import pandas as pd
import numpy as np
import gc
import os


def preprocess_data_simple(df_input, is_train=False, hourly_time=None):

    print(">>> 开始数据预处理")
    # 城市码映射成数字(不用)

    # 更新日期是周几
    df_input['update_week'] = df_input['update_hour'].dt.dayofweek + 1
    
    # gid：基于指定字段的分组标记（整数）
    df_input['gid'] = (
        df_input
        .groupby(
            ['citypair', 'flight_numbers', 'from_date'],    # 'baggage_weight' 先不进分组
            sort=False
        )
        .ngroup()
    )

    # 在 gid 与 baggage_weight 内按时间降序
    df_input = df_input.sort_values(
        by=['gid', 'baggage_weight', 'hours_until_departure'],
        ascending=[True, True, False]
    ).reset_index(drop=True)

    df_input = df_input[df_input['hours_until_departure'] <= 480]
    df_input = df_input[df_input['baggage_weight'] == 20]   # 先保留20公斤行李的

    # 在hours_until_departure 的末尾 保留到当前时刻的数据
    if not is_train:
        df_input = df_input[df_input['update_hour'] <= hourly_time].copy()
    else:
        df_input = df_input.copy()  # 训练集也 copy 一下保持一致性
    
    df_input = df_input.reset_index(drop=True)

    # 价格变化最小量阈值
    price_change_amount_threshold = 5
    df_input['_raw_price_diff'] = df_input.groupby(['gid', 'baggage_weight'], group_keys=False)['price_total'].diff()

    # 计算价格变化量
    df_input['price_change_amount'] = (
        df_input['_raw_price_diff']
        .mask(df_input['_raw_price_diff'].abs() < price_change_amount_threshold, 0)
        .replace(0, np.nan)
        .groupby([df_input['gid'], df_input['baggage_weight']], group_keys=False)
        .ffill()
        .fillna(0)
        .round(2)
    )

    # 计算价格变化百分比（相对于上一时间点的变化率）
    df_input['price_change_percent'] = (
        df_input.groupby(['gid', 'baggage_weight'], group_keys=False)['price_total']
        .pct_change()
        .mask(df_input['_raw_price_diff'].abs() < price_change_amount_threshold, 0)
        .replace(0, np.nan)
        .groupby([df_input['gid'], df_input['baggage_weight']], group_keys=False)
        .ffill()
        .fillna(0)
        .round(4)
    )

    # 第一步：标记价格变化段
    df_input['price_change_segment'] = (
        df_input.groupby(['gid', 'baggage_weight'], group_keys=False)['price_change_amount']
        .apply(lambda s: (s != s.shift()).cumsum())
    )

    # 第二步：计算每个变化段内的持续时间
    df_input['price_duration_hours'] = (
        df_input.groupby(['gid', 'baggage_weight', 'price_change_segment'], group_keys=False)
        .cumcount()
        .add(1)
    )

    # 可选：删除临时列
    df_input = df_input.drop(columns=['price_change_segment', '_raw_price_diff'])

    # 训练过程
    if is_train:
        df_target = df_input[(df_input['hours_until_departure'] >= 24) & (df_input['hours_until_departure'] <= 360)].copy()
        df_target = df_target.sort_values(
            by=['gid', 'baggage_weight', 'hours_until_departure'],
            ascending=[True, True, False]
        ).reset_index(drop=True)

        # 每条对应的前一条记录
        prev_pct = df_target.groupby(['gid', 'baggage_weight'], group_keys=False)['price_change_percent'].shift(1)
        prev_amo = df_target.groupby(['gid', 'baggage_weight'], group_keys=False)['price_change_amount'].shift(1)
        prev_dur = df_target.groupby(['gid', 'baggage_weight'], group_keys=False)['price_duration_hours'].shift(1)
        prev_price = df_target.groupby(['gid', 'baggage_weight'], group_keys=False)['price_total'].shift(1)
        
        # 对于先升后降（先降再降）的分析
        seg_start_mask = df_target['price_duration_hours'].eq(1)   # 开始变价节点
        drop_mask = seg_start_mask & ((prev_pct > 0) | (prev_pct < 0)) & (df_target['price_change_percent'] < 0)

        df_drop_nodes = df_target.loc[drop_mask, ['gid', 'baggage_weight', 'hours_until_departure', 'days_to_departure', 'update_hour', 'update_week']].copy()
        df_drop_nodes.rename(columns={'hours_until_departure': 'drop_hours_until_departure'}, inplace=True)
        df_drop_nodes.rename(columns={'days_to_departure': 'drop_days_to_departure'}, inplace=True)
        df_drop_nodes.rename(columns={'update_hour': 'drop_update_hour'}, inplace=True)
        df_drop_nodes.rename(columns={'update_week': 'drop_update_week'}, inplace=True)
        df_drop_nodes['drop_price_change_percent'] = df_target.loc[drop_mask, 'price_change_percent'].astype(float).round(4).to_numpy()
        df_drop_nodes['drop_price_change_amount'] = df_target.loc[drop_mask, 'price_change_amount'].astype(float).round(2).to_numpy()
        df_drop_nodes['high_price_duration_hours'] = prev_dur.loc[drop_mask].astype(float).to_numpy()
        df_drop_nodes['high_price_change_percent'] = prev_pct.loc[drop_mask].astype(float).round(4).to_numpy()
        df_drop_nodes['high_price_change_amount'] = prev_amo.loc[drop_mask].astype(float).round(2).to_numpy()
        df_drop_nodes['high_price_amount'] = prev_price.loc[drop_mask].astype(float).round(2).to_numpy()
        df_drop_nodes = df_drop_nodes.reset_index(drop=True)

        flight_info_cols = [
            'citypair', 'flight_numbers', 'from_time', 'from_date', 'currency',
        ]
        flight_info_cols = [c for c in flight_info_cols if c in df_target.columns]
        df_gid_info = df_target[['gid', 'baggage_weight'] + flight_info_cols].drop_duplicates(subset=['gid', 'baggage_weight']).reset_index(drop=True)
        df_drop_nodes = df_drop_nodes.merge(df_gid_info, on=['gid', 'baggage_weight'], how='left')

        drop_info_cols = [
            'drop_update_hour', 'drop_update_week',
            'drop_days_to_departure', 'drop_hours_until_departure', 'drop_price_change_percent', 'drop_price_change_amount',
            'high_price_duration_hours', 'high_price_change_percent', 'high_price_change_amount', 'high_price_amount', 
        ]
        # 按顺序排列 去掉gid
        df_drop_nodes = df_drop_nodes[flight_info_cols + ['baggage_weight'] + drop_info_cols]
        
        # 对于先升再升（先降再升）的分析
        # seg_start_mask = df_target['price_duration_hours'].eq(1)
        rise_mask = seg_start_mask & ((prev_pct > 0) | (prev_pct < 0)) & (df_target['price_change_percent'] > 0)

        df_rise_nodes = df_target.loc[rise_mask, ['gid', 'baggage_weight', 'hours_until_departure', 'days_to_departure', 'update_hour', 'update_week']].copy()
        df_rise_nodes.rename(columns={'hours_until_departure': 'rise_hours_until_departure'}, inplace=True)
        df_rise_nodes.rename(columns={'days_to_departure': 'rise_days_to_departure'}, inplace=True)
        df_rise_nodes.rename(columns={'update_hour': 'rise_update_hour'}, inplace=True)
        df_rise_nodes.rename(columns={'update_week': 'rise_update_week'}, inplace=True)
        df_rise_nodes['rise_price_change_percent'] = df_target.loc[rise_mask, 'price_change_percent'].astype(float).round(4).to_numpy()
        df_rise_nodes['rise_price_change_amount'] = df_target.loc[rise_mask, 'price_change_amount'].astype(float).round(2).to_numpy()
        df_rise_nodes['prev_rise_duration_hours'] = prev_dur.loc[rise_mask].astype(float).to_numpy()
        df_rise_nodes['prev_rise_change_percent'] = prev_pct.loc[rise_mask].astype(float).round(4).to_numpy()
        df_rise_nodes['prev_rise_change_amount'] = prev_amo.loc[rise_mask].astype(float).round(2).to_numpy()
        df_rise_nodes['prev_rise_amount'] = prev_price.loc[rise_mask].astype(float).round(2).to_numpy()
        df_rise_nodes = df_rise_nodes.reset_index(drop=True)

        df_rise_nodes = df_rise_nodes.merge(df_gid_info, on=['gid', 'baggage_weight'], how='left')
        
        rise_info_cols = [
            'rise_update_hour', 'rise_update_week',
            'rise_days_to_departure', 'rise_hours_until_departure', 'rise_price_change_percent', 'rise_price_change_amount',
            'prev_rise_duration_hours', 'prev_rise_change_percent', 'prev_rise_change_amount', 'prev_rise_amount',
        ]
        df_rise_nodes = df_rise_nodes[flight_info_cols + ['baggage_weight'] + rise_info_cols]
        
        # 制作历史包络线
        envelope_group = ['citypair', 'flight_numbers', 'from_date', 'baggage_weight']
        idx_peak = df_input.groupby(envelope_group)['price_total'].idxmax()
        df_envelope = df_input.loc[idx_peak, envelope_group + [
            'from_time', 'price_total', 'hours_until_departure', 'days_to_departure', 'update_hour', 'update_week',
        ]].rename(columns={
            'price_total': 'peak_price',
            'hours_until_departure': 'peak_hours',
            'days_to_departure': 'peak_days',
            'update_hour': 'peak_time',
            'update_week': 'peak_week',
        }).reset_index(drop=True)
        
        del df_gid_info
        del df_target

        return df_input, df_drop_nodes, df_rise_nodes, df_envelope
    
    return df_input, None, None, None
 

def predict_data_simple(df_input, city_pair, output_dir, predict_dir=".", pred_time_str=""):
    if df_input is None or df_input.empty:
        return pd.DataFrame()

    df_sorted = df_input.sort_values(
        by=['gid', 'baggage_weight', 'hours_until_departure'],
        ascending=[True, True, False],
    ).reset_index(drop=True)

    df_sorted = df_sorted[
        df_sorted['hours_until_departure'].between(24, 360)
    ].reset_index(drop=True)

    # 每个 gid  baggage_weight 取 hours_until_departure 最小的一条 (当前小时)
    df_min_hours = (
        df_sorted.drop_duplicates(subset=['gid', 'baggage_weight'], keep='last')
        .reset_index(drop=True)
    )

    # 读历史降价场景
    drop_info_csv_path = os.path.join(output_dir, f'{city_pair}_drop_info.csv')
    if os.path.exists(drop_info_csv_path):
        df_drop_nodes = pd.read_csv(drop_info_csv_path)
    else:
        df_drop_nodes = pd.DataFrame()

    # 读历史升价场景
    rise_info_csv_path = os.path.join(output_dir, f'{city_pair}_rise_info.csv')
    if os.path.exists(rise_info_csv_path):
        df_rise_nodes = pd.read_csv(rise_info_csv_path)
    else:
        df_rise_nodes = pd.DataFrame()
    
    # 联合价格分布
    # 统一初始化
    df_min_hours['relative_position'] = np.nan
    if not df_drop_nodes.empty:
        df_drop_nodes['relative_position'] = np.nan
    if not df_rise_nodes.empty:
        df_rise_nodes['relative_position'] = np.nan
    
    parts = []

    # 当前待预测
    if not df_min_hours.empty and 'price_total' in df_min_hours.columns:
        cur = df_min_hours[['price_total']].copy()
        cur['price'] = pd.to_numeric(cur['price_total'], errors='coerce')
        cur['source'] = 'min'
        cur['row_id'] = cur.index
        parts.append(cur[['price', 'source', 'row_id']])
    
    # 历史降价
    if not df_drop_nodes.empty and 'high_price_amount' in df_drop_nodes.columns:
        drop = df_drop_nodes[['high_price_amount']].copy()
        drop['price'] = pd.to_numeric(drop['high_price_amount'], errors='coerce')
        drop['source'] = 'drop'
        drop['row_id'] = drop.index
        parts.append(drop[['price', 'source', 'row_id']])
    
    # 历史升价
    if not df_rise_nodes.empty and 'prev_rise_amount' in df_rise_nodes.columns:
        rise = df_rise_nodes[['prev_rise_amount']].copy()
        rise['price'] = pd.to_numeric(rise['prev_rise_amount'], errors='coerce')
        rise['source'] = 'rise'
        rise['row_id'] = rise.index
        parts.append(rise[['price', 'source', 'row_id']])
    
    if parts:
        all_prices = pd.concat(parts, ignore_index=True)
        all_prices = all_prices.dropna(subset=['price']).reset_index(drop=True)

        # 计算价格百分位
        dense_rank = all_prices['price'].rank(method='dense')
        max_rank = dense_rank.max()
        if pd.notna(max_rank) and max_rank > 1:
            all_prices['relative_position'] = (dense_rank - 1) / (max_rank - 1)
        else:
            all_prices['relative_position'] = 1.0
        all_prices['relative_position'] = all_prices['relative_position'].round(4)

        # 回填到三个表
        m = all_prices['source'] == 'min'
        df_min_hours.loc[all_prices.loc[m, 'row_id'], 'relative_position'] = all_prices.loc[m, 'relative_position'].values

        if not df_drop_nodes.empty:
            m = all_prices['source'] == 'drop'
            df_drop_nodes.loc[all_prices.loc[m, 'row_id'], 'relative_position'] = all_prices.loc[m, 'relative_position'].values

        if not df_rise_nodes.empty:
            m = all_prices['source'] == 'rise'
            df_rise_nodes.loc[all_prices.loc[m, 'row_id'], 'relative_position'] = all_prices.loc[m, 'relative_position'].values
    
    pass