#pragma once

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

#include <osg/ref_ptr>
#include <osg/Group>
#include <osgAnimation/Skeleton>
#include <osgAnimation/Bone>
#include <osgAnimation/RigGeometry>
#include <osgAnimation/MorphGeometry>

// Forward declarations
struct aiScene;
struct aiNode;
struct aiMesh;

/**
 * SkeletonLoader
 * --------------
 * Reads the Assimp scene's bone hierarchy and mesh skin weights,
 * and builds an osgAnimation scene graph:
 *
 *   osgAnimation::Skeleton
 *     └─ osgAnimation::Bone  (Hips)
 *          └─ osgAnimation::Bone  (Spine)
 *               └─ ...
 *
 * Each skinned aiMesh becomes an osgAnimation::RigGeometry instead
 * of a plain osg::Geometry, so the GPU handles skinning automatically.
 *
 * Usage:
 *   SkeletonLoader loader;
 *   auto result = loader.load(assimpScene, baseDir, morphMgr);
 *   // result.root    — attach to scene graph
 *   // result.boneMap — name → Bone* for posing
 */
class MorphManager;

class SkeletonLoader {
public:
    struct Result {
        osg::ref_ptr<osg::Group>                            root;
        osg::ref_ptr<osgAnimation::Skeleton>                skeleton;
        std::unordered_map<std::string,
            osg::ref_ptr<osgAnimation::Bone>>               boneMap;
        std::unordered_map<std::string, osg::Vec3>         bindPositions; // world pos from inverted offset
        bool valid = false;
    };

    Result load(const struct aiScene* scene,
                const std::string&   baseDir,
                MorphManager*        morphMgr = nullptr);

private:
    // ── Bone hierarchy ────────────────────────────────────────────────────────

    /// Recursively build Bone nodes from the aiNode tree.
    osg::ref_ptr<osgAnimation::Bone> buildBoneTree(
        const aiNode*  node,
        const std::unordered_map<std::string, bool>& boneNames,
        std::unordered_map<std::string,
            osg::ref_ptr<osgAnimation::Bone>>& boneMap,
        const osg::Matrix& parentAccum = osg::Matrix::identity());

    /// Find the armature root node (first ancestor whose children are all bones).
    const aiNode* findArmatureRoot(const aiNode* root,
        const std::unordered_map<std::string, bool>& boneNames);

    // ── Mesh conversion ───────────────────────────────────────────────────────

    /// Convert a skinned aiMesh to RigGeometry.
    osg::ref_ptr<osgAnimation::RigGeometry> convertSkinnedMesh(
        const aiMesh*  mesh,
        const aiScene* scene,
        const std::string& baseDir,
        MorphManager*  morphMgr,
        const std::unordered_map<std::string,
            osg::ref_ptr<osgAnimation::Bone>>& boneMap);

    /// Convert an unskinned aiMesh to plain osg::Geometry (same as before).
    osg::ref_ptr<osg::Geode> convertStaticMesh(
        const aiMesh*  mesh,
        const aiScene* scene,
        const std::string& baseDir,
        MorphManager*  morphMgr);

    /// Shared material/texture setup used by both converters.
    void applyMaterial(osg::StateSet* ss,
                       const aiMesh*  mesh,
                       const aiScene* scene,
                       const std::string& baseDir);
};