#!/usr/bin/env python

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

from django.conf import settings

from pithos.backends.modular import ModularBackend


class Migration(object):
    def __init__(self, db):
        self.engine = create_engine(db)
        self.metadata = MetaData(self.engine)
        #self.engine.echo = True
        self.conn = self.engine.connect()

        options = getattr(settings, 'BACKEND', None)[1]
        self.backend = ModularBackend(*options)

    def execute(self):
        pass


class Cache():
    def __init__(self, db):
        self.engine = create_engine(db)
        metadata = MetaData(self.engine)

        columns = []
        columns.append(Column('path', String(2048), primary_key=True))
        columns.append(Column('hash', String(255)))
        self.files = Table('files', metadata, *columns)
        self.conn = self.engine.connect()
        self.engine.echo = True
        metadata.create_all(self.engine)

    def 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 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]