ImportSongs: Implement Google Drive beta testing

Instances that wish to enable Google Drive support should first enable it to only a small subset of users (100 maximum) to allow the OAuth screen to be verified by Google without hitting the user limit. Minimum level in the config can be set to enable beta testing of this feature and then disabled by setting it to None.

- Add user level assignment screen to the administration panel
- Add privacy policy and links to it in various places
- Add switch accounts link near the Google Drive picker

app.py

@@ -9,9 +9,10 @@ import re
 import requests
 import schema
 import os
+import time
 
 from functools import wraps
-from flask import Flask, g, jsonify, render_template, request, abort, redirect, session, flash
+from flask import Flask, g, jsonify, render_template, request, abort, redirect, session, flash, make_response
 from flask_caching import Cache
 from flask_session import Session
 from flask_wtf.csrf import CSRFProtect, generate_csrf, CSRFError
@@ -113,15 +114,27 @@ def before_request_func():
             session.clear()
 
 
-def get_config():
+def get_config(credentials=False):
     config_out = {
         'songs_baseurl': config.SONGS_BASEURL,
         'assets_baseurl': config.ASSETS_BASEURL,
         'email': config.EMAIL,
         'accounts': config.ACCOUNTS,
-        'custom_js': config.CUSTOM_JS,
-        'google_credentials': config.GOOGLE_CREDENTIALS
+        'custom_js': config.CUSTOM_JS
     }
+    if credentials:
+        min_level = config.GOOGLE_CREDENTIALS['min_level'] or 0
+        if not session.get('username'):
+            user_level = 0
+        else:
+            user = db.users.find_one({'username': session.get('username')})
+            user_level = user['user_level']
+        if user_level >= min_level:
+            config_out['google_credentials'] = config.GOOGLE_CREDENTIALS
+        else:
+            config_out['google_credentials'] = {
+                'gdrive_enabled': False
+            }
 
     if not config_out.get('songs_baseurl'):
         config_out['songs_baseurl'] = ''.join([request.host_url, 'songs']) + '/'
@@ -342,6 +355,43 @@ def route_admin_songs_id_delete(id):
     return redirect('/admin/songs')
 
 
+@app.route('/admin/users')
+@admin_required(level=50)
+def route_admin_users():
+    user = db.users.find_one({'username': session.get('username')})
+    max_level = user['user_level'] - 1
+    return render_template('admin_users.html', config=get_config(), max_level=max_level, username='', level='')
+
+
+@app.route('/admin/users', methods=['POST'])
+@admin_required(level=50)
+def route_admin_users_post():
+    admin_name = session.get('username')
+    admin = db.users.find_one({'username': admin_name})
+    max_level = admin['user_level'] - 1
+    
+    username = request.form.get('username')
+    level = int(request.form.get('level')) or 0
+    
+    user = db.users.find_one({'username': username})
+    if not user:
+        flash('Error: User was not found.')
+    elif admin_name == username:
+        flash('Error: You cannot modify your own level.')
+    else:
+        user_level = user['user_level']
+        if level < 0 or level > max_level:
+            flash('Error: Invalid level.')
+        elif user_level > max_level:
+            flash('Error: This user has higher level than you.')
+        else:
+            output = {'user_level': level}
+            db.users.update_one({'username': username}, {'$set': output})
+            flash('User updated.')
+    
+    return render_template('admin_users.html', config=get_config(), max_level=max_level, username=username, level=level)
+
+
 @app.route('/api/preview')
 @app.cache.cached(timeout=15, query_string=True)
 def route_api_preview():
@@ -400,7 +450,7 @@ def route_api_categories():
 @app.route('/api/config')
 @app.cache.cached(timeout=15)
 def route_api_config():
-    config = get_config()
+    config = get_config(credentials=True)
     return jsonify(config)
 
 
@@ -611,6 +661,16 @@ def route_api_scores_get():
     return jsonify({'status': 'ok', 'scores': scores, 'username': user['username'], 'display_name': user['display_name'], 'don': don})
 
 
+@app.route('/privacy')
+def route_api_privacy():
+    last_modified = time.strftime('%d %B %Y', time.gmtime(os.path.getmtime('templates/privacy.txt')))
+    integration = config.GOOGLE_CREDENTIALS['gdrive_enabled']
+    
+    response = make_response(render_template('privacy.txt', last_modified=last_modified, config=get_config(), integration=integration))
+    response.headers['Content-type'] = 'text/plain; charset=utf-8'
+    return response
+
+
 def make_preview(song_id, song_type, song_ext, preview):
     song_path = 'public/songs/%s/main.%s' % (song_id, song_ext)
     prev_path = 'public/songs/%s/preview.mp3' % song_id