import datetime
from typing import Union, List

import psycopg2
import psycopg2.extras
from dbutils.pooled_db import PooledDB

from Config.Config import *

POOL = PooledDB(
    creator=psycopg2,  # 使用链接数据库的模块
    maxconnections=6,  # 连接池允许的最大连接数，0和None表示不限制连接数
    mincached=2,  # 初始化时，链接池中至少创建的空闲的链接，0表示不创建
    maxcached=5,  # 链接池中最多闲置的链接，0和None不限制
    maxshared=3,
    # 链接池中最多共享的链接数量，0和None表示全部共享。PS: 无用，因为pymysql和MySQLdb等模块的 threadsafety都为1，所有值无论设置为多少，_maxcached永远为0，所以永远是所有链接都共享。
    blocking=True,  # 连接池中如果没有可用连接后，是否阻塞等待。True，等待；False，不等待然后报错
    maxusage=None,  # 一个链接最多被重复使用的次数，None表示无限制
    setsession=[],  # 开始会话前执行的命令列表。如：["set datestyle to ...", "set time zone ..."]
    ping=0,
    host=host,
    port=port,
    user=user,
    password=password,
    database=dbname
)


class Db(object):
    @staticmethod
    def fetchOne(sql, _id):
        conn = POOL.connection()
        cursor = conn.cursor(cursor_factory=psycopg2.extras.DictCursor)
        cursor.execute(sql)
        id = cursor.fetchone()[_id]
        conn.commit()
        conn.close()
        return id

    @staticmethod
    def find(sql):
        conn = POOL.connection()
        cursor = conn.cursor(cursor_factory=psycopg2.extras.DictCursor)
        cursor.execute(sql)
        des = cursor.description
        t = ",".join([item[0] for item in des])
        table_head = t.split(',')  # # 查询表列名 用,分割
        result = cursor.fetchall()
        conn.close()

        list1 = []
        for a in result:
            c = {}
            for b in table_head:
                if type(a[b]) == datetime.datetime:
                    a[b] = datetime.datetime.strftime(a[b], '%Y-%m-%d %H:%M:%S')
                c[b] = a[b]
            list1.append(c)
        return list1

    @staticmethod
    def findFirst(sql):
        return Db.find(sql)[0]

    @staticmethod
    def findFirstValue(sql):
        row = Db.find(sql)[0]
        for key in row:
            return row[key]

    @staticmethod
    def paginate(sql, page, limit):
        conn = POOL.connection()
        cursor = conn.cursor(cursor_factory=psycopg2.extras.DictCursor)
        pageSql = "select * from (" + sql + ") as t100 limit " + str(limit) + " offset " + str((page - 1) * limit)
        cursor.execute(pageSql)
        des = cursor.description
        t = ",".join([item[0] for item in des])
        table_head = t.split(',')  # # 查询表列名 用,分割
        result = cursor.fetchall()
        list1 = []
        for a in result:
            c = {}
            for b in table_head:
                if type(a[b]) == datetime.datetime:
                    a[b] = datetime.datetime.strftime(a[b], '%Y-%m-%d %H:%M:%S')
                c[b] = a[b]
            list1.append(c)

        # 一共多少个
        sql = "select count(1) as c from (" + sql + ") as t100"
        cursor.execute(sql)
        cnt = cursor.fetchone()["c"]
        conn.close()
        return list1, cnt

    @staticmethod
    def execute(sql):
        conn = POOL.connection()
        cursor = conn.cursor(cursor_factory=psycopg2.extras.DictCursor)
        res = cursor.execute(sql)
        conn.commit()
        conn.close()
        return res

    # 执行类ORM插入
    @staticmethod
    def save(table, data):
        conn = POOL.connection()
        cursor = conn.cursor(cursor_factory=psycopg2.extras.DictCursor)
        keys = ', '.join(data.keys())
        values = ', '.join(['%s'] * len(data))
        sql = 'INSERT INTO {table}({keys}) VALUES ({values})'.format(table=table, keys=keys, values=values)
        sql = sql % tuple(data.values())
        cursor.execute(sql)
        conn.commit()
        conn.close()

    # 执行类ORM更新(目前只支持单主键)
    @staticmethod
    def update(table, primaryKey, data):
        conn = POOL.connection()
        cursor = conn.cursor(cursor_factory=psycopg2.extras.DictCursor)
        sql1 = "update {table} set ".format(table=table)
        sql2 = ''
        primaryKeyValue = ''
        for key in data:
            if key != primaryKey:
                sql2 = sql2 + key + "='" + str(data[key]).replace("'",'"') + "',"
            else:
                primaryKeyValue = str(data[key])
        sql2 = sql2[:-1]
        sql2 = sql2 + " where " + primaryKey + "='" + primaryKeyValue + "';"
        sql = sql1 + sql2
        cursor.execute(sql)
        conn.commit()
        conn.close()

    @staticmethod
    def execute_by_execute_values(sql: str, data: Union[list, set], template: str = None, page_size: int = 100,
                                  fetch: bool = False):
        """
        使用execute_values批量插入、更新，效率比execute_batch和executemany高
        """
        conn = POOL.connection()
        cursor = conn.cursor(cursor_factory=psycopg2.extras.DictCursor)
        try:
            psycopg2.extras.execute_values(cursor, sql, data, template=template, page_size=page_size, fetch=fetch)
            conn.commit()
            conn.close()
        except Exception as e:
            conn.rollback()
            raise e

    @staticmethod
    def execute_by_execute_batch(sql: str, data: List[dict], page_size: int = 100):
        conn = POOL.connection()
        cursor = conn.cursor(cursor_factory=psycopg2.extras.DictCursor)
        try:
            psycopg2.extras.execute_batch(cursor, sql, data, page_size=page_size)
            conn.commit()
            conn.close()
        except Exception as e:
            conn.rollback()
            raise e


if __name__ == '__main__':
    pass