# standard imports
import os
import sys
import pickle
# non-standard imports
import numpy as np
from sklearn import svm
from sqlite3 import dbapi2 as sqlite3
# local imports
from utils import safe_pickle_dump, strip_version, Config

num_recommendations = 1000 # papers to recommend per user
# -----------------------------------------------------------------------------

if not os.path.isfile(Config.database_path):
  print("the database file as.db should exist. You can create an empty database with sqlite3 as.db < schema.sql")
  sys.exit()

sqldb = sqlite3.connect(Config.database_path)
sqldb.row_factory = sqlite3.Row # to return dicts rather than tuples

def query_db(query, args=(), one=False):
  """Queries the database and returns a list of dictionaries."""
  cur = sqldb.execute(query, args)
  rv = cur.fetchall()
  return (rv[0] if rv else None) if one else rv

# -----------------------------------------------------------------------------

# fetch all users
users = query_db('''select * from user''')
print('number of users: ', len(users))

# load the tfidf matrix and meta
meta = pickle.load(open(Config.meta_path, 'rb'))
out = pickle.load(open(Config.tfidf_path, 'rb'))
X = out['X']
X = X.todense().astype(np.float32)

xtoi = { strip_version(x):i for x,i in meta['ptoi'].items() }

user_sim = {}
for ii,u in enumerate(users):
  print("%d/%d building an SVM for %s" % (ii, len(users), u['username'].encode('utf-8')))
  uid = u['user_id']
  lib = query_db('''select * from library where user_id = ?''', [uid])
  pids = [x['paper_id'] for x in lib] # raw pids without version
  posix = [xtoi[p] for p in pids if p in xtoi]
  
  if not posix:
    continue # empty library for this user maybe?

  print(pids)
  y = np.zeros(X.shape[0])
  for ix in posix: y[ix] = 1

  clf = svm.LinearSVC(class_weight='balanced', verbose=False, max_iter=10000, tol=1e-6, C=0.1)
  clf.fit(X,y)
  s = clf.decision_function(X)

  sortix = np.argsort(-s)
  sortix = sortix[:min(num_recommendations, len(sortix))] # crop paper recommendations to save space
  user_sim[uid] = [strip_version(meta['pids'][ix]) for ix in list(sortix)]

print('writing', Config.user_sim_path)
safe_pickle_dump(user_sim, Config.user_sim_path)