/** Defines the collada loader class */

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*/

#ifndef AI_COLLADALOADER_H_INC
#define AI_COLLADALOADER_H_INC

#include "ColladaParser.h"
#include <assimp/BaseImporter.h>

struct aiNode;
struct aiCamera;
struct aiLight;
struct aiTexture;
struct aiAnimation;

namespace Assimp {

struct ColladaMeshIndex {
    std::string mMeshID;
    size_t mSubMesh;
    std::string mMaterial;
    ColladaMeshIndex(const std::string &pMeshID, size_t pSubMesh, const std::string &pMaterial) :
            mMeshID(pMeshID), mSubMesh(pSubMesh), mMaterial(pMaterial) {
        ai_assert(!pMeshID.empty());
    }

    bool operator<(const ColladaMeshIndex &p) const {
        if (mMeshID == p.mMeshID) {
            if (mSubMesh == p.mSubMesh)
                return mMaterial < p.mMaterial;
            else
                return mSubMesh < p.mSubMesh;
        } else {
            return mMeshID < p.mMeshID;
        }
    }
};

/**
 * @brief Loader class to read Collada scenes.
 *
 * Collada is over-engineered to death, with every new iteration bringing  more useless stuff,
 * so I limited the data to what I think is useful for games.
*/
class ColladaLoader final : public BaseImporter {
public:
    /// The class constructor.
    ColladaLoader();

    /// The class destructor.
    ~ColladaLoader() override = default;

    /// Returns whether the class can handle the format of the given file.
    /// @see BaseImporter::CanRead() for more details.
    bool CanRead(const std::string &pFile, IOSystem *pIOHandler, bool checkSig) const override;

protected:
    /// See #BaseImporter::GetInfo for the details
    const aiImporterDesc *GetInfo() const override;

    /// See #BaseImporter::SetupProperties for the details
    void SetupProperties(const Importer *pImp) override;

    /// See #BaseImporter::InternReadFile for the details
    void InternReadFile(const std::string &pFile, aiScene *pScene, IOSystem *pIOHandler) override;

    /// Recursively constructs a scene node for the given parser node and returns it.
    aiNode *BuildHierarchy(const ColladaParser &pParser, const Collada::Node *pNode);

    /// Resolve node instances
    void ResolveNodeInstances(const ColladaParser &pParser, const Collada::Node *pNode,
            std::vector<const Collada::Node *> &resolved) const;

    /// Builds meshes for the given node and references them
    void BuildMeshesForNode(const ColladaParser &pParser, const Collada::Node *pNode,
            aiNode *pTarget);

    /// Lookup for meshes by their name
    aiMesh *findMesh(const std::string &meshid);

    /// Creates a mesh for the given ColladaMesh face subset and returns the newly created mesh
    aiMesh *CreateMesh(const ColladaParser &pParser, const Collada::Mesh *pSrcMesh, const Collada::SubMesh &pSubMesh,
            const Collada::Controller *pSrcController, size_t pStartVertex, size_t pStartFace);

    /// Builds cameras for the given node and references them
    void BuildCamerasForNode(const ColladaParser &pParser, const Collada::Node *pNode,
            aiNode *pTarget);

    /// Builds lights for the given node and references them
    void BuildLightsForNode(const ColladaParser &pParser, const Collada::Node *pNode,
            aiNode *pTarget);

    /// Stores all meshes in the given scene
    void StoreSceneMeshes(aiScene *pScene);

    /// Stores all materials in the given scene
    void StoreSceneMaterials(aiScene *pScene);

    /// Stores all lights in the given scene
    void StoreSceneLights(aiScene *pScene);

    /// Stores all cameras in the given scene
    void StoreSceneCameras(aiScene *pScene);

    /// Stores all textures in the given scene
    void StoreSceneTextures(aiScene *pScene);

    /// Stores all animations
    /// @param pScene   Target scene to store the anims
    /// @param parser   The collada parser
    void StoreAnimations(aiScene *pScene, const ColladaParser &parser);

    /** Stores all animations for the given source anim and its nested child animations
     * @param pScene target scene to store the anims
     * @param pSrcAnim the source animation to process
     * @param pPrefix Prefix to the name in case of nested animations
     */
    void StoreAnimations(aiScene *pScene, const ColladaParser &pParser, const Collada::Animation *pSrcAnim, const std::string &pPrefix);

    /** Constructs the animation for the given source anim */
    void CreateAnimation(aiScene *pScene, const ColladaParser &pParser, const Collada::Animation *pSrcAnim, const std::string &pName);

    /** Constructs materials from the collada material definitions */
    void BuildMaterials(ColladaParser &pParser, aiScene *pScene);

    /** Fill materials from the collada material definitions */
    void FillMaterials(const ColladaParser &pParser, aiScene *pScene);

    /** Add a texture and all of its sampling properties to a material*/
    void AddTexture(aiMaterial &mat, const ColladaParser &pParser,
            const Collada::Effect &effect,
            const Collada::Sampler &sampler,
            aiTextureType type, unsigned int idx = 0);

    /** Resolves the texture name for the given effect texture entry */
    aiString FindFilenameForEffectTexture(const ColladaParser &pParser,
            const Collada::Effect &pEffect, const std::string &pName);

    /** Reads a string value from an accessor and its data array.
     * @param pAccessor The accessor to use for reading
     * @param pData The data array to read from
     * @param pIndex The index of the element to retrieve
     * @return the specified value
     */
    [[nodiscard]] const std::string &ReadString(const Collada::Accessor &pAccessor, const Collada::Data &pData, size_t pIndex) const;

    /** Recursively collects all nodes into the given array */
    void CollectNodes(const aiNode *pNode, std::vector<const aiNode *> &poNodes) const;

    /** Finds a node in the collada scene by the given name */
    const Collada::Node *FindNode(const Collada::Node *pNode, const std::string &pName) const;
    /** Finds a node in the collada scene by the given SID */
    const Collada::Node *FindNodeBySID(const Collada::Node *pNode, const std::string &pSID) const;

    /** Finds a proper name for a node derived from the collada-node's properties */
    std::string FindNameForNode(const Collada::Node *pNode);

private:
    /** Filename, for a verbose error message */
    std::string mFileName;

    /** Which mesh-material compound was stored under which mesh ID */
    std::map<ColladaMeshIndex, size_t> mMeshIndexByID;

    /** Which material was stored under which index in the scene */
    std::map<std::string, size_t> mMaterialIndexByName;

    /** Accumulated meshes for the target scene */
    std::vector<aiMesh *> mMeshes;

    /** Accumulated morph target meshes */
    std::vector<aiMesh *> mTargetMeshes;

    /** Temporary material list */
    std::vector<std::pair<Collada::Effect *, aiMaterial *>> newMats;

    /** Temporary camera list */
    std::vector<aiCamera *> mCameras;

    /** Temporary light list */
    std::vector<aiLight *> mLights;

    /** Temporary texture list */
    std::vector<aiTexture *> mTextures;

    /** Accumulated animations for the target scene */
    std::vector<aiAnimation *> mAnims;

    bool noSkeletonMesh;
    bool removeEmptyBones;
    bool ignoreUpDirection;
    bool ignoreUnitSize;
    bool useColladaName;

    /** Used by FindNameForNode() to generate unique node names */
    unsigned int mNodeNameCounter;
};

} // end of namespace Assimp

#endif // AI_COLLADALOADER_H_INC
