#!/usr/bin/env python
# -*- coding: cp936 -*-

"""

用于批量转换特定目录下所有MP3名称（包括改目录下所有子目录），新名称格式：“演唱者－歌曲名称”。

Mp3文件格式：

at end of file - 128 bytes

offset  type  len   name
--------------------------------------------
0       char  3                   "TAG"
3       char  30    title
33      char  30    artist
63      char  30    album
93      char  4     year
97      char  30    comments
127     byte  1     genre
--------------------------------------------
"""

import sys
import os
import os.path

class MP3INFO:

    """读取mp3文件中的演唱者和歌曲名称信息"""

    def __init__(self, filename):
        self.title = \'\'
        self.artist = \'\'
        
        f = file(filename,\'rb\')
        f.seek(-128,2)
        s=f.read(3)

        if s == \'TAG\': # 判断是否是mp3文件
            strlist = []
            for i in (30,30):
                s = f.read(i)
                pos = s.find(\'/0\')
                if pos == 0:
                    s = \'\'
                elif pos > 0:
                    s = s[0:pos]
                strlist.append(s.strip())
            self.title, self.artist = strlist

        f.close()

def RenameMp3File(arg,dirname,names):
     """dirname: 目录名；names：目录下所有文件列表"""
    for name in names:
        filename = dirname + \'/\' + name
        if os.path.isdir(filename) or name[-3:].lower() != \'mp3\':
            pass   #该文件如果是目录或不是.mp3文件，则什么也不作
        else:
            mp3 = MP3INFO(filename)
            #拼装新的文件名
            if mp3.title == \'\':
                mp3filename = name
            elif mp3.artist == \'\':
                mp3filename = mp3.title + \'.mp3\'
            else:
                mp3filename = mp3.artist + \' - \' + mp3.title + \'.mp3\'

            #消除新文件名中的非法字符

            a = \'//:*?"<>|\'
            t = [ x for x in mp3filename if x not in a]
            mp3filename = \'\'
            for x in t:
                mp3filename += x

             #如果是在winxp下，无需判断字符编码
            #linux下需要将原来的字符编码格式转换为UTF8的格式，否则显示乱码

            codelist =  [\'gbk\', \'hz\', \'euc-tw\',  \'big5\', \'gb18030\', \'gb2312\', /
                         \'utf-8\', \'utf-16\', \'big5-hkscs\',\'iso-2022-cn\',/
                         \'iso-2022-jp\', \'iso-2022-kr\', \'iso-8859-1\']
            #codelist =  [\'utf-8\', \'gbk\',  \'big5\', \'iso-8859-1\']
            for code in codelist:
                try:
                    mp3filename = unicode(mp3filename, code)
                    mp3filename = mp3filename.encode(\'utf-8\')
                    
                    # Judge that mp3.title not empty, because destination
                    # filename will be equal to source filename when mp3.title
                    # is empty. If not, it will throw OSError: duplication of
                    # filename when run \'os.rename(...)\'
                    if mp3.title != \'\' and mp3filename != name:
                        os.rename(filename, dirname + \'/\' + mp3filename)
                        print code, \'---\', filename, \' --> \', mp3filename
                    break
                except OSError:
                    print \'duplication of name: \',filename
                    pass
                except:
                    if code == codelist[-1]:
                        print code, \'---\', filename, \' ---\', mp3filename
                        print "Unexpected error:", sys.exc_info()[0]
                    pass

if __name__ == \'__main__\':
    p=r\'/home/ljh/MyMusic\'
    if len(sys.argv) > 1:
        p = sys.argv[1]
    os.path.walk(p, RenameMp3File,0)