'''
  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

  import pickle

  import csv

  from sklearn.preprocessing import LabelEncoder
  from sklearn.metrics.pairwise import pairwise_distances

  from sklearn.cluster import KMeans
  from sklearn.manifold import TSNE

  from sklearn.metrics import f1_score, homogeneity_score, completeness_score, v_measure_score

  import matplotlib.pyplot as plt
  
  from volia.data_io import read_features,read_lst

  from volia.measures import entropy_score, purity_score

  '''
  TODO: 
  - Add an option allowing the user to choose the number of 
  clustering to train in order to compute the average and the
  '''

  def train_clustering(label_encoder, feats, classes, outdir):
      num_classes = len(label_encoder.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_}")

      with open(os.path.join(outdir, f"{args.prefix}kmeans.pkl"), "wb") as f:

          pickle.dump(estimator, f)
      

      # 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))))

      
      # Entropy
      _, _, entropy = entropy_score(labels, predicted_labels)
  
      # Homogenity
      homogeneity = homogeneity_score(labels, predicted_labels)
  
      # Completeness
      completeness = completeness_score(labels, predicted_labels)
  
      # V-Measure
      v_measure = v_measure_score(labels, predicted_labels)

      # Purity
      purity_scores = purity_score(labels, predicted_labels)
      purity_class_score = purity_scores["purity_class_score"]
      purity_cluster_score = purity_scores["purity_cluster_score"]
      K = purity_scores["K"]

      # Write results

      with open(os.path.join(outdir, args.prefix + "eval_clustering.log"), "w") as fd:

          print(f"F1-scores for each classes:
  {fscores_str}", file=fd)

          print(f"Entropy: {entropy}", file=fd)

          print(f"Global score : {np.mean(fscores)}", file=fd)

          print(f"Homogeneity: {homogeneity}", file=fd)
          print(f"completeness: {completeness}", file=fd)
          print(f"v-measure: {v_measure}", file=fd)

          print(f"purity class score: {purity_class_score}", file=fd)
          print(f"purity cluster score: {purity_cluster_score}", file=fd)
          print(f"purity overall evaluation criterion (K): {K}", 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(

          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))
      return {
          "f1": np.mean(fscores),
          "entropy": entropy,
          "homogeneity": homogeneity,
          "completeness": completeness,

          "v-measure": v_measure,
          "purity_class_score": purity_class_score,
          "purity_cluster score": purity_cluster_score,
          "K": K

      }

  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")
      parser.add_argument("--nmodels",
                          type=int,
                          default=1,
                          help="specifies the number of models to train")   
      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)
      
      measures = {}
      for i in range(1, args.nmodels+1):
          subdir = os.path.join(args.outdir, str(i))
          if not os.path.exists(subdir):
              os.mkdir(subdir)
          print(f"[{i}/{args.nmodels}] => {subdir}")
          results = train_clustering(le, feats, classes, subdir)
  
          for key, value in results.items():
              if key not in measures:
                  measures[key] = []
              measures[key].append(results[key])
      
  
      # File with results

      file_results = os.path.join(args.outdir, args.prefix + "clustering_measures.txt")

  
      with open(file_results, "w") as f:
          f.write(f"[nmodels: {args.nmodels}]
  ")
          for key in measures.keys():
              values = np.asarray(measures[key], dtype=float)
              mean = np.mean(values)
              std = np.std(values)
              f.write(f"[{key} => mean: {mean}, std: {std}] 
  ")
              
      # CSV File with all the values

      file_csv_measures = os.path.join(args.outdir, args.prefix + "clustering_measures.csv")

  
      with open(file_csv_measures, "w", newline="") as f:
          writer = csv.writer(f, delimiter=",")
          writer.writerow(["measure"] + list(range(1, args.nmodels+1)) + ["mean"] + ["std"])
          for key in measures.keys():
              values = np.asarray(measures[key], dtype=float)
              mean = np.mean(values)
              std = np.std(values)
              writer.writerow([key] + list(values) + [mean] + [std])