import datetime
from peewee import *

DATABASE = 'budget.db'
instance = SqliteDatabase(DATABASE, pragmas=[('foreign_keys', 'on')])

def create_tables():
    """Helper function to create database tables. Should be called manually."""
    with instance:
        instance.create_tables([User, TransactionCategory, Transaction, Source])
    
    # Make my user.
    instance.connect()
    User.create(username='ciphercules')
    instance.close()

def add_default_categories():
    categories = [
        {"food": ["snacks", "fast_food", "groceries", "restaurant"]},
        {"clothing": []},
        {"event": ["event_food", "birthday", "movie_theater"]},
        {"finance": ["interest"]},
        {"hobby": ["gym", "game_development", "projects", "education"]},
        {"home_improvement": []},
        {"pet": ["health", "dog_food"]},
        {"media": ["book", "music", "television", "video_game"]},
        {"health": ["medicine"]},
        {"transit": ["car_insurance", "car_registration", "gas", "parking", "taxi", "car_maintenance"]},
        {"utilities": ["electricity", "gas", "laundry", "cell_phone", "trash", "water"]},
        {"rent": []},
    ]

    instance.connect()
    with instance.atomic():
        for parent, children in categories.items():
            parent_db = TransactionCategory.create(name=parent)
            for child in children:
                TransactionCategory.create(name=child, parent=parent_db)

class BaseModel(Model):
    class Meta:
        database = instance

class User(BaseModel):
    username = CharField(unique=True, primary_key=True)

class TransactionCategory(BaseModel):
    primary_key = AutoField(primary_key=True)
    name = CharField(unique=True)
    parent = ForeignKeyField('self', null=True, backref='children')

class Source(BaseModel):
    filename=CharField(unique=True, primary_key=True)
    type = IntegerField()
    created_date = DateTimeField(default=datetime.datetime.now)
    user = ForeignKeyField(User, backref='transactions')

class Transaction(BaseModel):
    # Metadata
    primary_key = AutoField(primary_key=True)
    source = ForeignKeyField(Source, backref='transactions')
    created_date = DateTimeField(default=datetime.datetime.now)
    user = ForeignKeyField(User, backref='transactions')

    # Real data
    transaction_date = DateTimeField()
    description = CharField()
    amount = FloatField()
    subcategory = ForeignKeyField(TransactionCategory, backref='+', null=True)