from __future__ import annotations

from typing import Any, Dict, List, Optional, Set
from urllib.parse import urlparse
import logging
import re

logger = logging.getLogger(__name__)

TRUE_VALUES = {"true", "1", "yes", "on"}
FALSE_VALUES = {"false", "0", "no", "off"}
EMAIL_REGEX = re.compile(r"^[^@\\s]+@[^@\\s]+\\.[^@\\s]+$")


class Variable:
  """Represents a single templating variable with lightweight validation."""

  def __init__(self, data: dict[str, Any]) -> None:
    """Initialize Variable from a dictionary containing variable specification.
    
    Args:
        data: Dictionary containing variable specification with required 'name' key
              and optional keys: description, type, options, prompt, value, default, section, origin
              
    Raises:
        ValueError: If data is not a dict, missing 'name' key, or has invalid default value
    """
    # Validate input
    if not isinstance(data, dict):
      raise ValueError("Variable data must be a dictionary")
    
    if "name" not in data:
      raise ValueError("Variable data must contain 'name' key")
    
    # Track which fields were explicitly provided in source data
    self._explicit_fields: Set[str] = set(data.keys())
    
    # Initialize fields
    self.name: str = data["name"]
    self.description: Optional[str] = data.get("description") or data.get("display", "")
    self.type: str = data.get("type", "str")
    self.options: Optional[List[Any]] = data.get("options", [])
    self.prompt: Optional[str] = data.get("prompt")
    self.value: Any = data.get("value") if data.get("value") is not None else data.get("default")
    self.origin: Optional[str] = data.get("origin")
    self.sensitive: bool = data.get("sensitive", False)
    # Optional extra explanation used by interactive prompts
    self.extra: Optional[str] = data.get("extra")
    # Flag indicating this variable should be auto-generated when empty
    self.autogenerated: bool = data.get("autogenerated", False)
    # Original value before config override (used for display)
    self.original_value: Optional[Any] = data.get("original_value")

    # Validate and convert the default/initial value if present
    if self.value is not None:
      try:
        self.value = self.convert(self.value)
      except ValueError as exc:
        raise ValueError(f"Invalid default for variable '{self.name}': {exc}")


  def convert(self, value: Any) -> Any:
    """Validate and convert a raw value based on the variable type.
    
    This method performs type conversion but does NOT check if the value
    is required. Use validate_and_convert() for full validation including
    required field checks.
    """
    if value is None:
      return None

    # Treat empty strings as None to avoid storing "" for missing values.
    if isinstance(value, str) and value.strip() == "":
      return None

    # Type conversion mapping for cleaner code
    converters = {
      "bool": self._convert_bool,
      "int": self._convert_int, 
      "float": self._convert_float,
      "enum": self._convert_enum,
      "url": self._convert_url,
      "email": self._convert_email,
    }
    
    converter = converters.get(self.type)
    if converter:
      return converter(value)
    
    # Default to string conversion
    return str(value)
  
  def validate_and_convert(self, value: Any, check_required: bool = True) -> Any:
    """Validate and convert a value with comprehensive checks.
    
    This method combines type conversion with validation logic including
    required field checks. It's the recommended method for user input validation.
    
    Args:
        value: The raw value to validate and convert
        check_required: If True, raises ValueError for required fields with empty values
        
    Returns:
        The converted and validated value
        
    Raises:
        ValueError: If validation fails (invalid format, required field empty, etc.)
        
    Examples:
        # Basic validation
        var.validate_and_convert("example@email.com")  # Returns validated email
        
        # Required field validation
        var.validate_and_convert("", check_required=True)  # Raises ValueError if required
        
        # Autogenerated variables - allow empty values
        var.validate_and_convert("", check_required=False)  # Returns None for autogeneration
    """
    # First, convert the value using standard type conversion
    converted = self.convert(value)
    
    # Special handling for autogenerated variables
    # Allow empty values as they will be auto-generated later
    if self.autogenerated and (converted is None or (isinstance(converted, str) and (converted == "" or converted == "*auto"))):
      return None  # Signal that auto-generation should happen
    
    # Check if this is a required field and the value is empty
    if check_required and self.is_required():
      if converted is None or (isinstance(converted, str) and converted == ""):
        raise ValueError("This field is required and cannot be empty")
    
    return converted

  def _convert_bool(self, value: Any) -> bool:
    """Convert value to boolean."""
    if isinstance(value, bool):
      return value
    if isinstance(value, str):
      lowered = value.strip().lower()
      if lowered in TRUE_VALUES:
        return True
      if lowered in FALSE_VALUES:
        return False
    raise ValueError("value must be a boolean (true/false)")

  def _convert_int(self, value: Any) -> Optional[int]:
    """Convert value to integer."""
    if isinstance(value, int):
      return value
    if isinstance(value, str) and value.strip() == "":
      return None
    try:
      return int(value)
    except (TypeError, ValueError) as exc:
      raise ValueError("value must be an integer") from exc

  def _convert_float(self, value: Any) -> Optional[float]:
    """Convert value to float."""
    if isinstance(value, float):
      return value
    if isinstance(value, str) and value.strip() == "":
      return None
    try:
      return float(value)
    except (TypeError, ValueError) as exc:
      raise ValueError("value must be a float") from exc

  def _convert_enum(self, value: Any) -> Optional[str]:
    if value == "":
      return None
    val = str(value)
    if self.options and val not in self.options:
      raise ValueError(f"value must be one of: {', '.join(self.options)}")
    return val

  def _convert_url(self, value: Any) -> str:
    val = str(value).strip()
    if not val:
      return None
    parsed = urlparse(val)
    if not (parsed.scheme and parsed.netloc):
      raise ValueError("value must be a valid URL (include scheme and host)")
    return val

  def _convert_email(self, value: Any) -> str:
    val = str(value).strip()
    if not val:
      return None
    if not EMAIL_REGEX.fullmatch(val):
      raise ValueError("value must be a valid email address")
    return val

  def to_dict(self) -> Dict[str, Any]:
    """Serialize Variable to a dictionary for storage."""
    result = {}
    
    # Always include type
    if self.type:
      result['type'] = self.type
    
    # Include value/default if not None
    if self.value is not None:
      result['default'] = self.value
    
    # Include string fields if truthy
    for field in ('description', 'prompt', 'extra', 'origin'):
      if value := getattr(self, field):
        result[field] = value
    
    # Include boolean/list fields if truthy (but empty list is OK for options)
    if self.sensitive:
      result['sensitive'] = True
    if self.autogenerated:
      result['autogenerated'] = True
    if self.options is not None:  # Allow empty list
      result['options'] = self.options
    
    return result
  
  def get_display_value(self, mask_sensitive: bool = True, max_length: int = 30, show_none: bool = True) -> str:
    """Get formatted display value with optional masking and truncation.
    
    Args:
        mask_sensitive: If True, mask sensitive values with asterisks
        max_length: Maximum length before truncation (0 = no limit)
        show_none: If True, display "(none)" for None values instead of empty string
        
    Returns:
        Formatted string representation of the value
    """
    if self.value is None or self.value == "":
      # Show (*auto) for autogenerated variables instead of (none)
      if self.autogenerated:
        return "[dim](*auto)[/dim]" if show_none else ""
      return "[dim](none)[/dim]" if show_none else ""
    
    # Mask sensitive values
    if self.sensitive and mask_sensitive:
      return "********"
    
    # Convert to string
    display = str(self.value)
    
    # Truncate if needed
    if max_length > 0 and len(display) > max_length:
      return display[:max_length - 3] + "..."
    
    return display
  
  def get_normalized_default(self) -> Any:
    """Get normalized default value suitable for prompts and display."""
    try:
      typed = self.convert(self.value)
    except Exception:
      typed = self.value
    
    # Autogenerated: return display hint
    if self.autogenerated and not typed:
      return "*auto"
    
    # Type-specific handlers
    if self.type == "enum":
      if not self.options:
        return typed
      return self.options[0] if typed is None or str(typed) not in self.options else str(typed)
    
    if self.type == "bool":
      return typed if isinstance(typed, bool) else (None if typed is None else bool(typed))
    
    if self.type == "int":
      try:
        return int(typed) if typed not in (None, "") else None
      except Exception:
        return None
    
    # Default: return string or None
    return None if typed is None else str(typed)
  
  def get_prompt_text(self) -> str:
    """Get formatted prompt text for interactive input.
    
    Returns:
        Prompt text with optional type hints and descriptions
    """
    prompt_text = self.prompt or self.description or self.name
    
    # Add type hint for semantic types if there's a default
    if self.value is not None and self.type in ["email", "url"]:
      prompt_text += f" ({self.type})"
    
    return prompt_text
  
  def get_validation_hint(self) -> Optional[str]:
    """Get validation hint for prompts (e.g., enum options).
    
    Returns:
        Formatted hint string or None if no hint needed
    """
    hints = []
    
    # Add enum options
    if self.type == "enum" and self.options:
      hints.append(f"Options: {', '.join(self.options)}")
    
    # Add extra help text
    if self.extra:
      hints.append(self.extra)
    
    return " — ".join(hints) if hints else None
  
  def is_required(self) -> bool:
    """Check if this variable requires a value (cannot be empty/None).
    
    A variable is considered required if:
    - It doesn't have a default value (value is None)
    - It's not marked as autogenerated (which can be empty and generated later)
    - It's not a boolean type (booleans default to False if not set)
    
    Returns:
        True if the variable must have a non-empty value, False otherwise
    """
    # Autogenerated variables can be empty (will be generated later)
    if self.autogenerated:
      return False
    
    # Boolean variables always have a value (True or False)
    if self.type == "bool":
      return False
    
    # Variables with a default value are not required
    if self.value is not None:
      return False
    
    # No default value and not autogenerated = required
    return True
  
  def clone(self, update: Optional[Dict[str, Any]] = None) -> 'Variable':
    """Create a deep copy of the variable with optional field updates.
    
    This is more efficient than converting to dict and back when copying variables.
    
    Args:
        update: Optional dictionary of field updates to apply to the clone
        
    Returns:
        New Variable instance with copied data
        
    Example:
        var2 = var1.clone(update={'origin': 'template'})
    """
    data = {
      'name': self.name,
      'type': self.type,
      'value': self.value,
      'description': self.description,
      'prompt': self.prompt,
      'options': self.options.copy() if self.options else None,
      'origin': self.origin,
      'sensitive': self.sensitive,
      'extra': self.extra,
      'autogenerated': self.autogenerated,
      'original_value': self.original_value,
    }
    
    # Apply updates if provided
    if update:
      data.update(update)
    
    # Create new variable
    cloned = Variable(data)
    
    # Preserve explicit fields from original, and add any update keys
    cloned._explicit_fields = self._explicit_fields.copy()
    if update:
      cloned._explicit_fields.update(update.keys())
    
    return cloned