import bpy
from os import path
import os
from dataclasses import dataclass
import shutil

@dataclass
class OBJMetadata:
    materials: list[str]
    objects: list[str]

D = bpy.data
C = bpy.context

def select_one_object(obj):
    bpy.ops.object.select_all(action='DESELECT')
    bpy.context.view_layer.objects.active = obj # type: ignore
    obj.select_set(True)

def iter_buttons():
    object_names = D.objects.keys()
    assert object_names
    for name in object_names:
        print(name)
        if name.startswith("Buttons "):
            yield D.objects[name]

def extract_metadata(obj_path):
    mtl_filename = None
    objects = []
    with open(obj_path, "r") as f:
        for line in f.readlines():
            if line.startswith("mtllib"):
                mtl_filename = line.removeprefix("mtllib ")
            elif line.startswith("o"):
                object_name = line.strip().removeprefix("o ")
                objects.append(object_name)

    materials = []
    if mtl_filename:
        mtl_path = path.join(path.dirname(obj_path), mtl_filename).strip()
        with open(mtl_path, "r") as f:
            for line in f.readlines():
                if not line.startswith("newmtl"): continue
                material_name = line.strip().removeprefix("newmtl ")
                materials.append(material_name)

    return OBJMetadata(materials, objects)

def write_list_to_file(filename, values):
    with open(filename, "w") as f:
        for i in range(len(values)):
            if i > 0: f.write("\n")
            f.writelines(values[i])

export_options = {
    "use_triangles": True,
    "use_materials": True,
    "use_normals": True,
    "use_vertex_groups": True,
    "path_mode": "RELATIVE",
}

bpy.ops.object.select_all(action="SELECT")
for btn in iter_buttons():
    btn.select_set(False)

bpy.ops.export_scene.obj(
    filepath="emulator.obj",
    use_selection=True,
    **export_options
)

metadata = extract_metadata("emulator.obj")
write_list_to_file("emulator.mtls.txt", metadata.materials)
write_list_to_file("emulator.objs.txt", metadata.objects)

object_names = D.objects.keys()
assert object_names
for name in object_names:
    if name.startswith("Buttons "):
        button_name = name.removeprefix("Buttons ")
        button_obj_path = f"buttons/Button {button_name}.obj"
        button_mtl_path = f"buttons/Button {button_name}.mtl"
        select_one_object(D.objects[name])
        bpy.ops.export_scene.obj(
            filepath=button_obj_path,
            use_selection=True,
            **export_options
        )

        tmp_file = "/tmp/blender_export"
        with open(button_obj_path, "r") as src:
            with open(tmp_file, "w") as dst:
                for line in src.readlines():
                    if line.startswith("mtllib"):
                        dst.write("mtllib Button.mtl\n")
                    else:
                        dst.write(line)
        os.remove(button_obj_path)
        shutil.move(tmp_file, button_obj_path)

        if button_name == "0":
            os.rename("buttons/Button 0.mtl", "buttons/Button.mtl")
        else:
            os.remove(button_mtl_path)