import json
import os
import sys

import bpy


TYPE_NAMES = {
    "CURVE": "CURVE",
    "SURFACE": "SURFACE",
    "FONT": "FONT",
    "META": "METABALL",
}


def rounded(value):
    return round(float(value), 7)


def geometry_record(obj, depsgraph):
    evaluated = obj.evaluated_get(depsgraph)
    mesh = evaluated.to_mesh()
    try:
        mesh.calc_loop_triangles()
        positions = [component for vertex in mesh.vertices for component in vertex.co]
        edge_indices = [index for edge in mesh.edges for index in edge.vertices]
        indices = [index for triangle in mesh.loop_triangles for index in triangle.vertices]
        point_count = len(mesh.vertices)
        bounds_min = [min((vertex.co[axis] for vertex in mesh.vertices), default=0.0) for axis in range(3)]
        bounds_max = [max((vertex.co[axis] for vertex in mesh.vertices), default=0.0) for axis in range(3)]
        centroid = [
            sum((vertex.co[axis] for vertex in mesh.vertices), 0.0) / point_count
            if point_count else 0.0
            for axis in range(3)
        ]
        return {
            "object": obj.name,
            "sourceType": TYPE_NAMES[obj.type],
            "vertexCount": point_count,
            "edgeCount": len(mesh.edges),
            "triangleCount": len(mesh.loop_triangles),
            "boundsMin": [rounded(value) for value in bounds_min],
            "boundsMax": [rounded(value) for value in bounds_max],
            "centroid": [rounded(value) for value in centroid],
            "surfaceArea": rounded(sum((triangle.area for triangle in mesh.loop_triangles), 0.0)),
            "positionMoment": rounded(sum((index + 1) * value for index, value in enumerate(positions))),
            "edgeIndexMoment": sum((index + 1) * (value + 1) for index, value in enumerate(edge_indices)),
            "indexMoment": sum((index + 1) * (value + 1) for index, value in enumerate(indices)),
        }
    finally:
        evaluated.to_mesh_clear()


def main(output_path):
    depsgraph = bpy.context.evaluated_depsgraph_get()
    records = [
        geometry_record(obj, depsgraph)
        for obj in bpy.context.scene.objects
        if obj.type in TYPE_NAMES
    ]
    records.sort(key=lambda record: record["object"])
    payload = {
        "schemaVersion": 1,
        "blenderVersion": bpy.app.version_string,
        "fixture": os.path.basename(bpy.data.filepath),
        "tolerance": {
            "coordinate": 0.00001,
            "surfaceArea": 0.0001,
            "positionMoment": 0.001,
        },
        "geometries": records,
    }
    with open(output_path, "w", encoding="ascii") as output:
        json.dump(payload, output, indent=2, sort_keys=True)
        output.write("\n")
    print(f"nonmesh-desktop-golden-generated output={os.path.abspath(output_path)} geometries={len(records)}")


if __name__ == "__main__":
    if "--" not in sys.argv or len(sys.argv) <= sys.argv.index("--") + 1:
        raise SystemExit("usage: blender -b fixture.blend --python generate-nonmesh-desktop-golden.py -- output.json")
    main(sys.argv[sys.argv.index("--") + 1])