import os
import torch
import time
import threading
import json
import gc
from flask import Flask, request, jsonify, send_file, Response, stream_with_context
from werkzeug.utils import secure_filename
from PIL import Image
import io
import zipfile
import uuid
import traceback
from huggingface_hub import snapshot_download
from flask_cors import CORS
import numpy as np
import trimesh
import cv2
import pymeshlab
from hy3dgen.shapegen import Hunyuan3DDiTFlowMatchingPipeline

# Force CPU usage
os.environ["CUDA_VISIBLE_DEVICES"] = ""  # Disable GPU detection
torch.set_default_device("cpu")  # Set CPU as default device

app = Flask(__name__)
CORS(app)  # Enable CORS for all routes

# Configure directories
UPLOAD_FOLDER = '/tmp/uploads'
RESULTS_FOLDER = '/tmp/results'
CACHE_DIR = '/tmp/huggingface'
ALLOWED_EXTENSIONS = {'png', 'jpg', 'jpeg'}

# Create necessary directories
os.makedirs(UPLOAD_FOLDER, exist_ok=True)
os.makedirs(RESULTS_FOLDER, exist_ok=True)
os.makedirs(CACHE_DIR, exist_ok=True)

# Set Hugging Face cache environment variables
os.environ['HF_HOME'] = CACHE_DIR
os.environ['TRANSFORMERS_CACHE'] = os.path.join(CACHE_DIR, 'transformers')
os.environ['HF_DATASETS_CACHE'] = os.path.join(CACHE_DIR, 'datasets')

app.config['UPLOAD_FOLDER'] = UPLOAD_FOLDER
app.config['MAX_CONTENT_LENGTH'] = 16 * 1024 * 1024  # 16MB max

# Job tracking dictionary
processing_jobs = {}

# Global model variables
hunyuan_pipeline = None
model_loaded = False
model_loading = False

# Configuration for processing
TIMEOUT_SECONDS = 600  # 10 minutes max for Hunyuan3D-2mini on CPU
MAX_DIMENSION = 256    # Reduced for CPU memory constraints

# TimeoutError for handling timeouts
class TimeoutError(Exception):
    pass

# Thread-safe timeout implementation
def process_with_timeout(function, args, timeout):
    result = [None]
    error = [None]
    completed = [False]
    
    def target():
        try:
            result[0] = function(*args)
            completed[0] = True
        except Exception as e:
            error[0] = e
    
    thread = threading.Thread(target=target)
    thread.daemon = True
    thread.start()
    
    thread.join(timeout)
    
    if not completed[0]:
        if thread.is_alive():
            return None, TimeoutError(f"Processing timed out after {timeout} seconds")
        elif error[0]:
            return None, error[0]
    
    if error[0]:
        return None, error[0]
    
    return result[0], None

def allowed_file(filename):
    return '.' in filename and filename.rsplit('.', 1)[1].lower() in ALLOWED_EXTENSIONS

# Simplified image preprocessing for Hunyuan3D-2mini
def preprocess_image(image_path):
    with Image.open(image_path) as img:
        img = img.convert("RGB")
        
        # Resize to smaller dimensions for CPU
        if img.width > MAX_DIMENSION or img.height > MAX_DIMENSION:
            if img.width > img.height:
                new_width = MAX_DIMENSION
                new_height = int(img.height * (MAX_DIMENSION / img.width))
            else:
                new_height = MAX_DIMENSION
                new_width = int(img.width * (MAX_DIMENSION / img.height))
            img = img.resize((new_width, new_height), Image.LANCZOS)
        
        return img

def load_model():
    global hunyuan_pipeline, model_loaded, model_loading
    
    if model_loaded:
        return hunyuan_pipeline
    
    if model_loading:
        while model_loading and not model_loaded:
            time.sleep(0.5)
        return hunyuan_pipeline
    
    try:
        model_loading = True
        print("Starting model loading...")
        
        model_name = "tencent/Hunyuan3D-2mini"
        
        # Download model with retry mechanism
        max_retries = 3
        retry_delay = 5
        for attempt in range(max_retries):
            try:
                snapshot_download(
                    repo_id=model_name,
                    cache_dir=CACHE_DIR,
                    resume_download=True,
                )
                break
            except Exception as e:
                if attempt < max_retries - 1:
                    print(f"Download attempt {attempt+1} failed: {str(e)}. Retrying in {retry_delay} seconds...")
                    time.sleep(retry_delay)
                    retry_delay *= 2
                else:
                    raise
        
        # Load Hunyuan3D-2mini pipeline
        hunyuan_pipeline = Hunyuan3DDiTFlowMatchingPipeline.from_pretrained(
            model_name,
            subfolder="hunyuan3d-dit-v2-mini",
            use_safetensors=True,
            torch_dtype=torch.float16,
            cache_dir=CACHE_DIR,
            device_map="cpu"  # Explicitly set to CPU
        )
        
        model_loaded = True
        print("Model loaded successfully on CPU")
        return hunyuan_pipeline
    
    except Exception as e:
        print(f"Error loading model: {str(e)}")
        print(traceback.format_exc())
        raise
    finally:
        model_loading = False

# Optimize mesh for Unity
def optimize_mesh(mesh_path, target_faces=10000):
    ms = pymeshlab.MeshSet()
    ms.load_new_mesh(mesh_path)
    ms.meshing_decimation_quadric_edge_collapse(targetfacenum=target_faces)
    optimized_path = mesh_path.replace(".glb", "_optimized.glb")
    ms.save_current_mesh(optimized_path)
    return optimized_path

@app.route('/health', methods=['GET'])
def health_check():
    return jsonify({
        "status": "healthy",
        "model": "Hunyuan3D-2mini 3D Generator",
        "device": "cpu"
    }), 200

@app.route('/progress/<job_id>', methods=['GET'])
def progress(job_id):
    def generate():
        if job_id not in processing_jobs:
            yield f"data: {json.dumps({'error': 'Job not found'})}\n\n"
            return
            
        job = processing_jobs[job_id]
        
        yield f"data: {json.dumps({'status': 'processing', 'progress': job['progress']})}\n\n"
        
        last_progress = job['progress']
        check_count = 0
        while job['status'] == 'processing':
            if job['progress'] != last_progress:
                yield f"data: {json.dumps({'status': 'processing', 'progress': job['progress']})}\n\n"
                last_progress = job['progress']
            
            time.sleep(0.5)
            check_count += 1
            
            if check_count > 60:
                if 'thread_alive' in job and not job['thread_alive']():
                    job['status'] = 'error'
                    job['error'] = 'Processing thread died unexpectedly'
                    break
                check_count = 0
        
        if job['status'] == 'completed':
            yield f"data: {json.dumps({'status': 'completed', 'progress': 100, 'result_url': job['result_url'], 'preview_url': job['preview_url']})}\n\n"
        else:
            yield f"data: {json.dumps({'status': 'error', 'error': job['error']})}\n\n"
    
    return Response(stream_with_context(generate()), mimetype='text/event-stream')

@app.route('/convert', methods=['POST'])
def convert_image_to_3d():
    if 'image' not in request.files:
        return jsonify({"error": "No image provided"}), 400
    
    file = request.files['image']
    if file.filename == '':
        return jsonify({"error": "No image selected"}), 400
    
    if not allowed_file(file.filename):
        return jsonify({"error": f"File type not allowed. Supported types: {', '.join(ALLOWED_EXTENSIONS)}"}), 400
    
    try:
        output_format = request.form.get('output_format', 'glb').lower()
        detail_level = request.form.get('detail_level', 'medium').lower()
    except ValueError:
        return jsonify({"error": "Invalid parameter values"}), 400
    
    if output_format not in ['glb']:
        return jsonify({"error": "Only GLB format is supported with Hunyuan3D-2mini"}), 400
    
    job_id = str(uuid.uuid4())
    output_dir = os.path.join(RESULTS_FOLDER, job_id)
    os.makedirs(output_dir, exist_ok=True)
    
    filename = secure_filename(file.filename)
    filepath = os.path.join(app.config['UPLOAD_FOLDER'], f"{job_id}_{filename}")
    file.save(filepath)
    
    processing_jobs[job_id] = {
        'status': 'processing',
        'progress': 0,
        'result_url': None,
        'preview_url': None,
        'error': None,
        'output_format': output_format,
        'created_at': time.time()
    }
    
    def process_image():
        thread = threading.current_thread()
        processing_jobs[job_id]['thread_alive'] = lambda: thread.is_alive()
        
        try:
            processing_jobs[job_id]['progress'] = 5
            image = preprocess_image(filepath)
            processing_jobs[job_id]['progress'] = 10
            
            try:
                model = load_model()
                processing_jobs[job_id]['progress'] = 30
            except Exception as e:
                processing_jobs[job_id]['status'] = 'error'
                processing_jobs[job_id]['error'] = f"Error loading model: {str(e)}"
                return
            
            try:
                def generate_3d():
                    # Adjust settings based on detail level
                    steps = {'low': 20, 'medium': 30, 'high': 40}
                    resolution = {'low': 200, 'medium': 256, 'high': 300}
                    
                    mesh = model(
                        image=image,
                        num_inference_steps=steps[detail_level],
                        octree_resolution=resolution[detail_level],
                        num_chunks=10000,
                        generator=torch.manual_seed(12345),
                        output_type="trimesh"
                    )[0]
                    return mesh
                
                mesh, error = process_with_timeout(generate_3d, [], TIMEOUT_SECONDS)
                
                if error:
                    if isinstance(error, TimeoutError):
                        processing_jobs[job_id]['status'] = 'error'
                        processing_jobs[job_id]['error'] = f"Processing timed out after {TIMEOUT_SECONDS} seconds"
                        return
                    else:
                        raise error
                        
                processing_jobs[job_id]['progress'] = 80
                
                # Export and optimize
                glb_path = os.path.join(output_dir, "model.glb")
                mesh.export(glb_path, file_type='glb')
                
                # Optimize for Unity
                optimized_path = optimize_mesh(glb_path)
                
                processing_jobs[job_id]['result_url'] = f"/download/{job_id}"
                processing_jobs[job_id]['preview_url'] = f"/preview/{job_id}"
                
                processing_jobs[job_id]['status'] = 'completed'
                processing_jobs[job_id]['progress'] = 100
                print(f"Job {job_id} completed successfully")
                
            except Exception as e:
                error_details = traceback.format_exc()
                processing_jobs[job_id]['status'] = 'error'
                processing_jobs[job_id]['error'] = f"Error during processing: {str(e)}"
                print(f"Error processing job {job_id}: {str(e)}")
                print(error_details)
                return
            
            if os.path.exists(filepath):
                os.remove(filepath)
            
            gc.collect()
            
        except Exception as e:
            error_details = traceback.format_exc()
            processing_jobs[job_id]['status'] = 'error'
            processing_jobs[job_id]['error'] = f"{str(e)}\n{error_details}"
            print(f"Error processing job {job_id}: {str(e)}")
            print(error_details)
            
            if os.path.exists(filepath):
                os.remove(filepath)
    
    processing_thread = threading.Thread(target=process_image)
    processing_thread.daemon = True
    processing_thread.start()
    
    return jsonify({"job_id": job_id}), 202

@app.route('/download/<job_id>', methods=['GET'])
def download_model(job_id):
    if job_id not in processing_jobs or processing_jobs[job_id]['status'] != 'completed':
        return jsonify({"error": "Model not found or processing not complete"}), 404
    
    output_dir = os.path.join(RESULTS_FOLDER, job_id)
    glb_path = os.path.join(output_dir, "model_optimized.glb")
    
    if os.path.exists(glb_path):
        return send_file(glb_path, as_attachment=True, download_name="model.glb")
    
    return jsonify({"error": "File not found"}), 404

@app.route('/preview/<job_id>', methods=['GET'])
def preview_model(job_id):
    if job_id not in processing_jobs or processing_jobs[job_id]['status'] != 'completed':
        return jsonify({"error": "Model not found or processing not complete"}), 404
    
    output_dir = os.path.join(RESULTS_FOLDER, job_id)
    glb_path = os.path.join(output_dir, "model_optimized.glb")
    
    if os.path.exists(glb_path):
        return send_file(glb_path, mimetype='model/gltf-binary')
    
    return jsonify({"error": "Model file not found"}), 404

def cleanup_old_jobs():
    current_time = time.time()
    job_ids_to_remove = []
    
    for job_id, job_data in processing_jobs.items():
        if job_data['status'] == 'completed' and (current_time - job_data.get('created_at', 0)) > 3600:
            job_ids_to_remove.append(job_id)
        elif job_data['status'] == 'error' and (current_time - job_data.get('created_at', 0)) > 1800:
            job_ids_to_remove.append(job_id)
    
    for job_id in job_ids_to_remove:
        output_dir = os.path.join(RESULTS_FOLDER, job_id)
        try:
            import shutil
            if os.path.exists(output_dir):
                shutil.rmtree(output_dir)
        except Exception as e:
            print(f"Error cleaning up job {job_id}: {str(e)}")
        
        if job_id in processing_jobs:
            del processing_jobs[job_id]
    
    threading.Timer(300, cleanup_old_jobs).start()

@app.route('/model-info/<job_id>', methods=['GET'])
def model_info(job_id):
    if job_id not in processing_jobs:
        return jsonify({"error": "Model not found"}), 404
        
    job = processing_jobs[job_id]
    
    if job['status'] != 'completed':
        return jsonify({
            "status": job['status'],
            "progress": job['progress'],
            "error": job.get('error')
        }), 200
    
    output_dir = os.path.join(RESULTS_FOLDER, job_id)
    model_stats = {}
    
    glb_path = os.path.join(output_dir, "model_optimized.glb")
    if os.path.exists(glb_path):
        model_stats['model_size'] = os.path.getsize(glb_path)
    
    return jsonify({
        "status": job['status'],
        "model_format": job['output_format'],
        "download_url": job['result_url'],
        "preview_url": job['preview_url'],
        "model_stats": model_stats,
        "created_at": job.get('created_at'),
        "completed_at": job.get('completed_at')
    }), 200

@app.route('/', methods=['GET'])
def index():
    return jsonify({
        "message": "Image to 3D API (Hunyuan3D-2mini)",
        "endpoints": [
            "/convert",
            "/progress/<job_id>",
            "/download/<job_id>",
            "/preview/<job_id>",
            "/model-info/<job_id>"
        ],
        "parameters": {
            "output_format": "glb",
            "detail_level": "low, medium, or high - controls mesh detail"
        },
        "description": "This API creates full 3D models from 2D images using Hunyuan3D-2mini"
    }), 200

if __name__ == '__main__':
    cleanup_old_jobs()
    port = int(os.environ.get('PORT', 7860))
    app.run(host='0.0.0.0', port=port)