"""
ShortSmith v2 - Helper Utilities

Common utility functions for file handling, validation, and data manipulation.
"""

import os
import shutil
import tempfile
import uuid
from pathlib import Path
from typing import Optional, List, Tuple, Union
from dataclasses import dataclass

from utils.logger import get_logger

logger = get_logger("utils.helpers")

# Supported file formats
SUPPORTED_VIDEO_FORMATS = {".mp4", ".avi", ".mov", ".mkv", ".webm", ".flv", ".wmv", ".m4v"}
SUPPORTED_IMAGE_FORMATS = {".jpg", ".jpeg", ".png", ".webp", ".bmp", ".gif"}
SUPPORTED_AUDIO_FORMATS = {".mp3", ".wav", ".aac", ".flac", ".ogg", ".m4a"}


@dataclass
class ValidationResult:
    """Result of file validation."""
    is_valid: bool
    error_message: Optional[str] = None
    file_path: Optional[Path] = None
    file_size: int = 0


class FileValidationError(Exception):
    """Exception raised for file validation errors."""
    pass


class VideoProcessingError(Exception):
    """Exception raised for video processing errors."""
    pass


class ModelLoadError(Exception):
    """Exception raised when model loading fails."""
    pass


class InferenceError(Exception):
    """Exception raised during model inference."""
    pass


def validate_video_file(
    file_path: Union[str, Path],
    max_size_mb: float = 500.0,
    check_exists: bool = True,
) -> ValidationResult:
    """
    Validate a video file for processing.

    Args:
        file_path: Path to the video file
        max_size_mb: Maximum allowed file size in megabytes
        check_exists: Whether to check if file exists

    Returns:
        ValidationResult with validation status and details

    Raises:
        FileValidationError: If validation fails and raise_on_error is True
    """
    try:
        path = Path(file_path)

        # Check existence
        if check_exists and not path.exists():
            return ValidationResult(
                is_valid=False,
                error_message=f"Video file not found: {path}"
            )

        # Check extension
        if path.suffix.lower() not in SUPPORTED_VIDEO_FORMATS:
            return ValidationResult(
                is_valid=False,
                error_message=f"Unsupported video format: {path.suffix}. "
                             f"Supported: {', '.join(SUPPORTED_VIDEO_FORMATS)}"
            )

        # Check file size
        if check_exists:
            file_size = path.stat().st_size
            size_mb = file_size / (1024 * 1024)

            if size_mb > max_size_mb:
                return ValidationResult(
                    is_valid=False,
                    error_message=f"Video file too large: {size_mb:.1f}MB (max: {max_size_mb}MB)",
                    file_size=file_size
                )
        else:
            file_size = 0

        logger.debug(f"Video file validated: {path}")
        return ValidationResult(
            is_valid=True,
            file_path=path,
            file_size=file_size
        )

    except Exception as e:
        logger.error(f"Error validating video file {file_path}: {e}")
        return ValidationResult(
            is_valid=False,
            error_message=f"Validation error: {str(e)}"
        )


def validate_image_file(
    file_path: Union[str, Path],
    max_size_mb: float = 10.0,
    check_exists: bool = True,
) -> ValidationResult:
    """
    Validate an image file (e.g., reference image for person detection).

    Args:
        file_path: Path to the image file
        max_size_mb: Maximum allowed file size in megabytes
        check_exists: Whether to check if file exists

    Returns:
        ValidationResult with validation status and details
    """
    try:
        path = Path(file_path)

        # Check existence
        if check_exists and not path.exists():
            return ValidationResult(
                is_valid=False,
                error_message=f"Image file not found: {path}"
            )

        # Check extension
        if path.suffix.lower() not in SUPPORTED_IMAGE_FORMATS:
            return ValidationResult(
                is_valid=False,
                error_message=f"Unsupported image format: {path.suffix}. "
                             f"Supported: {', '.join(SUPPORTED_IMAGE_FORMATS)}"
            )

        # Check file size
        if check_exists:
            file_size = path.stat().st_size
            size_mb = file_size / (1024 * 1024)

            if size_mb > max_size_mb:
                return ValidationResult(
                    is_valid=False,
                    error_message=f"Image file too large: {size_mb:.1f}MB (max: {max_size_mb}MB)",
                    file_size=file_size
                )
        else:
            file_size = 0

        logger.debug(f"Image file validated: {path}")
        return ValidationResult(
            is_valid=True,
            file_path=path,
            file_size=file_size
        )

    except Exception as e:
        logger.error(f"Error validating image file {file_path}: {e}")
        return ValidationResult(
            is_valid=False,
            error_message=f"Validation error: {str(e)}"
        )


def get_temp_dir(prefix: str = "shortsmith_") -> Path:
    """
    Create a temporary directory for processing.

    Args:
        prefix: Prefix for the temp directory name

    Returns:
        Path to the created temporary directory

    Raises:
        OSError: If directory creation fails
    """
    try:
        # Use system temp dir or custom if configured
        base_temp = tempfile.gettempdir()
        unique_id = str(uuid.uuid4())[:8]
        temp_dir = Path(base_temp) / f"{prefix}{unique_id}"
        temp_dir.mkdir(parents=True, exist_ok=True)

        logger.debug(f"Created temp directory: {temp_dir}")
        return temp_dir

    except Exception as e:
        logger.error(f"Failed to create temp directory: {e}")
        raise OSError(f"Could not create temporary directory: {e}") from e


def cleanup_temp_files(
    temp_dir: Union[str, Path],
    ignore_errors: bool = True
) -> bool:
    """
    Clean up temporary files and directories.

    Args:
        temp_dir: Path to the temporary directory to clean
        ignore_errors: Whether to ignore cleanup errors

    Returns:
        True if cleanup was successful, False otherwise
    """
    try:
        path = Path(temp_dir)
        if path.exists():
            shutil.rmtree(path, ignore_errors=ignore_errors)
            logger.debug(f"Cleaned up temp directory: {path}")
        return True

    except Exception as e:
        logger.warning(f"Failed to cleanup temp directory {temp_dir}: {e}")
        return False


def format_duration(seconds: float) -> str:
    """
    Format duration in seconds to human-readable string.

    Args:
        seconds: Duration in seconds

    Returns:
        Formatted string (e.g., "1:23:45" or "5:30")
    """
    if seconds < 0:
        return "0:00"

    hours = int(seconds // 3600)
    minutes = int((seconds % 3600) // 60)
    secs = int(seconds % 60)

    if hours > 0:
        return f"{hours}:{minutes:02d}:{secs:02d}"
    else:
        return f"{minutes}:{secs:02d}"


def format_timestamp(seconds: float, include_ms: bool = False) -> str:
    """
    Format timestamp for display.

    Args:
        seconds: Timestamp in seconds
        include_ms: Whether to include milliseconds

    Returns:
        Formatted timestamp string
    """
    hours = int(seconds // 3600)
    minutes = int((seconds % 3600) // 60)
    secs = seconds % 60

    if include_ms:
        if hours > 0:
            return f"{hours}:{minutes:02d}:{secs:06.3f}"
        else:
            return f"{minutes}:{secs:06.3f}"
    else:
        secs = int(secs)
        if hours > 0:
            return f"{hours}:{minutes:02d}:{secs:02d}"
        else:
            return f"{minutes}:{secs:02d}"


def safe_divide(
    numerator: float,
    denominator: float,
    default: float = 0.0
) -> float:
    """
    Safely divide two numbers, returning default if denominator is zero.

    Args:
        numerator: The numerator
        denominator: The denominator
        default: Value to return if denominator is zero

    Returns:
        Result of division or default value
    """
    if denominator == 0:
        return default
    return numerator / denominator


def clamp(
    value: float,
    min_value: float,
    max_value: float
) -> float:
    """
    Clamp a value to a specified range.

    Args:
        value: The value to clamp
        min_value: Minimum allowed value
        max_value: Maximum allowed value

    Returns:
        Clamped value
    """
    return max(min_value, min(value, max_value))


def normalize_scores(scores: List[float]) -> List[float]:
    """
    Normalize a list of scores to [0, 1] range.

    Args:
        scores: List of raw scores

    Returns:
        Normalized scores
    """
    if not scores:
        return []

    min_score = min(scores)
    max_score = max(scores)
    score_range = max_score - min_score

    if score_range == 0:
        return [0.5] * len(scores)

    return [(s - min_score) / score_range for s in scores]


def batch_list(items: List, batch_size: int) -> List[List]:
    """
    Split a list into batches of specified size.

    Args:
        items: List to split
        batch_size: Size of each batch

    Returns:
        List of batches
    """
    return [items[i:i + batch_size] for i in range(0, len(items), batch_size)]


def merge_overlapping_segments(
    segments: List[Tuple[float, float]],
    min_gap: float = 0.0
) -> List[Tuple[float, float]]:
    """
    Merge overlapping or closely spaced time segments.

    Args:
        segments: List of (start, end) tuples
        min_gap: Minimum gap to keep segments separate

    Returns:
        List of merged segments
    """
    if not segments:
        return []

    # Sort by start time
    sorted_segments = sorted(segments, key=lambda x: x[0])
    merged = [sorted_segments[0]]

    for start, end in sorted_segments[1:]:
        last_start, last_end = merged[-1]

        # Check if segments overlap or are close enough
        if start <= last_end + min_gap:
            # Merge by extending the end
            merged[-1] = (last_start, max(last_end, end))
        else:
            merged.append((start, end))

    return merged


def ensure_dir(path: Union[str, Path]) -> Path:
    """
    Ensure a directory exists, creating it if necessary.

    Args:
        path: Path to the directory

    Returns:
        Path object for the directory
    """
    path = Path(path)
    path.mkdir(parents=True, exist_ok=True)
    return path


def get_unique_filename(
    directory: Union[str, Path],
    base_name: str,
    extension: str
) -> Path:
    """
    Generate a unique filename in the given directory.

    Args:
        directory: Directory for the file
        base_name: Base name for the file
        extension: File extension (with or without dot)

    Returns:
        Path to a unique file
    """
    directory = Path(directory)
    extension = extension if extension.startswith(".") else f".{extension}"

    # Try base name first
    candidate = directory / f"{base_name}{extension}"
    if not candidate.exists():
        return candidate

    # Add counter
    counter = 1
    while True:
        candidate = directory / f"{base_name}_{counter}{extension}"
        if not candidate.exists():
            return candidate
        counter += 1


# Export all public functions
__all__ = [
    "SUPPORTED_VIDEO_FORMATS",
    "SUPPORTED_IMAGE_FORMATS",
    "SUPPORTED_AUDIO_FORMATS",
    "ValidationResult",
    "FileValidationError",
    "VideoProcessingError",
    "ModelLoadError",
    "InferenceError",
    "validate_video_file",
    "validate_image_file",
    "get_temp_dir",
    "cleanup_temp_files",
    "format_duration",
    "format_timestamp",
    "safe_divide",
    "clamp",
    "normalize_scores",
    "batch_list",
    "merge_overlapping_segments",
    "ensure_dir",
    "get_unique_filename",
]