# ------------------------------------------------------------------------------
import time

# ------------------------------------------------------------------------------
class Migrator:
    '''This class is responsible for performing migrations, when, on
       installation, we've detected a new Appy version.'''
    def __init__(self, installer):
        self.installer = installer

    def migrateTo_0_7_1(self):
        '''Appy 0.7.1 has its own management of Ref fields. So we must
           update data structures that store Ref info on instances.'''
        ins = self.installer
        ins.info('Migrating to Appy 0.7.1...')
        allClassNames = [ins.tool.__class__.__name__] + ins.config.allClassNames
        for className in allClassNames:
            i = -1
            updated = 0
            ins.info('Analysing class "%s"...' % className)
            refFields = None
            for obj in ins.tool.executeQuery(className,\
                                             noSecurity=True)['objects']:
                i += 1
                if i == 0:
                    # Get the Ref fields for objects of this class
                    refFields = [f for f in obj.getAllAppyTypes() \
                                 if (f.type == 'Ref') and not f.isBack]
                    if refFields:
                        refNames = ', '.join([rf.name for rf in refFields])
                        ins.info('  Ref fields found: %s' % refNames)
                    else:
                        ins.info('  No Ref field found.')
                        break
                isUpdated = False
                for field in refFields:
                    # Attr for storing UIDs of referred objects has moved
                    # from _appy_[fieldName] to [fieldName].
                    refs = getattr(obj, '_appy_%s' % field.name)
                    if refs:
                        isUpdated = True
                        setattr(obj, field.name, refs)
                        exec 'del obj._appy_%s' % field.name
                        # Set the back references
                        for refObject in field.getValue(obj):
                            refObject.link(field.back.name, obj, back=True)
                if isUpdated: updated += 1
            if updated:
                ins.info('  %d/%d object(s) updated.' % (updated, i+1))

    def run(self):
        i = self.installer
        installedVersion = i.appyTool.appyVersion
        startTime = time.time()
        migrationRequired = False
        if not installedVersion or (installedVersion <= '0.7.0'):
            migrationRequired = True
            self.migrateTo_0_7_1()
        stopTime = time.time()
        if migrationRequired:
            i.info('Migration done in %d minute(s).'% ((stopTime-startTime)/60))
# ------------------------------------------------------------------------------