import os
import spaces
import trimesh
import traceback
import numpy as np
import gradio as gr
from multiprocessing import Process, Queue

import torch
from torch import nn
from transformers import (
    AutoTokenizer, Qwen2ForCausalLM, Qwen2Model, PreTrainedModel)
from transformers.modeling_outputs import CausalLMOutputWithPast


class FourierPointEncoder(nn.Module):
    def __init__(self, hidden_size):
        super().__init__()
        frequencies = 2.0 ** torch.arange(8, dtype=torch.float32)
        self.register_buffer('frequencies', frequencies, persistent=False)
        self.projection = nn.Linear(54, hidden_size)

    def forward(self, points):
        x = points[..., :3]
        x = (x.unsqueeze(-1) * self.frequencies).view(*x.shape[:-1], -1)
        x = torch.cat((points[..., :3], x.sin(), x.cos()), dim=-1)
        x = self.projection(torch.cat((x, points[..., 3:]), dim=-1))
        return x


class CADRecode(Qwen2ForCausalLM):
    def __init__(self, config):
        PreTrainedModel.__init__(self, config)
        self.model = Qwen2Model(config)
        self.vocab_size = config.vocab_size
        self.lm_head = nn.Linear(config.hidden_size, config.vocab_size, bias=False)
        
        torch.set_default_dtype(torch.float32)
        self.point_encoder = FourierPointEncoder(config.hidden_size)
        torch.set_default_dtype(torch.bfloat16)

    def forward(self,
                input_ids=None,
                attention_mask=None,
                point_cloud=None,
                position_ids=None,
                past_key_values=None,
                inputs_embeds=None,
                labels=None,
                use_cache=None,
                output_attentions=None,
                output_hidden_states=None,
                return_dict=None,
                cache_position=None):
        output_attentions = output_attentions if output_attentions is not None else self.config.output_attentions
        output_hidden_states = output_hidden_states if output_hidden_states is not None else self.config.output_hidden_states
        return_dict = return_dict if return_dict is not None else self.config.use_return_dict

        # concatenate point and text embeddings
        if past_key_values is None or past_key_values.get_seq_length() == 0:
            assert inputs_embeds is None
            inputs_embeds = self.model.embed_tokens(input_ids)
            point_embeds = self.point_encoder(point_cloud).bfloat16()
            inputs_embeds[attention_mask == -1] = point_embeds.reshape(-1, point_embeds.shape[2])
            attention_mask[attention_mask == -1] = 1
            input_ids = None
            position_ids = None

        # decoder outputs consists of (dec_features, layer_state, dec_hidden, dec_attn)
        outputs = self.model(
            input_ids=input_ids,
            attention_mask=attention_mask,
            position_ids=position_ids,
            past_key_values=past_key_values,
            inputs_embeds=inputs_embeds,
            use_cache=use_cache,
            output_attentions=output_attentions,
            output_hidden_states=output_hidden_states,
            return_dict=return_dict,
            cache_position=cache_position)

        hidden_states = outputs[0]
        logits = self.lm_head(hidden_states)
        logits = logits.float()

        loss = None
        if labels is not None:
            # Shift so that tokens < n predict n
            shift_logits = logits[..., :-1, :].contiguous()
            shift_labels = labels[..., 1:].contiguous()
            # Flatten the tokens
            loss_fct = nn.CrossEntropyLoss()
            shift_logits = shift_logits.view(-1, self.config.vocab_size)
            shift_labels = shift_labels.view(-1)
            # Enable model parallelism
            shift_labels = shift_labels.to(shift_logits.device)
            loss = loss_fct(shift_logits, shift_labels)

        if not return_dict:
            output = (logits,) + outputs[1:]
            return (loss,) + output if loss is not None else output

        return CausalLMOutputWithPast(
            loss=loss,
            logits=logits,
            past_key_values=outputs.past_key_values,
            hidden_states=outputs.hidden_states,
            attentions=outputs.attentions)

    def prepare_inputs_for_generation(self, *args, **kwargs):
        model_inputs = super().prepare_inputs_for_generation(*args, **kwargs)
        model_inputs['point_cloud'] = kwargs['point_cloud']
        return model_inputs


def mesh_to_point_cloud(mesh, n_points=256):
    vertices, faces = trimesh.sample.sample_surface(mesh, n_points)
    point_cloud = np.concatenate((
        np.asarray(vertices),
        mesh.face_normals[faces]
    ), axis=1)
    ids = np.lexsort((point_cloud[:, 0], point_cloud[:, 1], point_cloud[:, 2]))
    point_cloud = point_cloud[ids]
    return point_cloud


def py_string_to_mesh_file(py_string, mesh_path, queue):
    try:
        exec(py_string, globals())
        compound = globals()['r'].val()
        vertices, faces = compound.tessellate(0.001, 0.1)
        mesh = trimesh.Trimesh([(v.x, v.y, v.z) for v in vertices], faces)
        mesh.export(mesh_path)
    except:
        queue.put(traceback.format_exc())


def py_string_to_mesh_file_safe(py_string, mesh_path):
    # CadQuery code predicted by LLM may be unsafe and cause memory leaks.
    # That's why we execute it in a separace Process with timeout.
    queue = Queue()
    process = Process(
        target=py_string_to_mesh_file,
        args=(py_string, mesh_path, queue))
    process.start()
    process.join(3)

    if process.is_alive():
        process.terminate()
        process.join()
        raise RuntimeError('Process is alive after 3 seconds')
    
    if not queue.empty():
        raise RuntimeError(queue.get())


@spaces.GPU(duration=20)
def run_gpu(model, input_ids, attention_mask, point_cloud, pad_token_id):
    if torch.cuda.is_available():
        model = model.cuda()
    with torch.no_grad():
        batch_ids = model.generate(
            input_ids=torch.tensor(input_ids).unsqueeze(0).to(model.device),
            attention_mask=torch.tensor(attention_mask).unsqueeze(0).to(model.device),
            point_cloud=torch.tensor(point_cloud.astype(np.float32)).unsqueeze(0).to(model.device),
            max_new_tokens=768,
            pad_token_id=pad_token_id).cpu()
    return batch_ids


def run_test(in_mesh_path, seed, results):
    mesh = trimesh.load(in_mesh_path)
    mesh.apply_translation(-(mesh.bounds[0] + mesh.bounds[1]) / 2.0)
    mesh.apply_scale(2.0 / max(mesh.extents))
    np.random.seed(seed)
    point_cloud = mesh_to_point_cloud(mesh)
    
    pcd_path = '/tmp/pcd.obj'
    trimesh.points.PointCloud(point_cloud[:, :3]).export(pcd_path)
    results.append(pcd_path)

    tokenizer = AutoTokenizer.from_pretrained(
        'Qwen/Qwen2-1.5B',
        pad_token='<|im_end|>',
        padding_side='left')
    model = CADRecode.from_pretrained(
        'filapro/cad-recode',
        torch_dtype='auto').eval()

    input_ids = [tokenizer.pad_token_id] * len(point_cloud) + [tokenizer('<|im_start|>')['input_ids'][0]]
    attention_mask = [-1] * len(point_cloud) + [1]
    batch_ids = run_gpu(model, input_ids, attention_mask, point_cloud, tokenizer.pad_token_id)
    py_string = tokenizer.batch_decode(batch_ids)[0]
    begin = py_string.find('<|im_start|>') + 12
    end = py_string.find('<|endoftext|>')
    py_string = py_string[begin: end]
    results.append(py_string)

    out_mesh_path = '/tmp/mesh.stl'
    py_string_to_mesh_file_safe(py_string, out_mesh_path)
    results.append(out_mesh_path)


def run_test_safe(in_mesh_path, seed):
    results, log = list(), str()
    try:
        run_test(in_mesh_path, seed, results)
    except:
        log += 'Status: FAILED\n' + traceback.format_exc()
    return results + [None] * (3 - len(results)) + [log]
    

def run():
    with gr.Blocks() as demo:
        with gr.Row():
            gr.Markdown('## CAD-Recode Demo\n'
                        'Upload mesh or select from examples and press Run! Mesh ⇾ 256 points ⇾ Python code by CAD-Recode ⇾ CAD model.')

        with gr.Row(equal_height=True):
            in_model = gr.Model3D(label='1. Input Mesh', interactive=True)
            point_model = gr.Model3D(label='2. Sampled Point Cloud', display_mode='point_cloud', interactive=False)
            out_model = gr.Model3D(
                label='4. Result CAD Model', interactive=False
            )
        
        with gr.Row():
            with gr.Column():
                with gr.Row():
                    seed_slider = gr.Slider(label='Random Seed', value=42, interactive=True)
                with gr.Row():
                    _ = gr.Examples(
                        examples=[
                            ['./data/49215_5368e45e_0000.stl', 42],
                            ['./data/00882236.stl', 6],
                            ['./data/User Library-engrenage.stl', 18],
                            ['./data/00010900.stl', 42],
                            ['./data/21492_8bd34fc1_0008.stl', 42],
                            ['./data/00375556.stl', 53],
                            ['./data/49121_adb01620_0000.stl', 42]],
                        example_labels=[
                            'fusion360_table1', 'deepcad_star', 'cc3d_gear', 'deepcad_barrels',
                            'fusion360_gear', 'deepcad_house', 'fusion360_table2'],
                        inputs=[in_model, seed_slider],
                        cache_examples=False)
                with gr.Row():
                    run_button = gr.Button('Run')

            with gr.Column():
                out_code = gr.Code(language='python', label='3. Generated Python Code', wrap_lines=True, interactive=False)

            with gr.Column():
                log_textbox = gr.Textbox(label='Log', placeholder='Status: OK', interactive=False)
        
        run_button.click(
            run_test_safe, inputs=[in_model, seed_slider], outputs=[point_model, out_code, out_model, log_textbox])

    demo.launch()


os.environ['TOKENIZERS_PARALLELISM'] = 'False'
run()