'''
Named Entity Recognition (NER)
==============================

NER takes a text as input and searches for names of persons, companies
and countries. 
'''
from nltk import ne_chunk, pos_tag, sent_tokenize, word_tokenize
from nltk.tree import Tree 

''' TODO: falsch klassifiert:
[('PERSON', 'Bangkok '), ('PERSON', 'Krung Thai Bank Pcl '),
('PERSON', 'Maybank Kim Eng Securities '), ('PERSON', 'Krung Thai Bank '),
 ('PERSON', 'Siam Commercial Bank '), ('PERSON', 'Singapore '),
 ('PERSON', 'Keppel Corp '), ('ORGANIZATION', 'Companies ')]
'''

class NER:
      
    def get_ne_with_label(text):
        labels = []
        names = []
        # TODO: letztes Wort wird nicht erkannt
        for chunk in ne_chunk(pos_tag(word_tokenize(text + 'lastword.'))):
            if hasattr(chunk, 'label'):
                name = ''
                for c in chunk:
                    name += c[0] + ' '
                if name not in names:
                    names.append(name.strip())
                    labels.append(chunk.label())
                    #print(chunk.label(), ' '.join(c[0] for c in chunk))
        return list(zip(labels, names))

test_article = '''BANGKOK, Sept 22 (Reuters) - Southeast Asian stock markets 
                \nmostly fell in light volumes on Tuesday as energy shares 
                tracked \nfalls in global oil prices, while weaknesses in banking shares
                \namid concerns about loans to an ailing steel firm sent the Thai 
                \nindex to a one-week closing low. \nBangkok's SET index shed nearly 
                1 percent after four \nsessions of gains. The index closed at 1,379.32, 
                its lowest \nclosing since Sept. 15. \nShares of Krung Thai Bank Pcl,
                the most actively \ntraded by turnover, dropped 2.8 percent to a near 
                one-month low, \nreflecting potential impact of loans to Sahaviriya Steel 
                \nIndustries Pcl on the bank's earnings. \nMaybank Kim Eng Securities 
                downgraded Krung Thai Bank to \n\"hold\" from \"buy\". \n\"Even as exposure 
                to SSI loans will be fully provisioned, \nKTB's NPL coverage will still be 
                lower than 130 percent, the \ndesired level we think and hence the need for 
                more provisioning \nin the following quarters,\" the broker said in a report. 
                \nSSI shares plunged 20 percent and Siam Commercial Bank \n, among its 
                creditors, dropped 1 percent. The steel firm \nand its three creditors 
                agreed on Monday to consider options to \nrestructure debt worth over 
                50 billion baht ($1.40 \nbillion). \nStocks in Malaysia extended their 
                slides for a third \nsession, Singapore gave up early gains and Indonesia 
                \nhit a near one-week low, all with trading volumes below \nthe 30-day 
                average ahead of a public holiday on Thursday. \nAmong top losers in the 
                region, Indonesia's Perusahaan Gas \nNegara was down 4.4 percent and 
                Singapore's Keppel \nCorp was down 2.5 percent as crude oil prices fell 
                \namid uncertainty over global demand. \nFor Asian Companies click.'''

print(NER.get_ne_with_label(test_article))