"""A LatentSlave that uses EC2 to instantiate the slaves on demand.

Tested with Python boto 1.5c
"""

# Portions copyright Canonical Ltd. 2009

import cStringIO
import os
import re
import time
import urllib

import boto
import boto.exception
from twisted.internet import defer, threads
from twisted.python import log

from buildbot.buildslave import AbstractLatentBuildSlave
from buildbot import interfaces

PENDING = 'pending'
RUNNING = 'running'
SHUTTINGDOWN = 'shutting-down'
TERMINATED = 'terminated'

class EC2LatentBuildSlave(AbstractLatentBuildSlave):

    instance = image = None
    _poll_resolution = 5 # hook point for tests

    def __init__(self, name, password, instance_type, ami=None,
                 valid_ami_owners=None, valid_ami_location_regex=None,
                 elastic_ip=None, identifier=None, secret_identifier=None,
                 aws_id_file_path=None, user_data=None,
                 keypair_name='latent_buildbot_slave',
                 security_name='latent_buildbot_slave',
                 max_builds=None, notify_on_missing=[], missing_timeout=60*20,
                 build_wait_timeout=60*10, properties={}):
        AbstractLatentBuildSlave.__init__(
            self, name, password, max_builds, notify_on_missing,
            missing_timeout, build_wait_timeout, properties)
        if not ((ami is not None) ^
                (valid_ami_owners is not None or
                 valid_ami_location_regex is not None)):
            raise ValueError(
                'You must provide either a specific ami, or one or both of '
                'valid_ami_location_regex and valid_ami_owners')
        self.ami = ami
        if valid_ami_owners is not None:
            if isinstance(valid_ami_owners, (int, long)):
                valid_ami_owners = (valid_ami_owners,)
            else:
                for element in valid_ami_owners:
                    if not isinstance(element, (int, long)):
                        raise ValueError(
                            'valid_ami_owners should be int or iterable '
                            'of ints', element)
        if valid_ami_location_regex is not None:
            if not isinstance(valid_ami_location_regex, basestring):
                raise ValueError(
                    'valid_ami_location_regex should be a string')
            else:
                # verify that regex will compile
                re.compile(valid_ami_location_regex)
        self.valid_ami_owners = valid_ami_owners
        self.valid_ami_location_regex = valid_ami_location_regex
        self.instance_type = instance_type
        self.keypair_name = keypair_name
        self.security_name = security_name
        self.user_data = user_data
        if identifier is None:
            assert secret_identifier is None, (
                'supply both or neither of identifier, secret_identifier')
            if aws_id_file_path is None:
                home = os.environ['HOME']
                aws_id_file_path = os.path.join(home, '.ec2', 'aws_id')
            if not os.path.exists(aws_id_file_path):
                raise ValueError(
                    "Please supply your AWS access key identifier and secret "
                    "access key identifier either when instantiating this %s "
                    "or in the %s file (on two lines).\n" %
                    (self.__class__.__name__, aws_id_file_path))
            aws_file = open(aws_id_file_path, 'r')
            try:
                identifier = aws_file.readline().strip()
                secret_identifier = aws_file.readline().strip()
            finally:
                aws_file.close()
        else:
            assert aws_id_file_path is None, \
                    'if you supply the identifier and secret_identifier, ' \
                    'do not specify the aws_id_file_path'
            assert secret_identifier is not None, \
                    'supply both or neither of identifier, secret_identifier'
        # Make the EC2 connection.
        self.conn = boto.connect_ec2(identifier, secret_identifier)

        # Make a keypair
        #
        # We currently discard the keypair data because we don't need it.
        # If we do need it in the future, we will always recreate the keypairs
        # because there is no way to
        # programmatically retrieve the private key component, unless we
        # generate it and store it on the filesystem, which is an unnecessary
        # usage requirement.
        try:
            key_pair = self.conn.get_all_key_pairs(keypair_name)[0]
            # key_pair.delete() # would be used to recreate
        except boto.exception.EC2ResponseError, e:
            if e.code != 'InvalidKeyPair.NotFound':
                if e.code == 'AuthFailure':
                    print ('POSSIBLE CAUSES OF ERROR:\n'
                           '  Did you sign up for EC2?\n'
                           '  Did you put a credit card number in your AWS '
                           'account?\n'
                           'Please doublecheck before reporting a problem.\n')
                raise
            # make one; we would always do this, and stash the result, if we
            # needed the key (for instance, to SSH to the box).  We'd then
            # use paramiko to use the key to connect.
            self.conn.create_key_pair(keypair_name)

        # create security group
        try:
            group = self.conn.get_all_security_groups(security_name)[0]
        except boto.exception.EC2ResponseError, e:
            if e.code == 'InvalidGroup.NotFound':
                self.security_group = self.conn.create_security_group(
                    security_name,
                    'Authorization to access the buildbot instance.')
                # Authorize the master as necessary
                # TODO this is where we'd open the hole to do the reverse pb
                # connect to the buildbot
                # ip = urllib.urlopen(
                #     'http://checkip.amazonaws.com').read().strip()
                # self.security_group.authorize('tcp', 22, 22, '%s/32' % ip)
                # self.security_group.authorize('tcp', 80, 80, '%s/32' % ip)
            else:
                raise

        # get the image
        if self.ami is not None:
            self.image = self.conn.get_image(self.ami)
        else:
            # verify we have access to at least one acceptable image
            discard = self.get_image()

        # get the specified elastic IP, if any
        if elastic_ip is not None:
            elastic_ip = self.conn.get_all_addresses([elastic_ip])[0]
        self.elastic_ip = elastic_ip

    def get_image(self):
        if self.image is not None:
            return self.image
        if self.valid_ami_location_regex:
            level = 0
            options = []
            get_match = re.compile(self.valid_ami_location_regex).match
            for image in self.conn.get_all_images(
                owners=self.valid_ami_owners):
                # gather sorting data
                match = get_match(image.location)
                if match:
                    alpha_sort = int_sort = None
                    if level < 2:
                        try:
                            alpha_sort = match.group(1)
                        except IndexError:
                            level = 2
                        else:
                            if level == 0:
                                try:
                                    int_sort = int(alpha_sort)
                                except ValueError:
                                    level = 1
                    options.append([int_sort, alpha_sort,
                                    image.location, image.id, image])
            if level:
                log.msg('sorting images at level %d' % level)
                options = [candidate[level:] for candidate in options]
        else:
            options = [(image.location, image.id, image) for image
                       in self.conn.get_all_images(
                        owners=self.valid_ami_owners)]
        options.sort()
        log.msg('sorted images (last is chosen): %s' %
                (', '.join(
                    ['%s (%s)' % (candidate[-1].id, candidate[-1].location)
                    for candidate in options])))
        if not options:
            raise ValueError('no available images match constraints')
        return options[-1][-1]

    def dns(self):
        if self.instance is None:
            return None
        return self.instance.public_dns_name
    dns = property(dns)

    def start_instance(self):
        if self.instance is not None:
            raise ValueError('instance active')
        return threads.deferToThread(self._start_instance)

    def _start_instance(self):
        image = self.get_image()
        reservation = image.run(
            key_name=self.keypair_name, security_groups=[self.security_name],
            instance_type=self.instance_type, user_data=self.user_data)
        self.instance = reservation.instances[0]
        log.msg('%s %s starting instance %s' %
                (self.__class__.__name__, self.slavename, self.instance.id))
        duration = 0
        interval = self._poll_resolution
        while self.instance.state == PENDING:
            time.sleep(interval)
            duration += interval
            if duration % 60 == 0:
                log.msg('%s %s has waited %d minutes for instance %s' %
                        (self.__class__.__name__, self.slavename, duration//60,
                         self.instance.id))
            self.instance.update()
        if self.instance.state == RUNNING:
            self.output = self.instance.get_console_output()
            minutes = duration//60
            seconds = duration%60
            log.msg('%s %s instance %s started on %s '
                    'in about %d minutes %d seconds (%s)' %
                    (self.__class__.__name__, self.slavename,
                     self.instance.id, self.dns, minutes, seconds,
                     self.output.output))
            if self.elastic_ip is not None:
                self.instance.use_ip(self.elastic_ip)
                return [self.instance.id,
                        image.id,
                        '%02d:%02d:%02d' % (minutes//60, minutes%60, seconds)]
        else:
            log.msg('%s %s failed to start instance %s (%s)' %
                    (self.__class__.__name__, self.slavename,
                     self.instance.id, self.instance.state))
            raise interfaces.LatentBuildSlaveFailedToSubstantiate(
                self.instance.id, self.instance.state)

    def stop_instance(self, fast=False):
        if self.instance is None:
            # be gentle.  Something may just be trying to alert us that an
            # instance never attached, and it's because, somehow, we never
            # started.
            return defer.succeed(None)
        instance = self.instance
        self.output = self.instance = None
        return threads.deferToThread(
            self._stop_instance, instance, fast)

    def _stop_instance(self, instance, fast):
        if self.elastic_ip is not None:
            self.conn.disassociate_address(self.elastic_ip.public_ip)
        instance.update()
        if instance.state not in (SHUTTINGDOWN, TERMINATED):
            instance.stop()
            log.msg('%s %s terminating instance %s' %
                    (self.__class__.__name__, self.slavename, instance.id))
        duration = 0
        interval = self._poll_resolution
        if fast:
            goal = (SHUTTINGDOWN, TERMINATED)
            instance.update()
        else:
            goal = (TERMINATED,)
        while instance.state not in goal:
            time.sleep(interval)
            duration += interval
            if duration % 60 == 0:
                log.msg(
                    '%s %s has waited %d minutes for instance %s to end' %
                    (self.__class__.__name__, self.slavename, duration//60,
                     instance.id))
            instance.update()
        log.msg('%s %s instance %s %s '
                'after about %d minutes %d seconds' %
                (self.__class__.__name__, self.slavename,
                 instance.id, goal, duration//60, duration%60))
