import os
import sys
import argparse
import json
import torch
from dataclasses import dataclass, field
from typing import Optional, Dict, Any

# Add project root to path
current_dir = os.getcwd()
if 'VidChain' in current_dir:
    root_dir = os.path.join(current_dir, "..", "..")
else:
    root_dir = current_dir
sys.path.append(root_dir)

try:
    import transformers
    from transformers import HfArgumentParser
    from vtimellm.train.train_dpo import (
        ModelArguments, 
        TrainingArguments, 
        DataArguments,
        train
    )
    from vtimellm.train.dataset import make_supervised_dpo_data_module
    from vtimellm.model import VTimeLLMLlamaForCausalLM
    from vtimellm.model.builder import load_lora
    from vtimellm.mm_utils import print_trainable_parameters
    from trl.trl.trainer import DPOTrainer
    print("✓ Training modules imported successfully")
except ImportError as e:
    print(f"✗ Error importing training modules: {e}")
    print("Make sure you're in the correct environment and all dependencies are installed")
    sys.exit(1)


@dataclass
class DPOConfig:
    """Configuration class for DPO training demo"""
    
    # Model paths
    model_name_or_path: str = "checkpoints/vicuna-7b-v1.5"
    stage2_path: str = "checkpoints/vtimellm-vicuna-v1-5-7b-stage2"
    stage3_path: str = "checkpoints/vtimellm-vicuna-v1-5-7b-stage3"
    stage4_path: str = "checkpoints/vtimellm-vicuna-v1-5-7b-activitynet-stage4"
    pretrain_mm_mlp_adapter: str = "checkpoints/vtimellm-vicuna-v1-5-7b-stage1/mm_projector.bin"
    
    # Data paths
    data_path: str = "data/activitynet/mdpo-train.json"
    data_folder: str = "data/activitynet/videos/train"
    feat_folder: str = "data/activitynet/clipvitl14-vtimellm.pth"
    
    # Training parameters
    output_dir: str = "outputs/vtimellm-dpo-demo"
    num_train_epochs: int = 1
    per_device_train_batch_size: int = 2
    gradient_accumulation_steps: int = 4
    learning_rate: float = 1e-6
    model_max_length: int = 2048
    
    # DPO parameters
    beta: float = 0.5  # DPO beta parameter (controls preference strength)
    dpo_alpha: float = 1.0  # DPO alpha parameter
    gamma: float = 0.0  # Additional regularization parameter
    
    # LoRA parameters
    lora_enable: bool = True
    lora_r: int = 64
    lora_alpha: int = 128
    lora_dropout: float = 0.05
    
    # Other settings
    bf16: bool = True
    gradient_checkpointing: bool = True
    dataloader_num_workers: int = 4
    logging_steps: int = 10
    save_steps: int = 500
    save_total_limit: int = 3
    warmup_ratio: float = 0.1
    weight_decay: float = 0.0
    freeze_mm_mlp_adapter: bool = True


def check_training_requirements(config: DPOConfig) -> bool:
    """Check if all requirements for training are met"""
    print("🔍 Checking training requirements...")
    
    # Check model files
    model_files = [
        config.model_name_or_path,
        config.stage2_path,
        config.stage3_path,
        config.stage4_path,
        config.pretrain_mm_mlp_adapter
    ]
    
    missing_files = []
    for file_path in model_files:
        if not os.path.exists(file_path):
            missing_files.append(file_path)
    
    if missing_files:
        print("❌ Missing model files:")
        for file_path in missing_files:
            print(f"  - {file_path}")
        print("\nPlease download the required model checkpoints.")
        return False
    
    # Check data files
    if not os.path.exists(config.data_path):
        print(f"❌ Training data not found: {config.data_path}")
        print("Please prepare your DPO training data.")
        return False
    
    # Check GPU
    if not torch.cuda.is_available():
        print("⚠ No CUDA GPU available. Training will be very slow on CPU.")
    else:
        gpu_memory = torch.cuda.get_device_properties(0).total_memory / 1024**3
        print(f"✓ GPU available: {torch.cuda.get_device_name(0)} ({gpu_memory:.1f} GB)")
        
        if gpu_memory < 16:
            print("⚠ Warning: GPU memory is less than 16GB. Consider reducing batch size.")
    
    # Check output directory
    os.makedirs(config.output_dir, exist_ok=True)
    print(f"✓ Output directory: {config.output_dir}")
    
    print("✅ Training requirements check completed")
    return True


def create_training_arguments(config: DPOConfig) -> tuple:
    """Create training arguments from config"""
    
    # Model arguments
    model_args = ModelArguments(
        model_name_or_path=config.model_name_or_path,
        stage2_path=config.stage2_path,
        stage3_path=config.stage3_path,
        stage4_path=config.stage4_path,
        pretrain_mm_mlp_adapter=config.pretrain_mm_mlp_adapter,
        version="v1"
    )
    
    # Data arguments
    data_args = DataArguments(
        data_path=config.data_path,
        data_folder=config.data_folder,
        feat_folder=config.feat_folder
    )
    
    # Training arguments
    training_args = TrainingArguments(
        output_dir=config.output_dir,
        num_train_epochs=config.num_train_epochs,
        per_device_train_batch_size=config.per_device_train_batch_size,
        gradient_accumulation_steps=config.gradient_accumulation_steps,
        learning_rate=config.learning_rate,
        model_max_length=config.model_max_length,
        bf16=config.bf16,
        gradient_checkpointing=config.gradient_checkpointing,
        dataloader_num_workers=config.dataloader_num_workers,
        logging_steps=config.logging_steps,
        save_steps=config.save_steps,
        save_total_limit=config.save_total_limit,
        warmup_ratio=config.warmup_ratio,
        weight_decay=config.weight_decay,
        freeze_mm_mlp_adapter=config.freeze_mm_mlp_adapter,
        
        # DPO specific
        beta=config.beta,
        dpo_alpha=config.dpo_alpha,
        gamma=config.gamma,
        train4dpo=True,
        
        # LoRA specific
        lora_enable=config.lora_enable,
        lora_r=config.lora_r,
        lora_alpha=config.lora_alpha,
        lora_dropout=config.lora_dropout,
        
        # Single GPU training settings
        no_cuda=False,  # Keep CUDA enabled
        local_rank=-1,  # Force single GPU by setting local_rank to -1
        dataloader_pin_memory=False,  # Disable pin memory for single GPU
        
        # Other settings
        training_stage=3,
        finetuning=True,
        evaluation_strategy="no",
        save_strategy="steps",
        lr_scheduler_type="cosine",
        tf32=True,
        report_to="none",  # Disable wandb for demo
        remove_unused_columns=False
    )
    
    return model_args, data_args, training_args


def load_and_prepare_model(model_args, training_args):
    """Load and prepare the model for DPO training"""
    print("🤖 Loading and preparing model...")
    
    # Load base model
    model = VTimeLLMLlamaForCausalLM.from_pretrained(
        model_args.model_name_or_path,
        cache_dir=training_args.cache_dir,
        torch_dtype=torch.bfloat16 if training_args.bf16 else torch.float16
    )
    model.config.use_cache = False
    
    # Load tokenizer
    tokenizer = transformers.AutoTokenizer.from_pretrained(
        model_args.model_name_or_path,
        cache_dir=training_args.cache_dir,
        model_max_length=training_args.model_max_length,
        padding_side="right",
        use_fast=False,
    )
    tokenizer.pad_token = tokenizer.unk_token
    
    # Initialize vision modules
    model.get_model().initialize_vision_modules(model_args)
    model.cuda()
    
    # Load stage 2 weights
    print("📥 Loading stage 2 weights...")
    model = load_lora(model, model_args.stage2_path)
    model = model.merge_and_unload()
    
    # Load stage 3 weights
    print("📥 Loading stage 3 weights...")
    model = load_lora(model, model_args.stage3_path)
    model = model.merge_and_unload()
    
    # Load stage 4 weights (for DPO training)
    print("📥 Loading stage 4 weights...")
    model = load_lora(model, model_args.stage4_path)
    model = model.merge_and_unload()
    
    # Add LoRA adapters for DPO training
    if training_args.lora_enable:
        from peft import LoraConfig, get_peft_model
        
        # Find target modules for LoRA
        def find_all_linear_explicit_names(model):
            cls = torch.nn.Linear
            lora_module_names = set()
            multimodal_keywords = ['mm_projector', 'vision_tower', 'vision_resampler']
            for name, module in model.named_modules():
                if any(mm_keyword in name for mm_keyword in multimodal_keywords):
                    continue
                if isinstance(module, cls):
                    lora_module_names.add(name)
            if 'lm_head' in lora_module_names:
                lora_module_names.remove('lm_head')
            return list(lora_module_names)
        
        explicit_linear = find_all_linear_explicit_names(model)
        lora_config = LoraConfig(
            r=training_args.lora_r,
            lora_alpha=training_args.lora_alpha,
            target_modules=explicit_linear,
            lora_dropout=training_args.lora_dropout,
            bias="none",
            task_type="CAUSAL_LM",
        )
        
        print("🔧 Adding LoRA adapters...")
        model = get_peft_model(model, lora_config)
        print_trainable_parameters(model)
    
    # Move to GPU
    model = model.cuda()
    
    return model, tokenizer


def save_training_results(model, trainer, training_args, config):
    """Save training results and model"""
    print("💾 Saving training results...")
    
    # Save model
    if training_args.lora_enable:
        from vtimellm.train.train_dpo import get_peft_state_maybe_zero_3, get_peft_state_non_lora_maybe_zero_3
        
        state_dict = get_peft_state_maybe_zero_3(
            model.named_parameters(), training_args.lora_bias
        )
        non_lora_state_dict = get_peft_state_non_lora_maybe_zero_3(
            model.named_parameters()
        )
        
        if training_args.local_rank in [0, -1]:
            model.config.save_pretrained(training_args.output_dir)
            model.save_pretrained(training_args.output_dir, state_dict=state_dict)
            torch.save(non_lora_state_dict, os.path.join(training_args.output_dir, 'non_lora_trainables.bin'))
    
    # Save training config
    config_dict = {
        "model_paths": {
            "model_name_or_path": config.model_name_or_path,
            "stage2_path": config.stage2_path,
            "stage3_path": config.stage3_path,
            "stage4_path": config.stage4_path,
        },
        "training_params": {
            "num_train_epochs": config.num_train_epochs,
            "per_device_train_batch_size": config.per_device_train_batch_size,
            "learning_rate": config.learning_rate,
            "beta": config.beta,
            "dpo_alpha": config.dpo_alpha,
        },
        "lora_params": {
            "lora_r": config.lora_r,
            "lora_alpha": config.lora_alpha,
            "lora_dropout": config.lora_dropout,
        }
    }
    
    with open(os.path.join(training_args.output_dir, "training_config.json"), "w") as f:
        json.dump(config_dict, f, indent=2)
    
    print(f"✅ Results saved to: {training_args.output_dir}")


def demo_dpo_training(config: DPOConfig):
    """Main function for DPO training demo"""
    print("🎬 VTimeLLM DPO Training Demo")
    print("=" * 50)
    
    # Force single GPU usage
    print("🔧 Setting up single GPU training...")
    if torch.cuda.is_available():
        # Set CUDA device to 0 (first GPU)
        torch.cuda.set_device(0)
        print(f"✓ Using GPU: {torch.cuda.get_device_name(0)}")
        
        # Set environment variables for single GPU
        os.environ['CUDA_VISIBLE_DEVICES'] = '0'
        os.environ['OMPI_COMM_WORLD_SIZE'] = '1'
        print("✓ Environment variables set for single GPU")
    else:
        print("⚠ No CUDA GPU available")
    
    # Check requirements
    if not check_training_requirements(config):
        print("❌ Training requirements not met. Please fix the issues above.")
        return False
    
    try:
        # Create training arguments
        model_args, data_args, training_args = create_training_arguments(config)
        
        # Load and prepare model
        model, tokenizer = load_and_prepare_model(model_args, training_args)
        
        # Create trainer
        trainer = create_dpo_trainer(model, tokenizer, data_args, training_args)
        
        # Train model
        train_model(trainer, training_args)
        
        # Save results
        save_training_results(model, trainer, training_args, config)
        
        print("\n🎉 DPO Training Demo Completed Successfully!")
        print(f"📁 Model saved to: {config.output_dir}")
        print("\nYou can now use the trained model for inference!")
        
        return True
        
    except Exception as e:
        print(f"❌ Training failed with error: {e}")
        import traceback
        traceback.print_exc()
        return False


def create_sample_config():
    """Create a sample configuration for students"""
    return DPOConfig(
        # Use smaller batch size for demo
        per_device_train_batch_size=1,
        gradient_accumulation_steps=2,
        num_train_epochs=1,
        logging_steps=5,
        save_steps=100,
        save_total_limit=2
    )


def main():
    """Main function with command line interface"""
    # Use default config
    config = DPOConfig()
    print("⚙️ Using default configuration")
    check_only = False
    if check_only:
        # Only check requirements
        check_training_requirements(config)
    else:
        # Run full training demo
        demo_dpo_training(config)


if __name__ == "__main__":
    main()