Alessandro Marin's submission

.gitignore

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+expenses
+*.pyc
+*.db
+.DS_Store

README.markdown

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+# Setup
+
+### Prerequisites
+
+  1. Python 2.7
+  2. Virtualenv
+
+### Run the demo
+
+  0. clone the repository and cd into it
+  1. `virtualenv expenses`
+  2. `source expenses/bin/activate`
+  3. `pip install -r requirements.txt`
+  4. `python setup.py`
+  5. `python run.py`
+  6. from another terminal window run
+    * `source expenses/bin/activate`
+    * `python client/expenses.py --upload ./data_examples.csv` to upload and view a summary of the expenses
+    * `python client/expenses.py` to only view the summary
+
+### Comments
+
+The project **lacks a web interface**, and needs to be interacted with through the terminal. I apologize for the incompleteness and lack of tests, but please do note that this solution was build 1/3 on a plane, 1/3 in a car and 1/3 in a room full of christmas guests.
+
+What I'm particularily proud of in my implementation: when I started working on this, I had grand ideas, which sadly didn't materialize. Now, although my pride is being overshadowed by a sense of forfeit, I can say that I'm satisfied with the derived database schema, which allows, in combination with a nice ORM, to generate complex queries while maintaining a decent level of extensibility. This might sound silly but I'm also satisfied with the folder structure for the project and the concerns separation into files, as it's intuitive and clean.
+
+### Implementation notes
+
+  1. **Models**: under the `models` folder you will find some Alchemy models representing the data in the csv in such a way to be easily extended in the future. In particular note that `categories`, `employees` and `taxes` have their own table.
+
+  2. **Seeding / Uploading**: the .csv is lacking unique ids, thus when creating records for categories, employees and taxes, I had to assume the uniqueness of some of its data, which isn't necessarily true.
+
+  3. **Testing**: Initially I wanted to use `pytest` to do some basic testing on the csv parsing and model generation results, and the server response, but I did not have enough time available.
+
+  4. **Templates**: I started building a web interface, but ultimately resorted to a vintage terminal-based solution due to the little time available, but I hear that's all the rage anyway.
+
+
 # Wave Software Development Challenge
 Applicants for the [Software developer](https://wave.bamboohr.co.uk/jobs/view.php?id=1) role at Wave must complete the following challenge, and submit a solution prior to the onsite interview. 
 

app/__init__.py

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+# -*- encoding: utf-8 -*-
+from flask import Flask
+from flask_sqlalchemy import SQLAlchemy
+
+
+app = Flask(__name__)
+app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///expenses.db'
+app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False
+db = SQLAlchemy(app)

app/models/Category.py

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+# -*- encoding: utf-8 -*-
+from app import db
+
+
+class Category(db.Model):
+    # id
+    id = db.Column(db.Integer, primary_key=True, autoincrement=True)
+
+    # name of category
+    name = db.Column(db.String(255))
+
+    def __init__(self, name):
+        self.name = name
+
+    def __repr__(self):
+        return '<Category %r>' % self.name

app/models/Employee.py

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+# -*- encoding: utf-8 -*-
+from app import db
+
+
+class Employee(db.Model):
+    # id
+    id = db.Column(db.Integer, primary_key=True, autoincrement=True)
+
+    # full name of employee
+    name = db.Column(db.String(255))
+
+    # employee's full address
+    address = db.Column(db.String(255))
+
+    def __init__(self, name, address):
+        self.name = name
+        self.address = address
+
+    def __repr__(self):
+        return '<Employee %r>' % self.name

app/models/Expense.py

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+# -*- encoding: utf-8 -*-
+from app import db
+from sqlalchemy.ext.hybrid import hybrid_property
+
+
+class Expense(db.Model):
+    # id
+    id = db.Column(db.Integer, primary_key=True, autoincrement=True)
+
+    # date
+    date = db.Column(db.Date)
+
+    # category
+    category_id = db.Column(db.Integer, db.ForeignKey('category.id'))
+    category = db.relationship(
+        'Category',
+        backref=db.backref('expenses', lazy='dynamic')
+    )
+
+    # employee
+    employee_id = db.Column(db.Integer, db.ForeignKey('employee.id'))
+    employee = db.relationship(
+        'Employee',
+        backref=db.backref('expenses', lazy='dynamic')
+    )
+
+    # tax
+    tax_id = db.Column(db.Integer, db.ForeignKey('tax.id'))
+    tax = db.relationship('Tax')
+
+    # expense description
+    description = db.Column(db.String(255))
+
+    # pre-tax amount
+    pre_tax_amount = db.Column(db.Float)
+
+    post_tax_amount = db.Column(db.Float)
+
+    def __init__(self, date, category, employee, tax, description,
+                 pre_tax_amount, post_tax_amount):
+        self.date = date
+        self.category = category
+        self.employee = employee
+        self.tax = tax
+        self.description = description
+        self.pre_tax_amount = pre_tax_amount
+        self.post_tax_amount = post_tax_amount
+
+    def __repr__(self):
+        return '<Expense %r>' % self.description

app/models/Tax.py

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+# -*- encoding: utf-8 -*-
+from app import db
+
+
+class Tax(db.Model):
+    # id
+    id = db.Column(db.Integer, primary_key=True, autoincrement=True)
+
+    # name of tax
+    name = db.Column(db.String(255))
+
+    # tax amount as a float
+    amount = db.Column(db.Float)
+
+    def __init__(self, name, amount):
+        self.name = name
+        self.amount = amount
+
+    def __repr__(self):
+        return '<Tax %r>' % self.name

app/models/__init__.py

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+from os.path import dirname, basename, isfile
+import glob
+
+
+modules = glob.glob(dirname(__file__)+"/*.py")
+__all__ = [basename(f)[:-3] for f in modules if isfile(f)]

app/repositories/expense.py

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+# -*- encoding: utf-8 -*-
+import csv
+from datetime import datetime
+from sqlalchemy import extract
+from sqlalchemy.sql import func
+
+from app import db
+from app.models.category import Category
+from app.models.employee import Employee
+from app.models.expense import Expense
+from app.models.tax import Tax
+
+
+class ExpenseRepository():
+    """Repository to create and retrieve Expenses"""
+    def by_month(self):
+        year = extract('year', Expense.date)
+        month = extract('month', Expense.date)
+
+        expenses = db.session.query(
+                year,
+                month,
+                func.sum(Expense.pre_tax_amount),
+                func.sum(Expense.post_tax_amount)
+            ).group_by(
+                year,
+                month
+            ).all()
+
+        return expenses
+
+    def from_csv(self, csvfile):
+        categories = {}
+        employees = {}
+        taxes = {}
+
+        data = csv.DictReader(csvfile)
+
+        for row in data:
+            if not row['category'] in categories:
+                new_category = Category(row['category'])
+                categories[row['category']] = new_category
+                db.session.add(new_category)
+
+            if not row['employee name'] in employees:
+                new_employee = Employee(row['employee name'],
+                                        row['employee address'])
+                employees[row['employee name']] = new_employee
+                db.session.add(new_employee)
+
+            pre_tax_amount = float(row['pre-tax amount'].replace(',', ''))
+            tax_amount = float(row['tax amount'].replace(',', ''))
+            tax_percentage = tax_amount / pre_tax_amount
+
+            if not row['tax name'] in taxes:
+                new_tax = Tax(row['tax name'], tax_percentage)
+                taxes[row['tax name']] = new_tax
+                db.session.add(new_tax)
+
+            # date, category, employee, tax, description, pre_tax_amount
+            new_expense = Expense(
+                datetime.strptime(row['date'], "%m/%d/%Y").date(),
+                categories[row['category']],
+                employees[row['employee name']],
+                taxes[row['tax name']],
+                row['expense description'],
+                pre_tax_amount,
+                tax_amount
+            )
+            db.session.add(new_expense)
+
+        db.session.commit()

app/routes.py

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+# -*- encoding: utf-8 -*-
+import json
+from app import app
+from app.repositories.expense import ExpenseRepository
+from flask import render_template, request, jsonify
+
+
+def render_report(expenses):
+    table_row = "Period %d/%d Total Expenses: %.2f, Total Taxes: %.2f\n"
+    by_month = reduce(
+        lambda res, (y, m, e, t): res + (table_row % (m, y, e, t)),
+        expenses,
+        ""
+    )
+
+
+@app.route('/expenses', methods=['GET', 'POST'])
+def upload():
+    expense = ExpenseRepository()
+    if request.method == 'POST':
+        # check if the post request has the file part
+        if 'file' not in request.files:
+            return redirect(request.url)
+
+        file = request.files['file']
+        # if user does not select file, browser also
+        # submit a empty part without filename
+        if file.filename == '':
+            return redirect(request.url)
+
+        expense.from_csv(file)
+        return jsonify({'success': True})
+    else:
+        return jsonify(expense.by_month())
+
+    return make_response(by_month)

app/templates/index.html

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+{% extends "layout.html" %}
+
+{% block title %}Expenses{% endblock %}
+
+{% block body %}
+<form action="/expenses" method="post" class="dropzone" enctype="multipart/form-data">
+</form>
+{% endblock %}

app/templates/layout.html

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+<!doctype html>
+<html>
+    <head>
+        {% block head %}
+        <link rel="stylesheet" href="{{ url_for('static', filename='style.css') }}">
+        <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/dropzone/4.3.0/dropzone.css">
+        <script src="https://cdnjs.cloudflare.com/ajax/libs/dropzone/4.3.0/min/dropzone.min.js"></script>
+        <title>{% block title %}{% endblock %}</title>
+        {% endblock %}
+    </head>
+    <body>
+        <div class="container">
+            {% block body %}{% endblock %}
+        </div>
+    </body>
+</html>

client/expenses.py

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+import os.path
+import click
+import requests
+from terminaltables import AsciiTable
+
+
+ENDPOINT = "http://localhost:5000"
+
+
+@click.command()
+@click.option('--upload', default=False, help='Path to a well-formatted .csv file')
+def expenses(upload):
+    """Simple querying CLI to upload and display expenses from a csv file"""
+    if upload:
+        if os.path.isfile(upload):
+            r = requests.post("%s/expenses" % ENDPOINT, files={
+                'file': open(upload, 'rb')
+            })
+            if r.status_code == 200:
+                print "Successfully uploaded %s" % upload
+        else:
+            raise "The file %s does not exist, check the given path" % upload
+
+    result = requests.get("%s/expenses" % ENDPOINT)
+    header = ['Year', 'Month', 'Total Expenses', 'Total Tax']
+    expenses = result.json()
+    expenses.insert(0, header)
+    table = AsciiTable(expenses)
+    print table.table
+
+if __name__ == '__main__':
+    expenses()

requirements.txt

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+click==6.6
+Flask==0.11.1
+Flask-SQLAlchemy==2.1
+itsdangerous==0.24
+Jinja2==2.8
+MarkupSafe==0.23
+requests==2.12.4
+SQLAlchemy==1.1.4
+terminaltables==3.1.0
+Werkzeug==0.11.11

run.py

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+# -*- encoding: utf-8 -*-
+import os
+from app import routes
+from app import app
+
+if __name__ == "__main__":
+    port = int(os.environ.get("PORT", 5000))
+    app.run(host='0.0.0.0', port=port)

setup.py

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+# -*- encoding: utf-8 -*-
+from app import db
+from app.models import *
+
+db.create_all()