from docker.client import APIError
import logging
import re
import os
import sys
from .container import Container

log = logging.getLogger(__name__)


class BuildError(Exception):
    pass


class Service(object):
    def __init__(self, name, client=None, project='default', links=[], **options):
        if not re.match('^[a-zA-Z0-9]+$', name):
            raise ValueError('Invalid name: %s' % name)
        if not re.match('^[a-zA-Z0-9]+$', project):
            raise ValueError('Invalid project: %s' % project)
        if 'image' in options and 'build' in options:
            raise ValueError('Service %s has both an image and build path specified. A service can either be built to image or use an existing image, not both.' % name)

        self.name = name
        self.client = client
        self.project = project
        self.links = links or []
        self.options = options

    def containers(self, stopped=False, one_off=False):
        l = []
        for container in self.client.containers(all=stopped):
            name = get_container_name(container)
            if not is_valid_name(name, one_off):
                continue
            project, name, number = parse_name(name)
            if project == self.project and name == self.name:
                l.append(Container.from_ps(self.client, container))
        return l

    def start(self):
        if len(self.containers()) == 0:
            return self.start_container()

    def stop(self):
        self.scale(0)

    def scale(self, num):
        while len(self.containers()) < num:
            self.start_container()

        while len(self.containers()) > num:
            self.stop_container()

    def create_container(self, one_off=False, **override_options):
        """
        Create a container for this service. If the image doesn't exist, attempt to pull
        it.
        """
        container_options = self._get_container_options(override_options, one_off=one_off)
        try:
            return Container.create(self.client, **container_options)
        except APIError, e:
            if e.response.status_code == 404 and e.explanation and 'No such image' in e.explanation:
                log.info('Pulling image %s...' % container_options['image'])
                self.client.pull(container_options['image'])
                return Container.create(self.client, **container_options)
            raise

    def start_container(self, container=None, **override_options):
        if container is None:
            container = self.create_container(**override_options)

        options = self.options.copy()
        options.update(override_options)

        port_bindings = {}

        if options.get('ports', None) is not None:
            for port in options['ports']:
                port = unicode(port)
                if ':' in port:
                    internal_port, external_port = port.split(':', 1)
                    port_bindings[int(internal_port)] = int(external_port)
                else:
                    port_bindings[int(port)] = None

        volume_bindings = {}

        if options.get('volumes', None) is not None:
            for volume in options['volumes']:
                external_dir, internal_dir = volume.split(':')
                volume_bindings[os.path.abspath(external_dir)] = internal_dir

        container.start(
            links=self._get_links(),
            port_bindings=port_bindings,
            binds=volume_bindings,
        )
        return container

    def stop_container(self):
        container = self.containers()[-1]
        container.kill()
        container.remove()

    def next_container_name(self, one_off=False):
        bits = [self.project, self.name]
        if one_off:
            bits.append('run')
        return '_'.join(bits + [unicode(self.next_container_number())])

    def next_container_number(self):
        numbers = [parse_name(c.name)[2] for c in self.containers(stopped=True)]

        if len(numbers) == 0:
            return 1
        else:
            return max(numbers) + 1

    def _get_links(self):
        links = {}
        for service in self.links:
            for container in service.containers():
                links[container.name[1:]] = container.name[1:]
        return links

    def _get_container_options(self, override_options, one_off=False):
        keys = ['image', 'command', 'hostname', 'user', 'detach', 'stdin_open', 'tty', 'mem_limit', 'ports', 'environment', 'dns', 'volumes', 'volumes_from']
        container_options = dict((k, self.options[k]) for k in keys if k in self.options)
        container_options.update(override_options)

        container_options['name'] = self.next_container_name(one_off)

        if 'ports' in container_options:
            container_options['ports'] = [unicode(p).split(':')[0] for p in container_options['ports']]

        if 'volumes' in container_options:
            container_options['volumes'] = dict((v.split(':')[1], {}) for v in container_options['volumes'])

        if 'build' in self.options:
            container_options['image'] = self.build()

        return container_options

    def build(self):
        log.info('Building %s...' % self.name)

        build_output = self.client.build(self.options['build'], stream=True)

        image_id = None

        for line in build_output:
            if line:
                match = re.search(r'Successfully built ([0-9a-f]+)', line)
                if match:
                    image_id = match.group(1)
            sys.stdout.write(line)

        if image_id is None:
            raise BuildError()

        return image_id


NAME_RE = re.compile(r'^([^_]+)_([^_]+)_(run_)?(\d+)$')


def is_valid_name(name, one_off=False):
    match = NAME_RE.match(name)
    if match is None:
        return False
    if one_off:
        return match.group(3) == 'run_'
    else:
        return match.group(3) is None


def parse_name(name, one_off=False):
    match = NAME_RE.match(name)
    (project, service_name, _, suffix) = match.groups()
    return (project, service_name, int(suffix))


def get_container_name(container):
    # inspect
    if 'Name' in container:
        return container['Name']
    # ps
    for name in container['Names']:
        if len(name.split('/')) == 2:
            return name[1:]