from django.db import models
from django.db.models import CASCADE, SET_NULL, PROTECT
from django.utils.translation import ugettext_lazy as _
from django.core.urlresolvers import reverse
import exceptions

# TODO: jobs and events model TBD
# TODO: reporting model TBD

JOB_TYPE_CHOICES = [
    ('run', _('Run')),
    ('check', _('Check')),
]

class CommonModel(models.Model):
    ''' 
    common model for all object types that have these standard fields 
    '''

    class Meta:
        abstract = True

    name          = models.CharField(max_length=512, unique=True)
    description   = models.TextField(blank=True, default='')
    created_by    = models.ForeignKey('auth.User', on_delete=SET_NULL, null=True, related_name='%s(class)s_created') # not blank=False on purpose for admin!
    creation_date = models.DateField(auto_now_add=True)
    tags          = models.ManyToManyField('Tag', related_name='%(class)s_by_tag', blank=True) 
    audit_trail   = models.ManyToManyField('AuditTrail', related_name='%(class)s_by_audit_trail', blank=True)
    active        = models.BooleanField(default=True)

    def __unicode__(self):
        return unicode(self.name)

    @classmethod 
    def can_user_administrate(cls, user, obj):
        # FIXME: do we want a seperate method to override put?  This is kind of general purpose
        raise exceptions.NotImplementedError()

    @classmethod 
    def can_user_delete(cls, user, obj):
        raise exceptions.NotImplementedError()

    @classmethod 
    def can_user_read(cls, user, obj):
        raise exceptions.NotImplementedError()

    @classmethod
    def can_user_add(cls, user):
        return user.is_superuser

    @classmethod
    def can_user_attach(cls, user, obj, sub_obj, relationship):
        ''' whether you can add sub_obj to obj using the relationship type in a subobject view '''
        if relationship in [ 'projects', 'admins', 'users' ]:
            if not sub_obj.can_user_read(user, sub_obj):
                return False
            rc = cls.can_user_administrate(user, obj)
            return rc

        raise Exception("unknown relationship type: %s" % relationship)
 
    @classmethod
    def can_user_unattach(cls, user, obj, sub_obj, relationship):
        return cls.can_user_administrate(user, obj)
 
class Tag(models.Model):
    ''' 
    any type of object can be given a search tag 
    '''
    
    class Meta:
        app_label = 'main'

    name = models.CharField(max_length=512)

    def __unicode__(self):
        return unicode(self.name)

    def get_absolute_url(self):
        import lib.urls
        return reverse(lib.urls.views_TagsDetail, args=(self.pk,))
 
class AuditTrail(CommonModel):
    ''' 
    changing any object records the change 
    '''
    
    class Meta:
        app_label = 'main'
 
    resource_type = models.CharField(max_length=64)
    modified_by   = models.ForeignKey('auth.User', on_delete=SET_NULL, null=True, blank=True)
    delta         = models.TextField() # FIXME: switch to JSONField
    detail        = models.TextField()
    comment       = models.TextField()

    # FIXME: this looks like this should be a ManyToMany
    tag           = models.ForeignKey('Tag', on_delete=SET_NULL, null=True, blank=True)

class Organization(CommonModel):
    ''' 
    organizations are the basic unit of multi-tenancy divisions 
    '''    
    
    class Meta:
        app_label = 'main'

    users    = models.ManyToManyField('auth.User', blank=True, related_name='organizations')
    admins   = models.ManyToManyField('auth.User', blank=True, related_name='admin_of_organizations')
    projects = models.ManyToManyField('Project', blank=True, related_name='organizations')

    def get_absolute_url(self):
        import lib.urls
        return reverse(lib.urls.views_OrganizationsDetail, args=(self.pk,))

    @classmethod 
    def can_user_delete(cls, user, obj):
        return user in obj.admins.all()

    @classmethod 
    def can_user_administrate(cls, user, obj):
        # FIXME: super user checks should be higher up so we don't have to repeat them
        if user.is_superuser:
            return True
        if obj.created_by == user:
            return True
        rc = user in obj.admins.all()
        return rc

    @classmethod 
    def can_user_read(cls, user, obj):
        return cls.can_user_administrate(user,obj) or user in obj.users.all()

    @classmethod 
    def can_user_delete(cls, user, obj):
        return cls.can_user_administrate(user, obj)

    def __unicode__(self):
        return self.name

class Inventory(CommonModel):
    ''' 
    an inventory source contains lists and hosts.
    '''
    
    class Meta:
        app_label = 'main'
        verbose_name_plural = _('inventories')
  
    organization = models.ForeignKey(Organization, null=True, on_delete=SET_NULL, related_name='inventories')    

    def __unicode__(self):
        if self.organization:
            return u'%s (%s)' % (self.name, self.organization)
        else:
            return self.name

class Host(CommonModel):
    '''
    A managed node
    '''
    
    class Meta:
        app_label = 'main'

    inventory = models.ForeignKey('Inventory', null=True, on_delete=SET_NULL, related_name='hosts')

    def __unicode__(self):
        return self.name

class Group(CommonModel):
    '''
    A group of managed nodes.  May belong to multiple groups
    '''
    
    class Meta:
        app_label = 'main'

    inventory = models.ForeignKey('Inventory', null=True, on_delete=SET_NULL, related_name='groups')
    parents   = models.ManyToManyField('self', symmetrical=False, related_name='children', blank=True)
    hosts     = models.ManyToManyField('Host', related_name='groups', blank=True)

    def __unicode__(self):
        return self.name

# FIXME: audit nullables
# FIXME: audit cascades

class VariableData(CommonModel):
    '''
    A set of host or group variables
    '''  
    
    class Meta:
        app_label = 'main'
        verbose_name_plural = _('variable data')

    host  = models.ForeignKey('Host', null=True, default=None, blank=True, on_delete=CASCADE, related_name='variable_data')
    group = models.ForeignKey('Group', null=True, default=None, blank=True, on_delete=CASCADE, related_name='variable_data')
    data  = models.TextField() # FIXME: JsonField

    def __unicode__(self):
        return '%s = %s' % (self.name, self.data)

class Credential(CommonModel):
    '''
    A credential contains information about how to talk to a remote set of hosts
    Usually this is a SSH key location, and possibly an unlock password.
    If used with sudo, a sudo password should be set if required.
    '''
    
    class Meta:
        app_label = 'main'

    user            = models.ForeignKey('auth.User', null=True, default=None, blank=True, on_delete=SET_NULL, related_name='credentials')
    project         = models.ForeignKey('Project', null=True, default=None, blank=True, on_delete=SET_NULL, related_name='credentials')
    team            = models.ForeignKey('Team', null=True, default=None, blank=True, on_delete=SET_NULL, related_name='credentials')

    ssh_key_path    = models.CharField(blank=True, default='', max_length=4096)
    ssh_key_data    = models.TextField(blank=True, default='') # later
    ssh_key_unlock  = models.CharField(blank=True, default='', max_length=1024)
    ssh_password    = models.CharField(blank=True, default='', max_length=1024)
    sudo_password   = models.CharField(blank=True, default='', max_length=1024)
    

class Team(CommonModel):
    '''
    A team is a group of users that work on common projects.
    '''
    
    class Meta:
        app_label = 'main'
    
    projects        = models.ManyToManyField('Project', blank=True, related_name='teams')
    users           = models.ManyToManyField('auth.User', blank=True, related_name='teams')
    organization    = models.ManyToManyField('Organization', related_name='teams')

class Project(CommonModel):
    '''  
    A project represents a playbook git repo that can access a set of inventories
    '''   
    
    inventories      = models.ManyToManyField('Inventory', blank=True, related_name='projects')
    local_repository = models.CharField(max_length=1024)
    scm_type         = models.CharField(max_length=64)
    default_playbook = models.CharField(max_length=1024)

    def get_absolute_url(self):
        import lib.urls
        return reverse(lib.urls.views_ProjectsDetail, args=(self.pk,))

    @classmethod 
    def can_user_administrate(cls, user, obj):
        if user.is_superuser:
            return True
        if obj.created_by == user:
            return True
        organizations = Organization.objects.filter(admins__in = [ user ], projects__in = [ obj ])
        for org in organizations:
            if org in project.organizations():
                return True
        return False

    @classmethod
    def can_user_read(cls, user, obj):
        if cls.can_user_administrate(user,obj):
            return True
        # and also if I happen to be on a team inside the project
        # FIXME: add this too
        return False


class Permission(CommonModel):
    '''
    A permission allows a user, project, or team to be able to use an inventory source.
    '''
    
    class Meta:
        app_label = 'main'

    user            = models.ForeignKey('auth.User', null=True, on_delete=SET_NULL, blank=True, related_name='permissions')
    project         = models.ForeignKey('Project', null=True, on_delete=SET_NULL, blank=True, related_name='permissions')
    team            = models.ForeignKey('Team', null=True, on_delete=SET_NULL, blank=True, related_name='permissions')
    job_type        = models.CharField(max_length=64, choices=JOB_TYPE_CHOICES)

# TODO: other job types (later)

class LaunchJob(CommonModel):
    ''' 
    a launch job is a request to apply a project to an inventory source with a given credential 
    '''
    
    class Meta:
        app_label = 'main'

    inventory      = models.ForeignKey('Inventory', on_delete=SET_NULL, null=True, default=None, blank=True, related_name='launch_jobs')
    credential     = models.ForeignKey('Credential', on_delete=SET_NULL, null=True, default=None, blank=True, related_name='launch_jobs')
    project        = models.ForeignKey('Project', on_delete=SET_NULL, null=True, default=None, blank=True, related_name='launch_jobs')
    user           = models.ForeignKey('auth.User', on_delete=SET_NULL, null=True, default=None, blank=True, related_name='launch_jobs')
    job_type       = models.CharField(max_length=64, choices=JOB_TYPE_CHOICES)

    def start(self):
        from lib.main.tasks import run_launch_job
        return run_launch_job.delay(self.pk)

    # project has one default playbook but really should have a list of playbooks and flags ...
    
    
    # ENOUGH_TO_RUN_DJANGO=foo ACOM_INVENTORY_ID=<pk> ansible-playbook <path to project selected playbook.yml> -i ansible-commander-inventory.py 
    #                                                                            ^-- this is a hard coded path
    # ssh-agent bash
    # ssh-add ... < key entry
    #
    # inventory script I can write, and will use ACOM_INVENTORY_ID
    # 
    #
    # playbook in source control is already on the disk 
    
    # job_type:
    #   run, check -- enough for now, more initially
    #      if check, add "--check" to parameters

    # we'll extend ansible core to have callback context like
    #    self.context.playbook
    #    self.context.runner
    #    and the callback will read the environment for ACOM_CELERY_JOB_ID or similar
    #    and log tons into the database
 
    # we'll also log stdout/stderr somewhere for debugging

    # the ansible commander setup instructions will include installing the database logging callback
    # inventory script is going to need some way to load Django models
    #    it is documented on ansible.cc under API docs and takes two parameters
    #    --list
    #    -- host <hostname>

    # posting the LaunchJob should return some type of resource that we can check for status
    # that all the log data will use as a Foreign Key

# TODO: Events

class LaunchJobStatus(CommonModel):
    
    class Meta:
        app_label = 'main'
        verbose_name_plural = _('launch job statuses')

    launch_job     = models.ForeignKey('LaunchJob', null=True, on_delete=SET_NULL, related_name='launch_job_statuses')
    status         = models.IntegerField()
    result_data    = models.TextField()
     

# TODO: reporting (MPD)