"""Constraint validation classes for data quality checks."""

from __future__ import annotations
from typing import List, Any, Optional, Dict, Tuple
from dataclasses import dataclass
from enum import Enum
import pyarrow as pa

from .base import BaseProcessor, ValidationResult


class ErrorMode(Enum):
    """Error handling modes for constraint validation."""
    FAIL_FAST = "fail_fast"
    FAIL_COMPLETE = "fail_complete"
    BAD_ROWS = "bad_rows"


@dataclass
class ConstraintConfig:
    """Configuration for constraint validation."""
    error_mode: ErrorMode = ErrorMode.BAD_ROWS
    check_constraints: Dict[str, Any] = None
    unique_constraints: List[str] = None
    foreign_key_constraints: Dict[str, Any] = None

    def __post_init__(self):
        if self.check_constraints is None:
            self.check_constraints = {}
        if self.unique_constraints is None:
            self.unique_constraints = []
        if self.foreign_key_constraints is None:
            self.foreign_key_constraints = {}


@dataclass
class ConstraintViolation:
    """Represents a constraint violation found during data validation."""

    violation_type: str
    error_message: str
    columns: List[str]
    values: List[Any]
    constraint_name: str
    row_index: Optional[int] = None


class ConstraintValidator(BaseProcessor):
    """Validates data against constraints defined in the schema."""

    def __init__(self, config: ConstraintConfig):
        """Initialize the constraint validator.

        Args:
            config: Constraint configuration
        """
        self.config = config
        self.violations: List[ConstraintViolation] = []

    def process_batch(self, batch: pa.RecordBatch) -> Tuple[pa.RecordBatch, List[ValidationResult]]:
        """Process batch and validate against constraints.

        Args:
            batch: PyArrow RecordBatch to validate

        Returns:
            Tuple of (valid_batch, validation_results)
        """
        validation_results = []
        self.violations.clear()

        # For now, return the batch as-is since constraint validation
        # would require more complex implementation
        # In a real implementation, this would check various constraints

        return batch, validation_results

    def get_all_violations(self) -> List[ConstraintViolation]:
        """Get all constraint violations found during validation."""
        return self.violations.copy()

    def finalize(self):
        """Finalize validation and potentially raise exceptions based on error mode."""
        if self.violations and self.config.error_mode in [ErrorMode.FAIL_FAST, ErrorMode.FAIL_COMPLETE]:
            violation_count = len(self.violations)
            raise ValueError(f"Constraint validation failed with {violation_count} violations")


def create_constraint_config_from_schema(schema_dict: Dict[str, Any]) -> ConstraintConfig:
    """Create constraint configuration from schema dictionary.

    Args:
        schema_dict: Schema dictionary containing constraint definitions

    Returns:
        ConstraintConfig instance
    """
    # Extract error mode
    error_mode_str = "bad_rows"
    if "x-constraintHandling" in schema_dict:
        error_mode_str = schema_dict["x-constraintHandling"].get("errorMode", "bad_rows")

    try:
        error_mode = ErrorMode(error_mode_str)
    except ValueError:
        error_mode = ErrorMode.BAD_ROWS

    # Extract constraints from schema (simplified implementation)
    check_constraints = {}
    unique_constraints = []
    foreign_key_constraints = {}

    # Look for constraints in the schema properties
    properties = schema_dict.get("properties", {})
    for field_name, field_def in properties.items():
        # Check for minimum/maximum constraints
        if "minimum" in field_def or "maximum" in field_def:
            check_constraints[f"{field_name}_range"] = {
                "column": field_name,
                "min": field_def.get("minimum"),
                "max": field_def.get("maximum")
            }

        # Check for unique constraints
        if field_def.get("x-unique", False):
            unique_constraints.append(field_name)

    return ConstraintConfig(
        error_mode=error_mode,
        check_constraints=check_constraints,
        unique_constraints=unique_constraints,
        foreign_key_constraints=foreign_key_constraints
    )
