1 files changed, 205 insertions, 0 deletions
diff --git a/kosten/app/model.py b/kosten/app/model.py
new file mode 100644
index 0000000..4663685
--- /dev/null
+++ b/kosten/app/model.py
@@ -0,0 +1,205 @@
+from flask_sqlalchemy import SQLAlchemy
+from sqlalchemy import sql
+from sqlalchemy.ext.declarative import declared_attr
+
+import datetime
+import decimal
+from functools import partial
+from collections import namedtuple
+
+from . import app
+
+db = SQLAlchemy(app)
+
+__all__ = ['db', \
+        'Category', 'SingleExpense', 'ConstExpense', \
+        'CatExpense', 'MonthExpense']
+
+Column = db.Column
+ReqColumn = partial(Column, nullable = False)
+ExpNum = db.Numeric(scale = 2, precision = 10)
+
+def to_exp(d):
+    """Converts decimal into expense"""
+    return d.quantize(decimal.Decimal('.01'), rounding = decimal.ROUND_UP)
+
+#
+# Database Entities
+#
+class Model (db.Model):
+    """Abstract base class for all models.
+    Adds an id PK and several convenience accessors.
+    """
+
+    __abstract__ = True
+
+    id = Column(db.Integer, primary_key=True)
+
+    @declared_attr
+    def __tablename__ (cls):
+        return cls.__name__.lower()
+
+    @classmethod
+    def get_by (cls, *args, **kwargs):
+        return cls.query.filter_by(*args, **kwargs).first()
+
+    @classmethod
+    def get_by_or_404 (cls, *args, **kwargs):
+        return cls.query.filter_by(*args, **kwargs).first_or_404()
+
+    @classmethod
+    def get (cls, *args, **kwargs):
+        return cls.query.get(*args, **kwargs)
+
+    @classmethod
+    def get_or_404 (cls, *args, **kwargs):
+        return cls.query.get_or_404(*args, **kwargs)
+
+
+class User (Model):
+    # NB: This is abstract, the flesh is added in login.py
+
+    __abstract__ = True
+    name = ReqColumn(db.Unicode(50), unique = True)
+    pwd  = ReqColumn(db.Unicode(255))
+    description = Column(db.Unicode(100))
+
+
+class UserModel (Model):
+    """Abstract base class for tables that have a user column."""
+    __abstract__ = True
+
+    @declared_attr
+    def user_id(cls):
+        return ReqColumn(db.Integer, db.ForeignKey('user.id'))
+
+    @declared_attr
+    def user(cls):
+        return db.relationship('User')
+
+    @classmethod
+    def of (cls, user):
+        return cls.query.filter_by(user = user)
+
+
+class Category (UserModel):
+    name = ReqColumn(db.Unicode(50))
+    parent_id = Column(db.Integer, db.ForeignKey('category.id'))
+
+    children = db.relationship('Category',
+                            backref=db.backref('parent', remote_side="Category.id"))
+
+    def __init__ (self, name, user, parent_id = None):
+        Model.__init__(self)
+        self.name = name
+        self.user = user
+        self.parent_id = parent_id
+
+    def __repr__ (self):
+        if self.parent:
+            return '<Category "%s" of "%s">' % (self.name, self.parent.name)
+        else:
+            return '<Category "%s">' % self.name
+
+
+class CategoryModel (db.Model):
+    """Abstract base class for expenses: Adds the common fields
+    and establishes the connection to `Category`.
+    """
+    __abstract__ = True
+
+    @declared_attr
+    def category_id(cls):
+        return ReqColumn(db.Integer, db.ForeignKey(Category.id))
+
+    @declared_attr
+    def category(cls):
+        return db.relationship(Category, innerjoin = True)
+
+
+class SingleExpense (UserModel, CategoryModel):
+    description = Column(db.Unicode(50))
+    expense     = ReqColumn(ExpNum)
+    year = ReqColumn(db.Integer)
+    month = ReqColumn(db.SmallInteger)
+    day = ReqColumn(db.SmallInteger)
+
+    @classmethod
+    def of_month (cls, user, month, year):
+        return cls.of(user).filter_by(month = month, year = year)
+
+    @property
+    def date (self):
+        return datetime.date(self.year, self.month, self.day)
+
+    @date.setter
+    def date (self, d):
+        self.year = d.year
+        self.month = d.month
+        self.day = d.day
+
+
+class ConstExpense (UserModel, CategoryModel):
+    description = Column(db.Unicode(50))
+    expense     = ReqColumn(ExpNum)
+    months  = ReqColumn(db.SmallInteger)
+    start   = ReqColumn(db.Date, index = True)
+    end     = ReqColumn(db.Date, index = True)
+    prev_id = Column(db.Integer, db.ForeignKey('constexpense.id'))
+
+    prev = db.relationship('ConstExpense', remote_side = 'ConstExpense.id', uselist = False,
+                         backref=db.backref('next', uselist = False))
+
+    @property
+    def monthly(self):
+        return to_exp(self.expense / self.months)
+    
+    @classmethod
+    def of_month (cls, user, month, year):
+        d = datetime.date(year, month, 1)
+        return cls.of(user).filter(sql.between(d, cls.start, cls.end))
+
+#
+# Work entities (not stored in DB)
+#
+class CatExpense (namedtuple('CatExpense', 'cat sum exps')):
+    __slots__ = ()
+
+    @property
+    def all (self):
+        return self.exps.order_by(SingleExpense.day).all()
+
+class MonthExpense (namedtuple('MonthExpense', 'user date catexps')):
+
+    def __init__ (self, *args, **kwargs):
+        self._consts = None
+
+    @property
+    def consts (self):
+        if self._consts is None:
+            self._consts = ConstExpense.of_month(self.user, self.date.month, self.date.year).all()
+
+        return self._consts
+
+    @property
+    def constsum (self):
+        s = sum(c.monthly for c in self.consts)
+        return s or 0
+
+    @property
+    def sum (self):
+        return self.constsum + sum(x.sum for x in self.catexps)
+
+    @property
+    def all (self):
+        return SingleExpense.of_month(self.user, self.date.month, self.date.year).order_by(SingleExpense.day).all()
+
+    def __str__ (self):
+        return '<MonthExpense (user: %s) of "%s": %s>' % (self.user.name, self.date, self.sum)
+
+#
+# Extra indices have to be here
+#
+
+db.Index('idx_single_date', SingleExpense.user_id, SingleExpense.year, SingleExpense.month)
+db.Index('idx_start_end', ConstExpense.user_id, ConstExpense.start, ConstExpense.end)