from datetime import date, timedelta
import json

from django.db import models

from . import utils


def is_int(s):
    try:
        int(s)
        return True
    except ValueError:
        return False


class Section(models.Model):
    """ Filières """
    name = models.CharField(max_length=20, verbose_name='Nom')

    class Meta:
        verbose_name = "Filière"

    def __str__(self):
        return self.name


class Level(models.Model):
    name = models.CharField(max_length=10, verbose_name='Nom')

    class Meta:
        verbose_name = "Niveau"
        verbose_name_plural = "Niveaux"

    def __str__(self):
        return self.name

    def delta(self, diff):
        if diff == 0:
            return self
        try:
            return Level.objects.get(name=str(int(self.name)+diff))
        except Level.DoesNotExist:
            return None


class Klass(models.Model):
    name = models.CharField(max_length=10, verbose_name='Nom')
    section = models.ForeignKey(Section, verbose_name='Filière', on_delete=models.PROTECT)
    level = models.ForeignKey(Level, verbose_name='Niveau', on_delete=models.PROTECT)

    class Meta:
        verbose_name = "Classe"

    def __str__(self):
        return self.name


class Student(models.Model):
    ext_id = models.IntegerField(null=True, unique=True, verbose_name='ID externe')
    first_name = models.CharField(max_length=40, verbose_name='Prénom')
    last_name = models.CharField(max_length=40, verbose_name='Nom')
    birth_date = models.DateField(verbose_name='Date de naissance')
    street = models.CharField(max_length=150, blank=True, verbose_name='Rue')
    pcode = models.CharField(max_length=4, verbose_name='Code postal')
    city = models.CharField(max_length=40, verbose_name='Localité')
    tel = models.CharField(max_length=40, blank=True, verbose_name='Téléphone')
    mobile = models.CharField(max_length=40, blank=True, verbose_name='Portable')
    email = models.EmailField(verbose_name='Courriel', blank=True)
    klass = models.ForeignKey(Klass, verbose_name='Classe', blank=True, null=True,
        on_delete=models.SET_NULL)
    archived = models.BooleanField(default=False, verbose_name='Archivé')
    archived_text = models.TextField(blank=True)

    support_tabimport = True

    class Meta:
        verbose_name = "Étudiant"

    def __str__(self):
        return '%s %s' % (self.last_name, self.first_name)

    def save(self, **kwargs):
        if self.archived and not self.archived_text:
            # Fill archived_text with training data, JSON-formatted
            trainings = [
                tr.serialize() for tr in self.training_set.all().select_related('availability')
            ]
            self.archived_text = json.dumps(trainings)
        if self.archived_text and not self.archived:
            self.archived_text = ""
        super().save(**kwargs)

    def age_at(self, date_):
        """Return age of student at `date_` time, as a string."""
        age = (date.today() - self.birth_date) / timedelta(days=365.2425)
        age_y = int(age)
        age_m = int((age - age_y) * 12)
        return '%d ans%s' % (age_y, ' %d m.' % age_m if age_m > 0 else '')

    @classmethod
    def prepare_import(cls, values):
        ''' Hook for tabimport, before new object get created '''
        if 'klass' in values:
            try:
                k = Klass.objects.get(name=values['klass'])
            except Klass.DoesNotExist:
                raise Exception("La classe '%s' n'existe pas encore" % values['klass'])
            values['klass'] = k
        # See if postal code included in city, and split them
        if 'city' in values and is_int(values['city'][:4]):
            values['pcode'], _, values['city'] = values['city'].partition(' ')
        values['archived'] = False
        return values


class Referent(models.Model):
    first_name = models.CharField(max_length=40, verbose_name='Prénom')
    last_name = models.CharField(max_length=40, verbose_name='Nom')
    abrev = models.CharField(max_length=10, blank=True, verbose_name='Initiales')
    email = models.EmailField(blank=True, verbose_name='Courriel')
    archived = models.BooleanField(default=False, verbose_name='Archivé')

    support_tabimport = True

    class Meta:
        verbose_name = "Référent"
        ordering = ('last_name', 'first_name')

    def __str__(self):
        return '%s %s' % (self.last_name, self.first_name)


class Corporation(models.Model):
    ext_id = models.IntegerField(null=True, blank=True, verbose_name='ID externe')
    name = models.CharField(max_length=100, verbose_name='Nom', unique=True)
    short_name = models.CharField(max_length=40, blank=True, verbose_name='Nom court')
    parent = models.ForeignKey('self', null=True, blank=True, verbose_name='Institution mère',
        on_delete=models.SET_NULL)
    sector = models.CharField(max_length=40, blank=True, verbose_name='Secteur')
    typ = models.CharField(max_length=40, blank=True, verbose_name='Type de structure')
    street = models.CharField(max_length=100, blank=True, verbose_name='Rue')
    pcode = models.CharField(max_length=4, verbose_name='Code postal')
    city = models.CharField(max_length=40, verbose_name='Localité')
    tel = models.CharField(max_length=20, blank=True, verbose_name='Téléphone')
    email = models.EmailField(blank=True, verbose_name='Courriel')
    web = models.URLField(blank=True, verbose_name='Site Web')
    archived = models.BooleanField(default=False, verbose_name='Archivé')

    class Meta:
        verbose_name = "Institution"
        ordering = ('name',)

    def __str__(self):
        sect = ' (%s)' % self.sector if self.sector else ''
        return "%s%s, %s %s" % (self.name, sect, self.pcode, self.city)


class CorpContact(models.Model):
    corporation = models.ForeignKey(Corporation, verbose_name='Institution', on_delete=models.CASCADE)
    ext_id = models.IntegerField(null=True, blank=True, verbose_name='ID externe')
    is_main = models.BooleanField(default=False, verbose_name='Contact principal')
    always_cc = models.BooleanField(default=False, verbose_name='Toujours en copie')
    title = models.CharField(max_length=40, blank=True, verbose_name='Civilité')
    first_name = models.CharField(max_length=40, blank=True, verbose_name='Prénom')
    last_name = models.CharField(max_length=40, verbose_name='Nom')
    role = models.CharField(max_length=40, verbose_name='Fonction', blank=True)
    tel = models.CharField(max_length=20, blank=True, verbose_name='Téléphone')
    email = models.CharField(max_length=100, blank=True, verbose_name='Courriel')
    archived = models.BooleanField(default=False, verbose_name='Archivé')
    sections = models.ManyToManyField(Section, blank=True)

    class Meta:
        verbose_name = "Contact"

    def __str__(self):
        return '%s %s' % (self.last_name, self.first_name)


class Domain(models.Model):
    name = models.CharField(max_length=50, verbose_name='Nom')

    class Meta:
        verbose_name = "Domaine"
        ordering = ('name',)

    def __str__(self):
        return self.name


class Period(models.Model):
    """ Périodes de stages """
    title = models.CharField(max_length=150, verbose_name='Titre')
    section = models.ForeignKey(Section, verbose_name='Filière', on_delete=models.PROTECT)
    level = models.ForeignKey(Level, verbose_name='Niveau', on_delete=models.PROTECT)
    start_date = models.DateField(verbose_name='Date de début')
    end_date = models.DateField(verbose_name='Date de fin')

    class Meta:
        verbose_name = "Période de stage"
        ordering = ('-start_date',)

    def __str__(self):
        return '%s (%s)' % (self.dates, self.title)

    @property
    def dates(self):
        return '%s - %s' % (self.start_date, self.end_date)

    @property
    def school_year(self):
        return utils.school_year(self.start_date)

    @property
    def relative_level(self):
        """
        Return the level depending on current school year. For example, if the
        period is planned for next school year, level will be level - 1.
        """
        diff = (utils.school_year(self.start_date, as_tuple=True)[0] -
                utils.school_year(date.today(), as_tuple=True)[0])
        return self.level.delta(-diff)

    @property
    def weeks(self):
        """ Return the number of weeks of this period """
        return (self.end_date - self.start_date).days // 7


class Availability(models.Model):
    """ Disponibilités des institutions """
    corporation = models.ForeignKey(Corporation, verbose_name='Institution', on_delete=models.CASCADE)
    period = models.ForeignKey(Period, verbose_name='Période', on_delete=models.CASCADE)
    domain = models.ForeignKey(Domain, verbose_name='Domaine', on_delete=models.CASCADE)
    contact = models.ForeignKey(CorpContact, null=True, blank=True, verbose_name='Contact institution',
        on_delete=models.SET_NULL)
    priority = models.BooleanField('Prioritaire', default=False)
    comment = models.TextField(blank=True, verbose_name='Remarques')

    class Meta:
        verbose_name = "Disponibilité"

    def __str__(self):
        return '%s - %s (%s) - %s' % (self.period, self.corporation, self.domain, self.contact)

    @property
    def free(self):
        try:
            self.training
        except Training.DoesNotExist:
            return True
        return False


class Training(models.Model):
    """ Stages """
    student = models.ForeignKey(Student, verbose_name='Étudiant', on_delete=models.CASCADE)
    availability = models.OneToOneField(Availability, verbose_name='Disponibilité', on_delete=models.CASCADE)
    referent = models.ForeignKey(Referent, null=True, blank=True, verbose_name='Référent',
        on_delete=models.SET_NULL)
    comment = models.TextField(blank=True, verbose_name='Remarques')

    class Meta:
        verbose_name = "Stage"
        ordering = ("-availability__period",)

    def __str__(self):
        return '%s chez %s (%s)' % (self.student, self.availability.corporation, self.availability.period)

    def serialize(self):
        """
        Compute a summary of the training as a dict representation (for archiving purpose).
        """
        return {
            'period': str(self.availability.period),
            'corporation': str(self.availability.corporation),
            'referent': str(self.referent),
            'comment': self.comment,
            'contact': str(self.availability.contact),
            'comment_avail': self.availability.comment,
            'domain': str(self.availability.domain),
        }