import datetime
import functools
import os
import re
from urllib.parse import urlencode

from flask import (Flask, flash, redirect, render_template, request,
                   Response, session, url_for)
from markdown import markdown
from markdown.extensions.codehilite import CodeHiliteExtension
from markdown.extensions.extra import ExtraExtension
from markupsafe import Markup
from micawber import bootstrap_basic, parse_html
from micawber.cache import Cache as OEmbedCache
from peewee import *
from playhouse.flask_utils import FlaskDB, get_object_or_404, object_list
from playhouse.sqlite_ext import *


# Blog configuration values.

# You may consider using a one-way hash to generate the password, and then
# use the hash again in the login view to perform the comparison. This is just
# for simplicity.
ADMIN_PASSWORD = 'secret'
APP_DIR = os.path.dirname(os.path.realpath(__file__))

# The playhouse.flask_utils.FlaskDB object accepts database URL configuration.
DATABASE = 'sqlite:///%s' % os.path.join(APP_DIR, 'blog.db')
DEBUG = False

# The secret key is used internally by Flask to encrypt session data stored
# in cookies. Make this unique for your app.
SECRET_KEY = 'shhh, secret!'

# This is used by micawber, which will attempt to generate rich media
# embedded objects with maxwidth=800.
SITE_WIDTH = 800


# Create a Flask WSGI app and configure it using values from the module.
app = Flask(__name__)
app.config.from_object(__name__)

# FlaskDB is a wrapper for a peewee database that sets up pre/post-request
# hooks for managing database connections.
flask_db = FlaskDB(app)

# The `database` is the actual peewee database, as opposed to flask_db which is
# the wrapper.
database = flask_db.database

# Configure micawber with the default OEmbed providers (YouTube, Flickr, etc).
# We'll use a simple in-memory cache so that multiple requests for the same
# video don't require multiple network requests.
oembed_providers = bootstrap_basic(OEmbedCache())


class Entry(flask_db.Model):
    title = CharField()
    slug = CharField(unique=True)
    content = TextField()
    published = BooleanField(index=True)
    timestamp = DateTimeField(default=datetime.datetime.now, index=True)

    @property
    def html_content(self):
        """
        Generate HTML representation of the markdown-formatted blog entry,
        and also convert any media URLs into rich media objects such as video
        players or images.
        """
        hilite = CodeHiliteExtension(linenums=False, css_class='highlight')
        extras = ExtraExtension()
        markdown_content = markdown(self.content, extensions=[hilite, extras])
        oembed_content = parse_html(
            markdown_content,
            oembed_providers,
            urlize_all=True,
            maxwidth=app.config['SITE_WIDTH'])
        return Markup(oembed_content)

    def save(self, *args, **kwargs):
        # Generate a URL-friendly representation of the entry's title.
        if not self.slug:
            self.slug = re.sub(r'[^\w]+', '-', self.title.lower()).strip('-')
        ret = super(Entry, self).save(*args, **kwargs)

        # Store search content.
        self.update_search_index()
        return ret

    def update_search_index(self):
        # Store the post content in the FTSEntry table so we can use SQLite's
        # full-text search extension to search our entries. The search index
        # rowid is the entry id, which is how we join the two back together.
        # Replace acts as an upsert, so this handles new and edited entries.
        FTSEntry.replace(
            rowid=self.id,
            content='\n'.join((self.title, self.content))).execute()

    @classmethod
    def public(cls):
        return Entry.select().where(Entry.published == True)

    @classmethod
    def drafts(cls):
        return Entry.select().where(Entry.published == False)

    @classmethod
    def search(cls, query):
        # Whatever the user typed in the search box is translated into a valid
        # FTS5 query, so quoted phrases, OR/NOT and -exclusions work, and
        # nothing they can type raises an error. An empty search box matches
        # no entries.
        search = FTSEntry.web_query(query)

        # Query the full-text search index for entries matching the given
        # search query, then join the actual Entry data on the matching
        # search result.
        return (Entry
                .select(Entry, FTSEntry.rank().alias('score'))
                .join(FTSEntry, on=(Entry.id == FTSEntry.rowid))
                .where(
                    FTSEntry.match(search) &
                    (Entry.published == True))
                .order_by(SQL('score')))

class FTSEntry(FTS5Model):
    content = SearchField()

    class Meta:
        database = database

def login_required(fn):
    @functools.wraps(fn)
    def inner(*args, **kwargs):
        if session.get('logged_in'):
            return fn(*args, **kwargs)
        return redirect(url_for('login', next=request.path))
    return inner

@app.route('/login/', methods=['GET', 'POST'])
def login():
    next_url = request.args.get('next') or request.form.get('next')
    if request.method == 'POST' and request.form.get('password'):
        password = request.form.get('password')
        # TODO: If using a one-way hash, you would also hash the user-submitted
        # password and do the comparison on the hashed versions.
        if password == app.config['ADMIN_PASSWORD']:
            session['logged_in'] = True
            session.permanent = True  # Use cookie to store session.
            flash('You are now logged in.', 'success')
            return redirect(next_url or url_for('index'))
        else:
            flash('Incorrect password.', 'danger')
    return render_template('login.html', next_url=next_url)

@app.route('/logout/', methods=['GET', 'POST'])
def logout():
    if request.method == 'POST':
        session.clear()
        return redirect(url_for('login'))
    return render_template('logout.html')

@app.route('/')
def index():
    search_query = request.args.get('q')
    if search_query:
        query = Entry.search(search_query)
    else:
        query = Entry.public().order_by(Entry.timestamp.desc())

    # The `object_list` helper will take a base query and then handle
    # paginating the results if there are more than 20. For more info see
    # the docs: https://docs.peewee-orm.com/
    return object_list(
        'index.html',
        query,
        search=search_query,
        check_bounds=False)

def _create_or_edit(entry, template):
    if request.method == 'POST':
        entry.title = request.form.get('title') or ''
        entry.content = request.form.get('content') or ''
        entry.published = request.form.get('published') or False
        if not (entry.title and entry.content):
            flash('Title and Content are required.', 'danger')
        else:
            # Wrap the call to save in a transaction so we can roll it back
            # cleanly in the event of an integrity error.
            try:
                with database.atomic():
                    entry.save()
            except IntegrityError:
                flash('Error: this title is already in use.', 'danger')
            else:
                flash('Entry saved successfully.', 'success')
                if entry.published:
                    return redirect(url_for('detail', slug=entry.slug))
                else:
                    return redirect(url_for('edit', slug=entry.slug))

    return render_template(template, entry=entry)

@app.route('/create/', methods=['GET', 'POST'])
@login_required
def create():
    return _create_or_edit(Entry(title='', content=''), 'create.html')

@app.route('/drafts/')
@login_required
def drafts():
    query = Entry.drafts().order_by(Entry.timestamp.desc())
    return object_list('index.html', query, check_bounds=False)

@app.route('/<slug>/')
def detail(slug):
    if session.get('logged_in'):
        query = Entry.select()
    else:
        query = Entry.public()
    entry = get_object_or_404(query, Entry.slug == slug)
    return render_template('detail.html', entry=entry)

@app.route('/<slug>/edit/', methods=['GET', 'POST'])
@login_required
def edit(slug):
    entry = get_object_or_404(Entry, Entry.slug == slug)
    return _create_or_edit(entry, 'edit.html')

@app.template_filter('clean_querystring')
def clean_querystring(request_args, *keys_to_remove, **new_values):
    # We'll use this template filter in the pagination include. This filter
    # will take the current URL and allow us to preserve the arguments in the
    # querystring while replacing any that we need to overwrite. For instance
    # if your URL is /?q=search+query&page=2 and we want to preserve the search
    # term but make a link to page 3, this filter will allow us to do that.
    querystring = dict((key, value) for key, value in request_args.items())
    for key in keys_to_remove:
        querystring.pop(key, None)
    querystring.update(new_values)
    return urlencode(querystring)

@app.errorhandler(404)
def not_found(exc):
    return Response('<h3>Not found</h3>'), 404

def main():
    database.create_tables([Entry, FTSEntry], safe=True)
    app.run(debug=True)

if __name__ == '__main__':
    print('To login, open:')
    print('http://127.0.0.1:5000/login/')
    print('password is: %s' % ADMIN_PASSWORD)
    main()
