    /// \name Shader Source API
    /// 
    /// This section provides API for identifying the source of a shader's 
    /// implementation.
    /// 
    /// @{

    /// Reads the value of info:implementationSource attribute and returns a 
    /// token identifying the attribute that must be consulted to identify the 
    /// shader's source program.
    /// 
    /// This returns 
    /// * <b>id</b>, to indicate that the "info:id" attribute must be 
    /// consulted.
    /// * <b>sourceAsset</b> to indicate that the asset-valued 
    /// "info:{sourceType}:sourceAsset" attribute associated with the desired 
    /// <b>sourceType</b> should be consulted to locate the asset with the 
    /// shader's source.
    /// * <b>sourceCode</b> to indicate that the string-valued 
    /// "info:{sourceType}:sourceCode" attribute associated with the desired
    /// <b>sourceType</b> should be read to get shader's source.
    ///
    /// This issues a warning and returns <b>id</b> if the 
    /// <i>info:implementationSource</i> attribute has an invalid value.
    /// 
    /// <i>{sourceType}</i> above is a place holder for a token that identifies 
    /// the type of shader source or its implementation. For example: osl, 
    /// glslfx, riCpp etc. This allows a shader to specify different sourceAsset
    /// (or sourceCode) values for different sourceTypes. The sourceType tokens 
    /// usually correspond to the sourceType value of the NdrParserPlugin that's 
    /// used to parse the shader source (\ref NdrParserPlugin::SourceType).
    /// 
    /// When sourceType is empty, the corresponding sourceAsset or sourceCode is 
    /// considered to be "universal" (or fallback), which is represented by the 
    /// empty-valued token UsdShadeTokens->universalSourceType. When the 
    /// sourceAsset (or sourceCode) corresponding to a specific, requested 
    /// sourceType is unavailable, the universal sourceAsset (or sourceCode) is 
    /// returned by GetSourceAsset (and GetSourceCode} API, if present.
    /// 
    /// \sa GetShaderId()
    /// \sa GetSourceAsset()
    /// \sa GetSourceCode()
    USDSHADE_API
    TfToken GetImplementationSource() const; 
    
    /// Sets the shader's ID value. This also sets the 
    /// <i>info:implementationSource</i> attribute on the shader to
    /// <b>UsdShadeTokens->id</b>, if the existing value is different.
    USDSHADE_API
    bool SetShaderId(const TfToken &id) const; 

    /// Fetches the shader's ID value from the <i>info:id</i> attribute, if the 
    /// shader's <i>info:implementationSource</i> is <b>id</b>. 
    /// 
    /// Returns <b>true</b> if the shader's implementation source is <b>id</b> 
    /// and the value was fetched properly into \p id. Returns false otherwise.
    /// 
    /// \sa GetImplementationSource()
    USDSHADE_API
    bool GetShaderId(TfToken *id) const;

    /// Sets the shader's source-asset path value to \p sourceAsset for the 
    /// given source type, \p sourceType.
    /// 
    /// This also sets the <i>info:implementationSource</i> attribute on the 
    /// shader to <b>UsdShadeTokens->sourceAsset</b>.
    USDSHADE_API
    bool SetSourceAsset(
        const SdfAssetPath &sourceAsset,
        const TfToken &sourceType=UsdShadeTokens->universalSourceType) const;

    /// Fetches the shader's source asset value for the specified 
    /// \p sourceType value from the <b>info:<i>sourceType:</i>sourceAsset</b> 
    /// attribute, if the shader's <i>info:implementationSource</i> is 
    /// <b>sourceAsset</b>. 
    /// 
    /// If the <i>sourceAsset</i> attribute corresponding to the requested 
    /// <i>sourceType</i> isn't present on the shader, then the <i>universal</i> 
    /// <i>fallback</i> sourceAsset attribute, i.e. <i>info:sourceAsset</i> is 
    /// consulted, if present, to get the source asset path.
    /// 
    /// Returns <b>true</b> if the shader's implementation source is 
    /// <b>sourceAsset</b> and the source asset path value was fetched 
    /// successfully into \p sourceAsset. Returns false otherwise.
    /// 
    /// \sa GetImplementationSource()
    USDSHADE_API
    bool GetSourceAsset(
        SdfAssetPath *sourceAsset,
        const TfToken &sourceType=UsdShadeTokens->universalSourceType) const;

    /// Set a sub-identifier to be used with a source asset of the given source
    /// type.  This sets the <b>info:<i>sourceType:</i>sourceAsset:subIdentifier
    /// </b>.
    ///
    /// This also sets the <i>info:implementationSource</i> attribute on the
    /// shader to <b>UsdShadeTokens->sourceAsset</b>
    USDSHADE_API
    bool SetSourceAssetSubIdentifier(
        const TfToken &subIdentifier,
        const TfToken &sourceType=UsdShadeTokens->universalSourceType) const;

    /// Fetches the shader's sub-identifier for the source asset with the
    /// specified \p sourceType value from the <b>info:<i>sourceType:</i>
    /// sourceAsset:subIdentifier</b> attribute, if the shader's <i>info:
    /// implementationSource</i> is <b>sourceAsset</b>.
    ///
    /// If the <i>subIdentifier</i> attribute corresponding to the requested
    /// <i>sourceType</i> isn't present on the shader, then the <i>universal</i>
    /// <i>fallback</i> sub-identifier attribute, i.e. <i>info:sourceAsset:
    /// subIdentifier</i> is consulted, if present, to get the sub-identifier
    /// name.
    ///
    /// Returns <b>true</b> if the shader's implementation source is
    /// <b>sourceAsset</b> and the sub-identifier for the given source type was
    /// fetched successfully into \p subIdentifier. Returns false otherwise.
    USDSHADE_API
    bool GetSourceAssetSubIdentifier(
        TfToken *subIdentifier,
        const TfToken &sourceType=UsdShadeTokens->universalSourceType) const;

    /// Sets the shader's source-code value to \p sourceCode for the given 
    /// source type, \p sourceType.
    /// 
    /// This also sets the <i>info:implementationSource</i> attribute on the 
    /// shader to <b>UsdShadeTokens->sourceCode</b>.
    USDSHADE_API 
    bool SetSourceCode(
        const std::string &sourceCode, 
        const TfToken &sourceType=UsdShadeTokens->universalSourceType) const;

    /// Fetches the shader's source code for the specified \p sourceType value 
    /// by reading the <b>info:<i>sourceType:</i>sourceCode</b> attribute, if 
    /// the shader's <i>info:implementationSource</i> is <b>sourceCode</b>. 
    /// 
    /// If the <i>sourceCode</i> attribute corresponding to the 
    /// requested <i>sourceType</i> isn't present on the shader, then the 
    /// <i>universal</i> or <i>fallback</i> sourceCode attribute (i.e. 
    /// <i>info:sourceCode</i>) is consulted, if present, to get the source 
    /// code.
    /// 
    /// Returns <b>true</b> if the shader's implementation source is 
    /// <b>sourceCode</b> and the source code string was fetched successfully 
    /// into \p sourceCode. Returns false otherwise.    
    /// 
    /// \sa GetImplementationSource()
    USDSHADE_API
    bool GetSourceCode(
        std::string *sourceCode,
        const TfToken &sourceType=UsdShadeTokens->universalSourceType) const;

    /// @}

    // -------------------------------------------------------------------------

    /// \anchor UsdShadeShader_SdrMetadata_API
    /// \name Shader Sdr Metadata API
    /// 
    /// This section provides API for authoring and querying shader registry
    /// metadata. When the shader's implementationSource is <b>sourceAsset</b> 
    /// or <b>sourceCode</b>, the authored "sdrMetadata" dictionary value 
    /// provides additional metadata needed to process the shader source
    /// correctly. It is used in combination with the sourceAsset or sourceCode
    /// value to fetch the appropriate node from the shader registry.
    /// 
    /// We expect the keys in sdrMetadata to correspond to the keys 
    /// in \ref SdrNodeMetadata. However, this is not strictly enforced in the 
    /// API. The only allowed value type in the "sdrMetadata" dictionary is a 
    /// std::string since it needs to be converted into a NdrTokenMap, which Sdr
    /// will parse using the utilities available in \ref SdrMetadataHelpers.
    /// 
    /// @{

    /// Returns this shader's composed "sdrMetadata" dictionary as a 
    /// NdrTokenMap.
    USDSHADE_API
    NdrTokenMap GetSdrMetadata() const;
    
    /// Returns the value corresponding to \p key in the composed 
    /// <b>sdrMetadata</b> dictionary.
    USDSHADE_API
    std::string GetSdrMetadataByKey(const TfToken &key) const;
        
    /// Authors the given \p sdrMetadata on this shader at the current 
    /// EditTarget.
    USDSHADE_API
    void SetSdrMetadata(const NdrTokenMap &sdrMetadata) const;

    /// Sets the value corresponding to \p key to the given string \p value, in 
    /// the shader's "sdrMetadata" dictionary at the current EditTarget.
    USDSHADE_API
    void SetSdrMetadataByKey(
        const TfToken &key, 
        const std::string &value) const;

    /// Returns true if the shader has a non-empty composed "sdrMetadata" 
    /// dictionary value.
    USDSHADE_API
    bool HasSdrMetadata() const;

    /// Returns true if there is a value corresponding to the given \p key in 
    /// the composed "sdrMetadata" dictionary.
    USDSHADE_API
    bool HasSdrMetadataByKey(const TfToken &key) const;

    /// Clears any "sdrMetadata" value authored on the shader in the current 
    /// EditTarget.
    USDSHADE_API
    void ClearSdrMetadata() const;

    /// Clears the entry corresponding to the given \p key in the 
    /// "sdrMetadata" dictionary authored in the current EditTarget.
    USDSHADE_API
    void ClearSdrMetadataByKey(const TfToken &key) const;

    /// @}

    /// This method attempts to ensure that there is a ShaderNode in the shader 
    /// registry (i.e. \ref SdrRegistry) representing this shader for the 
    /// given \p sourceType. It may return a null pointer if none could be 
    /// found or created.
    USDSHADE_API
    SdrShaderNodeConstPtr GetShaderNodeForSourceType(const TfToken &sourceType) 
        const; 

};

PXR_NAMESPACE_CLOSE_SCOPE

#endif