import bpy
import bmesh
import mathutils

class TE_Vertex:
    pos = mathutils.Vector()
    normal = mathutils.Vector()
    uv = mathutils.Vector((0, 0))

class TE_Mesh:
    vertices = []
    indices = []


def prepare_mesh(mesh):

    bm = bmesh.new()
    bm.from_mesh(mesh)
    bmesh.ops.triangulate(bm, faces=bm.faces[:])

    export_mesh = TE_Mesh()
    export_mesh.vertices = [TE_Vertex() for _ in range(len(bm.verts))]
    export_mesh.indices = [-1 for _ in range(len(bm.faces) * 3)]

    uvl = bm.loops.layers.uv[0] if bm.loops.layers.uv else None

    for vert in bm.verts:
        export_vert = export_mesh.vertices[vert.index]

        export_vert.pos = vert.co
        export_vert.normal = vert.normal

    index = 0
    for face in bm.faces:
        vert0 = face.verts[0]
        vert1 = face.verts[1]
        vert2 = face.verts[2]

        export_mesh.indices[index] = vert0.index
        export_mesh.indices[index + 1] = vert1.index
        export_mesh.indices[index + 2] = vert2.index
        index += 3

        if not face.smooth:
            export_mesh.vertices[vert0.index].normal = face.normal
            export_mesh.vertices[vert1.index].normal = face.normal
            export_mesh.vertices[vert2.index].normal = face.normal

        if uvl:
            export_mesh.vertices[vert0.index].uv = mathutils.Vector(face.loops[0][uvl].uv)
            export_mesh.vertices[vert1.index].uv = mathutils.Vector(face.loops[1][uvl].uv)
            export_mesh.vertices[vert2.index].uv = mathutils.Vector(face.loops[2][uvl].uv)

    return export_mesh


def export_mesh_to_cpp(mesh, filepath):

    with open(filepath, 'w', encoding='utf-8') as f:
        f.write("unique_ptr<StaticMesh> GeometryFactory::mesh()\n")
        f.write("{\n")
        f.write("   unique_ptr<StaticMesh> result = make_unique<StaticMesh>();\n")
        f.write("\n")
        f.write("   result->vertices = \n")
        f.write("   {\n")

        for v in mesh.vertices:
            f.write(str.format('        {{ {{ {0}, {1}, {2} }},  {{ {3}, {4}, {5} }}, {{ {6}, {7} }} }},\n',
                v.pos.x, v.pos.y, v.pos.z, v.normal.x, v.normal.y, v.normal.z, v.uv.x, v.uv.y));
            print(v.uv)

        f.write("   };\n")
        f.write("\n")
        f.write("   result->indices = \n")
        f.write("   {")

        cnt = 0
        for i in mesh.indices:
            if cnt % 3 == 0:
                f.write('\n    ')

            f.write(str.format('{0}, ', i))
            cnt += 1

        f.write("\n")
        f.write("   };\n")
        f.write("\n")
        f.write("   return result;\n")
        f.write("}\n")


def export_to_cpp(context, filepath):
    print("Exporting to C++...")
    with open(filepath, 'w', encoding='utf-8') as f:

        for obj in bpy.context.selected_objects:

            if obj.type != 'MESH':
                continue

            mesh = prepare_mesh(obj.data)
            export_mesh_to_cpp(mesh, filepath)

    print("Exporting to C++... done")
    return {'FINISHED'}


# ExportHelper is a helper class, defines filename and
# invoke() function which calls the file selector.
from bpy_extras.io_utils import ExportHelper
from bpy.props import StringProperty, BoolProperty, EnumProperty
from bpy.types import Operator


class TE_CppExporter(Operator, ExportHelper):
    """Export as C++ source"""
    bl_idname = "te.cpp_export"  # important since its how bpy.ops.import_test.some_data is constructed
    bl_label = "TE Export To C++"

    # ExportHelper mixin class uses this
    filename_ext = ".txt"

    filter_glob: StringProperty(
        default="*.cpp",
        options={'HIDDEN'},
        maxlen=255,  # Max internal buffer length, longer would be clamped.
    )

    def execute(self, context):
        return export_to_cpp(context, self.filepath)


# Only needed if you want to add into a dynamic menu
def menu_func_export(self, context):
    self.layout.operator(TE_CppExporter.bl_idname, text="TE C++ Export")


def register():
    print("TE_CppExporter register")
    bpy.utils.register_class(TE_CppExporter)
    bpy.types.TOPBAR_MT_file_export.append(menu_func_export)


def unregister():
    print("TE_CppExporter unregister")
    bpy.utils.unregister_class(TE_CppExporter)
    bpy.types.TOPBAR_MT_file_export.remove(menu_func_export)


if __name__ == "__main__":
    register()

    # test call
    bpy.ops.te.cpp_export('INVOKE_DEFAULT')