#!/usr/bin/env python

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from binascii import hexlify

from sqlalchemy import create_engine
from sqlalchemy import Table, Column, String, MetaData
from sqlalchemy.sql import select

from pithos import settings
from pithos.backends.modular import ModularBackend

from lib.hashmap import HashMap
from lib.migrate import Migration

class DataMigration(Migration):
    def __init__(self, db):
        Migration.__init__(self, db)
        # XXX Need more columns for primary key - last modified timestamp...
        columns=[]
        columns.append(Column('path', String(2048), primary_key=True))
        columns.append(Column('hash', String(255)))
        self.files = Table('files', self.metadata, *columns)
        self.metadata.create_all(self.engine)
    
    def cache_put(self, path, hash):
        # Insert or replace.
        s = self.files.delete().where(self.files.c.path==path)
        r = self.conn.execute(s)
        r.close()
        s = self.files.insert()
        r = self.conn.execute(s, {'path': path, 'hash': hash})
        r.close()
    
    def cache_get(self, path):
        s = select([self.files.c.hash], self.files.c.path == path)
        r = self.conn.execute(s)
        l = r.fetchone()
        r.close()
        if not l:
            return l
        return l[0]
    
    def execute(self):
        blocksize = self.backend.block_size
        blockhash = self.backend.hash_algorithm
        
        # Loop for all available files.
        filebody = Table('filebody', self.metadata, autoload=True)
        s = select([filebody.c.storedfilepath])
        rp = self.conn.execute(s)
        paths = rp.fetchall()
        rp.close()
        
        for path in paths:
            map = HashMap(blocksize, blockhash)
            map.load(path)
            hash = hexlify(map.hash())
            
            if hash != self.cache_get(path):
                missing = self.backend.blocker.block_ping(map) # XXX Backend hack...
                status = '[>] ' + path
                if missing:
                    status += ' - %d block(s) missing' % len(missing)
                    with open(path) as fp:
                        for h in missing:
                            offset = map.index(h) * blocksize
                            fp.seek(offset)
                            block = fp.read(blocksize)
                            self.backend.put_block(block)
                else:
                    status += ' - no blocks missing'
                self.cache_put(path, hash)
            else:
                status = '[-] ' + path
            print status

if __name__ == "__main__":
    db = 'sqlite:///migrate.db'
    
    dt = DataMigration(db)
    dt.execute()