"""
Utilities for ImageNet-100 parquet data inspection and debugging.

This module provides functions to inspect the structure and content of the 
ImageNet-100 parquet dataset files.

Usage:
    # Debug the parquet file structure
    from scripts.utils import debug_structure
    debug_structure()
    
     # Check image sizes in the dataset
     from scripts.utils import check_image_sizes
     check_image_sizes()
     
     # Analyze memory usage
     from scripts.utils import analyze_memory_usage
     analyze_memory_usage()
"""

import pandas as pd
from PIL import Image
import io
from pathlib import Path
import sys
import torch
from torch.utils.data import DataLoader
from torchvision import transforms


def debug_structure(data_dir: str = "data") -> None:
    """
    Debug and inspect the parquet data structure.

    This function loads a sample parquet file and prints detailed information
    about the data structure, including column names, data types, and how
    image data is stored.

    Args:
        data_dir (str): Path to the directory containing parquet files.
                       Defaults to "data".

    Returns:
        None

    Example:
        >>> debug_structure()
        DataFrame shape: (7453, 2)
        Columns: ['image', 'label']
        First row data types:
          image: <class 'dict'>
          label: <class 'numpy.int64'>
        Image data type: <class 'dict'>
        Image dict keys: ['bytes', 'path']
          bytes: <class 'bytes'> - b'\x89PNG\r\n\x1a\n...
          path: <class 'NoneType'> - None...
    """
    data_path = Path(data_dir)
    parquet_file = data_path / "train-00000-of-00017.parquet"

    if not parquet_file.exists():
        raise FileNotFoundError(f"Parquet file not found: {parquet_file}")

    df = pd.read_parquet(parquet_file)
    print(f"DataFrame shape: {df.shape}")
    print(f"Columns: {list(df.columns)}")

    # Check first sample
    first_row = df.iloc[0]
    print(f"\nFirst row data types:")
    for col in df.columns:
        print(f"  {col}: {type(first_row[col])}")

    # Check image column structure
    image_data = first_row['image']
    print(f"\nImage data type: {type(image_data)}")
    if isinstance(image_data, dict):
        print(f"Image dict keys: {list(image_data.keys())}")
        for key, value in image_data.items():
            print(f"  {key}: {type(value)} - {str(value)[:100]}...")
    elif isinstance(image_data, bytes):
        print(f"Image bytes length: {len(image_data)}")
    else:
        print(f"Image data: {str(image_data)[:200]}...")


def check_image_sizes(data_dir: str = "data", num_samples: int = 10) -> None:
    """
    Check actual image sizes in the parquet data.

    This function inspects a sample of images from both train and validation
    splits to determine their original dimensions before any resizing.

    Args:
        data_dir (str): Path to the directory containing parquet files.
                       Defaults to "data".
        num_samples (int): Number of images to check from each file.
                          Defaults to 10.

    Returns:
        None

    Example:
        >>> check_image_sizes()

        === train-00000-of-00017.parquet ===
        Sample image sizes: [(213, 160), (160, 243), (160, 213), ...]
        Unique sizes found: [(160, 213), (213, 160), (241, 160), ...]
        Multiple sizes found!
    """
    data_path = Path(data_dir)

    # Check a few files from both train and validation
    files_to_check = [
        "train-00000-of-00017.parquet",
        "validation-00000-of-00001.parquet"
    ]

    for filename in files_to_check:
        file_path = data_path / filename
        if not file_path.exists():
            print(f"Warning: {filename} not found, skipping...")
            continue

        print(f"\n=== {filename} ===")
        df = pd.read_parquet(file_path)

        sizes = []
        for i in range(min(num_samples, len(df))):
            try:
                image_bytes = df.iloc[i]['image']['bytes']
                image = Image.open(io.BytesIO(image_bytes))
                sizes.append(image.size)
            except Exception as e:
                print(f"Error processing image {i}: {e}")
                continue

        print(f"Sample image sizes: {sizes}")

        # Get unique sizes
        unique_sizes = list(set(sizes))
        print(f"Unique sizes found: {unique_sizes}")

        if len(unique_sizes) == 1:
            print(
                f"All checked images are {unique_sizes[0][0]}x{unique_sizes[0][1]}")
        else:
            print("Multiple sizes found!")


def analyze_memory_usage(data_dir: str = "data", batch_size: int = 32,
                         num_batches: int = 5) -> None:
    """
    Analyze actual PyTorch tensor memory usage from dataloader.

    This function loads real batches through PyTorch dataloader and measures
    actual tensor memory usage for more accurate training memory estimates.

    Args:
        data_dir (str): Path to directory containing parquet files.
                        Defaults to "data".
        batch_size (int): Batch size to test with. Defaults to 32.
        num_batches (int): Number of batches to sample. Defaults to 5.

    Returns:
        None

    Example:
        >>> analyze_memory_usage()
        === PyTorch Memory Usage Analysis ===
        Loading ImageNet100Parquet dataset...

        === Batch Analysis ===
        Analyzing 5 batches of size 32...
        Batch 1: 13.2 MB (tensors: 2, samples: 32)
        Batch 2: 13.1 MB (tensors: 2, samples: 32)
        ...

        === Memory Estimates ===
        Per batch average: 13.1 MB
        Per sample average: 0.41 MB
        Estimated total memory: 52.5 GB
    """
    print("=== PyTorch Memory Usage Analysis ===")

    try:
        # Import the dataloader class
        import sys
        import os
        sys.path.append(os.path.dirname(__file__))
        from pytorch_dataloader import ImageNet100Parquet

        # Create dataset and dataloader
        transform = transforms.Compose([
            transforms.Resize((224, 224)),
            transforms.ToTensor(),
        ])

        print("Loading ImageNet100Parquet dataset...")
        dataset = ImageNet100Parquet(data_dir, "train", transform)
        dataloader = DataLoader(dataset, batch_size=batch_size, shuffle=False)

        print(f"Dataset size: {len(dataset):,} samples")
        print(f"Analyzing {num_batches} batches of size {batch_size}...\n")

        total_samples_analyzed = 0
        total_memory_per_batch = 0
        batch_memory_usages = []

        print("=== Batch Analysis ===")

        for batch_idx, (images, labels) in enumerate(dataloader):
            if batch_idx >= num_batches:
                break

            # Calculate actual tensor memory usage
            image_memory = images.element_size() * images.numel()
            label_memory = labels.element_size() * labels.numel()
            batch_memory = image_memory + label_memory
            batch_memory_mb = batch_memory / (1024**2)

            batch_memory_usages.append(batch_memory_mb)
            total_samples_analyzed += images.size(0)
            total_memory_per_batch += batch_memory_mb

            print(f"Batch {batch_idx + 1}: {batch_memory_mb:.1f} MB "
                  f"(tensors: {images.dim() + labels.dim()}, samples: {images.size(0)})")

            # Clean up tensors
            del images, labels
            torch.cuda.empty_cache() if torch.cuda.is_available() else None

        if not batch_memory_usages:
            print("No batches analyzed!")
            return

        avg_batch_memory = sum(batch_memory_usages) / len(batch_memory_usages)
        avg_sample_memory = avg_batch_memory / batch_size
        estimated_total_batches = len(dataset) / batch_size
        estimated_total_memory = avg_batch_memory * estimated_total_batches

        print(f"\n=== Memory Estimates ===")
        print(f"Per batch average: {avg_batch_memory:.1f} MB")
        print(f"Per sample average: {avg_sample_memory:.2f} MB")
        print(f"Dataset samples: {len(dataset):,}")
        print(f"Estimated total batches: {estimated_total_batches:.0f}")
        print(f"Estimated total memory: {estimated_total_memory:.1f} MB "
              f"({estimated_total_memory / 1024:.1f} GB)")

        # Also analyze validation
        print(f"\n=== Validation Dataset ===")
        try:
            val_dataset = ImageNet100Parquet(data_dir, "validation", transform)
            val_dataloader = DataLoader(
                val_dataset, batch_size=batch_size, shuffle=False)

            val_samples = 0
            val_memory_total = 0

            for images, labels in val_dataloader:
                image_memory = images.element_size() * images.numel()
                label_memory = labels.element_size() * labels.numel()
                val_memory_total += image_memory + label_memory
                val_samples += images.size(0)
                break  # Just analyze first batch for validation

            val_avg_memory = (val_memory_total / val_samples) / \
                (1024**2)  # Convert to MB
            val_total_memory = val_avg_memory * len(val_dataset)

            print(f"Validation samples: {len(val_dataset):,}")
            print(f"Validation per sample: {val_avg_memory:.2f} MB")
            print(f"Validation total memory: {val_total_memory:.1f} MB "
                  f"({val_total_memory / 1024:.1f} GB)")

        except Exception as e:
            print(f"Error analyzing validation: {e}")

        print(f"\n=== Memory Impact Assessment ===")
        if estimated_total_memory > 16:  # 16GB threshold
            print("⚠️  WARNING: High memory usage detected!")
            print("   This implementation may crash systems with <32GB RAM")
            print("   Consider reducing batch size or implementing gradient accumulation")
        elif estimated_total_memory > 8:
            print("⚡ CAUTION: Moderate memory usage")
            print("   May be slow on systems with <16GB RAM")
        else:
            print("✅ Memory usage is reasonable for most systems")

    except Exception as e:
        print(f"Error during PyTorch memory analysis: {e}")
        print("Make sure dataset files exist and are accessible.")


if __name__ == "__main__":
    """
    Run utility functions when executed as a script.

    Usage:
        python scripts/utils.py                    # Run both utilities
        python scripts/utils.py debug              # Run debug_structure only
        python scripts/utils.py sizes              # Run check_image_sizes only
    """
    import sys

    if len(sys.argv) > 1:
        if sys.argv[1] == "debug":
            debug_structure()
        elif sys.argv[1] == "sizes":
            check_image_sizes()
        elif sys.argv[1] == "memory":
            analyze_memory_usage()
        else:
            print("Usage: python utils.py [debug|sizes|memory]")
    else:
        debug_structure()
        check_image_sizes()
        analyze_memory_usage()