from django.db import models

# Create your models here.

"""
Recipe's creation workflow :

1. Create recipe with required info, optional preparation
2. Create recipe's list of ingredients
   a. Create new ingredients instances
   b. Create IngredientWithAmount instances
3. Add preparation steps if necessary

"""


class Recipe(models.Model):
    name = models.CharField(max_length=512)
    category = models.CharField(
        max_length=2,
        choices=(
            ('0', 'Petit-déjeuner'),
            ('1', 'Entrée'),
            ('2', 'Plat'),
            ('3', 'Dessert'),
        ))
    ingredients = models.ManyToManyField(
        'Ingredient',
        through='IngredientWithAmount'
    )

    def __str__(self):
        return "{}".format(self.name)


class Ingredient(models.Model):
    name = models.CharField(max_length=256)

    def __str__(self):
        return "{}".format(self.name)


class IngredientWithAmount(models.Model):
    """ A recipe-ingredient relation associated with amounts
    """

    recipe = models.ForeignKey(
        'Recipe',
        models.CASCADE)
    ingredient = models.ForeignKey(
        'Ingredient',
        models.CASCADE )
    amount = models.DecimalField(
        max_digits=6,
        decimal_places=2,
    )
    unit = models.CharField(
        max_length=2,
        choices=(
            ('gr', 'Grammes'),
            ('u', 'Units'),
            ('l', 'Litres'),
        ))

    def __repr__(self):
        return "<{}>".format(self.display())

    def display(self):
        """ Print info in a human friendly way.

        * Correct grammar
        * Apropriate units according to amount
        """
        # Note: amount has a .is_integer() method :)
        amount = self.amount
        name = self.ingredient.name.lower()
        particule = ""
        unit = ""
        if self.unit == 'u':
            integer = int(amount)
            fraction = amount - integer
            # Print subfractions of one as ratio
            if fraction: #TODO: if is not integer...
                fraction = "{}/{}".format(
                    *amount.as_integer_ratio()
                )
            else:
                fraction = ""
            if integer:
                # Plural
                if integer >= 2:
                    name += "s"
                integer = str(integer)
            else:
                integer = ""
            amount = "{}{}".format(integer, fraction)
        else:
            particule = "de "
            unit = self.unit

        return "{}{} {}{}".format(
            amount, unit, particule, name
        )