"""

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)