'''
  This script allows the user to evaluate a classification system on new labels using clustering methods.
  The algorithms are applied on the given latent space (embedding).
  '''
  import argparse
  import numpy as np
  import pandas as pd
  import os
  import time
  from sklearn.preprocessing import LabelEncoder
  from sklearn.metrics.pairwise import pairwise_distances
  from sklearn.metrics import f1_score
  from sklearn.cluster import KMeans
  from sklearn.manifold import TSNE
  import matplotlib.pyplot as plt
  
  from volia.data_io import read_features,read_lst
  
  if __name__ == "__main__":
      # Argparse
      parser = argparse.ArgumentParser("Compute clustering on a latent space")
      parser.add_argument("features")
      parser.add_argument("utt2",
                          type=str,
                          help="file with [utt] [value]")

      parser.add_argument("--idsfrom",
                          type=str,
                          default="utt2",
                          choices=[
                              "features",
                              "utt2"
                          ],
                          help="from features or from utt2?")

      parser.add_argument("--prefix",
                          default="",

                          type=str,
                          help="prefix of saved files")
      parser.add_argument("--outdir",
                          default=None,
                          type=str,
                          help="Output directory")
      
      args = parser.parse_args()
  
      assert args.outdir
  
      start = time.time()
  
      # Load features and utt2
      features = read_features(args.features)
      utt2 = read_lst(args.utt2)

      # Take id list
      if args.idsfrom == "features":
          ids = list(features.keys())
      elif args.idsfrom == "utt2":
          ids = list(utt2.keys())
      else:
          print(f"idsfrom is not good: {args.idsfrom}")
          exit(1)
      

      feats = np.vstack([ features[id_] for id_ in ids ])
      classes = [ utt2[id_] for id_ in ids ]
  
      # Encode labels
      le = LabelEncoder()
      labels = le.fit_transform(classes)
      num_classes = len(le.classes_)
  
      # Compute KMEANS clustering on data
      estimator = KMeans(
          n_clusters=num_classes,
          n_init=100,
          tol=10-6,
          algorithm="elkan"
      )
      estimator.fit(feats)
      print(f"Kmeans: processed {estimator.n_iter_} iterations - intertia={estimator.inertia_}")
  
      # contains distance to each cluster for each sample
      dist_space = estimator.transform(feats)
      predictions = np.argmin(dist_space, axis=1)
  
      # gives each cluster a name (considering most represented character)
      dataframe = pd.DataFrame({
          "label": pd.Series(list(map(lambda x: le.classes_[x], labels))),
          "prediction": pd.Series(predictions)
      })
  
      def find_cluster_name_fn(c):
          mask = dataframe["prediction"] == c
          return dataframe[mask]["label"].value_counts(sort=False).idxmax()
      
      cluster_names = list(map(find_cluster_name_fn, range(num_classes)))
      predicted_labels = le.transform(
          [cluster_names[pred] for pred in predictions])
      
      # F-measure
      fscores = f1_score(labels, predicted_labels, average=None)
      fscores_str = "
  ".join(map(lambda i: "{0:25s}: {1:.4f}".format(le.classes_[i], fscores[i]), range(len(fscores))))
      print(f"F1-scores for each classes:
  {fscores_str}")
      print(f"Global score : {np.mean(fscores)}")
      with open(os.path.join(args.outdir, args.prefix + "eval_clustering.log"), "w") as fd:
          print(f"F1-scores for each classes:
  {fscores_str}", file=fd)
          print(f"Global score : {np.mean(fscores)}", file=fd)
      
      # Process t-SNE and plot
      tsne_estimator = TSNE()
      embeddings = tsne_estimator.fit_transform(feats)
      print("t-SNE: processed {0} iterations - KL_divergence={1:.4f}".format(
          tsne_estimator.n_iter_, tsne_estimator.kl_divergence_))
  
      fig, [axe1, axe2] = plt.subplots(1, 2, figsize=(10, 5))
      for c, name in enumerate(le.classes_):
          c_mask = np.where(labels == c)
          axe1.scatter(embeddings[c_mask][:, 0], embeddings[c_mask][:, 1], label=name, alpha=0.2, edgecolors=None)
  
          try:
              id_cluster = cluster_names.index(name)
          except ValueError:
              print("WARNING: no cluster found for {}".format(name))
              continue
          c_mask = np.where(predictions == id_cluster)
          axe2.scatter(embeddings[c_mask][:, 0], embeddings[c_mask][:, 1], label=name, alpha=0.2, edgecolors=None)
      
      axe1.legend(loc="lower center", bbox_to_anchor=(0.5, -0.35))
      axe1.set_title("true labels")
      axe2.legend(loc="lower center", bbox_to_anchor=(0.5, -0.35))
      axe2.set_title("predicted cluster label")
  
      plt.suptitle("Kmeans Clustering")
  
      loc = os.path.join(
          args.outdir,
          args.prefix + "kmeans.pdf"
      )
      plt.savefig(loc, bbox_inches="tight")
      plt.close()
  
      print("INFO: figure saved at {}".format(loc))
  
      end = time.time()
      print("program ended in {0:.2f} seconds".format(end-start))