import os
import torch
import torch.nn as nn
import logging
from pathlib import Path
from huggingface_hub import hf_hub_download
from diffsynth import ModelManager, WanVideoReCamMasterPipeline

logger = logging.getLogger(__name__)

# Get model storage path from environment variable or use default
MODELS_ROOT_DIR = os.environ.get("RECAMMASTER_MODELS_DIR", "/data/models")
logger.info(f"Using models root directory: {MODELS_ROOT_DIR}")

# Define model repositories and files
WAN21_REPO_ID = "Wan-AI/Wan2.1-T2V-1.3B"
WAN21_LOCAL_DIR = f"{MODELS_ROOT_DIR}/Wan-AI/Wan2.1-T2V-1.3B"
WAN21_FILES = [
    "diffusion_pytorch_model.safetensors",
    "models_t5_umt5-xxl-enc-bf16.pth",
    "Wan2.1_VAE.pth"
]

# Define tokenizer files to download
UMT5_XXL_TOKENIZER_FILES = [
    "google/umt5-xxl/special_tokens_map.json",
    "google/umt5-xxl/spiece.model",
    "google/umt5-xxl/tokenizer.json",
    "google/umt5-xxl/tokenizer_config.json"
]

RECAMMASTER_REPO_ID = "KwaiVGI/ReCamMaster-Wan2.1"
RECAMMASTER_CHECKPOINT_FILE = "step20000.ckpt"
RECAMMASTER_LOCAL_DIR = f"{MODELS_ROOT_DIR}/ReCamMaster/checkpoints"

class ModelLoader:
    def __init__(self):
        self.model_manager = None
        self.pipe = None
        self.is_loaded = False
    
    def download_umt5_xxl_tokenizer(self, progress_callback=None):
        """Download UMT5-XXL tokenizer files from HuggingFace"""
        
        total_files = len(UMT5_XXL_TOKENIZER_FILES)
        downloaded_paths = []
        
        for i, file_path in enumerate(UMT5_XXL_TOKENIZER_FILES):
            local_dir = f"{WAN21_LOCAL_DIR}/{os.path.dirname(file_path)}"
            filename = os.path.basename(file_path)
            full_local_path = f"{WAN21_LOCAL_DIR}/{file_path}"
            
            # Update progress
            if progress_callback:
                progress_callback(i/total_files, desc=f"Checking tokenizer file {i+1}/{total_files}: {filename}")
            
            # Check if already exists
            if os.path.exists(full_local_path):
                logger.info(f"✓ Tokenizer file {filename} already exists at {full_local_path}")
                downloaded_paths.append(full_local_path)
                continue
            
            # Create directory if it doesn't exist
            os.makedirs(local_dir, exist_ok=True)
            
            # Download the file
            logger.info(f"Downloading tokenizer file {filename} from {WAN21_REPO_ID}/{file_path}...")
            
            if progress_callback:
                progress_callback(i/total_files, desc=f"Downloading tokenizer file {i+1}/{total_files}: {filename}")
            
            try:
                # Download using huggingface_hub
                downloaded_path = hf_hub_download(
                    repo_id=WAN21_REPO_ID,
                    filename=file_path,
                    local_dir=WAN21_LOCAL_DIR,
                    local_dir_use_symlinks=False
                )
                logger.info(f"✓ Successfully downloaded tokenizer file {filename} to {downloaded_path}!")
                downloaded_paths.append(downloaded_path)
            except Exception as e:
                logger.error(f"✗ Error downloading tokenizer file {filename}: {e}")
                raise
        
        if progress_callback:
            progress_callback(1.0, desc=f"All tokenizer files downloaded successfully!")
        
        return downloaded_paths

    def download_wan21_models(self, progress_callback=None):
        """Download Wan2.1 model files from HuggingFace"""
        
        total_files = len(WAN21_FILES)
        downloaded_paths = []
        
        # Create directory if it doesn't exist
        Path(WAN21_LOCAL_DIR).mkdir(parents=True, exist_ok=True)
        
        for i, filename in enumerate(WAN21_FILES):
            local_path = Path(WAN21_LOCAL_DIR) / filename
            
            # Update progress
            if progress_callback:
                progress_callback(i/total_files, desc=f"Checking Wan2.1 file {i+1}/{total_files}: {filename}")
            
            # Check if already exists
            if local_path.exists():
                logger.info(f"✓ {filename} already exists at {local_path}")
                downloaded_paths.append(str(local_path))
                continue
            
            # Download the file
            logger.info(f"Downloading {filename} from {WAN21_REPO_ID}...")
            
            if progress_callback:
                progress_callback(i/total_files, desc=f"Downloading Wan2.1 file {i+1}/{total_files}: {filename}")
            
            try:
                # Download using huggingface_hub
                downloaded_path = hf_hub_download(
                    repo_id=WAN21_REPO_ID,
                    filename=filename,
                    local_dir=WAN21_LOCAL_DIR,
                    local_dir_use_symlinks=False
                )
                logger.info(f"✓ Successfully downloaded {filename} to {downloaded_path}!")
                downloaded_paths.append(downloaded_path)
            except Exception as e:
                logger.error(f"✗ Error downloading {filename}: {e}")
                raise
        
        if progress_callback:
            progress_callback(1.0, desc=f"All Wan2.1 models downloaded successfully!")
        
        return downloaded_paths

    def download_recammaster_checkpoint(self, progress_callback=None):
        """Download ReCamMaster checkpoint from HuggingFace using huggingface_hub"""
        checkpoint_path = Path(RECAMMASTER_LOCAL_DIR) / RECAMMASTER_CHECKPOINT_FILE

        # Check if already exists
        if checkpoint_path.exists():
            logger.info(f"✓ ReCamMaster checkpoint already exists at {checkpoint_path}")
            return checkpoint_path

        # Create directory if it doesn't exist
        Path(RECAMMASTER_LOCAL_DIR).mkdir(parents=True, exist_ok=True)

        # Download the checkpoint
        logger.info("Downloading ReCamMaster checkpoint from HuggingFace...")
        logger.info(f"Repository: {RECAMMASTER_REPO_ID}")
        logger.info(f"File: {RECAMMASTER_CHECKPOINT_FILE}")
        logger.info(f"Destination: {checkpoint_path}")
        
        if progress_callback:
            progress_callback(0.0, desc=f"Downloading ReCamMaster checkpoint...")

        try:
            # Download using huggingface_hub
            downloaded_path = hf_hub_download(
                repo_id=RECAMMASTER_REPO_ID,
                filename=RECAMMASTER_CHECKPOINT_FILE,
                local_dir=RECAMMASTER_LOCAL_DIR,
                local_dir_use_symlinks=False
            )
            logger.info(f"✓ Successfully downloaded ReCamMaster checkpoint to {downloaded_path}!")
            
            if progress_callback:
                progress_callback(1.0, desc=f"ReCamMaster checkpoint downloaded successfully!")
                
            return downloaded_path
        except Exception as e:
            logger.error(f"✗ Error downloading checkpoint: {e}")
            raise

    def create_symlink_for_tokenizer(self):
        """Create symlink for google/umt5-xxl to handle potential path issues"""
        try:
            google_dir = f"{MODELS_ROOT_DIR}/google"
            if not os.path.exists(google_dir):
                os.makedirs(google_dir, exist_ok=True)
            
            umt5_xxl_symlink = f"{google_dir}/umt5-xxl"
            umt5_xxl_source = f"{WAN21_LOCAL_DIR}/google/umt5-xxl"
            
            # Create a symlink if it doesn't exist
            if not os.path.exists(umt5_xxl_symlink) and os.path.exists(umt5_xxl_source):
                if os.name == 'nt':  # Windows
                    import ctypes
                    kdll = ctypes.windll.LoadLibrary("kernel32.dll")
                    kdll.CreateSymbolicLinkA(umt5_xxl_symlink.encode(), umt5_xxl_source.encode(), 1)
                else:  # Unix/Linux
                    os.symlink(umt5_xxl_source, umt5_xxl_symlink)
                logger.info(f"Created symlink from {umt5_xxl_source} to {umt5_xxl_symlink}")
        except Exception as e:
            logger.warning(f"Could not create symlink for google/umt5-xxl: {str(e)}")
            # This is a warning, not an error, as we'll try to proceed anyway

    def load_models(self, progress_callback=None):
        """Load the ReCamMaster models"""
        
        if self.is_loaded:
            return "Models already loaded!"
        
        try:
            logger.info("Starting model loading...")
            
            # Import test data creator
            from test_data import create_test_data_structure
            
            # First create the test data structure
            if progress_callback:
                progress_callback(0.05, desc="Setting up test data structure...")
            
            try:
                create_test_data_structure(progress_callback)
            except Exception as e:
                error_msg = f"Error creating test data structure: {str(e)}"
                logger.error(error_msg)
                return error_msg
            
            # Second, ensure the checkpoint is downloaded
            if progress_callback:
                progress_callback(0.1, desc="Checking for ReCamMaster checkpoint...")
            
            try:
                ckpt_path = self.download_recammaster_checkpoint(progress_callback)
                logger.info(f"Using checkpoint at {ckpt_path}")
            except Exception as e:
                error_msg = f"Error downloading ReCamMaster checkpoint: {str(e)}"
                logger.error(error_msg)
                return error_msg
            
            # Third, download Wan2.1 models if needed
            if progress_callback:
                progress_callback(0.2, desc="Checking for Wan2.1 models...")
            
            try:
                wan21_paths = self.download_wan21_models(progress_callback)
                logger.info(f"Using Wan2.1 models: {wan21_paths}")
            except Exception as e:
                error_msg = f"Error downloading Wan2.1 models: {str(e)}"
                logger.error(error_msg)
                return error_msg
            
            # Fourth, download UMT5-XXL tokenizer files
            if progress_callback:
                progress_callback(0.3, desc="Checking for UMT5-XXL tokenizer files...")
            
            try:
                tokenizer_paths = self.download_umt5_xxl_tokenizer(progress_callback)
                logger.info(f"Using UMT5-XXL tokenizer files: {tokenizer_paths}")
            except Exception as e:
                error_msg = f"Error downloading UMT5-XXL tokenizer files: {str(e)}"
                logger.error(error_msg)
                return error_msg
            
            # Now, load the models
            if progress_callback:
                progress_callback(0.4, desc="Loading model manager...")
            
            # Create symlink for tokenizer
            self.create_symlink_for_tokenizer()
            
            # Load Wan2.1 pre-trained models
            self.model_manager = ModelManager(torch_dtype=torch.bfloat16, device="cpu")
            
            if progress_callback:
                progress_callback(0.5, desc="Loading Wan2.1 models...")
            
            # Build full paths for the model files
            model_files = [f"{WAN21_LOCAL_DIR}/{filename}" for filename in WAN21_FILES]
            
            for model_file in model_files:
                logger.info(f"Loading model from: {model_file}")
                if not os.path.exists(model_file):
                    error_msg = f"Error: Model file not found: {model_file}"
                    logger.error(error_msg)
                    return error_msg
            
            # Set environment variable for transformers to find the tokenizer
            os.environ["TRANSFORMERS_CACHE"] = MODELS_ROOT_DIR
            os.environ["TOKENIZERS_PARALLELISM"] = "false"  # Disable tokenizers parallelism warning
            
            self.model_manager.load_models(model_files)
            
            if progress_callback:
                progress_callback(0.7, desc="Creating pipeline...")
            
            self.pipe = WanVideoReCamMasterPipeline.from_model_manager(self.model_manager, device="cuda")
            
            if progress_callback:
                progress_callback(0.8, desc="Initializing ReCamMaster modules...")
            
            # Initialize additional modules introduced in ReCamMaster
            dim = self.pipe.dit.blocks[0].self_attn.q.weight.shape[0]
            for block in self.pipe.dit.blocks:
                block.cam_encoder = nn.Linear(12, dim)
                block.projector = nn.Linear(dim, dim)
                block.cam_encoder.weight.data.zero_()
                block.cam_encoder.bias.data.zero_()
                block.projector.weight = nn.Parameter(torch.eye(dim))
                block.projector.bias = nn.Parameter(torch.zeros(dim))
            
            if progress_callback:
                progress_callback(0.9, desc="Loading ReCamMaster checkpoint...")
            
            # Load ReCamMaster checkpoint
            if not os.path.exists(ckpt_path):
                error_msg = f"Error: ReCamMaster checkpoint not found at {ckpt_path} even after download attempt."
                logger.error(error_msg)
                return error_msg
            
            state_dict = torch.load(ckpt_path, map_location="cpu")
            self.pipe.dit.load_state_dict(state_dict, strict=True)
            self.pipe.to("cuda")
            self.pipe.to(dtype=torch.bfloat16)
            
            self.is_loaded = True
            
            if progress_callback:
                progress_callback(1.0, desc="Models loaded successfully!")
            
            logger.info("Models loaded successfully!")
            return "Models loaded successfully!"
        
        except Exception as e:
            logger.error(f"Error loading models: {str(e)}")
            return f"Error loading models: {str(e)}"