"""
回归任务评估指标
"""
import numpy as np
from sklearn.metrics import (
    mean_squared_error, mean_absolute_error, r2_score,
    mean_absolute_percentage_error, median_absolute_error
)
from typing import Dict, Any
import logging

logger = logging.getLogger(__name__)


class RegressionMetrics:
    """回归任务评估指标"""
    
    def __init__(self):
        """初始化回归指标"""
        pass
    
    def mse(self, y_true: np.ndarray, y_pred: np.ndarray) -> float:
        """均方误差 (Mean Squared Error)"""
        return mean_squared_error(y_true, y_pred)
    
    def rmse(self, y_true: np.ndarray, y_pred: np.ndarray) -> float:
        """均方根误差 (Root Mean Squared Error)"""
        return np.sqrt(mean_squared_error(y_true, y_pred))
    
    def mae(self, y_true: np.ndarray, y_pred: np.ndarray) -> float:
        """平均绝对误差 (Mean Absolute Error)"""
        return mean_absolute_error(y_true, y_pred)
    
    def mape(self, y_true: np.ndarray, y_pred: np.ndarray) -> float:
        """平均绝对百分比误差 (Mean Absolute Percentage Error)"""
        return mean_absolute_percentage_error(y_true, y_pred)
    
    def r2_score(self, y_true: np.ndarray, y_pred: np.ndarray) -> float:
        """决定系数 (R-squared)"""
        return r2_score(y_true, y_pred)
    
    def median_ae(self, y_true: np.ndarray, y_pred: np.ndarray) -> float:
        """中位数绝对误差 (Median Absolute Error)"""
        return median_absolute_error(y_true, y_pred)
    
    def mape_robust(self, y_true: np.ndarray, y_pred: np.ndarray, 
                   epsilon: float = 1e-8) -> float:
        """鲁棒的平均绝对百分比误差"""
        return np.mean(np.abs((y_true - y_pred) / (np.abs(y_true) + epsilon))) * 100
    
    def smape(self, y_true: np.ndarray, y_pred: np.ndarray) -> float:
        """对称平均绝对百分比误差 (Symmetric Mean Absolute Percentage Error)"""
        return np.mean(2 * np.abs(y_true - y_pred) / (np.abs(y_true) + np.abs(y_pred))) * 100
    
    def mase(self, y_true: np.ndarray, y_pred: np.ndarray, 
             y_naive: np.ndarray) -> float:
        """平均绝对标度误差 (Mean Absolute Scaled Error)"""
        mae = self.mae(y_true, y_pred)
        mae_naive = self.mae(y_true, y_naive)
        return mae / mae_naive if mae_naive != 0 else 0
    
    def compute_all_metrics(self, y_true: np.ndarray, y_pred: np.ndarray, 
                           y_naive: Optional[np.ndarray] = None) -> Dict[str, float]:
        """计算所有回归指标"""
        metrics = {
            'mse': self.mse(y_true, y_pred),
            'rmse': self.rmse(y_true, y_pred),
            'mae': self.mae(y_true, y_pred),
            'mape': self.mape(y_true, y_pred),
            'r2_score': self.r2_score(y_true, y_pred),
            'median_ae': self.median_ae(y_true, y_pred),
            'mape_robust': self.mape_robust(y_true, y_pred),
            'smape': self.smape(y_true, y_pred)
        }
        
        if y_naive is not None:
            metrics['mase'] = self.mase(y_true, y_pred, y_naive)
        
        return metrics


class TimeSeriesMetrics:
    """时间序列评估指标"""
    
    def __init__(self):
        """初始化时间序列指标"""
        pass
    
    def directional_accuracy(self, y_true: np.ndarray, y_pred: np.ndarray) -> float:
        """方向准确率"""
        true_direction = np.diff(y_true)
        pred_direction = np.diff(y_pred)
        return np.mean((true_direction * pred_direction) > 0)
    
    def theil_u(self, y_true: np.ndarray, y_pred: np.ndarray) -> float:
        """Theil's U统计量"""
        mse = np.mean((y_true - y_pred) ** 2)
        mse_naive = np.mean((y_true[1:] - y_true[:-1]) ** 2)
        return np.sqrt(mse / mse_naive) if mse_naive != 0 else 0
    
    def mean_absolute_scaled_error(self, y_true: np.ndarray, y_pred: np.ndarray) -> float:
        """平均绝对标度误差"""
        mae = np.mean(np.abs(y_true - y_pred))
        mae_naive = np.mean(np.abs(y_true[1:] - y_true[:-1]))
        return mae / mae_naive if mae_naive != 0 else 0
    
    def mean_absolute_percentage_error(self, y_true: np.ndarray, y_pred: np.ndarray) -> float:
        """平均绝对百分比误差"""
        return np.mean(np.abs((y_true - y_pred) / y_true)) * 100


class RankingMetrics:
    """排序任务评估指标"""
    
    def __init__(self):
        """初始化排序指标"""
        pass
    
    def ndcg(self, y_true: np.ndarray, y_pred: np.ndarray, k: int = None) -> float:
        """归一化折扣累积增益 (Normalized Discounted Cumulative Gain)"""
        if k is None:
            k = len(y_true)
        
        # 按预测分数排序
        sorted_indices = np.argsort(y_pred)[::-1]
        sorted_true = y_true[sorted_indices]
        
        # 计算DCG
        dcg = 0
        for i in range(min(k, len(sorted_true))):
            dcg += sorted_true[i] / np.log2(i + 2)
        
        # 计算IDCG
        sorted_true_ideal = np.sort(y_true)[::-1]
        idcg = 0
        for i in range(min(k, len(sorted_true_ideal))):
            idcg += sorted_true_ideal[i] / np.log2(i + 2)
        
        return dcg / idcg if idcg > 0 else 0
    
    def hit_rate(self, y_true: np.ndarray, y_pred: np.ndarray, k: int = 10) -> float:
        """命中率 (Hit Rate)"""
        # 获取前k个预测
        top_k_indices = np.argsort(y_pred)[::-1][:k]
        return np.sum(y_true[top_k_indices] > 0) / k
    
    def precision_at_k(self, y_true: np.ndarray, y_pred: np.ndarray, k: int = 10) -> float:
        """K位置精确率"""
        top_k_indices = np.argsort(y_pred)[::-1][:k]
        return np.sum(y_true[top_k_indices] > 0) / k
    
    def recall_at_k(self, y_true: np.ndarray, y_pred: np.ndarray, k: int = 10) -> float:
        """K位置召回率"""
        top_k_indices = np.argsort(y_pred)[::-1][:k]
        relevant_items = np.sum(y_true > 0)
        return np.sum(y_true[top_k_indices] > 0) / relevant_items if relevant_items > 0 else 0