import os
import random
import sqlite3
import time
import zipfile


class Backend:

    def __init__(self, db="data.db"):
        self.db_path = db
        # 先解压
        if not os.path.exists(self.db_path) and os.path.exists(self.db_path + ".zip"):
            with zipfile.ZipFile(self.db_path + ".zip", 'r') as zip_ref:
                zip_ref.extractall(".")


        self.time = time.time()
        self.title_filter = self.get_source_type()
        self.global_filter = ""



    def get_question(self):
        conn = sqlite3.connect(self.db_path)
        cursor = conn.cursor()

        # 构造 IN 子句的占位符
        placeholders = ','.join('?' for _ in self.title_filter)

        # 总权重查询
        total_query = f"""
            SELECT SUM(q.count) 
            FROM questions q
            WHERE q.count > 0 AND title IN ({placeholders}) {self.global_filter}
        """

        print(total_query)
        #print(self.title_filter)

        cursor.execute(total_query, self.title_filter)
        total_weights = cursor.fetchone()[0]
        if total_weights is None or total_weights == 0:
            conn.close()
            return None

        # 生成随机数 [0, total_weights)
        random_num = random.uniform(0, total_weights)

        # 主查询：加权随机选择
        query = f"""
            SELECT *
            FROM (
                SELECT *,
                       SUM(q.count) OVER (ORDER BY id ROWS UNBOUNDED PRECEDING) AS cum_weight
                FROM questions q
                WHERE q.count > 0 AND title IN ({placeholders}) {self.global_filter}
            )
            WHERE ? < cum_weight
            ORDER BY cum_weight
            LIMIT 1;
        """

        params = tuple(self.title_filter) + (random_num,)
        cursor.execute(query, params)

        row = cursor.fetchone()
        print(total_weights, row)

        conn.close()
        self.time = time.time()

        return list(row) if row else None

    def update(self, id, state):
        conn = sqlite3.connect(self.db_path)
        cursor = conn.cursor()

        # 作对-1 错了+2
        if state != 0:
            query = """
                    UPDATE questions
                    SET count = count + 2
                    WHERE id = ?
                      and count > 0"""
        else:
            query = """
                    UPDATE questions
                    SET count = count - 1
                    WHERE id = ?
                    """
        cursor.execute(query, (id,))

        # 记录用时
        query = "INSERT INTO answers_history (id, time_used, state) VALUES (?, ?, ?)"
        cursor.execute(query, (id, time.time() - self.time, state))

        conn.commit()
        conn.close()

    def reset_time(self):
        self.time = time.time()

    def get_acc(self, top_n=0):
        conn = sqlite3.connect(self.db_path)
        cursor = conn.cursor()

        try:
            if top_n > 0:
                query = """
                        SELECT CAST(SUM(CASE WHEN state = 0 THEN 1 ELSE 0 END) AS FLOAT) / COUNT(*) AS accuracy
                        FROM (SELECT state
                              FROM answers_history
                              ORDER BY time DESC
                              LIMIT ?)
                        """
                params = (top_n,)
            else:
                query = """
                        SELECT CAST(SUM(CASE WHEN state = 0 THEN 1 ELSE 0 END) AS FLOAT) / COUNT(*) AS accuracy FROM answers_history
                        """
                params = ()

            cursor.execute(query, params)
            result = cursor.fetchone()[0]
            return result * 100 if result is not None else 0.0

        except sqlite3.Error as e:
            print(f"数据库错误：{e}")
            return 0.0
        finally:
            conn.close()

    def get_avg_time(self, top_n=0):
        conn = sqlite3.connect(self.db_path)
        cursor = conn.cursor()

        try:
            if top_n > 0:
                query = """
                        SELECT CAST(SUM(time_used) AS FLOAT) / COUNT(*) AS accuracy
                        FROM (SELECT time_used
                              FROM answers_history
                              where time_used is not null
                              ORDER BY time DESC
                              LIMIT ?)
                        """
                params = (top_n,)
            else:
                query = """
                        SELECT CAST(SUM(time_used) AS FLOAT) / COUNT(*) AS accuracy FROM answers_history where time_used is not null
                        """
                params = ()

            cursor.execute(query, params)
            result = cursor.fetchone()[0]
            return result if result is not None else 0.0

        except sqlite3.Error as e:
            print(f"数据库错误：{e}")
            return 0.0
        finally:
            conn.close()

    def get_statistics(self):
        avg_all = self.get_avg_time()
        avg_50 = self.get_avg_time(50)
        avg_100 = self.get_avg_time(100)

        result = [
            ["正确率", f"{self.get_acc():.1f}/60%"],
            [],
            ["最近50题正确率", f"{self.get_acc(50):.1f}/60%"],
            ["最近100题正确率", f"{self.get_acc(120):.1f}/60%"],
            ["平均耗时", f"{avg_all:.1f}/72s"],
            ["预计做完用时", f"{avg_all * 1.667:.1f}/120min"],
            ["50平均耗时", f"{avg_50:.1f}/72s"],
            ["预计做完用时", f"{avg_50 * 1.667:.1f}/120min"],
            ["120平均耗时", f"{avg_100:.1f}/72s"],
            ["预计做完用时", f"{avg_100 * 1.667:.1f}/120min"],
        ]
        return result

    def get_source_type(self):
        conn = sqlite3.connect(self.db_path)
        cursor = conn.cursor()
        query = "SELECT DISTINCT title FROM questions"
        cursor.execute(query)
        result = cursor.fetchall()
        new_list = [item[0] for item in result]
        return new_list

    def set_config(self,a,b):
        self.title_filter = a

        self.global_filter = ""
        if len(b)>0:
            self.global_filter = " and ( FALSE "
            for item in b:
                if item == "未做过的题":
                    self.global_filter +=" OR q.count = 3 "
                elif item == "错过的题":
                    self.global_filter +=" OR q.count > 3 "
            self.global_filter += ")"