"""
Firewall rule service layer for business logic and database operations.

This module handles all database operations for firewall rules, providing a clean
separation between the API routes and data access layer.
"""

from typing import Optional
from uuid import UUID

from fastapi import HTTPException, status
from sqlalchemy.exc import IntegrityError
from sqlalchemy.orm import Session

from api.models.firewall_rule import FirewallRule
from api.models.infrastructure import Infrastructure
from api.schemas.firewall_rule import FirewallRuleCreate, FirewallRuleUpdate


def get_firewall_rules(db: Session, skip: int = 0, limit: int = 100) -> tuple[list[FirewallRule], int]:
    """
    Retrieve a paginated list of firewall rules.

    Args:
        db: Database session
        skip: Number of records to skip (for pagination)
        limit: Maximum number of records to return

    Returns:
        tuple: (list of firewall rules, total count)

    Example:
        ```python
        rules, total = get_firewall_rules(db, skip=0, limit=50)
        print(f"Retrieved {len(rules)} of {total} firewall rules")
        ```
    """
    # Get total count
    total = db.query(FirewallRule).count()

    # Get paginated results, ordered by created_at descending (newest first)
    rules = (
        db.query(FirewallRule)
        .order_by(FirewallRule.created_at.desc())
        .offset(skip)
        .limit(limit)
        .all()
    )

    return rules, total


def get_firewall_rule_by_id(db: Session, firewall_rule_id: UUID) -> FirewallRule:
    """
    Retrieve a single firewall rule by its ID.

    Args:
        db: Database session
        firewall_rule_id: UUID of the firewall rule to retrieve

    Returns:
        FirewallRule: The firewall rule object

    Raises:
        HTTPException: 404 if firewall rule not found

    Example:
        ```python
        rule = get_firewall_rule_by_id(db, firewall_rule_id)
        print(f"Found rule: {rule.rule_name}")
        ```
    """
    rule = db.query(FirewallRule).filter(FirewallRule.id == str(firewall_rule_id)).first()

    if not rule:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail=f"Firewall rule with ID {firewall_rule_id} not found"
        )

    return rule


def get_firewall_rules_by_infrastructure(db: Session, infrastructure_id: UUID, skip: int = 0, limit: int = 100) -> tuple[list[FirewallRule], int]:
    """
    Retrieve firewall rules belonging to a specific infrastructure.

    Args:
        db: Database session
        infrastructure_id: UUID of the infrastructure
        skip: Number of records to skip (for pagination)
        limit: Maximum number of records to return

    Returns:
        tuple: (list of firewall rules, total count for this infrastructure)

    Raises:
        HTTPException: 404 if infrastructure not found

    Example:
        ```python
        rules, total = get_firewall_rules_by_infrastructure(db, infrastructure_id, skip=0, limit=50)
        print(f"Retrieved {len(rules)} of {total} firewall rules for infrastructure")
        ```
    """
    # Verify infrastructure exists
    infrastructure = db.query(Infrastructure).filter(Infrastructure.id == str(infrastructure_id)).first()
    if not infrastructure:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail=f"Infrastructure with ID {infrastructure_id} not found"
        )

    # Get total count for this infrastructure
    total = db.query(FirewallRule).filter(FirewallRule.infrastructure_id == str(infrastructure_id)).count()

    # Get paginated results
    rules = (
        db.query(FirewallRule)
        .filter(FirewallRule.infrastructure_id == str(infrastructure_id))
        .order_by(FirewallRule.rule_order.asc(), FirewallRule.created_at.desc())
        .offset(skip)
        .limit(limit)
        .all()
    )

    return rules, total


def get_firewall_rules_by_action(db: Session, action: str, skip: int = 0, limit: int = 100) -> tuple[list[FirewallRule], int]:
    """
    Retrieve firewall rules by action type (allow, deny, drop).

    Args:
        db: Database session
        action: Action type to filter by (allow, deny, drop)
        skip: Number of records to skip (for pagination)
        limit: Maximum number of records to return

    Returns:
        tuple: (list of firewall rules, total count for this action)

    Raises:
        HTTPException: 422 if invalid action provided

    Example:
        ```python
        rules, total = get_firewall_rules_by_action(db, "allow", skip=0, limit=50)
        print(f"Retrieved {len(rules)} of {total} allow rules")
        ```
    """
    # Validate action
    valid_actions = ["allow", "deny", "drop"]
    if action not in valid_actions:
        raise HTTPException(
            status_code=status.HTTP_422_UNPROCESSABLE_ENTITY,
            detail=f"Invalid action '{action}'. Must be one of: {', '.join(valid_actions)}"
        )

    # Get total count for this action
    total = db.query(FirewallRule).filter(FirewallRule.action == action).count()

    # Get paginated results
    rules = (
        db.query(FirewallRule)
        .filter(FirewallRule.action == action)
        .order_by(FirewallRule.created_at.desc())
        .offset(skip)
        .limit(limit)
        .all()
    )

    return rules, total


def create_firewall_rule(db: Session, firewall_rule_data: FirewallRuleCreate) -> FirewallRule:
    """
    Create a new firewall rule.

    Args:
        db: Database session
        firewall_rule_data: Firewall rule creation data

    Returns:
        FirewallRule: The created firewall rule object

    Raises:
        HTTPException: 404 if infrastructure not found
        HTTPException: 422 if invalid action provided
        HTTPException: 500 if database error occurs

    Example:
        ```python
        rule_data = FirewallRuleCreate(
            infrastructure_id="123e4567-e89b-12d3-a456-426614174000",
            rule_name="Allow SSH",
            action="allow",
            port=22
        )
        rule = create_firewall_rule(db, rule_data)
        print(f"Created firewall rule: {rule.id}")
        ```
    """
    # Verify infrastructure exists if provided
    if firewall_rule_data.infrastructure_id:
        infrastructure = db.query(Infrastructure).filter(
            Infrastructure.id == str(firewall_rule_data.infrastructure_id)
        ).first()
        if not infrastructure:
            raise HTTPException(
                status_code=status.HTTP_404_NOT_FOUND,
                detail=f"Infrastructure with ID {firewall_rule_data.infrastructure_id} not found"
            )

    # Validate action if provided
    if firewall_rule_data.action:
        valid_actions = ["allow", "deny", "drop"]
        if firewall_rule_data.action not in valid_actions:
            raise HTTPException(
                status_code=status.HTTP_422_UNPROCESSABLE_ENTITY,
                detail=f"Invalid action '{firewall_rule_data.action}'. Must be one of: {', '.join(valid_actions)}"
            )

    try:
        # Create new firewall rule instance
        db_rule = FirewallRule(**firewall_rule_data.model_dump())

        # Add to database
        db.add(db_rule)
        db.commit()
        db.refresh(db_rule)

        return db_rule

    except IntegrityError as e:
        db.rollback()
        raise HTTPException(
            status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
            detail=f"Database error: {str(e)}"
        )
    except Exception as e:
        db.rollback()
        raise HTTPException(
            status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
            detail=f"Failed to create firewall rule: {str(e)}"
        )


def update_firewall_rule(db: Session, firewall_rule_id: UUID, firewall_rule_data: FirewallRuleUpdate) -> FirewallRule:
    """
    Update an existing firewall rule.

    Args:
        db: Database session
        firewall_rule_id: UUID of the firewall rule to update
        firewall_rule_data: Firewall rule update data (only provided fields will be updated)

    Returns:
        FirewallRule: The updated firewall rule object

    Raises:
        HTTPException: 404 if firewall rule or infrastructure not found
        HTTPException: 422 if invalid action provided
        HTTPException: 500 if database error occurs

    Example:
        ```python
        update_data = FirewallRuleUpdate(
            rule_name="Allow SSH - Updated",
            action="deny"
        )
        rule = update_firewall_rule(db, firewall_rule_id, update_data)
        print(f"Updated firewall rule: {rule.rule_name}")
        ```
    """
    # Get existing firewall rule
    rule = get_firewall_rule_by_id(db, firewall_rule_id)

    try:
        # Update only provided fields
        update_data = firewall_rule_data.model_dump(exclude_unset=True)

        # If updating infrastructure_id, verify new infrastructure exists
        if "infrastructure_id" in update_data and update_data["infrastructure_id"]:
            infrastructure = db.query(Infrastructure).filter(
                Infrastructure.id == str(update_data["infrastructure_id"])
            ).first()
            if not infrastructure:
                raise HTTPException(
                    status_code=status.HTTP_404_NOT_FOUND,
                    detail=f"Infrastructure with ID {update_data['infrastructure_id']} not found"
                )

        # Validate action if provided
        if "action" in update_data and update_data["action"]:
            valid_actions = ["allow", "deny", "drop"]
            if update_data["action"] not in valid_actions:
                raise HTTPException(
                    status_code=status.HTTP_422_UNPROCESSABLE_ENTITY,
                    detail=f"Invalid action '{update_data['action']}'. Must be one of: {', '.join(valid_actions)}"
                )

        # Apply updates
        for field, value in update_data.items():
            setattr(rule, field, value)

        db.commit()
        db.refresh(rule)

        return rule

    except HTTPException:
        db.rollback()
        raise
    except IntegrityError as e:
        db.rollback()
        raise HTTPException(
            status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
            detail=f"Database error: {str(e)}"
        )
    except Exception as e:
        db.rollback()
        raise HTTPException(
            status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
            detail=f"Failed to update firewall rule: {str(e)}"
        )


def delete_firewall_rule(db: Session, firewall_rule_id: UUID) -> dict:
    """
    Delete a firewall rule by its ID.

    Args:
        db: Database session
        firewall_rule_id: UUID of the firewall rule to delete

    Returns:
        dict: Success message

    Raises:
        HTTPException: 404 if firewall rule not found
        HTTPException: 500 if database error occurs

    Example:
        ```python
        result = delete_firewall_rule(db, firewall_rule_id)
        print(result["message"])  # "Firewall rule deleted successfully"
        ```
    """
    # Get existing firewall rule (raises 404 if not found)
    rule = get_firewall_rule_by_id(db, firewall_rule_id)

    try:
        db.delete(rule)
        db.commit()

        return {
            "message": "Firewall rule deleted successfully",
            "firewall_rule_id": str(firewall_rule_id)
        }

    except Exception as e:
        db.rollback()
        raise HTTPException(
            status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
            detail=f"Failed to delete firewall rule: {str(e)}"
        )