import Levenshtein
import re
from collections import Counter

#Get columns in query (input_ string; output: list)
def get_columns_name_in_query(query):
  cols_from_select = get_cols_name_for_select(query) 
  cols_from_where = get_cols_name_for_where(query)
  return list(set(cols_from_select + cols_from_where))

# Sometime column name maybe ill-defined. This function replace weird chars with underscore (input:list; output:string)
def replace_nonalphanumeric_chars_with_us(l):
  well_defined = [re.sub('[^0-9a-zA-Z]+', '_', s) for s in l]
  return well_defined

# Adjust column name using columns name from original table (input: column name in SQL query (string), 
#list of columns names from table (string); output: corrected column name (if needed) (string))
def adjust_col_name(col_name, columns_available): 
  columns_available = [x.upper() for x in columns_available]
  if col_name.upper() in set(columns_available):
    return col_name
  else:
    max = -100
    most_similar_column = 'column123456789011'
    for col in columns_available:      
      score = -Levenshtein.distance(col_name, col)               
      if score > max:
        most_similar_column = col  
        max = score           
    return most_similar_column

def min_positive(a,b):
  if (b < a) and (b > 0): return b
  else: return a

#Return corrected syntax for aggregator operators (input: string; output: string)
#USE only for wikisql dataset
def aggregator_parser(query): 
  query = query.upper() 
  if query.find('SELECT MAX') > -1:
    end = min_positive(query.find('FROM'), query.find(','))    
    adjusted_query = query.replace(query[10:end],'(' + query[11:end-1] + ') ')
    return adjusted_query
  elif query.find('SELECT COUNT') > -1:
    end = min_positive(query.find('FROM'), query.find(','))
    adjusted_query = query.replace(query[12:end],'(' + query[13:end-1] + ') ')
    return adjusted_query
  elif query.find('SELECT MIN') > -1:
    end = min_positive(query.find('FROM'), query.find(','))
    adjusted_query = query.replace(query[10:end],'(' + query[11:end-1] + ') ')
    return adjusted_query
  #elif query.find('SELECT DISTINCT') > -1:
   #end = query.find('FROM')
    #adjusted_query = query.replace(query[15:end],'(' + query[16:end-1] + ') ')
    #return adjusted_query
  else: 
    return query

#Return columns name from SELECT operator (input: string; output: list)
def get_cols_name_for_select(query):
  query = query.upper()  
  if query.find('SELECT DISTINCT') > -1:
    end = query.find('FROM')
    cols = query[15:end-1].split(',')
  elif query.find('SELECT MAX') > -1:
    end = query.find('FROM')
    cols = query[10:end-1].split(',')  
  elif query.find('SELECT MIN') > -1:
    end = query.find('FROM')
    cols = query[10:end-1].split(',')     
  elif query.find('SELECT COUNT') > -1:
    end = query.find('FROM')
    cols = query[13:end-1].split(',')    
  elif query.find('SELECT') > -1:
    end = query.find('FROM')
    cols = query[7:end-1].split(',')    
  else:  
    cols = ['']    
  return [x.replace(' ','').replace(')','').replace('(','').upper() for x in cols]

def get_indexes(l):
  ops = []
  idx = []
  for i in range(len(l)):
    if l[i] in ['=', '>', '<', '>=', '<=', '<>', 'LIKE', 'AND', 'OR']:
      idx.append(i)
  return idx

def add_spaces_cmp_operators(string):
  ops = ['=', '>', '<', '>=', '<=', '<>']
  for op in ops:
    string = string.replace(op, ' ' + op + ' ') 
  return ' '.join(string.split())

#Check if string and add quotes (input: string; output: string)
#USE only for wikisql dataset
def add_quotes_to_string(query):
  query = query.upper()
  if query.find('WHERE') > 0:
    query_list = query.split(' ')
    query_list = [x.replace(' ','') for x in query_list]
    query_list[:] = filter(None, query_list)  
    idx_list = get_indexes(query_list)  
    idx_list.append(len(query_list))  
    subs = []
    for i in range(len(idx_list)):
      if i % 2 == 0:
        b = idx_list[i] + 1
        e = idx_list[i+1] - 1
        if b != e:
          s = ''
          for ix in range(b,e + 1):          
            s = s + query_list[ix] + ' ' 
          s = s[:-1]   
        else:
          s = query_list[b]     
        if not(s.isnumeric()):
          s = "'" + s + "'"
        subs.append((idx_list[i] + 1, idx_list[i+1] - 1, s))  
    subs = subs[::-1]       
    for i in range(len(subs)):
      e = subs[i]
      if e[0] == e[1]:
        query_list[e[0]] = e[2]
      else:
        query_list[e[0]] = e[2]
        idx = e[1]
        while idx > e[0]:
          query_list.pop(idx)
          idx = idx - 1
    final_query = ''
    for word in query_list:
      final_query = final_query + word + ' '     
    return final_query[:-1]
  else:
    return query

#Get values from where clause (input: string; output: list)
def get_values_for_query_filter(query):
  query = query.upper()
  if query.find('WHERE') > 0:
    query_list = query.split(' ')
    query_list = [x.replace(' ','') for x in query_list]
    query_list[:] = filter(None, query_list)  
    idx_list = get_indexes(query_list)  
    idx_list.append(len(query_list))  
    subs = []
    for i in range(len(idx_list)):
      if i % 2 == 0:
        b = idx_list[i] + 1
        e = idx_list[i+1] - 1
        if b != e:
          s = ''
          for ix in range(b,e + 1):          
            s = s + query_list[ix] + ' ' 
          s = s[:-1]   
        else:
          s = query_list[b]        
        subs.append(s.replace("'",""))
  return subs


# Get columns name after where (input: string, output: list)
def get_cols_name_for_where(query):
  query = query.upper()
  subs = []  
  if query.find('WHERE') > 0:
    query_list = query.split(' ')
    query_list = [x.replace(' ','') for x in query_list]
    query_list[:] = filter(None, query_list)  
    idx_list = get_indexes(query_list)  
    #idx_list.append(len(query_list))
    idx_list.insert(0, query_list.index('WHERE'))      
    for i in range(len(idx_list)-1):
      if i % 2 == 0:     
        b = idx_list[i] + 1
        e = idx_list[i+1] - 1
        if b != e:
          s = ''
          for ix in range(b,e + 1):          
            s = s + query_list[ix] + ' ' 
          s = s[:-1]   
        else:
          s = query_list[b]
        subs.append(s)    
  return subs   

def check_if_number(s):
  try:
    a = float(s)
    return True
  except:
    return False

#Correct missing compare operator (input: string; output: string)
#T5 seems to have problem with '<' operator so if there is none this is used.
def check_if_correct_cmp_operators(query):
  query = query.upper()
  if query.find('WHERE') > 0:
    query = add_spaces_cmp_operators(query)
    query_list = query.split(' ')
    w = query_list.index('WHERE')
    cmp_operators = ['=', '>', '<', '>=', '<=', '<>', 'LIKE']
    s = 0
    for op in cmp_operators:
      s = s + query_list.count(op)
    if s == 0:      
      if check_if_number(query_list[-1]):
        query_list.insert(len(query_list)-1,'<')
      else:
        query_list.insert(len(query_list)-1,'=')
      return ' '.join(query_list)
    else:
      return query
  else: return query

#Correct SQL syntax using info from table (input: string, list; output:string)
#Use only for wikisql dataset
def correct_query(query, table_columns):  
    query = check_if_correct_cmp_operators(query)
    query = add_spaces_cmp_operators(query)    
  #try: 
    query = aggregator_parser(query) 
  #except: pass 
  #try: 
    query = add_quotes_to_string(query) 
  #except: pass 
  #try:
    cols_name = get_columns_name_in_query(query)      
    for col in cols_name:    
      corrected_col = adjust_col_name(col, table_columns)      
      query = query.replace(col, corrected_col)
  #except: pass
    return query

#Correct mispelling using info from question (input: string, string; output:string)
def correct_mispelling(question, query):  
  query = query.upper()
  if query.find('WHERE') > 0:
    question = question.upper()
    corrections = []
    values = get_values_for_query_filter(query)
    for value in values:    
      l = len(value.split(' '))
      tokens = question.replace('  ', ' ').split(' ')
      l_gram = ''
      max = -100
      for i in range(0, len(tokens)-l+1, 1):
        filter = ' '.join(tokens[i:i+l]).strip('.,?')
        #filter = re.sub(r"[,.;@#?!&$]+\ *", " ", filter).strip()    
        score = -Levenshtein.distance(value, filter)        
        if score > max:
          max = score
          correct_filter = filter        
      corrections.append([value, correct_filter])    
    for corr in corrections:
      query = query.replace(corr[0], corr[1])
  return query

#Get both text and tables in separate string (input:string; output: string, list)
def get_text_and_cols(text):
  out = text.split(' table ID: ')
  return out[0], out[1].split(',')