"""
Unified price display system for all subscription and balance pricing.

This module provides a centralized way to:
- Calculate prices with all applicable discounts (promo groups, promo offers)
- Format price buttons consistently across all flows
- Ensure uniform discount display throughout the application
"""

from dataclasses import dataclass
from typing import Optional
import logging

from app.database.models import User
from app.config import settings

logger = logging.getLogger(__name__)


@dataclass
class PriceInfo:
    """Container for pricing information with discounts."""

    base_price: int  # Original price without any discounts (kopeks)
    final_price: int  # Final price after all discounts (kopeks)
    discount_percent: int  # Total discount percentage

    @property
    def has_discount(self) -> bool:
        """Check if there's any discount applied."""
        return self.base_price > self.final_price and self.discount_percent > 0

    @property
    def discount_value(self) -> int:
        """Get the absolute discount value in kopeks."""
        return self.base_price - self.final_price


def calculate_user_price(
    user: Optional[User],
    base_price: int,
    period_days: int,
    category: str = "period"
) -> PriceInfo:
    """
    Calculate final price for a user with all applicable discounts.

    Args:
        user: User object (None for base/default pricing from settings)
        base_price: Base price without discounts (kopeks)
        period_days: Subscription period in days
        category: Discount category ("period", "servers", "devices", "traffic")

    Returns:
        PriceInfo with base_price, final_price, and discount_percent

    Example:
        >>> user = get_user_from_db(123)
        >>> price_info = calculate_user_price(user, 100000, 30, "period")
        >>> print(f"{price_info.base_price} -> {price_info.final_price} ({price_info.discount_percent}%)")
        100000 -> 80000 (20%)

        >>> # For base pricing (no user)
        >>> price_info = calculate_user_price(None, 100000, 30, "period")
        >>> # Uses BASE_PROMO_GROUP_PERIOD_DISCOUNTS from settings
    """
    if not base_price or base_price <= 0:
        return PriceInfo(base_price=base_price or 0, final_price=base_price or 0, discount_percent=0)

    # Get discount percentage
    if user:
        # Get user's promo group discount for this category
        discount_percent = user.get_promo_discount(category, period_days)
    else:
        # For None user, use base settings discount
        discount_percent = settings.get_base_promo_group_period_discount(period_days)

    logger.debug(
        f"calculate_user_price: user={user.telegram_id if user else 'None'}, "
        f"base_price={base_price}, period_days={period_days}, category={category}, "
        f"discount_percent={discount_percent}"
    )

    if discount_percent <= 0:
        return PriceInfo(base_price=base_price, final_price=base_price, discount_percent=0)

    # Calculate discounted price
    discount_value = (base_price * discount_percent) // 100
    final_price = base_price - discount_value

    logger.debug(
        f"Calculated price for user {user.telegram_id if user else 'None'}: "
        f"{base_price} -> {final_price} (-{discount_percent}%) "
        f"[category={category}, period={period_days}]"
    )

    return PriceInfo(
        base_price=base_price,
        final_price=final_price,
        discount_percent=discount_percent
    )


def format_price_button(
    period_label: str,
    price_info: PriceInfo,
    format_price_func,
    emphasize: bool = False,
    add_exclamation: bool = True
) -> str:
    """
    Format a price button text with unified discount display.

    Args:
        period_label: Label for the period (e.g., "30 дней", "1 месяц")
        price_info: PriceInfo object with pricing details
        format_price_func: Function to format price (usually texts.format_price)
        emphasize: Add fire emojis for emphasis (for best deals)
        add_exclamation: Add exclamation mark after discount percent

    Returns:
        Formatted button text

    Examples:
        With discount and price > 0:
            "📅 30 дней - 990₽ ➜ 693₽ (-30%)!"

        With final price = 0:
            "📅 30 дней"

        With emphasis:
            "🔥 📅 30 дней - 8990₽ ➜ 6293₽ (-30%)! 🔥"

        Without discount:
            "📅 30 дней - 990₽"
    """
    # Format button text differently if final price is 0
    if price_info.final_price == 0:
        button_text = f"📅 {period_label}"
    elif price_info.has_discount:
        exclamation = "!" if add_exclamation else ""
        button_text = (
            f"📅 {period_label} - "
            f"{format_price_func(price_info.base_price)} ➜ "
            f"{format_price_func(price_info.final_price)} "
            f"(-{price_info.discount_percent}%){exclamation}"
        )
    else:
        button_text = f"📅 {period_label} - {format_price_func(price_info.final_price)}"

    # Add emphasis for best deals
    if emphasize:
        button_text = f"🔥 {button_text} 🔥"

    logger.debug(f"Formatted button: {button_text}")
    return button_text


def format_price_text(
    period_label: str,
    price_info: PriceInfo,
    format_price_func
) -> str:
    """
    Format a price for message text (not button) with unified discount display.

    Args:
        period_label: Label for the period (e.g., "30 дней")
        price_info: PriceInfo object with pricing details
        format_price_func: Function to format price (usually texts.format_price)

    Returns:
        Formatted price text for messages

    Examples:
        With discount:
            "📅 30 дней - 990₽ ➜ 693₽"

        Without discount:
            "📅 30 дней - 990₽"
            
        With zero price:
            "📅 30 дней"
    """
    if price_info.final_price == 0:
        return f"📅 {period_label}"
    elif price_info.has_discount:
        return (
            f"📅 {period_label} - "
            f"{format_price_func(price_info.base_price)} ➜ "
            f"{format_price_func(price_info.final_price)}"
        )
    else:
        return f"📅 {period_label} - {format_price_func(price_info.final_price)}"