import sqlite3
import pandas as pd
import interface_sqlite3.encdec.de_code as dc

from interface_sqlite3.actual_queries import prepareQuery

# First version
class queryHandlerBasicSqlite:

    def __init__(self, dataConfig):
        
        try:
            dbPath = dataConfig['dbPath']
            dbfileDefault = dataConfig.get('dbfile_default')
        except:
            raise Exception('Missing required input in Data Provider Configuration')
        self.dbPath = dbPath
        self.dbfileDefault = dbfileDefault

        # Encoding
        self.dbEncoded = True if dataConfig.get("db_encoded") is True else False
        self.textsEncoded = True if dataConfig.get("texts_encoded") is True else False
        self.keyRing = None
        if self.dbEncoded or self.textsEncoded:
            keyPath = self.dbPath + 'keys/'
            self.keyRing = dc.keyRing(keyPath, self.dbEncoded, self.textsEncoded)

    
    def query(self, queryData, pandas=False, dbFile=None):

        # PREPARE THE QUERY
        # Formerly, a query string was pre-generated outside and
        # sent directly
        # Now the method processes a query data OBJECT
        # and creates the query (which may be complex)
        # accordingly
        queryData['pandas'] = pandas # Mostly redundant
        if self.dbEncoded:
            queryData = self.encodeQuery(queryData)
        queryToExecute = prepareQuery(queryData)

        # Get the connection to the DB
        dbFileLocal = dbFile if dbFile is not None else self.dbfileDefault
        if dbFileLocal is None:
            raise Exception("No db file specified with no default given -- can't execute query")
        #
        db = self.dbPath + dbFileLocal
        connection = sqlite3.connect(f"file:{db}?mode=ro", uri=True)


        # If the query is a simple string, execute it here:
        if type(queryToExecute)==str:
            if pandas:
                results = pd.read_sql(queryToExecute, connection)
                if(self.dbEncoded):
                    results = self.db_results_decode_pandas(results)
            else:
                connection.row_factory = dict_factory
                queryReponse = connection.cursor().execute(queryToExecute)
                results = queryReponse.fetchall()
                if(self.dbEncoded):
                    results = self.db_results_decode(results)
        
        else:
            # If not a string, 'queryToExecute' should be a method/function reference
            results = queryToExecute(connection, queryData)
            if self.dbEncoded:
                if pandas:
                    results = self.db_results_decode_pandas(results)
                else:
                    results = self.db_results_decode(results)

        connection.close()

        return results
    
    def textQuery(self, queryData, getFormatting=False):
        try:
            sigla = queryData['sigla']
            minChar = queryData['minChar']
            maxChar = queryData['maxChar']
        except:
            return None

        with open(f"{self.dbPath}/itxt/{sigla}", 'r', encoding="utf-32-le") as file1:
            file1.seek(4*minChar)
            cont = file1.read(maxChar-minChar)

        if self.textsEncoded and self.keyRing.textKeys.get(sigla) is not None:
            key = self.keyRing.textKeys.get(sigla)
            cont = dc.decodeTextByKey(cont, key, minChar-1)

        if not getFormatting:
            return cont
        else:
            return cont, self.getTextFormatting(sigla, minChar, maxChar)

    def getTextFormatting(self, sigla, minChar, maxChar):
        with open(f"{self.dbPath}/ftxt/{sigla}", 'rb') as file1:
            file1.seek(minChar-1)
            formatCodes = [char for char in file1.read(maxChar-minChar)]

        return formatCodes

    
    def encodeQuery(self, queryData):
        type = queryData.get('queryType')
        if type in ["forma", "lemma", "formaLemma", "lemmaForma"]:
            try:
                data = queryData['data']
                dataNorm = queryData['dataNorm']
                data = [dc.db_encode(self.keyRing.vettDictEnc, datum) for datum in data]
                dataNorm = [dc.db_encode(self.keyRing.vettDictEnc, datum) for datum in dataNorm]
                queryData['data'] = data
                queryData['dataNorm'] = dataNorm
            except KeyError as err:
                raise KeyError('Missing required data for query type ' + type + ': ' + str(err))
        
        return queryData

    def db_results_decode(self, result):
        for row in result:
            for key, value in row.items():
                if isColumnToDecode(key):
                    row[key] = dc.db_decode(self.keyRing.vettDictDec, value)
        return result

    def db_results_decode_pandas(self, df):
        for col in df.columns:
            if isColumnToDecode(col):
                df[col] = df[col].apply( lambda el: dc.db_decode(self.keyRing.vettDictDec, el) )
        return df


# Utilities

# Dict factory non-Pandas queries
def dict_factory(cursor, row):
    fields = [column[0] for column in cursor.description]
    return {key: value for key, value in zip(fields, row)}


# Does the column data (in returned results) need decoding?
def isColumnToDecode(col):
    columns = ['forma', 'lemma', 'cat_gr', 'disambiguatore']
    if col in columns or col.startswith('highlight'):
        return True
    return False