/** Helper structures for the Collada loader */

/*
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*/

#ifndef AI_COLLADAHELPER_H_INC
#define AI_COLLADAHELPER_H_INC

#include <assimp/light.h>
#include <assimp/material.h>
#include <assimp/mesh.h>
#include <stdint.h>
#include <map>
#include <set>
#include <vector>

struct aiMaterial;

namespace Assimp {
namespace Collada {

/** Collada file versions which evolved during the years ... */
enum FormatVersion {
    FV_1_5_n,
    FV_1_4_n,
    FV_1_3_n
};

/** Transformation types that can be applied to a node */
enum TransformType {
    TF_LOOKAT,
    TF_ROTATE,
    TF_TRANSLATE,
    TF_SCALE,
    TF_SKEW,
    TF_MATRIX
};

/** Different types of input data to a vertex or face */
enum InputType {
    IT_Invalid,
    IT_Vertex, // special type for per-index data referring to the <vertices> element carrying the per-vertex data.
    IT_Position,
    IT_Normal,
    IT_Texcoord,
    IT_Color,
    IT_Tangent,
    IT_Bitangent
};

/** Supported controller types */
enum ControllerType {
    Skin,
    Morph
};

/** Supported morph methods */
enum MorphMethod {
    Normalized,
    Relative
};

/** Common metadata keys as <Collada, Assimp> */
typedef std::pair<std::string, std::string> MetaKeyPair;
typedef std::vector<MetaKeyPair> MetaKeyPairVector;

// Collada as lower_case (native)
const MetaKeyPairVector &GetColladaAssimpMetaKeys();
// Collada as CamelCase (used by Assimp for consistency)
const MetaKeyPairVector &GetColladaAssimpMetaKeysCamelCase();

/** Convert underscore_separated to CamelCase "authoring_tool" becomes "AuthoringTool" */
void ToCamelCase(std::string &text);

/** Contains all data for one of the different transformation types */
struct Transform {
    std::string mID; ///< SID of the transform step, by which anim channels address their target node
    TransformType mType;
    ai_real f[16]; ///< Interpretation of data depends on the type of the transformation
};

/** A collada camera. */
struct Camera {
    Camera() :
            mOrtho(false),
            mHorFov(10e10f),
            mVerFov(10e10f),
            mAspect(10e10f),
            mZNear(0.1f),
            mZFar(1000.f) {}

    // Name of camera
    std::string mName;

    // True if it is an orthografic camera
    bool mOrtho;

    //! Horizontal field of view in degrees
    ai_real mHorFov;

    //! Vertical field of view in degrees
    ai_real mVerFov;

    //! Screen aspect
    ai_real mAspect;

    //! Near& far z
    ai_real mZNear, mZFar;
};

#define ASSIMP_COLLADA_LIGHT_ANGLE_NOT_SET 1e9f

/** A collada light source. */
struct Light {
    Light() :
            mType(aiLightSource_UNDEFINED),
            mAttConstant(1.f),
            mAttLinear(0.f),
            mAttQuadratic(0.f),
            mFalloffAngle(180.f),
            mFalloffExponent(0.f),
            mPenumbraAngle(ASSIMP_COLLADA_LIGHT_ANGLE_NOT_SET),
            mOuterAngle(ASSIMP_COLLADA_LIGHT_ANGLE_NOT_SET),
            mIntensity(1.f) {}

    //! Type of the light source aiLightSourceType + ambient
    unsigned int mType;

    //! Color of the light
    aiColor3D mColor;

    //! Light attenuation
    ai_real mAttConstant, mAttLinear, mAttQuadratic;

    //! Spot light falloff
    ai_real mFalloffAngle;
    ai_real mFalloffExponent;

    // -----------------------------------------------------
    // FCOLLADA extension from here

    //! ... related stuff from maja and max extensions
    ai_real mPenumbraAngle;
    ai_real mOuterAngle;

    //! Common light intensity
    ai_real mIntensity;
    ai_real mPPS;
    ai_real mdt;

    aiString env_map;
};

/** Short vertex index description */
struct InputSemanticMapEntry {
    InputSemanticMapEntry() :
            mSet(0),
            mType(IT_Invalid) {}

    //! Index of set, optional
    unsigned int mSet;

    //! Type of referenced vertex input
    InputType mType;
};

/** Table to map from effect to vertex input semantics */
struct SemanticMappingTable {
    //! Name of material
    std::string mMatName;

    //! List of semantic map commands, grouped by effect semantic name
    std::map<std::string, InputSemanticMapEntry> mMap;

    //! For std::find
    bool operator==(const std::string &s) const {
        return s == mMatName;
    }
};

/** A reference to a mesh inside a node, including materials assigned to the various subgroups.
 * The ID refers to either a mesh or a controller which specifies the mesh
 */
struct MeshInstance {
    ///< ID of the mesh or controller to be instanced
    std::string mMeshOrController;

    ///< Map of materials by the subgroup ID they're applied to
    std::map<std::string, SemanticMappingTable> mMaterials;
};

/** A reference to a camera inside a node*/
struct CameraInstance {
    ///< ID of the camera
    std::string mCamera;
};

/** A reference to a light inside a node*/
struct LightInstance {
    ///< ID of the camera
    std::string mLight;
};

/** A reference to a node inside a node*/
struct NodeInstance {
    ///< ID of the node
    std::string mNode;
};

/** A node in a scene hierarchy */
struct Node {
    std::string mName;
    std::string mID;
    std::string mSID;
    Node *mParent;
    std::vector<Node *> mChildren;

    /** Operations in order to calculate the resulting transformation to parent. */
    std::vector<Transform> mTransforms;

    /** Meshes at this node */
    std::vector<MeshInstance> mMeshes;

    /** Lights at this node */
    std::vector<LightInstance> mLights;

    /** Cameras at this node */
    std::vector<CameraInstance> mCameras;

    /** Node instances at this node */
    std::vector<NodeInstance> mNodeInstances;

    /** Root-nodes: Name of primary camera, if any */
    std::string mPrimaryCamera;

    //! Constructor. Begin with a zero parent
    Node() :
            mParent(nullptr) {
        // empty
    }

    //! Destructor: delete all children subsequently
    ~Node() {
        for (std::vector<Node *>::iterator it = mChildren.begin(); it != mChildren.end(); ++it)
            delete *it;
    }
};

/** Data source array: either floats or strings */
struct Data {
    bool mIsStringArray;
    std::vector<ai_real> mValues;
    std::vector<std::string> mStrings;
};

/** Accessor to a data array */
struct Accessor {
    size_t mCount; // in number of objects
    size_t mSize; // size of an object, in elements (floats or strings, mostly 1)
    size_t mOffset; // in number of values
    size_t mStride; // Stride in number of values
    std::vector<std::string> mParams; // names of the data streams in the accessors. Empty string tells to ignore.
    size_t mSubOffset[4]; // Suboffset inside the object for the common 4 elements. For a vector, that's XYZ, for a color RGBA and so on.
            // For example, SubOffset[0] denotes which of the values inside the object is the vector X component.
    std::string mSource; // URL of the source array
    mutable const Data *mData; // Pointer to the source array, if resolved. NULL else

    Accessor() {
        mCount = 0;
        mSize = 0;
        mOffset = 0;
        mStride = 0;
        mData = NULL;
        mSubOffset[0] = mSubOffset[1] = mSubOffset[2] = mSubOffset[3] = 0;
    }
};

/** A single face in a mesh */
struct Face {
    std::vector<size_t> mIndices;
};

/** An input channel for mesh data, referring to a single accessor */
struct InputChannel {
    InputType mType; // Type of the data
    size_t mIndex; // Optional index, if multiple sets of the same data type are given
    size_t mOffset; // Index offset in the indices array of per-face indices. Don't ask, can't explain that any better.
    std::string mAccessor; // ID of the accessor where to read the actual values from.
    mutable const Accessor *mResolved; // Pointer to the accessor, if resolved. NULL else

    InputChannel() {
        mType = IT_Invalid;
        mIndex = 0;
        mOffset = 0;
        mResolved = NULL;
    }
};

/** Subset of a mesh with a certain material */
struct SubMesh {
    std::string mMaterial; ///< subgroup identifier
    size_t mNumFaces; ///< number of faces in this submesh
};

/** Contains data for a single mesh */
struct Mesh {
    Mesh(const std::string &id) :
            mId(id) {
        for (unsigned int i = 0; i < AI_MAX_NUMBER_OF_TEXTURECOORDS; ++i)
            mNumUVComponents[i] = 2;
    }

    const std::string mId;
    std::string mName;

    // just to check if there's some sophisticated addressing involved...
    // which we don't support, and therefore should warn about.
    std::string mVertexID;

    // Vertex data addressed by vertex indices
    std::vector<InputChannel> mPerVertexData;

    // actual mesh data, assembled on encounter of a <p> element. Verbose format, not indexed
    std::vector<aiVector3D> mPositions;
    std::vector<aiVector3D> mNormals;
    std::vector<aiVector3D> mTangents;
    std::vector<aiVector3D> mBitangents;
    std::vector<aiVector3D> mTexCoords[AI_MAX_NUMBER_OF_TEXTURECOORDS];
    std::vector<aiColor4D> mColors[AI_MAX_NUMBER_OF_COLOR_SETS];

    unsigned int mNumUVComponents[AI_MAX_NUMBER_OF_TEXTURECOORDS];

    // Faces. Stored are only the number of vertices for each face.
    // 1 == point, 2 == line, 3 == triangle, 4+ == poly
    std::vector<size_t> mFaceSize;

    // Position indices for all faces in the sequence given in mFaceSize -
    // necessary for bone weight assignment
    std::vector<size_t> mFacePosIndices;

    // Submeshes in this mesh, each with a given material
    std::vector<SubMesh> mSubMeshes;
};

/** Which type of primitives the ReadPrimitives() function is going to read */
enum PrimitiveType {
    Prim_Invalid,
    Prim_Lines,
    Prim_LineStrip,
    Prim_Triangles,
    Prim_TriStrips,
    Prim_TriFans,
    Prim_Polylist,
    Prim_Polygon
};

/** A skeleton controller to deform a mesh with the use of joints */
struct Controller {
    // controller type
    ControllerType mType;

    // Morphing method if type is Morph
    MorphMethod mMethod;

    // the URL of the mesh deformed by the controller.
    std::string mMeshId;

    // accessor URL of the joint names
    std::string mJointNameSource;

    ///< The bind shape matrix, as array of floats. I'm not sure what this matrix actually describes, but it can't be ignored in all cases
    ai_real mBindShapeMatrix[16];

    // accessor URL of the joint inverse bind matrices
    std::string mJointOffsetMatrixSource;

    // input channel: joint names.
    InputChannel mWeightInputJoints;
    // input channel: joint weights
    InputChannel mWeightInputWeights;

    // Number of weights per vertex.
    std::vector<size_t> mWeightCounts;

    // JointIndex-WeightIndex pairs for all vertices
    std::vector<std::pair<size_t, size_t>> mWeights;

    std::string mMorphTarget;
    std::string mMorphWeight;
};

/** A collada material. Pretty much the only member is a reference to an effect. */
struct Material {
    std::string mName;
    std::string mEffect;
};

/** Type of the effect param */
enum ParamType {
    Param_Sampler,
    Param_Surface
};

/** A param for an effect. Might be of several types, but they all just refer to each other, so I summarize them */
struct EffectParam {
    ParamType mType;
    std::string mReference; // to which other thing the param is referring to.
};

/** Shading type supported by the standard effect spec of Collada */
enum ShadeType {
    Shade_Invalid,
    Shade_Constant,
    Shade_Lambert,
    Shade_Phong,
    Shade_Blinn
};

/** Represents a texture sampler in collada */
struct Sampler {
    Sampler() :
            mWrapU(true),
            mWrapV(true),
            mMirrorU(),
            mMirrorV(),
            mOp(aiTextureOp_Multiply),
            mUVId(UINT_MAX),
            mWeighting(1.f),
            mMixWithPrevious(1.f) {}

    /** Name of image reference
     */
    std::string mName;

    /** Wrap U?
     */
    bool mWrapU;

    /** Wrap V?
     */
    bool mWrapV;

    /** Mirror U?
     */
    bool mMirrorU;

    /** Mirror V?
     */
    bool mMirrorV;

    /** Blend mode
     */
    aiTextureOp mOp;

    /** UV transformation
     */
    aiUVTransform mTransform;

    /** Name of source UV channel
     */
    std::string mUVChannel;

    /** Resolved UV channel index or UINT_MAX if not known
     */
    unsigned int mUVId;

    // OKINO/MAX3D extensions from here
    // -------------------------------------------------------

    /** Weighting factor
     */
    ai_real mWeighting;

    /** Mixing factor from OKINO
     */
    ai_real mMixWithPrevious;
};

/** A collada effect. Can contain about anything according to the Collada spec,
    but we limit our version to a reasonable subset. */
struct Effect {
    // Shading mode
    ShadeType mShadeType;

    // Colors
    aiColor4D mEmissive, mAmbient, mDiffuse, mSpecular,
            mTransparent, mReflective;

    // Textures
    Sampler mTexEmissive, mTexAmbient, mTexDiffuse, mTexSpecular,
            mTexTransparent, mTexBump, mTexReflective;

    // Scalar factory
    ai_real mShininess, mRefractIndex, mReflectivity;
    ai_real mTransparency;
    bool mHasTransparency;
    bool mRGBTransparency;
    bool mInvertTransparency;

    // local params referring to each other by their SID
    typedef std::map<std::string, Collada::EffectParam> ParamLibrary;
    ParamLibrary mParams;

    // MAX3D extensions
    // ---------------------------------------------------------
    // Double-sided?
    bool mDoubleSided, mWireframe, mFaceted;

    Effect() :
            mShadeType(Shade_Phong),
            mEmissive(0, 0, 0, 1),
            mAmbient(0.1f, 0.1f, 0.1f, 1),
            mDiffuse(0.6f, 0.6f, 0.6f, 1),
            mSpecular(0.4f, 0.4f, 0.4f, 1),
            mTransparent(0, 0, 0, 1),
            mShininess(10.0f),
            mRefractIndex(1.f),
            mReflectivity(0.f),
            mTransparency(1.f),
            mHasTransparency(false),
            mRGBTransparency(false),
            mInvertTransparency(false),
            mDoubleSided(false),
            mWireframe(false),
            mFaceted(false) {
    }
};

/** An image, meaning texture */
struct Image {
    std::string mFileName;

    /** Embedded image data */
    std::vector<uint8_t> mImageData;

    /** File format hint of embedded image data */
    std::string mEmbeddedFormat;
};

/** An animation channel. */
struct AnimationChannel {
    /** URL of the data to animate. Could be about anything, but we support only the
     * "NodeID/TransformID.SubElement" notation
     */
    std::string mTarget;

    /** Source URL of the time values. Collada calls them "input". Meh. */
    std::string mSourceTimes;
    /** Source URL of the value values. Collada calls them "output". */
    std::string mSourceValues;
    /** Source URL of the IN_TANGENT semantic values. */
    std::string mInTanValues;
    /** Source URL of the OUT_TANGENT semantic values. */
    std::string mOutTanValues;
    /** Source URL of the INTERPOLATION semantic values. */
    std::string mInterpolationValues;
};

/** An animation. Container for 0-x animation channels or 0-x animations */
struct Animation {
    /** Anim name */
    std::string mName;

    /** the animation channels, if any */
    std::vector<AnimationChannel> mChannels;

    /** the sub-animations, if any */
    std::vector<Animation *> mSubAnims;

    double duration, fps;

    /** Destructor */
    ~Animation() {
        for (std::vector<Animation *>::iterator it = mSubAnims.begin(); it != mSubAnims.end(); ++it)
            delete *it;
    }

    /** Collect all channels in the animation hierarchy into a single channel list. */
    void CollectChannelsRecursively(std::vector<AnimationChannel> &channels) {
        channels.insert(channels.end(), mChannels.begin(), mChannels.end());

        for (std::vector<Animation *>::iterator it = mSubAnims.begin(); it != mSubAnims.end(); ++it) {
            Animation *pAnim = (*it);

            pAnim->CollectChannelsRecursively(channels);
        }
    }

    /** Combine all single-channel animations' channel into the same (parent) animation channel list. */
    void CombineSingleChannelAnimations() {
        CombineSingleChannelAnimationsRecursively(this);
    }

    void CombineSingleChannelAnimationsRecursively(Animation *pParent) {
        std::set<std::string> childrenTargets;
        bool childrenAnimationsHaveDifferentChannels = true;

        for (std::vector<Animation *>::iterator it = pParent->mSubAnims.begin(); it != pParent->mSubAnims.end();) {
            Animation *anim = *it;
            CombineSingleChannelAnimationsRecursively(anim);

            if (childrenAnimationsHaveDifferentChannels && anim->mChannels.size() == 1 &&
                    childrenTargets.find(anim->mChannels[0].mTarget) == childrenTargets.end()) {
                childrenTargets.insert(anim->mChannels[0].mTarget);
            } else {
                childrenAnimationsHaveDifferentChannels = false;
            }
            
            ++it;
        }

        // We only want to combine animations if they have different channels
        if (childrenAnimationsHaveDifferentChannels) {
            for (std::vector<Animation *>::iterator it = pParent->mSubAnims.begin(); it != pParent->mSubAnims.end();) {
                Animation *anim = *it;

                pParent->mChannels.push_back(anim->mChannels[0]);

                it = pParent->mSubAnims.erase(it);

                delete anim;
                continue;
            }
        }
    }

    void PropogateParams() {
        PropogateParamsRecursively(this);
    }

    void PropogateParamsRecursively(Animation *pParent) {
        for (std::vector<Animation *>::iterator it = pParent->mSubAnims.begin(); it != pParent->mSubAnims.end(); ++it) {
            Animation *anim = *it;
            anim->duration = duration;
            anim->fps = fps;
            anim->PropogateParamsRecursively(anim);
        }
    }
};

/** Description of a collada animation channel which has been determined to affect the current node */
struct ChannelEntry {
    const Collada::AnimationChannel *mChannel; ///> the source channel
    std::string mTargetId;
    std::string mTransformId; // the ID of the transformation step of the node which is influenced
    size_t mTransformIndex; // Index into the node's transform chain to apply the channel to
    size_t mSubElement; // starting index inside the transform data

    // resolved data references
    const Collada::Accessor *mTimeAccessor; ///> Collada accessor to the time values
    const Collada::Data *mTimeData; ///> Source data array for the time values
    const Collada::Accessor *mValueAccessor; ///> Collada accessor to the key value values
    const Collada::Data *mValueData; ///> Source datat array for the key value values

    ChannelEntry() :
            mChannel(),
            mTransformIndex(),
            mSubElement(),
            mTimeAccessor(),
            mTimeData(),
            mValueAccessor(),
            mValueData() {}
};

} // end of namespace Collada
} // end of namespace Assimp

#endif // AI_COLLADAHELPER_H_INC
