from django.db import models


class InvalidData(Exception):
    ''' Thrown when the DB contains invalid data, and cannot perform
    something '''

    def __init__(self, what):
        self.what = what
        super(InvalidData, self).__init__()

    def __str__(self):
        return self.what


class Keyword(models.Model):
    ''' A keyword/search term '''

    text = models.CharField(max_length=256)

    def __str__(self):
        return self.text


class Webpage(models.Model):
    url = models.URLField()

    def __str__(self):
        return self.url


class Website(models.Model):
    ''' A website usually visited '''

    name = models.CharField(max_length=256)
    url = models.URLField()
    keywords = models.ManyToManyField(Keyword)
    notable_pages = models.ManyToManyField(Webpage)

    def __str__(self):
        return self.name


class Place(models.Model):
    ''' A real-life place '''

    name = models.CharField(max_length=256)
    address = models.CharField(max_length=512)
    lat = models.FloatField('Latitude', blank=True)
    lon = models.FloatField('Longitude', blank=True)

    def __str__(self):
        return self.name


class Event(models.Model):
    ''' A real-life event (protests, meeting, ...) '''

    name = models.CharField(max_length=256)
    date = models.DateTimeField()
    place = models.ForeignKey(Place, on_delete=models.CASCADE)

    def __str__(self):
        return self.name


class BrowserFingerprint(models.Model):
    ''' A browser fingerprint, containing things like a user agent '''

    description = models.CharField(max_length=256)
    useragent = models.CharField(max_length=256)
    appname = models.CharField(max_length=256)
    appversion = models.CharField(max_length=256)
    platform = models.CharField(max_length=256)
    vendor = models.CharField(max_length=256)
    vendorsub = models.CharField(max_length=256)
    buildID = models.CharField(max_length=256)
    oscpu = models.CharField(max_length=256)
    accept_encoding = models.CharField(max_length=256)
    accept_default = models.CharField(max_length=256)
    accept_lang = models.CharField(max_length=256)
    pixeldepth = models.IntegerField()
    colordepth = models.IntegerField()
    screens = models.CharField(max_length=256)

    def __str__(self):
        return self.description


class SearchEngine(models.Model):
    ''' A search engine, and all the data needed to use it '''

    name = models.CharField(max_length=256)
    url = models.URLField()
    query_pattern = models.CharField(max_length=256)  # This field is the
    # query pattern. It should contain a `{}`, which, when substituted with a
    # search term (using `.format()`), must yield a URL that can be resolved to
    # perform the search

    def __str__(self):
        return self.name

    def search_url(self, search_term):
        ''' Obtain a url to search `search_term` with this search engine '''
        pattern = str(self.query_pattern)
        if '{}' not in pattern:
            raise InvalidData("Search engine {}: bad pattern".format(self))
        return str(self.query_pattern).format(search_term)


class Interest(models.Model):
    ''' A class of interests '''

    name = models.CharField(max_length=256)

    keywords = models.ManyToManyField(Keyword)
    places = models.ManyToManyField(Place)
    websites = models.ManyToManyField(Website)
    events = models.ManyToManyField(Event)

    def __str__(self):
        return self.name


class Profile(models.Model):
    ''' Represents a user profile, containing a few data to make their requests
    consistent '''

    nick = models.CharField(max_length=64,
                            help_text="The user's online identity")
    first_name = models.CharField(max_length=64)
    last_name = models.CharField(max_length=64)
    email = models.EmailField()
    uses_urls = models.BooleanField(
        help_text=('Does the user usually go to a given website using its url '
                   'or searching it in a search engine?'))
    interests = models.ManyToManyField(Interest)
    search_engine = models.ForeignKey(SearchEngine,
                                      on_delete=models.CASCADE)
    browser_fingerprint = models.ForeignKey(BrowserFingerprint,
                                            on_delete=models.CASCADE)