import json
import math
import os.path
import re
from datetime import datetime, timedelta
from email.utils import formatdate
from urllib.parse import quote

import flask
from flask_paginate import Pagination
from werkzeug import url_encode
from werkzeug.datastructures import CombinedMultiDict

from itsdangerous import BadSignature, URLSafeSerializer
from sqlalchemy.orm import joinedload

from nyaa import api_handler, app, backend, db, forms, models, torrents, views
from nyaa.search import (DEFAULT_MAX_SEARCH_RESULT, DEFAULT_PER_PAGE, SERACH_PAGINATE_DISPLAY_MSG,
                         _generate_query_string, search_db, search_elastic)
from nyaa.utils import cached_function, chain_get

DEBUG_API = False


# For static_cachebuster
_static_cache = {}


@app.template_global()
def static_cachebuster(filename):
    ''' Adds a ?t=<mtime> cachebuster to the given path, if the file exists.
        Results are cached in memory and persist until app restart! '''
    # Instead of timestamps, we could use commit hashes (we already load it in __init__)
    # But that'd mean every static resource would get cache busted. This lets unchanged items
    # stay in the cache.

    if app.debug:
        # Do not bust cache on debug (helps debugging)
        return flask.url_for('static', filename=filename)

    # Get file mtime if not already cached.
    if filename not in _static_cache:
        file_path = os.path.join(app.static_folder, filename)
        file_mtime = None
        if os.path.exists(file_path):
            file_mtime = int(os.path.getmtime(file_path))

        _static_cache[filename] = file_mtime

    return flask.url_for('static', filename=filename, t=_static_cache[filename])


@app.template_global()
def modify_query(**new_values):
    args = flask.request.args.copy()

    for key, value in new_values.items():
        args[key] = value

    return '{}?{}'.format(flask.request.path, url_encode(args))


@app.template_global()
def filter_truthy(input_list):
    ''' Jinja2 can't into list comprehension so this is for
        the search_results.html template '''
    return [item for item in input_list if item]


@app.template_global()
def category_name(cat_id):
    ''' Given a category id (eg. 1_2), returns a category name (eg. Anime - English-translated) '''
    return ' - '.join(get_category_id_map().get(cat_id, ['???']))


@app.errorhandler(404)
def not_found(error):
    return flask.render_template('404.html'), 404


@app.before_request
def before_request():
    flask.g.user = None
    if 'user_id' in flask.session:
        user = models.User.by_id(flask.session['user_id'])
        if not user:
            return views.account.logout()

        flask.g.user = user

        if 'timeout' not in flask.session or flask.session['timeout'] < datetime.now():
            flask.session['timeout'] = datetime.now() + timedelta(days=7)
            flask.session.permanent = True
            flask.session.modified = True

        if flask.g.user.status == models.UserStatusType.BANNED:
            return 'You are banned.', 403


@app.template_filter('utc_time')
def get_utc_timestamp(datetime_str):
    ''' Returns a UTC POSIX timestamp, as seconds '''
    UTC_EPOCH = datetime.utcfromtimestamp(0)
    return int((datetime.strptime(datetime_str, '%Y-%m-%dT%H:%M:%S') - UTC_EPOCH).total_seconds())


@app.template_filter('display_time')
def get_display_time(datetime_str):
    return datetime.strptime(datetime_str, '%Y-%m-%dT%H:%M:%S').strftime('%Y-%m-%d %H:%M')


@cached_function
def get_category_id_map():
    ''' Reads database for categories and turns them into a dict with
        ids as keys and name list as the value, ala
        {'1_0': ['Anime'], '1_2': ['Anime', 'English-translated'], ...} '''
    cat_id_map = {}
    for main_cat in models.MainCategory.query:
        cat_id_map[main_cat.id_as_string] = [main_cat.name]
        for sub_cat in main_cat.sub_categories:
            cat_id_map[sub_cat.id_as_string] = [main_cat.name, sub_cat.name]
    return cat_id_map


# Routes start here #


@app.route('/rss', defaults={'rss': True})
@app.route('/', defaults={'rss': False})
def home(rss):
    render_as_rss = rss
    req_args = flask.request.args
    if req_args.get('page') == 'rss':
        render_as_rss = True

    search_term = chain_get(req_args, 'q', 'term')

    sort_key = req_args.get('s')
    sort_order = req_args.get('o')

    category = chain_get(req_args, 'c', 'cats')
    quality_filter = chain_get(req_args, 'f', 'filter')

    user_name = chain_get(req_args, 'u', 'user')
    page_number = chain_get(req_args, 'p', 'page', 'offset')
    try:
        page_number = max(1, int(page_number))
    except (ValueError, TypeError):
        page_number = 1

    # Check simply if the key exists
    use_magnet_links = 'magnets' in req_args or 'm' in req_args

    results_per_page = app.config.get('RESULTS_PER_PAGE', DEFAULT_PER_PAGE)

    user_id = None
    if user_name:
        user = models.User.by_username(user_name)
        if not user:
            flask.abort(404)
        user_id = user.id

    special_results = {
        'first_word_user': None,
        'query_sans_user': None,
        'infohash_torrent': None
    }
    # Add advanced features to searches (but not RSS or user searches)
    if search_term and not render_as_rss and not user_id:
        # Check if the first word of the search is an existing user
        user_word_match = re.match(r'^([a-zA-Z0-9_-]+) *(.*|$)', search_term)
        if user_word_match:
            special_results['first_word_user'] = models.User.by_username(user_word_match.group(1))
            special_results['query_sans_user'] = user_word_match.group(2)

        # Check if search is a 40-char torrent hash
        infohash_match = re.match(r'(?i)^([a-f0-9]{40})$', search_term)
        if infohash_match:
            # Check for info hash in database
            matched_torrent = models.Torrent.by_info_hash_hex(infohash_match.group(1))
            special_results['infohash_torrent'] = matched_torrent

    query_args = {
        'user': user_id,
        'sort': sort_key or 'id',
        'order': sort_order or 'desc',
        'category': category or '0_0',
        'quality_filter': quality_filter or '0',
        'page': page_number,
        'rss': render_as_rss,
        'per_page': results_per_page
    }

    if flask.g.user:
        query_args['logged_in_user'] = flask.g.user
        if flask.g.user.is_moderator:  # God mode
            query_args['admin'] = True

    infohash_torrent = special_results.get('infohash_torrent')
    if infohash_torrent:
        # infohash_torrent is only set if this is not RSS or userpage search
        flask.flash(flask.Markup('You were redirected here because '
                                 'the given hash matched this torrent.'), 'info')
        # Redirect user from search to the torrent if we found one with the specific info_hash
        return flask.redirect(flask.url_for('view_torrent', torrent_id=infohash_torrent.id))

    # If searching, we get results from elastic search
    use_elastic = app.config.get('USE_ELASTIC_SEARCH')
    if use_elastic and search_term:
        query_args['term'] = search_term

        max_search_results = app.config.get('ES_MAX_SEARCH_RESULT', DEFAULT_MAX_SEARCH_RESULT)

        # Only allow up to (max_search_results / page) pages
        max_page = min(query_args['page'], int(math.ceil(max_search_results / results_per_page)))

        query_args['page'] = max_page
        query_args['max_search_results'] = max_search_results

        query_results = search_elastic(**query_args)

        if render_as_rss:
            return render_rss(
                '"{}"'.format(search_term), query_results,
                use_elastic=True, magnet_links=use_magnet_links)
        else:
            rss_query_string = _generate_query_string(
                search_term, category, quality_filter, user_name)
            max_results = min(max_search_results, query_results['hits']['total'])
            # change p= argument to whatever you change page_parameter to or pagination breaks
            pagination = Pagination(p=query_args['page'], per_page=results_per_page,
                                    total=max_results, bs_version=3, page_parameter='p',
                                    display_msg=SERACH_PAGINATE_DISPLAY_MSG)
            return flask.render_template('home.html',
                                         use_elastic=True,
                                         pagination=pagination,
                                         torrent_query=query_results,
                                         search=query_args,
                                         rss_filter=rss_query_string,
                                         special_results=special_results)
    else:
        # If ES is enabled, default to db search for browsing
        if use_elastic:
            query_args['term'] = ''
        else:  # Otherwise, use db search for everything
            query_args['term'] = search_term or ''

        query = search_db(**query_args)
        if render_as_rss:
            return render_rss('Home', query, use_elastic=False, magnet_links=use_magnet_links)
        else:
            rss_query_string = _generate_query_string(
                search_term, category, quality_filter, user_name)
            # Use elastic is always false here because we only hit this section
            # if we're browsing without a search term (which means we default to DB)
            # or if ES is disabled
            return flask.render_template('home.html',
                                         use_elastic=False,
                                         torrent_query=query,
                                         search=query_args,
                                         rss_filter=rss_query_string,
                                         special_results=special_results)


@app.template_filter('rfc822')
def _jinja2_filter_rfc822(date, fmt=None):
    return formatdate(date.timestamp())


@app.template_filter('rfc822_es')
def _jinja2_filter_rfc822_es(datestr, fmt=None):
    return formatdate(datetime.strptime(datestr, '%Y-%m-%dT%H:%M:%S').timestamp())


def render_rss(label, query, use_elastic, magnet_links=False):
    rss_xml = flask.render_template('rss.xml',
                                    use_elastic=use_elastic,
                                    magnet_links=magnet_links,
                                    term=label,
                                    site_url=flask.request.url_root,
                                    torrent_query=query)
    response = flask.make_response(rss_xml)
    response.headers['Content-Type'] = 'application/xml'
    # Cache for an hour
    response.headers['Cache-Control'] = 'max-age={}'.format(1 * 5 * 60)
    return response


@app.route('/user/activate/<payload>')
def activate_user(payload):
    s = get_serializer()
    try:
        user_id = s.loads(payload)
    except BadSignature:
        flask.abort(404)

    user = models.User.by_id(user_id)

    if not user:
        flask.abort(404)

    user.status = models.UserStatusType.ACTIVE

    db.session.add(user)
    db.session.commit()

    return flask.redirect('/login')


@cached_function
def _create_upload_category_choices():
    ''' Turns categories in the database into a list of (id, name)s '''
    choices = [('', '[Select a category]')]
    id_map = get_category_id_map()

    for key in sorted(id_map.keys()):
        cat_names = id_map[key]
        is_main_cat = key.endswith('_0')

        # cat_name = is_main_cat and cat_names[0] or (' - ' + cat_names[1])
        cat_name = ' - '.join(cat_names)
        choices.append((key, cat_name, is_main_cat))
    return choices


@app.route('/upload', methods=['GET', 'POST'])
def upload():
    upload_form = forms.UploadForm(CombinedMultiDict((flask.request.files, flask.request.form)))
    upload_form.category.choices = _create_upload_category_choices()

    if flask.request.method == 'POST' and upload_form.validate():
        torrent = backend.handle_torrent_upload(upload_form, flask.g.user)

        return flask.redirect('/view/' + str(torrent.id))
    else:
        # If we get here with a POST, it means the form data was invalid: return a non-okay status
        status_code = 400 if flask.request.method == 'POST' else 200
        return flask.render_template('upload.html', upload_form=upload_form), status_code


@app.route('/view/<int:torrent_id>', methods=['GET', 'POST'])
def view_torrent(torrent_id):
    if flask.request.method == 'POST':
        torrent = models.Torrent.by_id(torrent_id)
    else:
        torrent = models.Torrent.query \
                                .options(joinedload('filelist'),
                                         joinedload('comments')) \
                                .filter_by(id=torrent_id) \
                                .first()
    if not torrent:
        flask.abort(404)

    # Only allow admins see deleted torrents
    if torrent.deleted and not (flask.g.user and flask.g.user.is_moderator):
        flask.abort(404)

    comment_form = None
    if flask.g.user:
        comment_form = forms.CommentForm()

    if flask.request.method == 'POST':
        if not flask.g.user:
            flask.abort(403)

        if comment_form.validate():
            comment_text = (comment_form.comment.data or '').strip()

            comment = models.Comment(
                torrent_id=torrent_id,
                user_id=flask.g.user.id,
                text=comment_text)

            db.session.add(comment)
            db.session.flush()

            torrent_count = torrent.update_comment_count()
            db.session.commit()

            flask.flash('Comment successfully posted.', 'success')

            return flask.redirect(flask.url_for('view_torrent',
                                                torrent_id=torrent_id,
                                                _anchor='com-' + str(torrent_count)))

    # Only allow owners and admins to edit torrents
    can_edit = flask.g.user and (flask.g.user is torrent.user or flask.g.user.is_moderator)

    files = None
    if torrent.filelist:
        files = json.loads(torrent.filelist.filelist_blob.decode('utf-8'))

    report_form = forms.ReportForm()
    return flask.render_template('view.html', torrent=torrent,
                                 files=files,
                                 comment_form=comment_form,
                                 comments=torrent.comments,
                                 can_edit=can_edit,
                                 report_form=report_form)


@app.route('/view/<int:torrent_id>/comment/<int:comment_id>/delete', methods=['POST'])
def delete_comment(torrent_id, comment_id):
    if not flask.g.user:
        flask.abort(403)
    torrent = models.Torrent.by_id(torrent_id)
    if not torrent:
        flask.abort(404)

    comment = models.Comment.query.filter_by(id=comment_id).first()
    if not comment:
        flask.abort(404)

    if not (comment.user.id == flask.g.user.id or flask.g.user.is_moderator):
        flask.abort(403)

    db.session.delete(comment)
    db.session.flush()
    torrent.update_comment_count()

    url = flask.url_for('view_torrent', torrent_id=torrent.id)
    if flask.g.user.is_moderator:
        log = "Comment deleted on torrent [#{}]({})".format(torrent.id, url)
        adminlog = models.AdminLog(log=log, admin_id=flask.g.user.id)
        db.session.add(adminlog)
    db.session.commit()

    flask.flash('Comment successfully deleted.', 'success')

    return flask.redirect(url)


@app.route('/view/<int:torrent_id>/edit', methods=['GET', 'POST'])
def edit_torrent(torrent_id):
    torrent = models.Torrent.by_id(torrent_id)
    form = forms.EditForm(flask.request.form)
    form.category.choices = _create_upload_category_choices()

    editor = flask.g.user

    if not torrent:
        flask.abort(404)

    # Only allow admins edit deleted torrents
    if torrent.deleted and not (editor and editor.is_moderator):
        flask.abort(404)

    # Only allow torrent owners or admins edit torrents
    if not editor or not (editor is torrent.user or editor.is_moderator):
        flask.abort(403)

    if flask.request.method == 'POST' and form.validate():
        # Form has been sent, edit torrent with data.
        torrent.main_category_id, torrent.sub_category_id = \
            form.category.parsed_data.get_category_ids()
        torrent.display_name = (form.display_name.data or '').strip()
        torrent.information = (form.information.data or '').strip()
        torrent.description = (form.description.data or '').strip()

        torrent.hidden = form.is_hidden.data
        torrent.remake = form.is_remake.data
        torrent.complete = form.is_complete.data
        torrent.anonymous = form.is_anonymous.data

        if editor.is_trusted:
            torrent.trusted = form.is_trusted.data

        deleted_changed = torrent.deleted != form.is_deleted.data
        if editor.is_moderator:
            torrent.deleted = form.is_deleted.data

        url = flask.url_for('view_torrent', torrent_id=torrent.id)
        if deleted_changed and editor.is_moderator:
            log = "Torrent [#{0}]({1}) marked as {2}".format(
                torrent.id, url, "deleted" if torrent.deleted else "undeleted")
            adminlog = models.AdminLog(log=log, admin_id=editor.id)
            db.session.add(adminlog)

        db.session.commit()

        flask.flash(flask.Markup(
            'Torrent has been successfully edited! Changes might take a few minutes to show up.'),
            'info')

        return flask.redirect(url)
    else:
        if flask.request.method != 'POST':
            # Fill form data only if the POST didn't fail
            form.category.data = torrent.sub_category.id_as_string
            form.display_name.data = torrent.display_name
            form.information.data = torrent.information
            form.description.data = torrent.description

            form.is_hidden.data = torrent.hidden
            form.is_remake.data = torrent.remake
            form.is_complete.data = torrent.complete
            form.is_anonymous.data = torrent.anonymous

            form.is_trusted.data = torrent.trusted
            form.is_deleted.data = torrent.deleted

        return flask.render_template('edit.html',
                                     form=form,
                                     torrent=torrent)


@app.route('/view/<int:torrent_id>/magnet')
def redirect_magnet(torrent_id):
    torrent = models.Torrent.by_id(torrent_id)

    if not torrent:
        flask.abort(404)

    return flask.redirect(torrents.create_magnet(torrent))


@app.route('/view/<int:torrent_id>/torrent')
@app.route('/download/<int:torrent_id>.torrent')
def download_torrent(torrent_id):
    torrent = models.Torrent.by_id(torrent_id)

    if not torrent or not torrent.has_torrent:
        flask.abort(404)

    torrent_file, torrent_file_size = _get_cached_torrent_file(torrent)
    disposition = 'attachment; filename="{0}"; filename*=UTF-8\'\'{0}'.format(
        quote(torrent.torrent_name.encode('utf-8')))

    resp = flask.Response(torrent_file)
    resp.headers['Content-Type'] = 'application/x-bittorrent'
    resp.headers['Content-Disposition'] = disposition
    resp.headers['Content-Length'] = torrent_file_size
    return resp


@app.route('/view/<int:torrent_id>/submit_report', methods=['POST'])
def submit_report(torrent_id):
    if not flask.g.user:
        flask.abort(403)

    form = forms.ReportForm(flask.request.form)

    if flask.request.method == 'POST' and form.validate():
        report_reason = form.reason.data
        current_user_id = flask.g.user.id
        report = models.Report(
            torrent_id=torrent_id,
            user_id=current_user_id,
            reason=report_reason)

        db.session.add(report)
        db.session.commit()
        flask.flash('Successfully reported torrent!', 'success')

    return flask.redirect(flask.url_for('view_torrent', torrent_id=torrent_id))


def _get_cached_torrent_file(torrent):
    # Note: obviously temporary
    cached_torrent = os.path.join(app.config['BASE_DIR'],
                                  'torrent_cache', str(torrent.id) + '.torrent')
    if not os.path.exists(cached_torrent):
        with open(cached_torrent, 'wb') as out_file:
            out_file.write(torrents.create_bencoded_torrent(torrent))

    return open(cached_torrent, 'rb'), os.path.getsize(cached_torrent)


def get_serializer(secret_key=None):
    if secret_key is None:
        secret_key = app.secret_key
    return URLSafeSerializer(secret_key)


def get_activation_link(user):
    s = get_serializer()
    payload = s.dumps(user.id)
    return flask.url_for('activate_user', payload=payload, _external=True)


@app.template_filter()
def timesince(dt, default='just now'):
    """
    Returns string representing "time since" e.g.
    3 minutes ago, 5 hours ago etc.
    Date and time (UTC) are returned if older than 1 day.
    """

    now = datetime.utcnow()
    diff = now - dt

    periods = (
        (diff.days, 'day', 'days'),
        (diff.seconds / 3600, 'hour', 'hours'),
        (diff.seconds / 60, 'minute', 'minutes'),
        (diff.seconds, 'second', 'seconds'),
    )

    if diff.days >= 1:
        return dt.strftime('%Y-%m-%d %H:%M UTC')
    else:
        for period, singular, plural in periods:

            if period >= 1:
                return '%d %s ago' % (period, singular if int(period) == 1 else plural)

    return default


# #################################### BLUEPRINTS ####################################

def register_blueprints(flask_app):
    """ Register the blueprints using the flask_app object """

    # API routes
    flask_app.register_blueprint(api_handler.api_blueprint, url_prefix='/api')
    # Site routes
    flask_app.register_blueprint(views.account_bp)
    flask_app.register_blueprint(views.admin_bp)
    flask_app.register_blueprint(views.site_bp)
    flask_app.register_blueprint(views.users_bp)


# When done, this can be moved to nyaa/__init__.py instead of importing this file
register_blueprints(app)