journal.py

# -*- coding: utf-8 -*-

import os
import datetime
import psycopg2
from contextlib import closing
from passlib.hash import pbkdf2_sha256
from flask import Flask, g, render_template, session
from flask import abort, request, url_for, redirect
from flask.ext.markdown import Markdown

DB_SCHEMA = """
DROP TABLE IF EXISTS entries;
CREATE TABLE entries (
    id serial PRIMARY KEY,
    title VARCHAR (127) NOT NULL,
    text TEXT NOT NULL,
    created TIMESTAMP NOT NULL
);
"""
DB_INSERT_ENTRY = """
INSERT INTO entries (title, text, created) VALUES (%s, %s, %s)
"""
DB_SELECT_ENTRIES_LIST = """
SELECT id, title, text, created FROM entries ORDER BY created DESC
"""
DB_SELECT_ENTRY = """
SELECT * FROM entries WHERE id = %s
"""
DB_UPDATE_ENTRY = """
UPDATE entries SET title = %s, text = %s WHERE id = %s
"""

app = Flask(__name__)
app.config['DATABASE'] = os.environ.get(
    'DATABASE_URL', 'dbname=learning_journal user=charlesgust'
    )
# add the following two settings just below
app.config['ADMIN_USERNAME'] = os.environ.get(
    'ADMIN_USERNAME', 'admin'
)
app.config['ADMIN_PASSWORD'] = os.environ.get(
    'ADMIN_PASSWORD', pbkdf2_sha256.encrypt('admin')
)
app.config['SECRET_KEY'] = os.environ.get(
    'FLASK_SECRET_KEY', 'sooperseekritvaluenooneshouldknow'
)
Markdown(app, extensions=['codehilite'])


def connect_db():
    """ return a connection to the configured databse """
    return psycopg2.connect(app.config['DATABASE'])


def init_db():
    """ initialize the dabatase using DB_SCHEMA

    WARNING: executing this function will drop existing tables
    """
    with closing(connect_db()) as db:
        db.cursor().execute(DB_SCHEMA)
        db.commit()


def get_database_connection():
    db = getattr(g, 'db', None)
    if db is None:
        g.db = db = connect_db()
    return db


@app.teardown_request
def teardown_request(exception):
    db = getattr(g, 'db', None)
    if db is not None:
        if exception and isinstance(exception, psycopg2.Error):
            # if there was a problem with the database,
            #  rollback any existing transaction
            db.rollback()
        else:
            # otherwise, commit
            db.commit()
        db.close()


def write_entry(title, text):
    if not title or not text:
        raise ValueError("Title and text required for writing an entry")
    con = get_database_connection()
    cur = con.cursor()
    now = datetime.datetime.utcnow()
    cur.execute(DB_INSERT_ENTRY, [title, text, now])


def get_all_entries():
    """ return a list of all entries as dicts """
    con = get_database_connection()
    cur = con.cursor()
    cur.execute(DB_SELECT_ENTRIES_LIST)
    keys = ('id', 'title', 'text', 'created')
    return [dict(zip(keys, row)) for row in cur.fetchall()]


def get_entry(entry_id):
    """ return the entry corresponding to the primary key """
    conn = get_database_connection()
    cur = conn.cursor()
    cur.execute(DB_SELECT_ENTRY, (entry_id,))
    keys = ('id', 'title', 'text', 'created')
    return dict(zip(keys, cur.fetchone()))


def update_entry(entry_id, entry_title, entry_text):
    """ update the title and text of a single (unique) entry """

    if not entry_title or not entry_text:
        raise ValueError("Update to database entry must have title and text")
    con = get_database_connection()
    cur = con.cursor()
    cur.execute(DB_UPDATE_ENTRY, (entry_title, entry_text, entry_id))
    return


def find_entry(entries, entry_id):
    for entry in entries:
        if entry.id == entry_id:
            return entry_title
    raise IndexError("Cannot find entry in database by entry identifer")


@app.route('/')
def show_entries():
    session['editing'] = False
    entries = get_all_entries()
    default_entry = {'title': '', 'text': ''}
    return render_template('list_entries.html',
                           entries=entries,
                           default_entry=default_entry)


@app.route('/add', methods=['POST'])
def add_entry():
    try:
        write_entry(request.form['title'], request.form['text'])
    except psycopg2.Error:
        # this will catch any errors generated by the database
        abort(500)
    return redirect(url_for('show_entries'))


@app.route('/edit/<entry_id>')
def edit_entry(entry_id):
    session['editing'] = True
    entries = get_all_entries()

    # CMGTODO: since just hit the DB and have all the entries, the
    #  default_entry could just come from a lookup in entries.
    default_entry = get_entry(entry_id)

    return render_template('list_entries.html',
                           entries=entries,
                           default_entry=default_entry)


@app.route('/submit/<entry_id>', methods=['POST'])
def submit_entry(entry_id):
    try:
        update_entry(entry_id, request.form['title'], request.form['text'])
    except psycopg2.Error:
        # this will catch any errors generated by the database
        abort(500)
    return redirect(url_for('show_entries'))


@app.route('/login', methods=['GET', 'POST'])
def login():
    error = None
    if request.method == 'POST':
        try:
            do_login(request.form['username'].encode('utf-8'),
                     request.form['password'].encode('utf-8'))
        except ValueError:
            error = "Login Failed"
        else:
            return redirect(url_for('show_entries'))
    return render_template('login.html', error=error)


@app.route('/logout')
def logout():
    session.pop('logged_in', None)
    return redirect(url_for('show_entries'))


def do_login(username='', passwd=''):
    if username != app.config['ADMIN_USERNAME']:
        raise ValueError
    if not pbkdf2_sha256.verify(passwd, app.config['ADMIN_PASSWORD']):
        raise ValueError
    session['logged_in'] = True


if __name__ == "__main__":
    app.run(debug=True)