# -*- coding: UTF-8 -*-
import os
import uuid
import math
import time

class Client(object):
    """docstring for Client"""
    def __init__(self, namenode):
        self.namenode = namenode

    def write(self, filename, data):
        chunks = [] #存放data分出来的num_chunks份数据
        chunkloc = 1
        num_chunks = self.get_num_chunks(data)
        for i in range(0, len(data), self.namenode.chunksize):
            chunks.append(data[i:i+self.namenode.chunksize])
        chunk_uuids = self.namenode.alloc(filename, num_chunks) #为文件分配空间，更新元数据    
        for i in range(0, len(chunk_uuids)):            
            chunkloc = i % self.namenode.num_datanodes + 1
            self.namenode.datanodes[chunkloc].write(chunk_uuids[i], chunks[i])     
            #备份第二份        
            chunkloc = chunkloc % self.namenode.num_datanodes + 1
            self.namenode.datanodes[chunkloc].write(chunk_uuids[i], chunks[i]) 

    def read(self, filename):
        if True == self.namenode.exits(filename) :
            data = ‘‘
            chunk_uuids = self.namenode.filetable[filename]
            for chunk_uuid in chunk_uuids:
                chunkloc = self.namenode.chunktable[chunk_uuid] #获取uuid的DataNode的位置
                data_temp = self.namenode.datanodes[chunkloc].read(chunk_uuid)    
                if -1 == data_temp: #读取当前DataNode上的chunk不存在（即：某一个DataNode被损坏）
                    data_temp = self.namenode.datanodes[chunkloc%self.namenode.num_datanodes + 1].read(chunk_uuid)
                    print ‘Current chunk is broken.‘  #读取下一个DataNode的chunk
                data = data + data_temp
            return data
        else :
            print "The file: \"" + filename + "\" is not exits."        

    def delete(self, filename):  #删除文件：物理删除和元数据删除
        if True == self.namenode.exits(filename) :
            chunk_uuids = self.namenode.filetable[filename]
            for chunk_uuid in chunk_uuids :
                chunkloc = self.namenode.chunktable[chunk_uuid]
                self.namenode.datanodes[chunkloc].delete(chunk_uuid)  #物理删除:第一份
                self.namenode.datanodes[chunkloc%self.namenode.num_datanodes + 1].delete(chunk_uuid)  #物理删除：第二份
            self.namenode.delete(filename) #逻辑删除：在元数据删除信息
        else :
            print "The file: \"" + filename + "\" is not exits."

    def list_files(self):
        print "Files:"
        for (k, v) in self.namenode.filetable.items():
            print k

    def get_num_chunks(self, data):
        return int(math.ceil(len(data)*1.0 / self.namenode.chunksize))

class Namenode(object):
    """docstring for Namenode"""
    def __init__(self):
        self.num_datanodes = 3
        self.chunksize = 10
        self.filetable = {}
        self.chunktable = {}
        self.datanodes = {}
        self.init_datanodes() #初始化：loc<-->server

    def init_datanodes(self):
        for i in range(1, self.num_datanodes+1):
            self.datanodes[i] = Datanode(i)

    def alloc(self, filename, num_chunks): #完成映射：filetable和chunktable
        chunkloc = 1
        chunk_uuids = []
        for i in range(0, num_chunks):
            chunk_uuid = uuid.uuid1();
            chunk_uuids.append(chunk_uuid)
            self.chunktable[chunk_uuid] = chunkloc
            chunkloc = chunkloc % self.num_datanodes + 1 #！！注意：要+1，否则chunkloc值不会变坏
        self.filetable[filename] = chunk_uuids
        print self.filetable
        return chunk_uuids

    def delete(self, filename):
        chunk_uuids = self.filetable[filename]
        for chunk_uuid in chunk_uuids:
            self.chunktable.pop(chunk_uuid)
        self.filetable.pop(filename)

    def exits(self, filename): #检测文件是否存在
        if filename in self.filetable:
            return True
        else: 
            return False

class Datanode(object):
    """docstring for Datanode"""
    def __init__(self, chunkloc):
        self.chunkloc = chunkloc
        self.local_fs_root = "D:/HDFSTemp/Datanode" + str(chunkloc) #用不同的目录来模仿不同的Datanode
        if not os.path.isdir(self.local_fs_root):
            os.makedirs(self.local_fs_root)

    def write(self, chunk_uuid, chunk):#写入到chunk
        try:
            with open(self.local_fs_root + "/" + str(chunk_uuid), "w") as fw:
                fw.write(chunk)
        except IOError :
            print "The HDFS is broken."
    def read(self, chunk_uuid): #从chunk读取
        data = None
        try :
            with open(self.local_fs_root + "/" + str(chunk_uuid), "r") as fr:
                data = fr.read()
            return data
        except IOError :
            return -1

    def delete(self, chunk_uuid):
        try:
            os.remove(self.local_fs_root + "/" + str(chunk_uuid))
        except WindowsError:
            print "Filename:" + self.local_fs_root + "/" + str(chunk_uuid) + ‘dose not exits.‘

class Command(object):
    """docstring for Command"""
    def __init__(self, client):
        self.client = client

    def command_line(self):
        while True:
            cmd = raw_input(‘Input your command:\n‘)    
            if(‘upload‘ == cmd):
                self.upload_cmd()
            elif(‘download‘ == cmd):
                self.download_cmd()
            elif(‘delete‘ == cmd):
                filename = raw_input(‘Input the filename which you want to delete in HDFS:\n‘)
                self.client.delete(filename)
            elif(‘ls‘ == cmd):
                self.client.list_files()
            elif(‘exits‘ == cmd):
                break
            else:
                print "Wrong command. \n"

    def upload_cmd(self):
        filename = raw_input(‘Input the filename which you want to upload in local:\n‘)
        try :
            with open(filename, "r") as fr: #读取本地文件
                data = fr.read()
                self.client.write(filename, data)      #写入HDFS
        except IOError :
            print "No such file in local."

    def download_cmd(self):
        filename = raw_input(‘Input the filename which you want to download in HDFS:\n‘)
        data = self.client.read(filename)  #读取HDFS文件
        print data 
        with open(filename, "w") as fw:  
            fw.write(data)      #写入本地

def main():        
    nd = Namenode()
    client = Client(nd)    
    command = Command(client)
    command.command_line()

if __name__ == ‘__main__‘:
    main()