"""
Generation Result Model
=======================

Data model for image generation results.
Provides consistent structure for results from any backend.
"""

from dataclasses import dataclass, field
from typing import Optional
from datetime import datetime
from pathlib import Path
from PIL import Image


@dataclass
class GenerationResult:
    """
    Represents the result of an image generation request.

    This is the standard interface for all generation results,
    regardless of backend or generation type.

    Attributes:
        success: Whether generation succeeded
        image: Generated image (None if failed)
        message: Status/error message
        generation_time: Time taken in seconds
        saved_path: Path where image was saved (if saved)
        metadata: Additional metadata
    """

    # Required fields
    success: bool
    message: str

    # Optional fields
    image: Optional[Image.Image] = None
    generation_time: Optional[float] = None
    saved_path: Optional[Path] = None
    metadata: dict = field(default_factory=dict)

    # Auto-populated fields
    timestamp: datetime = field(default_factory=datetime.now)

    def __post_init__(self):
        """Validate data after initialization."""
        # Ensure success is boolean
        if not isinstance(self.success, bool):
            raise TypeError("success must be boolean")

        # Ensure message is string
        if not isinstance(self.message, str):
            raise TypeError("message must be a string")

        # If success, image should be provided
        if self.success and self.image is None:
            raise ValueError("Success result must have an image")

        # If failed, image should be None
        if not self.success and self.image is not None:
            raise ValueError("Failed result should not have an image")

    @property
    def is_successful(self) -> bool:
        """Alias for success field."""
        return self.success

    @property
    def has_image(self) -> bool:
        """Check if result has an image."""
        return self.image is not None

    @property
    def is_saved(self) -> bool:
        """Check if result was saved to disk."""
        return self.saved_path is not None and self.saved_path.exists()

    @classmethod
    def success_result(
        cls,
        image: Image.Image,
        message: str = "Generation successful",
        generation_time: Optional[float] = None,
        **kwargs
    ) -> 'GenerationResult':
        """
        Create a successful generation result.

        Args:
            image: Generated image
            message: Success message
            generation_time: Time taken in seconds
            **kwargs: Additional metadata

        Returns:
            GenerationResult instance
        """
        return cls(
            success=True,
            image=image,
            message=message,
            generation_time=generation_time,
            metadata=kwargs
        )

    @classmethod
    def error_result(
        cls,
        message: str,
        **kwargs
    ) -> 'GenerationResult':
        """
        Create a failed generation result.

        Args:
            message: Error message
            **kwargs: Additional metadata

        Returns:
            GenerationResult instance
        """
        return cls(
            success=False,
            image=None,
            message=message,
            metadata=kwargs
        )

    def to_dict(self) -> dict:
        """
        Convert result to dictionary (for metadata/logging).

        Note: Image is not included in dict (only status).

        Returns:
            Dictionary representation
        """
        result = {
            "success": self.success,
            "message": self.message,
            "timestamp": self.timestamp.isoformat(),
            "has_image": self.has_image
        }

        if self.generation_time is not None:
            result["generation_time_seconds"] = round(self.generation_time, 2)

        if self.saved_path:
            result["saved_path"] = str(self.saved_path)

        result["metadata"] = self.metadata

        return result

    def __repr__(self) -> str:
        """String representation for debugging."""
        status = "SUCCESS" if self.success else "FAILED"
        time_str = f", {self.generation_time:.2f}s" if self.generation_time else ""
        return f"GenerationResult({status}: {self.message}{time_str})"