'''
    Mooc 的虚基类：用于派生所有Mooc子类
'''

import os
from abc import ABC, abstractmethod
from Mooc.Mooc_Config import *
from Mooc.Mooc_Download import *
from Mooc.Mooc_Request import *

__all__ = [
    "Mooc_Base"
]

class Mooc_Base(ABC):
    def __init__(self):
        self.__mode = None
        self.__cid = None
        self.__title = None
        self.__infos = None
        self.__rootDir = None

    @property
    def mode(self):
        '''下载模式: 用于选择性下载'''
        return self.__mode

    @mode.setter
    def mode(self, mode):
        self.__mode = mode

    @property
    def cid(self):
        '''课程的 ID'''
        return self.__cid
    
    @cid.setter
    def cid(self, cid):
        self.__cid = cid

    @property
    def title(self):
        '''课程的标题'''
        return self.__title
    
    @title.setter
    def title(self, title):
        self.__title = title

    @property
    def infos(self):
        '''解析后的课程信息'''
        return self.__infos

    @property
    def rootDir(self):
        return self.__rootDir

    @rootDir.setter
    def rootDir(self, rootDir):
        self.__rootDir = rootDir
    
    @infos.setter
    def infos(self, infos):
        self.__infos = infos

    @abstractmethod
    def _get_cid(self):
        pass
    
    @abstractmethod
    def _get_title(self):
        pass

    @abstractmethod
    def _get_infos(self):
        pass

    @abstractmethod
    def _download(self):
        pass

    @abstractmethod
    def set_mode(self):
        pass

    @abstractmethod
    def prepare(self, url):
        pass

    @abstractmethod
    def download(self):
        pass

    @classmethod
    def download_video(cls, video_url, video_name, video_dir):
        '''下载 MP4 视频文件'''
        succeed = True
        if not cls.judge_file_existed(video_dir, video_name, '.mp4'):
            try:
                header =  request_head(video_url)
                size = float(header['Content-Length']) / (1024*1024)
                print("  |-{}  [mp4] 大小: {:.2f}M".format(cls.align(video_name,LENGTH), size))
                aria2_download_file(video_url, video_name+'.mp4', video_dir)
            except DownloadFailed:
                print("  |-{}  [mp4] 资源无法下载！".format(cls.align(video_name,LENGTH)))
                succeed = False
        else:
            print("  |-{}  [mp4] 已经成功下载！".format(cls.align(video_name,LENGTH)))
        return succeed

    @classmethod
    def download_pdf(cls, pdf_url, pdf_name, pdf_dir):
        '''下载 PDF '''
        succeed = True
        if not cls.judge_file_existed(pdf_dir, pdf_name, '.pdf'):
            try:
                aria2_download_file(pdf_url, pdf_name+'.pdf', pdf_dir)
                print("  |-{}  (pdf) 已经成功下载！".format(cls.align(pdf_name,LENGTH)))
            except DownloadFailed:
                print("  |-{}  (pdf) 资源无法下载！".format(cls.align(pdf_name,LENGTH)))
                succeed = False
        else:
            print("  |-{}  (pdf) 已经成功下载！".format(cls.align(pdf_name,LENGTH)))
        return succeed

    @classmethod
    def download_sub(cls, sub_url, sub_name, sub_dir):
        '''下载字幕'''
        succeed = True
        if not cls.judge_file_existed(sub_dir, sub_name, '.srt'):
            try:
                aria2_download_file(sub_url, sub_name+'.srt', sub_dir)
            except DownloadFailed:
                succeed = False
        return succeed

    @staticmethod
    def judge_file_existed(dirname, filename, fmt):
        '''
        judge_file_existed(dirname, filename, fmt) 
        判断在 dirname 目录下是否存在已下载成功的格式为 fmt 且文件名为 filename 的文件
        '''
        filepath = os.path.join(dirname, filename)
        exist1 = os.path.exists(filepath+fmt)
        exist2 = os.path.exists(filepath+fmt+'.aria2')
        return exist1 and not exist2

    @staticmethod
    def align(string, width):  #  对齐汉字字符窜，同时截断多余输出
        '''
        align(string, width) 根据width宽度居中对齐字符窜 string，主要用于汉字居中
        '''
        res = ""
        size = 0
        for ch in string:
            if (size+3 > width):
                break
            size += 1 if ord(ch) <= 127 else 2
            res += ch
        res += (width-size)*' '
        return res