"""Components to handle access codes.
"""
import csv
import grok
import os
from BTrees.OIBTree import OIBTree
from datetime import datetime
from random import SystemRandom as random
from waeup.sirp.interfaces import IWAeUPSIRPPluggable
from waeup.sirp.accesscodes.interfaces import (
    IAccessCode, IAccessCodeBatch, IAccessCodeBatchContainer
    )

class ManageACBatches(grok.Permission):
    grok.name('waeup.manageACBatches')

class AccessCode(grok.Context):
    grok.implements(IAccessCode)

    def __init__(self, batch_serial, random_num, invalidation_date=None,
                 student_id=None):
        self.batch_serial = batch_serial
        self.random_num = random_num
        self._invalidation_date = invalidation_date
        self.student_id = student_id

    @property
    def representation(self):
        return '%s-%s-%s' % (
            self.batch_prefix, self.batch_num, self.random_num)

    @property
    def batch(self):
        return getattr(self, '__parent__', None)

    @property
    def batch_prefix(self):
        if self.batch is None:
            return ''
        return self.batch.prefix

    @property
    def batch_num(self):
        if self.batch is None:
            return ''
        return self.batch.num

    @property
    def cost(self):
        if self.batch is None:
            return None
        return self.batch.cost

    @property
    def invalidation_date(self):
        # We define this as a property to make it unwritable.
        # This attribute should be set by the surrounding batch only.
        return self._invalidation_date
    
class AccessCodeBatch(grok.Model):
    """A batch of access codes.
    """
    grok.implements(IAccessCodeBatch)

    def __init__(self, creation_date, creator, batch_prefix, cost,
                 entry_num, num=None):
        super(AccessCodeBatch, self).__init__()
        self.creation_date = creation_date
        self.creator = creator
        self.prefix = batch_prefix.upper()
        self.cost = cost
        self.entry_num = entry_num
        self.num = num
        self.invalidated_num = 0
        self._entries = list()
        self._acids = OIBTree()
        self._createEntries()

    def _createEntries(self):
        """Create the entries for this batch.
        """
        for num, pin in enumerate(self._getNewRandomNum(num=self.entry_num)):
            self.addAccessCode(num, pin)
        self._p_changed = True # XXX: most probably not needed.
        return

    def _getNewRandomNum(self, num=1):
        """Create a set of ``num`` random numbers of 10 digits each.

        The number is returned as string.
        """
        curr = 1
        while curr <= num:
            pin = ''
            for x in range(10):
                pin += str(random().randint(0, 9))
            if not '%s-%s-%s' % (self.prefix, self.num, pin) in self._acids:
                curr += 1
                yield pin
            # PIN already in use

    def _getStoragePath(self):
        """Get the directory, where we store all batch-related CSV files.
        """
        site = grok.getSite()
        storagepath = site['datacenter'].storage
        ac_storage = os.path.join(storagepath, 'accesscodes')
        if not os.path.exists(ac_storage):
            os.mkdir(ac_storage)
        return ac_storage

    def entries(self):
        """Get all entries of this batch as generator.
        """
        for x in self._entries:
            yield x
            
    def getAccessCode(self, ac_id):
        """Get the AccessCode with ID ``ac_id`` or ``KeyError``.
        """
        return self._entries[self._acids[ac_id]]

    def addAccessCode(self, num, pin):
        """Add an access-code.
        """
        ac = AccessCode(num, pin)
        ac.__parent__ = self
        self._entries.append(ac)
        self._acids.update({ac.representation: num})
        return

    def invalidate(self, ac_id, student_id=None):
        """Invalidate the AC with ID ``ac_id``.
        """
        num = self._acids[ac_id]
        ac = self.getAccessCode(ac_id)
        ac._invalidation_date = datetime.now()
        ac.student_id = student_id
        self.invalidated_num += 1

    def createCSVLogFile(self):
        """Create a CSV file with data in batch.

        Data will not contain invalidation date nor student ids.  File
        will be created in ``accesscodes`` subdir of data center
        storage path.

        Returns name of created file.
        """
        date = self.creation_date.strftime('%Y_%m_%d_%H_%M_%S')
        ac_storage = self._getStoragePath()
        csv_path = os.path.join(
            ac_storage, '%s-%s-%s-%s.csv' % (
                self.prefix, self.num, date, self.creator)
            )
        writer = csv.writer(open(csv_path, 'w'), quoting=csv.QUOTE_ALL)
        writer.writerow(['serial', 'ac', 'cost'])
        writer.writerow([self.prefix, str(self.num), "%0.2f" % self.cost])

        for value in self._entries:
            writer.writerow(
                [str(value.batch_serial), str(value.representation)]
                )
        site = grok.getSite()
        logger = site.logger
        logger.info(
            "Created batch %s-%s" % (self.prefix, self.num))
        logger.info(
            "Written batch CSV to %s" % csv_path)
        return os.path.basename(csv_path)

    def archive(self):
        """Create a CSV file for archive.
        """
        ac_storage = self._getStoragePath()
        now = datetime.now()
        timestamp = now.strftime('%Y_%m_%d_%H_%M_%S')
        csv_path = os.path.join(
            ac_storage, '%s-%s_archive-%s-%s.csv' % (
                self.prefix, self.num, timestamp, self.creator)
            )
        writer = csv.writer(open(csv_path, 'w'), quoting=csv.QUOTE_ALL)
        writer.writerow(['prefix', 'serial', 'ac', 'student', 'date'])
        writer.writerow([self.prefix, '%0.2f' % self.cost, str(self.num),
                         str(self.entry_num)])
        for value in self._entries:
            date = ''
            if value.invalidation_date is not None:
                date = value.invalidation_date.strftime(
                    '%Y-%m-%d-%H-%M-%S')
            writer.writerow([
                    self.prefix, value.batch_serial, value.representation,
                    value.student_id, date
                    ])
        return os.path.basename(csv_path)

class AccessCodeBatchContainer(grok.Container):
    grok.implements(IAccessCodeBatchContainer)

    def _getStoragePath(self):
        """Get the directory, where batch import files are stored.
        """
        site = grok.getSite()
        storagepath = site['datacenter'].storage
        ac_storage = os.path.join(storagepath, 'accesscodes')
        import_path = os.path.join(ac_storage, 'imports')
        if not os.path.exists(import_path):
            os.mkdir(import_path)
        return import_path

    def addBatch(self, batch):
        """Add a batch.
        """
        batch.num = self.getNum(batch.prefix)
        key = "%s-%s" % (batch.prefix, batch.num)
        self[key] = batch
        self._p_changed = True

    def createBatch(self, creation_date, creator, batch_prefix, cost,
                    entry_num):
        """Create and add a batch.
        """
        batch_num = self.getNum(batch_prefix)
        batch = AccessCodeBatch(creation_date, creator, batch_prefix,
                                cost, entry_num, num=batch_num)
        self.addBatch(batch)
        return batch
        
    def getNum(self, prefix):
        """Get next unused num for given prefix.
        """
        num = 1
        while self.get('%s-%s' % (prefix, num), None) is not None:
            num += 1
        return num

    def getImportFiles(self):
        """Return a generator with basenames of available import files.
        """
        path = self._getStoragePath()
        for filename in sorted(os.listdir(path)):
            yield filename
    
    def reimport(self, filename, creator=u'UNKNOWN'):
        """Reimport a batch given in CSV file.

        CSV file must be of format as generated by createCSVLogFile
        method.
        """
        path = os.path.join(self._getStoragePath(), filename)
        reader = csv.DictReader(open(path, 'rb'), quoting=csv.QUOTE_ALL)
        entry = reader.next()
        cost = float(entry['cost'])
        num = int(entry['ac'])
        batch_name = '%s-%s' % (entry['serial'], num)
        if batch_name in self.keys():
            raise KeyError('Batch already exists: %s' % batch_name)
        batch = AccessCodeBatch(
            datetime.now(), creator, entry['serial'], cost, 0, num=num)
        num_entries = 0
        for row in reader:
            pin = row['ac']
            serial = int(row['serial'])
            rand_num = pin.rsplit('-', 1)[-1]
            batch.addAccessCode(serial, rand_num)
            num_entries += 1
        batch.entry_num = num_entries
        self[batch_name] = batch
        batch.createCSVLogFile()
        return
    
class AccessCodePlugin(grok.GlobalUtility):
    grok.name('accesscodes')
    grok.implements(IWAeUPSIRPPluggable)

    def setup(self, site, name, logger):
        site['accesscodes'] = AccessCodeBatchContainer()
        logger.info('Installed container for access code batches.')
        return

    def update(self, site, name, logger):
        if not 'accesscodes' in site.keys():
            logger.info('Updating site at %s. Installing access codes.' % (
                    site,))
            self.setup(site, name, logger)
        else:
            logger.info(
                'AccessCodePlugin: Updating site at %s: Nothing to do.' % (
                    site, ))
        return